Neck + HEad Muscls

Anatomy and Phiosology head and neck muscles + purposes

Frontalis

the frontal belly of the occipitofrontalis. It covers the forehead and the dome of the skull.

Its origin is the epicranial aponeurosis.

Its insertion is the skin of the eyebrows and the root of the nose.

When the epicranial aponeurosis is fixed, the frontalis raises the eyebrows. It wrinkles the forehead skin horizontally.

It is supplied by cranial nerve VII, the facial nerve.

Orbicularis Oris

is a multilayered muscle of the lips.

It arises indirectly from the maxilla and mandible.

It inserts into the tissues of the upper and lower lips.

The orbicularis oris closes the lips, purses and protrudes the lips, and produces kissing and whistling motions.

It is supplied by cranial nerve VII, the facial nerve.

Orbicularis Oculi

thin, flat sphincter that surrounds the rim of the orbit.

Its origin points are the frontal and maxillary bones and the ligaments surrounding the orbit.

It inserts into the tissue of the eyelid.

The orbicularis oris closes the eyes, produces blinking and squinting, and draws the eyebrows inferiorly.

It is supplied by cranial nerve VII, the facial nerve.

occipitus

It covers the lateral two-thirds of the superior nuchal line.

Its origin points are the occipital and temporal bones.

Its insertion is the epicranial aponeurosis.

The occipitalis fixes the aponeurosis and pulls the scalp posteriorly.

It is supplied by cranial nerve VII, the facial nerve.

Zygomaticus Major

is a paired muscle that extends diagonally from the cheekbone to the corner of the mouth.

It originates from the zygomatic bone.

It inserts into the skin and muscles at the corner of the mouth.

It raises the lateral corners of the mouth upwards; in other words, it produces smiling.

It is supplied by cranial nerve VII, the facial nerve.

Masseter

paired, powerful muscle that covers the lateral aspect of the mandibular ramus.

It originates from the zygomatic bone and the rest of the zygomatic arch.

It inserts into the mandibular angle and the mandibular ramus.

It closes the jaw, elevates and retracts the mandible, and maintains the resting position of the mandible.

It is supplied by cranial nerve V, the trigeminal nerve.

Sternocleidomastoid

is a paired, two-headed muscle on the anterolateral surface of the neck.

It originates from the manubrium of the sternum and the medial portion of the clavicle.

It inserts into the mastoid process of the temporal bone and the superior nuchal line of the occipital bone.

It flexes and laterally rotates the head.

It is supplied by cranial nerve XI, the accessory nerve, as well as the ventral rami of C2 and C3.

Trapezius

paired, superficial muscle of the posterior thorax; it is triangular.

It originates from the occipital bone, the ligamentum nuchae, and the spinous processes of C7 through T12.

It inserts continuously along the acromion and the spine of the scapula and the lateral third of the clavicle.

It stabilizes, raises, retracts, and rotates the scapula.

It is supplied by cranial nerve XI, the accessory nerve, as well as C3 and C4.

Buccinator

paired, thin, horizontal musse; it is the principal muscle of the cheek.

It originates from the alveolar process of the maxilla and mandible.

It inserts into the orbicularis oris.

It compresses the cheek, holds food between teeth during chewing, and draws the corner of the mouth laterally.

It is supplied by cranial nerve VII, the facial nerve.

External Intercostals

lie between the ribs.

They originate from the inferior borders of the ribs above them.

They insert into the superior borders of the ribs below them.

They pull the ribs towards one another to elevate the rib cage. They aid in inspiration and are synergists of the diaphragm.

They are supplied by the intercostal nerves.

Intenal intercostals

between the ribs.

They originate from the superior borders of the ribs below them.

They insert into the inferior borders of the ribs above them.

They draw the ribs together and depress the rib cage.

They are supplied by the intercostal nerves.

Transverse abdominis

is the innermost paired muscle of the abdominal wall.

It originates from the inguinal ligament, the lumbar fascia, the cartilages of the last six pairs of ribs, and the iliac crest.

It inserts into the linea alba, the pubic crest, the last three or four pairs of ribs, and the costal margin.

As a pair, it flexes the vertebral column and compresses the abdominal wall; as individuals, they rotate the trunk and flex laterally.

They are supplied by the intercostal nerves of T7 through L1

Rectus abdominis

are a medial superficial pair of muscles that extend from the pubis to the ribcage.

It originates from the pubic crest and pubic symphysis.

It inserts into the xiphoid process and the costal cartilages of rib pairs five through seven.

It flexes and rotates the lumbar region of the vertebral column, fixes and depresses the ribs, and stabilizes the pelvis during walking.

It is supplied by the intercostal nerves of T6 through T12.

Serratus anterior

paired, fan-shaped muscle that forms the medial wall of the axilla.

It originates from a series of muscle slips from rib pairs one through nine.

It inserts into the anterior surface of the vertebral border of the scapula.

It rotates the scapula so that its inferior angle moves laterally and upwards.

It is supplied by the long thoracic nerve.

Diaphragm

is a broad muscle that forms the floor of the thorax.

It originates from the inferior, internal surface of the ribcage and sternum, as well as the costal cartilages of the last six ribs and lumbar vertebrae.

It inserts into the central tendon.

It is the prime mover of inspiration; it flattens during contraction, increasing the vertical dimensions of the thorax.

It is supplied by the phrenic nerves.

pectoralis Major

large, paired, fan-shaped muscle covering the superior portion of the chest.

It originates from the sternal end of the clavicle, the sternum, the cartilage of rib pairs one through seven, and the aponeurosis of the external oblique muscle.

It inserts by a short tendon into the intertubercular sulcus and the greater tubercle of the humerus.

It is the prime mover of arm flexion; it rotates the arm medially and adducts the arm.

It is supplied by the lateral and medial pectoral nerves.

Latissimus dorsi

broad, flat, paired, triangular muscle of the lower back.

It originates from the lower six thoracic vertebrae, the lumbar vertebrae, the four lowest rib pairs, the iliac crest, and the inferior scapular angle.

It inserts into the floor of the intertubercular sulcus of the humerus.

It is the prime mover of arm extension; it is a powerful arm adductor; it medially rotates the arm at the shoulder.

It is supplied by the thoracodorsal nerve.

Deltoid

thick, paired, triangular, multipennate muscle at the shoulder.

It originates from the lateral part of the clavicle, the acromion, and the spine of the scapula.

It inserts into the deltoid tuberosity of the humerus.

It is the prime mover of arm abduction and the antagonist of the pectoralis major and the latissimus dorsi.

It is supplied by the axillary nerve.

Teres Major

hick, paired, rounded muscle on the posterior wall of the axilla.

It originates from the lateral border of the dorsal scapular surface.

It inserts into the greater tubercle of the humerus.

It rotates the humerus laterally and stabilizes the shoulder joint.

It is supplied by the axillary nerve.

Infraspinatus

paired, thick, triangular muscle of the scapula.

It originates from the infraspinous fossa of the scapula.

It inserts into the superior part of the greater tubercle of the humerus.

It initiates abduction of the arm, stabilizes the shoulder joint, and prevents the humerus from being dislocated.

It is supplied by the suprascapular nerve.

Biceps brachii

paired, two-headed fusiform muscle.

Its short head originates from the coracoid process, its long head from the supraglenoid tubercle and the lip of the glenoid cavity.

It inserts into the radial tuberosity by the common tendon.

It flexes the elbow joint and supinates the forearm, usually simultaneously.

It is supplied by the musculocutaneous nerve

Triceps brachii

large, paired, fleshy, three-headed muscle on the posterior compartment of the arm.

Its long head originates from the infraglenoid tubercle of the scapula, its lateral head from the posterior shaft of the humerus, and its medial head from the posterior humeral shaft.

It inserts into the olecranon of the ulna by the common tendon.

It is the prime mover of forearm extension and the antagonist of forearm flexion.

It is supplied by the radial nerve.

Brachialis

strong, paired muscle deep to the biceps brachii.

It originates from the front of the distal humerus.

It inserts into the coronoid process of the ulna and the capsule of the elbow joint.

It is a major forearm flexor.

It is supplied by the musculocutaneous nerve

Brachioradialis

is a paired, superficial muscle of the lateral forearm

It originates from the lateral supracondylar ridge at the distal end of the humerus.

It inserts into the base of the radial styloid process.

It is a synergist in forearm flexion.

It is supplied by the radial nerve.

Palmaris longus

is a small, paired, fleshy muscle that is often absent.

It originates from the medial epicondyle of the humerus.

It inserts into the palmar aponeurosis, the fascia of the palm.

It tenses the skin and fascia of the palm during hand movements; it is a weak wrist flexor and a weak synergist for elbow flexion.

It is supplied by the median nerve.

Flexor carpi radialis

paired muscle that runs diagonally across the forearm.

It originates from the medial epicondyle of the humerus.

It inserts into the base of the second and third metacarpals.

It is a powerful flexor of the wrist, abducts the hand, and is a weak synergist of elbow flexion.

It is supplied by the median nerve.

Flexor digitorum superficialis

paired, two-headed muscle at the distal end of the forearm.

It originates from the medial epicondyle of the humerus, the coronoid process of the ulna, and the shaft of the radius.

It inserts into the middle phalanges of the second through fifth fingers by four separate tendons.

It flexes the wrist and the middle phalanges of the second through fifth fingers.

It supplies the median nerve.

Extensor carpi radialis

is a paired muscle that parallels the brachioradialis on the lateral forearm.

It originates from the lateral supracondylar ridge of the humerus.

It inserts into the base of the second metacarpal.

It helps extend the wrist and abduct the wrist.

It is supplied by the radial nerve.

Extensor digitorum

is a paired muscle that lies medial to the extensor carpi radialis brevis, which lies deep to the extensor carpi radialis.

It originates from the lateral epicondyle of the humerus.

It inserts into the distal phalanges of the second through fifth fingers by four separate tendons.

It is the prime mover of finger extension; it extends the wrist and abducts the fingers.

It is supplied by the posterior interosseous branch of the radial nerve.

Extensor digiti minimi

is a detached portion of the extensor digitorum.

It originates from the lateral epicondyle of the humerus.

It inserts into the distal phalanges of the second through fifth fingers by four separate tendons.

It extends the fifth finger.

It is supplied by the posterior interosseous branch of the radial nerve.

Extensor carpi ulnaris

is a long, paired, slender muscle.

It originates from the lateral epicondyle of the humerus and the posterior border of the ulna.

It inserts into the base of the fifth metacarpal.

It helps extend the wrist and adduct the wrist.

It is supplied by the posterior interosseous branch of the radial nerve.

Iliopsoas

A composite of two paired muscles: the iliacus and the psoas major. The iliacus is large, fan-shaped, and more lateral. The psoas major is longer, thicker, and more medial.

The iliacus originates from the iliac fossa, the iliac crest, and the ala of the sacrum. The psoas major originates from the transverse processes, transverse bodies, and the discs of T12 through L5.

The iliacus inserts into the lesser trochanter of the femur via the tendon. The psoas major inserts into the lesser trochanter of the femur via the iliopsoas tendon.

is the prime mover for thigh flexion; it also is an important postural muscle.

The iliacus is supplied by the femoral nerve. The psoas major is supplied by the ventral rami.