Muscular System

MUSCULAR SYSTEM

Classification of Muscles by Location

1.       Skeletal Muscles

-          Usually attached to bones

2.       Visceral Muscles

-          Located in the walls of some organs

3.       Cardiac Muscles

-          Located in the heart (Myocardium)

Functions of Muscles

1.       Skeletal muscles contract and cause movement.

2.       They maintain position (posture) in the upright and other positions of the body.

3.       They give support to joints by maintaining a partial state of contraction.

·         Origin of a muscle is its more fixed, less movable, attachment, usually its proximal end.

·         Insertion of muscle is its more movable end, usually its distal end.

Tendon/Sinew/Cord/Leader

-          A cordlike connective structure that extends from the end of a muscle to a bony attachment.

Aponeurosis

-          A sheet of fibrous connective tissue that is often attached at one end to a muscle, often a flat ligament or other muscle.

Tendon Sheath

-          A tunnel-like channel that surrounds a tendon.

Tenosynovitis

-          Inflammation of tendon sheath.

Bursa

-          Saclike structure lying between a muscle or tendon and an adjacent bony prominence over the muscle or tendon moves.

Bursitis

-          An inflammation of a bursa and it is frequently very painful.

Calcification

-          The deposition of calcium, may occur in bursa or tendon sheath, and may be demonstrated radiographically.

Muscle Tone

-          Muscles do not completely relax when at rest, but remain partly contracted.

Contraction

-          The main function of all muscles is to contract and cause movement of the body or part of it.

1.       Prime Movers

-          Muscles that initiate and carry out some movement, such as flexion of the forearm.

2.       Antagonists

-          Muscles that perform some movement opposite to that caused by prime movers.

3.       Synergists

-          Muscles that act with the prime movers to accomplish some movement but prevent unwanted movement.

4.       Fixation Muscles

-          Those that hold the adjacent bones in a fixed position so that the prime movers may accomplish some certain movement.

Posture

-          The maintenance of the upright position of the body consits of a balanced contraction of some muscle groups and the partial relaxation of opposing groups.

Muscle Spasm

-          A contraction of muscles that may persist for a long period of time, without relaxation.

Paralysis of Muscles

-          It follows injury or destruction of the nerves supplying that muscles.

Distribution of Muscles by Location

1.       Muscles of the Head:

-          Muscles of the eyelids

-          Muscles of the eyes

-          Muscles of the nose

-          Muscles of the mouth

-          Muscles of mastication (chewing)

2.       Muscles of the Neck

-          Superficail cervical muscles

-          Lateral cervical muscles

-          Suprahyoid, and infrahyoid muscles (anterior neck)

-          Anterior vertebral muscles

-          Lateral vertebral muscles

3.       Muscles of the Trunk

-          Deep muscles of the back

-          Suboccipital muscles

-          Muscles of the thorax

-          Muscles of the abdomen

o   Anterolateral

o   Posterior

-          Muscles of the pelvis

-          Muscles of the perineum

4.       Muscles of the Upper Limb / Member

-          Connecting the limb to the vertebral column

-          Connection of the upperlimb to the chest wall

-          Muscles of the shoulder

-          Muscles of the arm – brachial muscles

-          Muscles of the forearm – antebrachial

-          Muscles of the hand

5.       Muscles of the Lowerlimb / Member

-          Muscle of the iliac region

-          Muscles of the thigh

o   Anterior femoral muscles

o   Medial femoral

o   Gluteal muscles – buttocks

o   Posterior femoral

-          Muscles of the leg, crural muscles

o   Anterior crural

o   Posterior crural (superficial)deep

-          Muscles of the foot

o   Dorsal muscles of the foot

o   Plantar muscles of the foot (1^st,2^nd,3^rd,4^th layers)

The Head

-          These are responsible for movements of the eyelids, eyes, nose, mouth, jaws, and ears.

The Neck

-          Rounded cylindrical appearance of the neck is due to the muscles located here.

The Thorax

-          Several of the muscles of the anterior and posterior chest wall pass laterally to the shoulder girdle or upper arm.

The Abdomen

-          The posterior abdominal wall on each side of the vertebrae is formed by psoas major and quadratus lumborum muscles.

The Pelvis

-          The muscles of the pelvis form a sling across the floor of the pelvic cavity, with openings fro the anla, urinary and female passages.

The Perineum

-          Space between the two schial tuberosities, the pubic arch and coccyx is filled in by the perineal muscles.

The Upper Limb

-          Muscles extending from the chest wall to the shoulder girdle have been noted.

Shoulder Muscles

-          Pass over the shoulder to the humerus and are responsible for the movements of the upper humerus.

Muscles of the Forearm

-          The antebrachial muscles control movements of the wrist and hand.

The Lower Limb

-          Muscles connect the lower limb to the trunk.

The Thigh

-          Muscles that make up the thigh control movements at the knee.

Flexor Muscles of the Leg

-          Lie on the posterior surface of femur, not the anterior.

Extensor Muscles of the Leg (Anterior Femoral Muscles)

-          Lie anterior to the femur

The Leg

-          Muscles of the leg overlying the tibia and fibula control movements of the ankle and foot.

The Anterior Crural Muscles

-          In front of the tibia and fibula, and in tendons that cross the anterior surface of the ankle to insert into the upper surface of the bones of the foot.

The Posterior Crural Muscles

-          Muscles from a superficial and a deep layer posterior to the tibia and fibula.

The Foot

-          Short muscles lie on the dorsal and plantar surfaces of the foot.

Muscles that are Important in Radiography

1.       Diaphragm / Phren

-          A dome shaped muscular partition that separates the thorax and abdomen.

Three Large Openings in the Diaphragm

1.       Aortic Hiatus – through which the aorta enters the abdomen from the thorax.

2.       Esophageal Hiatus – through which the esophagus enters the abdomen.

3.       Oprning (Foramen) of the Inferior Vena Cava – through which this vein enters the thorax.

Phrenic Arteries

-          Superior and inferior, and right and left are branches of the aorta supplying the diaphragm with blood.

2.       Pectoris Major Muscle

-          A right and left, fan-shaped muscles that covers the upper anterior chest wall.

3.       Psoas Major Muscle

-          Lies lateral to the lumbar vertebrae in the posterior wall of the abdomen.

4.       Intercostal Muscle

-          Fill in the spaces between adjacent ribs, and their costal cartilages – the intercostal spaces.

Example of Skeletal Muscle

1.       Sternomastoid Muscle

-          Strap-shaped muscle that passes obliquely down the neck from the mastoid process to the upper sternum and medial part of the clavicle.

2.       Pectoralis Minor Muscle

-          Lies behind the pectoralis major muscle and extends from the anterior chest wall to the process of the scapula.

3.       Deltoid Muscle

-          Forms the rounded curved of the shoulder. It connects the humerus to the shoulder.

4.       Brachialis Muscle

-          Lies in front of the lower humerus, but behind the biceps muscle, which hides most of it.

5.       Biceps Brachii

-          Located in front of the humerus.

6.       Triceps Brachii

-          Has three at its upper end, where it originates from the scapula and humerus.

7.       Flexor Digitorum Profundus

-          The deep flexor of the digits.

8.       Extensor Digitorum

-          Lies on the lateral margin of the forearm whereas the flexors lie on the medial and anterior margins.

9.       Trapezius Muscle

-          Triangular in shape, the two togethr form a four sided figure, diamond-shaped on the posterior surface of the neck and thorax.

10.   Latissimus Dorsi Muscle

-          Each is triangular is shape and is located on the back of the lower thorax and abdomen.

11.   Sacrospinalis Muscle

-          Extend vertically from the occipital bone to the sacrum on either side of the spinous process of the vertebrae.

12.   Psoas Minor Muscle

-          Lies in front of the psoas major muscle of the same side.

13.   Gluteus Maximus Muscle

-          Forms most of the tissue mass of the buttock on either side.

14.   Quadriceps Femoris Mscle

-          Actually four sided muscles located anterior to the femur

15.   Biceps Femoris Muscle

-          Located posterior to the femur in the thigh.

16.   Gatrocnemius Muscle

-          Forms most of the mass of the calf muscles on the back of the leg.

Ligaments and Tendons

1.       Inguinal Ligament

-          Lies obliquely in the crease between the anterior surface of the upper thigh and the lower abdomen on each side.

2.       Patellar Ligament

-          Part of the quadriceps femoris tendon that extends from the apex of the patella to the tibial tuberosity.

3.       Ligamentum Teres / Ligamentum Capitis Femoris

-          Ligament of femoral head lies within the hip joint.

4.       Calcaneal Tendon / Tendo Achilles or Achilles Tendon

-          Extends down from the calf muscles to the tuberosity of the calcaneus, posterior to the ankle and heel.

Myofibril – main unit of muscular system

Claudification – limping muscle

Rigor Mortise – rigidity muscle

Charlie Horse – muscle strain

Kymography – examination for involuntary muscle

Gluteus maximus ­– largest muscle

Brevis – shortest muscle

Strapedius – smallest muscle

Sartorius – longest muscle

Latisimus Dorsi – swimmer’s muscle

Diaphragm – the breathing muscle

Massetter – chewing muscle

Orbicularis Oris – smile muscle

Arrector Pili – hair muscle