Skeletal System

AXIAL SKELETON

-          Composed of 80 bones.

-          Composed of skull, vertebral column and the thorax

The Skull

Bones of the Skull

I.                    Cranium

·         Frontal (1)                                           - Sphenoid (1)

·         Parietal (2)                                          - Temporal (2)

·         Occipital (1)                                        - Ethmoid (1)

II.                  Visceral Cranium or Facial Bone

·         Maxillae                                               - Palatine

·         Zygomatic                                           - Inferior Conchae or Turbinates

·         Nasal                                                     - Vomer

·         Lacrimal                                                - Mandible

III.                Other Bones

·         Hyoid Bone (1)

·         Auditory Ossicles

-          Malleus (2)

-          Incus (2)

-          Stapes (2)

IV.                Teeth (32)

Regions of the Skull

·         Frontal, Anterior or Facial (1)

·         Lateral, Right and Left (2)

·         Posterior or Occipital (1)

·         Vertical, Superior or Vertex (1)

·         Basal or Inferior (1)

Sutures of the Skull

·         Coronal Suture (1)

·         Sagittal Suture (1)

·         Lambdoidal Suture (1)

·         Squamosal Suture (2)

·         Less obvious Suture-Several

Paranasal Sinuses : 4 pairs

·         Frontal Sinuses (2)

·         Ethmoidal Sinuses (2)

·         Maxillary Sinuses (2)

·         Sphenoidal Sinuses (2)

Cranial Fossae: 3

·         Anterior cranial fossa (1)

·         Middle cranial fossa (1)

·         Posterior cranial fossa (1)

Other General Terms:

·         Bregma (1)

·         Lambda (1)

·         Orbits (2)                                                                                             - External Acoustic Opening

·         Nasal Opening, Piriform Aperture                                            - External Acoustic Meatus

·         Nasal Septum (1)                                                                             - Mastoid Process

·         Nasal Cavities (1)                                                                              - External Occipital Protuberance

·         Mouth or Oral Cavity                                                                      - Squama or Squamous Part

·         Mentum, Chin (1)                                                                            - Process of cranial bones

·         Zygomatic Arch (1)

The Divisions of the Skull

-          Skull is also called as cranium or calvaria or calvarium

·         Cerebral Cranium

-          The part of the skull that encloses and protects the brain

-          Sometimes referred to as the brain case

·         Visceral Cranium or facial bone

-          Includes 14 bones of the face

-          It forms cavities (orbits) that protect the eyes, nasal passages, and mouth.

Joints of the Skull

-          These lie between adjacent bones and are of a special type with interlocking or overlapping edges named sutures.

·         Coronal Suture

-          Between the frontal and two parietal bones.

·         Sagittal Suture

-          Between two parietal bones.

·         Lambdoidal Suture

-          Between the occipital and parietal bones.

·         Squamosal Suture

-          Right and left, between the parietal and temporal bones of each side.

Surfaces or Regions of the Skull

1.       Frontal, Anterior or Facial Aspects

-          The part that is visible when viewed from the front.

2.       Lateral Aspect

-          The left or right surface visible when the skull is viewed from the side.

3.       Posterior Aspect or Occipital Aspect

-          The posterior surface of the skull which is visible from the rear.

4.       Vertical Aspect

-          The top or crown of the skull, visible from above

-          Also named as the vertex

5.       Basal Aspect or Inferior Aspect

-          The part visible from below, or basal view

Basic Terms

Ø  Orbits

-          the two core shaped cavities for the eyeballs

Ø  Lateral Canthus or external Canthus

-          The point at the outer margin of the eye where the upper and lower eyelids meet.

Ø  Nasal Cavities

-          The two chambers of the nose, a right and a left.

Ø  Nasal Septum

-          The partition between the two nasal cavities

Ø  Piriform Opening

-          The pear shaped hole between the two maxillary bones into the nasal cavities.

Ø  Paranasal Sinuses

-          Cavities within some of the cranial bones

Ø  Mouth

-          Expanded cavity at the upper end of the digestive tract.

-          Opens behind into the oral pharynx (throat)

Ø  Mentum

-          The chin, the prominence on the anterior part of the mandible at the midline.

Ø  External Acoustic Opening

-          The opening leading into the ear and ear drum.

Ø  Zygomatic Arch

-          A slender bridge of bone that extends on each side from in front of the external acoustic opening to the zygomatic bone below, and lateral to the orbit.

Ø  Mastoid Process

-          A bony prominence that extends down from the lateral surface of the skull behind the ear

Ø  External Occipital Protuberance

-          A small but definite prominence on the occipital bone in the midline, where this bone begins to curve forwards to help from the base of the skull.

Ø  Squamous Part of a bone

-          The flat part

-          Applied to the flat parts of the frontal, occipital and temporal bones.

Ø  Processes

-          The facial bones are named from the bone with which that process forms a joint.

Ø  Fontanelles

-          The unossified area at the junctions where three bones of the skull meet in the infant.

Ø  Bregma

-          Point on the vertex of the skull where the sagittal suture meets the coronal suture.

Ø  Lambda

-          Point at the posterior  end of the sagittal suture where the occipital and two parietal bones are in contact.

Ø  Cranial Fossae

-          Three depressions on the inner surface of the floor of the skull

Ø  Basal Foramina

-          Openings in the floor or base of the skull through which nerves and veins leave the cranial cavity or arteries enter it.

Cerebral Cranium: 8 Cranial Bones

1.       Frontal Bone

-          Forms the forehead and part of the vertex of the skull.

-          There are two frontal bones in fetus that meet at the midline.

-          Metopic Suture – a suture that lies between two parts.

Part of Frontal Bone

1.1. Squamous Part

-          Forms the forehead and part of the vertex.

-          Special features includes the frontal eminences, supraorbital margins, supraorbital notches, glabella and frontal sinuses.

·         Frontal Eminences

-          Two rounded prominences on the squamous part of the frontal bone, one of each side of the midline, visible on the forehead.

·         Supraorbital Margins

-          Right and left, are ridges of bone that form the superior borders of the circular opening into each orbit.

-          They are covered by the eyebrows.

·         Supraorbital Notch (foramen)

-          A small notch or sometimes a foramen located towards the medial end of each supraorbital margin.

·         Glabella

-          A smooth flat area between the medial ends of the supraorbital margins, and above the upper ends of the nasal bones.

·         Frontal Sinuses

-          Paired cavities in the squamous part of the frontal bone above the supraorbital margins.

1.2. Orbital Part

-          Consists of two flat plates of bone called the orbital plates

-          Form the roofs of the orbits and the floor of the anterior cranial fossa

-          Extend posteriorly from the supraorbital margins of the squamous part and join the sphenoid bone.

-          Has an ethmoidal notch

·         Ethmoidal Notch

-          A definite gap between the medial borders of the two orbital plates.

1.3. Nasal Part
-     Extends down in the midline between the supraorbital margins.
            ·          Nasal Spine

-          A pointed process that forms a small part of the nasal septum behind the nasofrontal articulations.

1.       Parietal Bones

-          A  two bones, a left and right, form part of the lateral walls and vertex or roof of the skull.

-          They meet at the midline of the vertex to form the sagittal suture.

-          They are rectangular in shape.

·         Parietal Prominence or Parietal Tuberosity

-          A rounded prominence on the lateral surface of each parietal bone.

-          The distance between the two eminences is the greatest transverse of the skull, important in child birth.

3.  Occipital Bone

- Forms part of the posterior wall and the posterior part of the base of the cranium.

·         Foramen magnum

-          A large opening in the inferior part of the occipital bone through which the medulla oblangata of the brain joins the spinal cord.

Parts of Occipital Bone

3.1. Squamous Part

- Flat curved part of the occipital bone.

- Forms the inferior part of the posterior wall of the cranium and curves forward to help form the base.

·         External Occipital Protruberance

-          A definite rounded bony prominence.

-          Located at the midline of the external surface of the squamous part where it begins to curve forward.

·         Internal Occipital Protruberance

-          A similar prominence on the internal surface of the squamous part opposite the external protruberance.

3.2. Lateral Part

- Lie on either side of the foramen magnum between the squamous part posteriorly and the basal part in front.

·         Occipital Condyles (2)

-          The right and left, oval shaped prominences located on the inferior surfaces of each lateral part.

-          Have smooth surfaces that articulate with the superior articular process of the atlas.

·         Hypoglossal Canals (2)

-          Short passages from each lateral margin of the foramen magnum, close to its front end that open below in front of the condyles.

1.1. Basilar (Basal) Part

-          Part anterior to the foramen magnum.

-          It unites with the sphenoid bone anteriorly and helps to form the base of the skull.

2.       Temporal Bone

-          A right and left, form a part of each lateral wall and part of the base of the skull.

·         Mastoid Process

-          A large bony prominence that extends down from the temporal bone posterior to the ear.

-          Contains small cavities, or cells, that open into the middle ear by which infection of the middle ear may be sometimes sprad to the mastoid.

·         Styloid process

-          Long slender sliver-like process that extends down from each temporal bone.

Parts of temporal Bone

2.1. Squamous Part

-          Flat part on the lateral side of the skull above the ear.

-          Has a zygomatic process and mandibular fossa.

·         Zygomatic Process

-          Slender bony process that extends horizontally forward from the opening of the ear.

·         Mandibula Fossa

-          A depresion on the temporal bone in front of the opening into the ear and below the origin of the zygomatic process.

2.2. Petrous Part

-          Extends medially in the floor of the cranium from the squama to the basal part of the occipital bone.

-          Have an internal acoustic opening, an internal acoustic meatus, and a carotid canal.

·         Internal Acoustic Opening / Porus

-          An opening on the dorsal surface of the petrous part clos e to each medial end.

·         Internal acoustic Meatus

-          A canal leading from the internal acoustic opening to the inner ear.

·         Carotid Canal

-          A short passage that begins as a circular opening on the inferior surface of the petrous pyramid close to its medial end.

-          It passes through the petrous part to enter the cranium at the foramen lacerum in front of the apex of the petrous part.

2.3. Tympanic Part

-          Forms the anterior and inferior walls of the external acoustic meatus as well as a part of the posterior wall.

-          Also helps in to form the mandibular fossa.

3.       Sphenoid Bone

-          A single bone that helps to form a small part of the lateral wall on each side, as well as part of the base of the skull.

Part of the Sphenoid Bone

3.1. Body

-          The central part and lies in the midline of the base of the skull, in front of the basla part of the occipital bone.

·         Chiasmatic Groove

-          A horizontal depression that crosses the body of the bone in front of the sella turcica.

·         Optic Canals

-          Two short passages extending anteriorly and laterally one form each side of the body of the sphenoid bone.

-          Opens into the posterior ends of the orbits and carry the optic nerves and opthalmic vessels from the cranium to the orbits.

·         Sella Turcica

-          A saddlelike bony depression on the upper surface of the body of the sphenoid.

-          Its deep central cavity contains the pituitary gland.

·         Dorsum Sella

-          The posterior wall of the sella turcica.

·         Pituitary Fossa

-          The central cavity of the sella turcica.

·         Posterior Clinoid Processes

-          Two small rounded prominences that are located one at each lateral end of the upper margin of the dorsum sella.

·         Middle Clinoid Processes

-          Lie one on each side of the upper anterior surface of the sella turcica, medial to and posterior to the opening of the optic canal.

·         Carotid Groove

-          An often poorly defined groove that passes vertically along each lateral surface of the body of the sphenoid, and accomodates the internal carotid artery.

·         Sphenoidal Air Sinuses

-          Two caivities within the body of the sphenoid bone one on either side of the midline, and separated by a bony septum.

3.2. Lesser Wings

-          Right and left, extend laterally from the horizontal anterior part of the body of this bone.

-          Triangular in shape and each joins an orbital plate of the frontal bone anteriorly.

·         Anterior Clinoid Processes

-          Two bony processes that extend posteriorly from the medial end of the posterior free margin of each lesser wing.

-          They lie lateral to the openings of the optic canals.

3.3. Greater Wings

-          Right and left, are two winglike bony plates that originate one from each lateral surface of the body of the sphenoid.

·         Foramen Rotundum

-          A small round opening in the medial basal part of the greater wing just lateral to the superior orbital fissure.

-          It transmits the maxillary nerve out of the cranium.

·         Foramen Ovale

-          A larger oval opening in the basal part of the greater wing lateral to and behind the foramen rotundum.

-          It transmits the mandibular branch of the trigeminal nerve out of the cranium.

·         Superior  Orbital Fissure

-          A comma shaped opening on the medial margin of each greater wing.

-          It opens in front into the posterior end of the orbit lateral to the optic canal.

1.1. Pterygoid Processes

-          A right and left extend down vertically from the inferior surface of the body of the sphenoid bone of each side.

-          Each consist of a medial and a lateral plate of bone that are joined together anteriorly

2.       Ethmoid Bone

-          Lies in the anterior part of the base of the skull between the orbits.

-          Have a cribriform plate, a perpendicular plate, and two labyrinths.

2.1. Cribform plate

-          It is wedged between the two orbital plates of the frontal bone in the ethmoidal notch on the floor of the anterior cranial fossa.

-          A small area and contains several minute openings by which the branches of the olfactory nerves enter the cranium.

-          These small openings serve to identify the cribriform plate positively.

·         Crista Galli

-          A very thin plate of bone that passes vertically up from the upper surface of the cribriform plate.

2.2.  Perpendicular Plate

-          A flat sheet of bone that extends down in the midline from the cribriform plate and forms a part of the nasal septum.

2.3. Ethmoidal Labyrinths

-          Right and left are suspended from the inferior surface of the cribriform plate.

-           The lateral wall of each labyrinth helps to form the medial wall of the orbit.

·         Ethmoidal Sinuses

-          Right and left are multiple small cavities, or cells in the labyrinths.

-          There are three groups- anterior, middle and posterior bilaterally.

·         Superior and middle Nasal Conchae

-          Bony shelves that extend into the nasal cavities from the lateral walls.

The visceral cranium or facial bone

-          Have fourteen bones, six paired and two single bones.

1.       Maxillac

-          Two bones a right and a left.

-          The reach from the infra orbital margins to the upper teeth and roof of the mouth.

-          They form parts of the floor of each orbit, the medial part of each infraorbital margin, the lateral wall of each nasal cavity, the floor of each nasal cavity and the floor of the mouth.

-          Each maxilla has a body and four processes.

1.1. Body

-          A box like structure forming part of each cheek, and lying on the lateral side of the nose.

-          Its special features include the maxillary sinus, the infraorbital margin , the infraorbital foramen, the anterior nasal spine, and the maxillary tuberosity.

·         Maxillary sinus

-          A large body within the body of the maxilla.

-          Contains air and has an opening into the corresponding nasal cavity.

·         Infraorbital Margin

-          A ridge of bone that forms the lower border of the orbital opening

-          Its medial half is formed by the maxilla, its lateral part by zygomatic bone.

·         Infraorbital Foramen

-          A small opening on the anterior surface of the maxilla just below the infraorbital margin.

·         Anterior Nasal Spine

-          A single small pointed projection in the midline at the base of the nasal septum.

·         Maxilla Tuberosity

-          A small rounded bony prominence posterior to the third upper molar tooth.

1.2. Processes

-          There are four processes, frontal, zygomatic, alveolar, and palatine.

·         Frontal Process

-          Extends up along the lateral side of the nose posterior to the nasal bone, and along the medial margin of the orbit.

-          It joins the frontal, nasal and lacrimal bone.

·         Zygomatic Process

-          Extends up and laterally from the body of the maxilla to meet the maxillary process of the zygomatic bone.

-          It helps to produce the prominence of the cheek here.

·         Alveolar Process

-          Extends down from the inferior part of the body of the maxilla to form soclats for eight upper teeth.

-          Palatine Process

-          A flat shelf of bone that extends medially from the lower part of the body of the maxilla to meet its mate and form all but the posterior part of the hard palate.

2. Zygomatic Bones

-           Two bones a right and a left

-          Quadrilateral in shape

-          Forms the prominent upper lateral part of each cheek, lateral to the orbit

-          The superior margin is concave and forms the lateral part of each orbital margin as well as part of the lateral wall and floor of each orbit.

-          Have three processes, maxillary, frontal, and temporal.

2.1. Maxillary process

-          Its lower margin joins the maxilla

2.2. Frontal Process

-          Joins the frontal bone at the upper lateral marginof the orbit

2.3. Temporal Process

-          Joins the zygomatic process of the temporal bone to form the long slender zygomatic arch.

3. Nasal Bones

-          Two bones a right and a left

-          Form the bony part of the bridge of the nose

-          Small flat rectangular shaped bone that joins the nasa part of the frontal bone above,and the nasal cartilages below

-          Two nasal bones meet at the midline and extend laterally to join the frontal process of the maxilla

4. Lacrimal bones

-          Paired right and left bones

-          Small flat bones located in the medial walls of the orbit.

-          Each line posterior to the frontal process of the maxilla with which it articulates

-          Lacrimal Groove- a groove where the two join.

-          This groove is occupied by the lacrimal sac above and below by the nasolacrimal duct which opens into a nasal cavity.

-          Tears are carried by this channel into the nasal cavity.

5. Palatine Bones

-          Two palatine bones a right and a left

-          They are named palatine as they help to form the hard palate, the bony part of the roof of the mouth

-          Each paltine bone is an “L” shaped structure and includes horizontal and vertical plates of bone.

1.1. Vertical Part

-          Forms the dorsal part of the lateral wall of the nasal cavity.

1.2. Horizontal Plate

-          Extends medially from the inferior part of the vertical plate to meet the horizontal plate of the other palatine bone.

-          Together the vertical part joins the palatine processes of the maxillae to form the posterior part of the hard palate.

2.       Inferior Conchae or Inferior Turbinate Bone

-          A two bone, a right and a left, one within each nasal cavity.

-          A thin curved plate of bone that extends medially like a shelf into the nasal cavity from the lateral wall.

3.       Vomer

-          A single flat four sided bone plate that resembles a plougshare.

-          It lies vertically within the nose and forms the lower posterior part of the nasal septum.

-          Its lower margin rests upon the upper surface of the hard palate.

-          It lies below and partly behind the perpendicular plate of the ethmoid bone that forms the upper anterior part of the nasal septum.

4.       Mandible

-          Shaped like a horseshoe with its posterior end on each side turned up to articulate with the temporal bone.

-          Have a body, and two rami, right and left, which meet the body at the angles.

-          The angle on each side is the prominent rounded posterior part where the horizontal section turns upward to become the vertical ramus.

-          The angle of mandible is also called Gonion.

4.1. Body

-          Horizontal part extending from one angle, around to the midline and back to the angle on the other side, forming a horseshoe curve.

Features of the Body of Mandible

4.1.1.        Symphysis

-          A faint ridge running vertically in the midline anteriorly where the segments of the mandible became fused to form a single bone.

4.1.2.        Mental Protuberance

-          The flat prominence at the inferior part of the symphysis anteriorly – the chin.

4.1.3.        Mental Foramen

-          A small opening on the outer surface of the body of the mandible on each side below the second premolar tooth.

4.1.4.        Alveolar Part

-          The upper part or border with sixteen sockets for the lower teeth.

4.2. Ramus

-          Two rami, a right and a left.

-          The flat part of the mandible that extends upwards from the posterior end of the angle on each side.

-          It forms a joint with the temporal bone called the temporomandibular joint.

4.2.1.        Coronoid Process

-          Flat thin upward extension of the anteriro part of the ramus.

4.2.2.        Condylar Process

-          Extends upward from the posterior part of the ramus to the adjacent joint.

·         Head or Caput or Condyle

-          The upper expanded end of the condylar process.

-          It articulates with the mandibular fossa of the temporal bone to form the temporomandibular joint in each side.

·         Neck

-          The constricted part that connects the head to the remainder of the ramus.

4.2.3.        Mandibular Notch

-          Half-moon shaped notch between the coronoid and condylar process of the ramus on each side.

4.2.4.        Mandibular Foramen

-          An opening on the medial surface of the ramus about its center.

-          It opens into the mandibular canal.

4.2.5.        Mandibular Canal

-          A passage within the lower part of the ramus and body of the mandible, below the roots of the lower teeth.

Hyoid Bone

-          A single bone in “U” shaped bone that is located in the anterior part of the neck.

-          It has no articulation and provides the base of the tongue.

·         Body

-          The curved anterior part of the hyoid bone

·         Greater Cornu

-          Extends back from the posterior end of the body on each side as a bent process.

·         Lesser Cornu

-          Much smaller and extends up from the greater cornu on each side.

Auditory Ossicles

-          From the Latin word os – bone, icle – small.

-          Has a three paired bones located in the middle ear within the petrous parts of the temporal bone.

·         Malleus – a hammer

·         Incus – an anvil

·         Stapes – a stirrup

Orbit

-          The cavities in the facial skeleton for the eyeballs.

-          They lie below the frontal bone and above the maxillae and the zygomatic bones.

Nasal Cavities

-          Two cavities, a right and a left.

-          They are the chambers of the nose, extending from the nostrils or openings (nares), on the face to the nasl pharynx or throat behind.

Nasal Septum

-          A partition between the two nasal cavities extending vertically fro front to back.

Paranasal Sinuses or Accessory Nasal or Post Nasal Sinuses

-          There are four pairs.

·         Frontal Sinuses

-          Right and left are paired cavities within the squamosal part of the frontal bone.

-          One lies on each side of the midline in the forehead.

·         Ethmoidal Sinuses

-          Located in the ethmoid bone.

-          They lie between the medial margin of the orbit and nasal cavity on each side.

·         Maxillary Sinuses

-          Two large cavities, one in each of the left and right maxillary bones behind the cheeks.

·         Sphenoidal Sinuses

-          Right and left, are cavities within the body of the sphenoid bone.

-          They are separated by a bony septum and each one opens into a nasal cavity.

Sutures of the Skull

1.       Coronal Suture

-          Crosses the vertex of the skull transversely (from side to side) from one lateral surface of the skull to the other.

2.       Sagittal Suture

-          Extends from front to back along the median line of the skull, between the adjacent superior margins of the two parietal bones.

-          It passes from the posterior margin of the frontal bone to the pointed upper end of the occipital bone.

3.       Lambdoidal Suture

-          Shaped like an inverted letter “V” on the posterior aspect of the skull.

4.       Squamosal Suture

-          Visible on lateral surfaces of the skull.

-          It forms a curved line, convex above, between the inferior margin of the parietal bone above and the upper margin of the temporal bone below.

Cranial Fossae

1.       Anterior Cranial Fossa

-          Lies above the orbits.

2.       Middle Cranial Fossa

-          Lies at a lower level posterior to the anterior one.

-          It extends from the free margin of the lesser wing of the sphenoid posteriorly to the ridges of the petrous parts of the temporal bone.

3.       Posterior Cranila Fossa

-          Large cavity located behind the middle fossa at the lowest level of the three, with the foramen magnum at its base.

Basal Foramina

1.       Optic Canals

-          Right and left, form short passages on the lateral margins of the body of the sphenoid under cover of the lesser wings.

-          They are located at the posterior end of each orbit on its medial wall.

2.       Superior Orbital Fissures

-          Right and left are comma shaped slits in the lateral wall of each orbit close to its posterior end.

-          They are formed by the margins of the greater and lesser wings of the sphenoid bone.

-          Right and left are comma shaped slits in the lateral wall of each orbit close to its posterior end.

-          They are formed by the margins of the greater and lesser wings of the sphenoid bone.

3.       Inferior Orbital Fissures

-          Right and left are narrow slits between the lateral wall and the floor of the orbit.

-          Each lies between the orbital part of the maxilla and greater wing of the sphenoid.

4.       Foramen Rotundum

-          A small circular opening at the medial margin of the greater wing of the sphenoid close to the medial end of the superior orbital fissure.

-          Transmit a maxillary nerve, a branch of the trigeminal, to the face.

5.       Foramen Ovale

-          An oval opening in the base of the greater wing of the sphenoid bone posterior and lateral to the foramen rotundum.

-          Transmit the mandibular division of the trigeminal nerve to the space in front of the ramus of the mandible.

6.       Foramen Spinosum

-          A very small circular opening in the greater wing of the sphenoid bone. Posterior and lateral to the large foramen ovale.

-          It transmits the middle meningeal artery to the inner surface of the skull.

7.       Foramen Lacerum

-          Ragged opening at the apex of the petrous pyramid between it and the posterolateral margin of the body of the sphenoid bone.

-          The internal carotid artery enters the cranium by this opening after it has passed through the carotid canal.

8.       Carotid Opening

-          A hole on the inferior surface of the petrous pyramid about 1 cm posterolateral to the apex.

-          It opens into the carotid canal, which in turn opens into the foramen lacerum.

9.       Carotid Canal

-          It carries the internal carotid artery.

10.   Jugular Foramen

-          A large irregular opening located between the lateral part of the occipital bone and the petrous pyramid.

-          The internal jugular vein leaves the cranium through this opening.

11.   Foramen Magnum

-          A single very large opening in the basal part of the occipital bone.

-          The medulla oblongata of the hindbrain joins the spinal cord at this opening.

12.   Internal Acoustic Opening

-          An opening on the posterior surface of the petrous pyramid above the jugular foramen.

-          It forms an opening into the internal acoustic or auditory meatus.

-          The vesticulocochlear or acoustic nerve passes through the meatus to reach the internal ear.

13.   Internal Acoustic Meatus

-          A canal that passes from the internal acoustic opening into the internal ear through the petrous part of the temporal bone, carrying the vestibulocochlear nerve.

Fontanelles

-          Gaps in the bone formation at the angles where several bones meet.

·         Anterior Fontanelle or Frontal Fontanelle

-          Located in the midline of the vertex of the skull where the posterior surface of the frontal bone meets the anterior and upper margins of both parietal bones.

-          Diamond shaped soft area.

-          It fills in with bone at about 18 months of age and is then called the Bregma.

·         Posterior Fontanelle or Occipital fontanelle

-          Lies in the midline on the upper posterior surface of the skull where the pointed end of the occipital bone meets the posterior margin of the two parietal bones.

-          It ossifies at about 6 months of age and then it becomes the Lambda.

Intracranial Grooves

-          Present on the internal surface of the lateral wall of the skull extending up and laterally from the foramen spinosum.

THE TEETH

-          20 baby teeth or deciduous teeth or milk teeth.

-          32 permanent teeth.

Parts of a Tooth

·         Crown

-          The exposed part, visible in the mouth.

o   Cusps

-          Small rounded prominences on the surfaces of the premolar and molar teeth.

-          It functions as to grind the food.

·         Neck

-          The constricted part where the crown and root meet.

·         Root

-          Smaller tapered end, is located in the alveolar process of the maxilla or at the alveolar part of the mandible.

Lingual Surface

-          The aspect that facing the tongue

Labial or Buccal Surface

-          The outer aspect facing the lip or cheek

Structure of a Tooth

1.       Pulp Cavity

-          The central cavity within a tooth extending from the crown down through the root.

-          It contains connective tissue, a nerve and blood vessels.

2.       Dentine

-          Modified bone that surrounds the pulp cavity in both the crown and root.

-          It makes up most of the solid part of each tooth.

3.       Enamel

-          A thin covering that forms an outer coat for the crown.

-          It is the hardest substance in the human body.

4.       Cement or Cementrum

-          A layer of modified bone that covers the dentine of the root.

5.       Apical Foramen

-          A minute opening in the tip of the root by which a nerve and an artery enter, and a vein leaves the pulp cavity.

6.       Peridental Membrane

-          A layer of fibrous tissue that surrounds the root of each tooth and attaches it to the wall of the socket in which the tooth lies.

Deciduous Teeth / Milk Teeth / Baby Teeth / Temporary Teeth

-          Also called as reborner teeth and fall teeth

-          the first set of teeth in the growth development of humans

Permanent Teeth

-          They are embedded in the alveolar processes of the maxilla, and in the alveolar part of the mandible.

·         Incisor Teeth

-          Teeth in front of the mouth.

-          There are 8 incisors, four upper and four lower, with 2 on either side of the midline.

o   Central Incisor

-          Incisor teeth adjacent to the midline

o   Lateral Incisor

-          Incisor teeth lateral to the central

·         Canine / Cuspid / Dog Teeth

-          Lie on the lateral side of each lateral incisor tooth.

-          Four canine teeth, a single right and left in both upper and lower jaws.

·         Premolar Teeth / Bicuspid Teeth

-          Lie posterior to the canines, and anterior to the molars.

-          There are 8 premolars, 2 right and 2 left in both upper and lower jaws.

o   First Premolar

-          The anterior one

o   Second premolar

-          The hind one

-          Each premolar tooth has two cusps, and usually they only have one root.

·         Molar Teeth

-          Lie posterior to the premolars.

-          There are 12 of them, three right and three left in both upper and lower jaws.

-          The first molar is often the first to permanent tooth to erupt.

-          It appears behind the last deciduous molar tooth of the infant.

o   Third Molar Tooth / Wisdom Tooth

-          The last permanent tooth to erupt and may appear at 20 to 25 years of age.

Occlussion

-          Refers to the position of the upper and lower teeth in relation to each other when the mouth is closed.

THE VETREBRAL COLUMN

Divisions of the Vertebral Column

1.       Cervical Vertebrae – seven in the neck.

2.       Thoracic Vertebrae – twelve in the thorax

3.       Lumbar Vertebrae – five, posterior to the abdomen

4.       Sacrum – five fused vertebrae, in pelvis

5.       Coccyx – 4 or 3, or 5 incomplete, in pelvis

Curvatures of Vertebral Column

Cervical Curvature

-          A lordotic curved with an anterior convexity

Thoracic Curvature

-          A kyphotic curve with its concave surface directed anteriorly, and the convexity posteriorly.

Lumbar Curvature

-          A lordotic curve like the cervical with convex curve anterior.

Pelvic Curvature

-          A lordotic curve with its concave surface anterior, similar to the thoracic curve.

-          The sacrum and coccyx form the pelvic curve.

Structure of a Vertebra

Vertebra

-          A bone of the vertebral column

1.       Body

-          The solid anterior part shaped like a cylinder, with the posterior surface flattened.

2.       Arch

-          The curved posterior part enclosing an opening.

-          It has two pedicles and two laminae that together with the posterior surface of the body form a vertebral foramen.

·         Pedicles

-          Two short rounded processes that extend posteriorly, one from each lateral margin of the dorsal surface of a vertebral body.

·         Laminae

-          Two flattened plates of the bone, one passing towards the midline from each pedicle.

-          They unite posteriorly in the midline to form the spinous process, and to complete the vertebral arch.

·         Vertebral Foramen

-          An opening formed by the vertebral arch with its pedicles and laminae, and the posterior surface of a vertebral body.

·         Vertebral Canal

-          A tubular passage extending from the foramen magnum of the skull to the lower sacrum.

·         Vertebral Notch

-          Formed by either the upper or lower curved surface of a pedicle; there is a superior and an inferior notch on each side at each level, posterior to the vertebral body.

·         Intervertebral Foramen

-          An opening on each side of the arch, formed by an inferior notch of one vertebra and the superior notch of the vertebra below.

-          A spinal nerve leaves the spinal cord through each of these openings.

3.       Seven Processes

3.1. Transverse Processes

-          Left and right, extend laterally from the junction of a pedicle with a lamina on each side.

3.2. Superior Articular Processes

-          Right and left, extend up towards the head from the junction of each pedicle and lamina.

3.3. Inferior Articular Processes

-          Right and left, project caudally from the junction of each pedicle and lamina.

3.4. Spinous Process

-          Extends posterioly from the dorsal margin of each vertebral arch, at the junction of the right and left laminae.

Characteristic of Some Vertebrae

1.       Cervical Vertebrae

-          Small, with spinous processes usually forked or bifid or double.

·         Atlas / C1

-          Have no body and no spinous process. Instead it has two lateral masses of bone and two arches.

o   Lareral Masses

-          Solid masses of bone that lie one on either side of the foramen and support the articular facets (fovea).

o   Anterior Arch

-          Forms the front wall of the foramen by uniting the two lateral masses.

o   Posterior Arch

-          A curved structure that joins the posterior parts of the lateral masses together, completing a bony ring.

o   Vertebral Foramen

-          Large and is formed in front by the anterior arch, laterally by the lateral mass, and behind by the posterior arch.

o   Superior and Inferior Articular Facets (Fovea)

-          Located on the superior and inferior surfaces of each lateral mass.

·         Axis / C2

-          Has a tooth shaped process extending upwards from its body.

·         Vertebra Prominens / C7

-          Has a longer and larger spinous process than the other cervical vertebra.

2.       Thoracic Vertebrae

-          Larger than the cervical.

·         Costal Pit / Fovea Costalis / Facet

-          A smooth round or semicircular smooth depression located on a vertebral body or its transverse process.

1.       Costal Pit of a thoracic Vertebra / Facet

-          Lies on the lateral surface of a thoracic vertebra close to its posterior margin, to articulate with the head of a rib.

2.       Costal Pit on a Transverse Process

-          This rounded pit lies on the anterior surface of a transverse process of thoracic vertebrae.

-          It forms a joint with a tubercle of a rib.

3.       Lumbar Vertebrae

-          Larger than the thoracic, and become progressively larger towards the sacrum.

4.       Sacrum

-          Made up of five vertebrae that have become united to form a single bone.

4.1. Body

-          Large curved area that is formed from the fused bodies of the five sacral segments.

4.2. Lateral Parts / Lateral Masses

-          Lie one on either side of the fused bodies, lateral to the sacral foramina.

o   Ala

-          Winglike upper part of each lateral mass.

o   Promontory

-          The prominent anterior margin of the upper sacral segment.

o   Superior Articular Processes

-          Extend up from the posterolateral margins of the sacrum on each side.

o   Apex

-          Its small inferior end which articulates with the first segment of the coccyx.

o   Sacral Canal

-          Tubelike passage that extends through the sacrum from top to bottom.

o   Sacral Hiatus

-          An opening in the sacral canal posteriorly at its lower end, causing a gap between the laminae of the fifth sacral segment.

o   Sacral Cornua

-          Two small bony projections that extend caudally from the sacral hiatus.

o   Four Dorsal Sacral Foramina

-          Open into the canal on either side.

-          They transmit the dorsal branches of the sacral nerves from the sacral canal.

o   Four Pelvic (Anterior) Sacral Foramina

-          Open into the sacral canal on each side, from the pelvic surfaces of the sacrum.

-          They transmit anterior branches of the sacral nerves to the pelvis.

o   Two Articular Surfaces

-          Located one on each lateral surface of the sacrum.

-          They join the auricular surfaces of the iliac bones to form the sacroiliac joints.

5.       Coccyx

-          Usually formed by 4 incompletely developed vertebrae.

·         Cornua

-          Two small bony processes that extend up from the posterior surface of the coccyx to meet similar cornua of the sacrum.

Joints of the Vertebral Column

1.       Intervertebral Joint

-          Located between the flat articular surfaces of bodies of adjacent vertebrae from the second cervical vertebrae to and including the lumbosacral joint between the fifth lumbar body and the sacrum.

-          These are cartilaginous joints permitting slight flexion.

·         Intervertebral disc

-          A flat circular plate lying between the articular cartilages covering each bone, and consisting of:

o   Anulus Fibrosus

-          An outer pad of fibrous tissue and fibrocartilage.

o   Nucleus Pulposus

-          The pulpy center of a disc in the center of an annulus fibrosus and surrounded by it.

·         Ligamenta

-          An anterior longitudinal ligament of fibrous tissue extending lengthwise along the anterior surfaces of the vertebrae;

-          A posterior longitudinal ligament passes lengthwise between adjacent vertebrae along their posterior surfaces;

-          The ligamenta flava pass lengthwise between the laminae of adjacent vertebrae;

-          Interspinal ligements connect adjacent spinous processes;

2.       Interarticular Joints

·         Zygaphyseal Joints

-          Right and left; located between articular processes of the adjacent vertebrae on each other.

3.       Atlantooccipital Joints

-          A right and a left; located between the atlas and occipital bone.

4.       Atlantoaxial Joint

-          One median and one lateral; located between the atlas and axis.

·         Median Atlantoaxial Joint

-          Located between the dens (odontoid process) of the axis and a ring formed by the anterior arch of the atlas and its transverse ligament.

·         Lateral Atlantoaxial Joints

-          A right and a left; located between the inferior articular surface (fovea) of the lateral mass of the atlas, and the superior articular process of the axis on each side.

5.       Accessory Cervical Joints

-          Located between the lateral margins of articular surfaces of lower cervical vertebrae, on each side.

6.       Lumbosarcal Joint

-          Located between fifth lumbar vertebrae and the upper end of sacrum.

7.       Sacroccygeal Joint

-          Located between sacrum and coccyx

THE THORAX

1.       Sternum / Breast Bone

-          A long flat bone that lies vertically in the midline of the anterior chest wall.

1.1. Manubrium

-          Upper part and represents the handle of the sword.

·         Jugular Notch (suprasternal notch)

-          A depression on the upper surface of the manubrium of the sternum.

·         Clavicular Notches

-          A right and a left are placed obliquely on either side of the jugular notch.

-          They form joints with the medial ends of the clavicles – the sternoclavicular joints.

1.2. Body / Gladiolus

-          Extends from the manubrium to the xiphoid process below and is the largest part of the sternum.

·         Sternal Angle / Angle of Louis or Ludwig

-          Marked by prominent transverse ridge at the junction of the manubrium and body of the sternum.

-          This ridge also indicates the level of the 2^nd costal cartilages, which in turn are attached to the 2^nd ribs.

1.3. Xiphoid Process

-          The inferior part of the sternum.

·         Costal Notches

-          Niches on the lateral margins of the sternum that articulate with the medial ends of the costal cartilages.

2.       Ribs / Costa

-          Twelve pairs of ribs, 12 left and 12 right.

-          Each rib is attached to a costal cartilage at its anterior end.

-          They are long, curved, flat bones that form the posterior wall, the lateral walls, and part of the anterior wall of the thorax.

2.1. Dorsal extremity

-          Has a head, a neck, and a tubercle.

2.1.1.        Head

-          Slightly expanded posterior end.

-          It has one or two small articular surfaces (facets) according to wether it articulates with one or two vertebral bodies.

2.1.2.        Neck

-          Slightly constricted part connecting the head to the body.

2.1.3.        Tubercle

-          A small prominence on the dorsal surface at the junction of the neck and body.

-          Has a small articular surface (facet) that forms a joint with a similar surface on a transverse process of a vertebra.

2.2. Body

-          Long, curved part that extends from the neck around the chest wall.

·         Angle of a Rib

-          A prominence in front of the neck where the rib becomes bent anteriorly.

2.3. Ventral or Sternal Extremity

-          The anterior end that articulates with its costal cartilage.

3.       Costal Cartilages

-          There are 12 pairs of costal cartilages, one attached to the sterna end of each rib.

-          These cartilages are flat plates of cartilage similar in shape to the adjacent rib.

·         Costal Arch

-          The curved formed by the anterior margins of the 7^th, 8^th, 9^th, and 10^th costal cartilages on each side and the rounded tip of the xiphoid process.

4.       True Ribs and False Ribs

·         True Ribs / Vertebrosternal Ribs

-          The upper 7 pairs articulate by means of their costal cartilages with the sternum at a costal notch.

·         False Ribs / Vertebrochondral Ribs

-          The lower 5 pairs do not articulate with the sternum.

·         Floating Ribs / Vertebral Ribs

-          The lower 2 pairs, the 11^th and 12^th have no connection with the sternum.

Joints of the Thorax

1.       Intervertebral and Interarticular Joints

·         Fovea = a small pit or depression at a joint.

·         Facet = a small smooth articular surface

·         Articular Surface = a smooth bone surface that helps to form a joint.

2.       Costovertebral Joints

-          Two types of joints between the thoracic vertebrae and ribs: joints of the heads of ribs and vertebral bodies; costotransverse joints between the tubercles of the ribs and transverse processes of vertebrae.

2.1. Costotransverse Joints

-          Located between ribs and transverse processes of vertebrae.

2.2. Joints of Head of ribs and vertebral bodies

-          The articular surface of the head of a rib articulates with a pit (fovea) on the lateral surface of the body of a vertebra.

3.       Costochondral Joints

-          Located at the anterior, or sterna, end of a rib and the adjacent costal cartilage.

4.       Sternocostal or Costosternal Joints

-          Located at the lateral margins of the sternum on each side.

5.       Interchondral Joints

-          Located between adjacent anterior margins of the seventh, eight, ninth, and tenth costal cartilages and the rib cartilage above each one.

6.       Sternoclavicular Joints

-          Located between the sterna end of the clavicle and clavicular notch of the sternum.

-          They are synovial gliding joints.

7.       Manubriosternal Joint

-          Located between the inferior margin of the manubrium and the upper margin of the body of the sternum at the sterna angle.

8.       Xiphisternal or xiphosternal Joint

-          Located between the inferior end of the body of the sternum and the xiphoid process of the sternum.

APPENDICULAR SKELETON

-          Composed of 206 bones

The Upper Extremity

-          Formed by the scapula and clavicle on each side of the body.

1.       Scapula / Shoulder Blade

-          A flat triangular bone that lies against the upper posterolateral chest wall.

1.1. Body

-          Flat and triangular and has three borders and three angles.

·         Medial border / Vertebral Border

-          Closest to the median line of the body and to the thoracic vertebrae.

·         Lateral Border / Axillary Border

-          Farthest away from the median line of the body and adjacent to the posterior border of the armpit or axilla.

·         Superior Border

-          Short and close to its lateral end.

·         Medial Angle

-          Upper medial part where the superior and medial borders meet.

·         Inferior Angle

-          The lower rounded end of the scapula where the medial and lateral borders meet.

·         Spine

-          Narrow ridge of bone that projects posteriorly from the dorsal surface of the body above its midpoint.

·         Acromion

-          Flat rounded lateral end of the spine.

1.2. Head

-          Poorly formed and slightly expanded lateral upper part of the scapula.

·         Glenoid Cavity

-          An oval depression on the lateral surface of the head of the scapula

1.3. Neck

-          Slightly constricted part continuous with the upper part of the body between the body and head.

1.4. Coracoids Process

-          Beaklike projection originating from the anterior border of the neck of the scapula.

2.       Clavicle / Collar Bone / Key Bone / Last Bone / Cleido

-          Long flat bone; has an acromial extremity, a body and a sterna extremity.

·         Conoid Tubercle

-          Small rough prominence on the posterior margin of the inferior surface of the clavicle towards its acromial end.

THE ARM / BRACHIUM

-          Has a single bone, the humerus.

3.       Humerus

-          Long cylindrical bone that reaches from the shoulder to the elbow.

3.1. Proximal Extremity

-          Has a head, neck, and greater and lesser tubercles with an intertubercular groove (bicipital Groove)

·         Head / Caput Humeri

-          Superior expanded smooth rounded end of the humerus.

·         Anatomical Neck

-          Slightly constricted obliquely directed part of the humerus between the head and remainder of the bone.

·         Greater Tubercle / Tuberculum Majus

-          Large bony prominence.

·         Lesser Tubercle / Tuberculum Minus

-          Smaller bony prominence on the anterior surface of the humerus just below the anatomical neck.

·         Intertubercular Groove / Bcipital Groove

-          Furrow that extends longitudinally on the anterior surface of the upper humerus between the greater and lesser tubercles.

·         Surgical Neck

-          The constricted part of the humerus below the tubercles.

3.2. Body

-          Long rounded part that becomes flattened from front to back as it nears the elbow.

3.3. Distal Extremity

-          Have a capitulum, trochlea, medial and lateral epicondyles, three fossae and ulnar groove.

·         Condyle

-          The distal extremity of the humerus.

·         Capitulum / Little Head

-          Small rounded prominence forming the lateral part of the lower articular end of the humerus.

·         Trochlea / Pulley

-          Forms the medial part of the distal articular surface of the humerus.

·         Conoid Fossa

-          A depression on the front of the lower humerus immediately above the trochlea.

·         Radial Fossa

-          Small depression on the front of the lower humerus above the capitulum.

·         Olecranon Fossa

-          A depression on the back of the lower humerus above the trochlea.

·         Medial Epicondyle

-          A knucklelike rounded bony prominence on the medial border of the lower humerus above the trochlea.

·         Lateral Epicondyle

-          Similar but smaller bony prominence on the lateral margin of the lower humerus above the capitulum.

·         Ulnar Groove

-          A furrow on the dorsal surface o the medial epicondyle through which the ulnar nerve descends to the forearm.

THE FOREARM / ANTEBRACHIUM / FUNNY BONE

-          Consists of ulna and radius.

4.       Radius

-          Lateral bone of the forearm.

4.1. Proximal Extremity

-          Have a head, neck and tuberosity.

·         Head

-          Upper expanded disclike end with a slightly concave upper articular surface.

·         Neck

-          The constricted part distal to the head, connecting the head to the body.

·         Radial Tuberosity

-          Rough prominence on the anteromedial surface of the radius below its neck.

4.2. Body

-          Becomes gradually larger as it approaches the wrist joint and its articular surface.

4.3. Distal Extremity

-          Have a styloid process, a carpal articular surface and an ulnar notch.

·         Styloid Process

-          Large bony prominence on the lateral border and distal end of the redius.

·         Carpal Articular Surface

-          Large smooth area on the distal end of the radius that articulates with the carpal bones to form the wrist joint.

·         Ulnar Notch

-          Small depression on the medial margin of the distal end of the radius above its articular surface.

5.       Ulna

-          Medial bone of the forearm

5.1. Proximal Extremity

-          Have an olecranon, coronoid process, trochlear notch, and a radial notch.

·         Oclecranon

-          Bluntly rounded end of the ulna that lies posterior to the elbow joint.

·         Coronoid Process

-          Extends anteriorly from the upper part of the body of the ulna.

·         Trochlear Notch / Semilunar Notch

-          A concave halfmoon shaped hollow on the anterior surface f the upper ulna.

·         Radial Notch

-          A depression on the lateral surface of the upper ulna below the trochlear notch.

5.2. Body

-          Large at its superior end, becomes smaller as it approaches the wrist.

5.3. Distal Extremity

-          Have a head, and a styloid process.

·         Head

-          Lower expanded end and can be felt through the skin.

·         Styloid Process

-          Small, pointed prominence that extends distally from the posteromedial border of the ulnar head.

THE HAND / MANUS

-          Includes all the bones of the wrist, bones of the palm and the bones of the digits.

6.       Wrist / Carpals / Carpus

-          There are eight bones, classified as short bones.

Proximal Row

6.1. Scaphoid / Navicular / Os Scaphoideum

-          Boat in shape and lies on the radial side of the wrist.

6.2. Lunate Bone / Semilunar Bone / Os Lunatum

-          Lies between the scaphoid and triquetral bones.

6.3. Triquetral Bone / Os Triquetrum

-          Lies on the ulnar side of the wrist and is somewhat triangular in shape.

6.4. Pisiform Bone / Os Pisiforme

-          Lies anterior to the triquetral bone, not medial to it.

Distal Row

6.5. Trapezium / Greater Multangular Bone

-          Lies on the radial or thumb side of the wrist in the distal row of carpal bones.

6.6. Trapezoid Bone / Lesser Multangular Bone

-          Lies between the trapezium and the capitates bones.

6.7. Capitate Bone / Os Magnum / Os Capitatum

-          Lies between the trapezoid and hamate bones.

6.8. Hamate Bone

-          Lies on ulnar border of the wrist and it has a hooklike process the hamulus.

7.       Metacarpals / Metacarpus

-          Five bones from the bony framework of the palm of the hand.

-          They are named from the thumb or radial side as 1^st, 2^nd, 3^rd, 4^th, 5^th metacarpal bones.

8.       Digits / Phalanges

-          14 phalanges from the digits.

-          Each digit has three phalanges – a proximal, middle and a distal phalanx except the thumb.

Thumb – Pollex / 1^st Digit

2^nd Digit – index Finger

3^rd Digit – Middle Finger

4^th Digit – Ring Finger

5^th Finger – Little Finger

Joints of the Upper Limb

1.       Sternoclavicular Joint

-          Located between the upper lateral margin of the manubrium and the sterna end of the clavicle.

2.       Acromioclavicular Joint

-          Located between the acromial end of the clavicle and the medial border of the acromion of the scapula.

3.       Shoulder Joint / Humeral Joint

-          Located between the head of the humerus and the glenoid cavity of the scapula.

4.       Elbow Joint / Cubital Joint / Elnboga / Cubitus Joint

-          Located between the condyle of the humerus and the proximal ends of the radius and ulna.

5.       Proximal Radioulnar Joint

-          Located between the radial notch of the ulna and the fibrous ring encircling the head of the radius.

6.       Distal Radioulnar Joint

-          Located between the head of the ulna and the ulnar notch of the medial margin of the lower of the radius, with the upper surface of the articular disc at the lower end of the ulna forming its inferior boundary.

7.       Wrist Joint / Radiocarpal Joint

-          Located between the carpal articular surface of the distal end of the radius and articular disc articulating with three of the proximal row of carpal bones.

8.       Intercarpal Joint

-          Located between adjacent carpal bones.

9.       Carpometacarpal Joint

-          Located between the distal row of carpals and the bases of adjacent metacarpal bones.

10.   Metacarpophalangeal Joint

-          Located between metacarpal bones and bases of proximal phalanges.

11.   Interphalangeal Joint

-          Located between the head of one phalanx and the base of the phalanx distal to it.

·         Proximal Interphalangeal Joint

-          Located between head of a proximal and base of a middle phalanx.

·         Distal Interphalangeal Joint

-          Located between head of a middle phalanx and base of a distal phalanx.

Congenital Anomalies of the Upper Limb

Abrachium

-          One or both upper limbs may be absent.

Supernumerary

-          There may be an extra digit present.

Sprengel’s Deformity

-          Elevation and deformity of the scapula.

Madelung’s Deformity

-          A curvature of the body of the radius, so that the wrist joint lies obliquely.

Fusion

-          Joining together of the upper ends of the radius and ulna with inability to supinate or pronate the hand.

THE LOWER LIMB

Pelvic Girdle

-          Consisting of the right and left hip bones, connects the lower limbs and trunk.

1.       Hip Bone / Os Coxae / Coxal Bone / Innominate Bone

-          Large irregular bone that connects the lower limb to the trunk

1.1. Acetabulum

-          Deep circular cup shaped depressions on the lateral depression on the lateral surface of the hip bone below its middle.

1.2. Acetabular Notch

-          A gap on the inferior margin of the rim of the acetabulum.

1.3. Acetabular Fossa

-          Flat central part of the acetabulum.

1.4. Obturator Foramen

-          Large opening in the inferior part of the hip bone, between the pubis and ischium.

2.       Ilium / Flank Bone

-          Forms the upper two-fifths of the acetabulum and all of the hip bone above it.

2.1. Body

-          Thickened part close to the acetabulum of which it forms the upper two-fifths.

2.2. Ala / Wing

-          Thin flattened upper part of the ilium above the body.

·         Crest

-          The upper curved border of the ala.

·         Iliac Fossa

-          The concave inner surface of the wing of the ilium.

·         Articular Surface

-          Rough, ear-shaped part posterior to the iliac fossa that articulates with the upper hip bone below and dorsal to the acetabulum.

3.       Ischium / Sciatic

-          Forms the lower two-fifths of the acetabulum and that part of the hip bone below and dorsal to the acetabulum.

3.1. Body / Superior Ramus

-          Forms the inferior and posterior part of the ischium

·         Spine of the Ischium / Ischial Spine

-          Pointed process that extends dorsally and medially from the body of the ischium.

·         Tuberosity of the Ischium / Ischial Tuberosity

-          Large rounded process on the posterior surface of the lower end of the body of the ischium.

3.2. Ramus / Inferior / Ascending Ramus

-          Extends anteriorly, medially and upwards from the body.

4.       Pubis / Pubic Bone

-          Forms the anterior one fifth of the acetabulum and the anterior part of the hip bone in front of the acetabulum and obturator foramen.

4.1. Body

-          Forms the anterior one fifth of the acetabulum and is continued anteriorly as the superior ramus.

4.2. Superior Ramus

-          Extends anteriorly from the body to the symphysis pubis, the joint between the two pubic bones.

4.3. Inferior Ramus

-          Extends down from the lower end of the superior ramus, and joins the ramus of the ischium.

·         Pubic Tubercle

-          Very small process on the superior margin of the pubic bone slightly lateral to the symphysis pubis.

·         Pubic Crest

-          Small ridge on the upper margin extending from the symphysis to the pubic tubercle.

·         Pubic Arch

-          Curved surface formed by the medial margins of both inferior rami of the pubic bones and the lower border of the symphysis pubis.

5.       Pelvis

-          Hollow curved cylinder with bony walls, at the inferior end of the vertebral column.

·         Linea Terminalis / Terminal Line

-          Ridge of bone that begins at the upper margin of the symphysis pubis.

·         Superior Aperture / Inlet / Pelvic Rim

-          Marked by the terminal line. Heart shaped opening into the true pelvis and forms the plane of the inlet.

·         Inferior Aperture / Outlet

-          An opening at the lower end of the pelvis composed of the incomplete bony ring and the ligaments.

·         True Pelvis / Minor Pelvis

-          Cavity located between the pelvic inlet and pelvic outlet.

·         False Pelvis / Major Pelvis

-          Lies above the plane of the inlet that is above the true pelvis.

·         Greater Sciatic Notch

-          Deep notch on the posterior margin of the hip bone.

·         Lesser Sciatic Notch

-          Lies between the spine of the ischium above and the ischial tuberosity below.

6.       Femur / Thigh Bone

-          Long bone and the longest none in the body, extending from the hip to the knee.

6.1. Proximal Extremity

·         Head / Caput Femoris

-          The upper expanded rounded end that articulates with the acetabulum to form the hip joint.

o   Pit of the Femoral Head / Fovea Capitis Femoris

-          Small but definite hole at the center of the head.

o   Ligamentum Teres / Ligament of the Femoral Head

-          Attached to this depression and to the acetabular notch of the hip bone.

·         Neck

-          Constricted part connecting the head to the body of the femur.

·         Greater Trochanter

-          Large prominence on the lateral surface of the upper femur.

·         Lesser Trochanter

-          Much smaller rounded process that extends medially from the posteromedial margin of the upper femur at the junction of the neck and shaft.

·         Intertrochanteric Crest

-          Ridge of bone that passes obliquely across the back of the upper femur between the greater and lesser trochanter.

·         Intertrachanteric Line

-          Ridge that extends obliquely across the anterior surface of the upper femur from the greater trochanter to the medial border of the femur in front of the lesser trochanter.

6.2. Body / Shaft

-          Long cylindrical part that becomes broadened as it approaches the knee.

·         Linea Aspera

-          Double bony ridge that passes longitudinally down the posterior surface of the body of the femur.

·         Popliteal Surface

-          Flat area on the dorsal surface of the lower femur between the divided ridges of the linea aspera.

6.3. Distal Extremity

·         Medial Condyle

-          Rounded knoblike process that forms the medial part of the distal end of the femur.

·         Lateral Condyle

-          Similar rounded process forming the lateral part of the distal end of jthe femur.

·         Intercondylar Fossa

-          Deep notch located between the posterior parts of the femoral condyles.

·         Patellar Surface

-          Smooth anterior surface of the distal part of the femur between the anterior parts of the femoral condyles.

·         Medial Epicondyle

-          Large prominence on the medial surface of the femur just above the medial condyle.

·         Lateral Epicondyle

-          Smaller rounded process on the lateral surface of the lower femur above the lateral condyle.

7.       Patella / Knee Cap

-          A sesamoid bone lying within the tendon of the quadriceps muscle tendon.

7.1. Base

-          Proximal slightly rounded upper border.

7.2. Apex

-          Lower pointed end.

7.3. Posterior Surface

-          Smooth and glides over the smooth patellar surface of the femur as the knee is flexed or extended.

The Leg / Crus

8.       Tibia / Shin Bone

-          Large sturdy bone and lies medial to the fibula.

8.1. Proximal Extremity

·         Medial Condyle

-          Medial part of the upper expanded end of the tibia.

·         Lateral Condyle

-          Lateral part of the upper expanded end of the tibia.

·         Intercondylar Eminence

-          Small, double pointed process on the proximal end of the tibia, located between the articular surfaces of the medial and lateral condyles of the tibia, slightly posterior to its midpoint.

·         Tibial Tuberosity

-          Rounded prominence on the anterior surface of the tibia below the condyles.

·         Fibular Articular Surface / Fibular Facet

-          Small smooth rounded area on the posterolateral border of the lateral tibial condyle.

8.2. Body

-          Long sturdy part that becomes flattened as it approaches the ankle.

8.3. Distal Extremity

·         Inferior Articular Surface

-          A four sided smooth surface on the distal end of the tibia that articulates with the talus, forming the ankle joint.

·         Medial Malleolus

-          Projects down from the medial margin of the distal end of the tibia.

·         Fibular Notch

-          Concave depression on the lateral surface of the tibia just above the ankle joint.

9.       Fibula / Calf Bone

-          Long slender none lying on the lateral side of the tibia and parallel to it.

9.1. Head

-          Upper expanded end that articulate with the fibular articular surface of the tibia, forming the proximal tibiofibular joint.

·         Apex / Styloid

-          Process of the fibula is the pointed upper end of the head.

9.2. Body

-          Long and very slender

9.3. Lateral Malleolus

-          Distal expanded end of the fibula.

The Foot / Pes

10.   Tarsals / Tarsus / Instep

Posterior Tarsal Bones

10.1.                      Talus / Astragalus / Ankle Bone

-          Lies between the distal end of the tibia and the calcaneus transmitting the body weight to the calcaneus.

·         Body

-          Large posterior part.

·         Trochlea / Pulley

-          Upper smooth convex surface that articulates with the lower end of the tibia.

·         Neck

-          Constricted part lying between the body and the head.

·         Head

-          Rounded anterior end of the talus.

10.2.                      Calcaneus / Os Calsis / Heel Bone

-          Largest tarsal bone and forms the heel.

·         Calcaneal Tuberosity

-          The enlarged posterior end.

·         Sustentaculum Tali

-          A small but definite shelf of bone that projects medially from the medial surface of the calcaneus immediately below the talus, which it helps to support.

10.3.                      Navicular / Scaphoid

-          Boat in shape, and lies anterior to the talus and behind the three cuneiform bones.

·         Tuberosity

-          The prominent medial border of the navicular.

10.4.          Medial Cuneiform / First Cuneiform

-          Located on the medial border of the foot anterior to the navicular and posterior to the first metatarsal bone.

10.5.                      Intermediate Cuneiform / Second Cuneiform

-          Located lateral to the medial cuneiform, posterior to the second metatarsal bone and anterior to the navicular.

10.6.                      Lateral Cuneiform / Third Cuneiform

-          Lies lateral to the intermediate cuneiform, posterior to the third metatarsal, and in front of the navicular bone.

10.7.                      Cuboid

-          Roughly cube shaped, and it lies on the lateral side of the foot, and has the calcaneus behind it, with the fourth and fifth metatarsal in front.

11.   Metatarsal / Metatarsus

-          Five metatarsal bones lie side by side in front of the tarsals and behind the toes.

12.   Digits / Phalanges

-          14 phalanges from the five digits or toes.

Hallux – alternative name for the great toe.

Joints of the Lower Limb

1.       Sacroiliac Joint

-          Located between the auricular surfaces of the sacrum and ilium.

2.       Pubic Symphysis

-          Located between the two pubic bones.

3.       Hip Joint / Coxal Joint

-          Located between the head of the femur and the acetabulum of the hip bone.

4.       Knee Joint

-          Located between the medial and lateral condyles of the femur articulating with the medial and lateral condyles of the tibia and the patellar surface of the femur articulating with the patella.

5.       Superior Tibiofibular Joint

-          Located between fibular articular surface on the upper posterior margin of the lateral tibial condyle articulating with the articular surface on the medial margin of the head of the fibula.

6.       Inferior Tibiofibular Joint

-          Located between the inferior margins of the tibia and fibular above the ankle joint.

7.       Ankle Joint / Talocrural Joint

-          Located between the distal ends of the tibia and fibula where they join the foot.

8.       Intertarsal Joint

-          Located between adjacent tarsal bones.

9.       Tarsometatarsal Joint

-          Located between the tarsal and metatarsal bones of the foot.

10.   Intermetatarsal Joint

-          Located between the bases of the adjacent metatarsal bones.

11.   Metatarsophalangeal Joint

-          Located between the metatarsal bones and the toes.

12.   Interphalangeal Joint

-          Located between the phalanges of each toe.

Congenital Anomalies in the Lower Limb

Congenital Dislocation

-          The femoral head lies outside of and above the acetabulum.

Absence of one or both Patellae

-          This bone may fail to develop at one or both knees.

Bipartite Patella

-          The patella may present as two separate bones.

Os Trigonum

-          A small triangular bone posterior to the talus that has formed from a separate epiphysis to that of the talus, and may failed to unite with it.

Accessory Navicular Bone

-          The posteromedial part of the navicular bone may be separate from the main part of this bone.