SMD 261- Shoulder and Chest Muscles Complete

Pectoralis Major

Origin: Medial half of clavicle, sternum, and cartilage of first through sixth ribs

Insertion: Crest of greater tubercle of humerus

Action: All Fibers adduct the shoulder, medially rotate the shoulder, assist to elevate the thorax during forced inhalation. Upper fibers flex the shoulder and horizontally adduct the shoulder. Lower fibers extend the shoulder.

Nerve: Lateral and medial pectoral

Pectoralis Minor

Origin: Third, fourth, and fifth ribs.

Insertion: Medial surface of coracoid process of the scapula.

Action: Depress the scapula, abduct the scapula, downwardly rotate the scapula, assist to elevate the thorax during forced inhalation

Nerve: Medial pectoral and fibers from lateral pectoral

Biceps Brachii long head

Origin: Supraglenoid tubercle of scapula

Insertion: Tuberosity of the radius and aponeurosis of the biceps brachii

Action: Flex the shoulder

Nerve: Musculocutaneous

Biceps brachii Short Head

Origin: Coracoid process of scapula

Insertion: Tuberosity of radius and aponeurosis of the biceps brachii

Action: Flex the shoulder

Nerve: Musculocutaneous

Deltoid

Origin: Lateral 1/3rd of clavicle, acromion, and spine of scapula

Insertion: Deltoid tuberosity

Action: All fibers abduct the shoulder, Anterior fibers flex the shoulder, medially rotate the shoulder, and horizontally adduct the shoulder. Posterior fibers extend the shoulder, laterally rotate the shoulder, and horizontally abduct the shoulder.

Nerve: Axillary

Latissimus dorsi

Origin: Inferior angle of scapula, spinous processes of last six thoracic vertebrae, last three or four ribs, thoracolumbar fascia, and posterior iliac crest.

Insertion: Intertubercular groove of the humerus

Action: Extend the shoulder, adduct the shoulder, medially rotate the shoulder.

Nerve: Thoracodorsal

Teres Major

Origin: Inferior angle and lower one-third of lateral border of the scapula.

Insertion: Crest of the lesser tubercle of the humerus

Action: Extend the shoulder, adduct the shoulder, medially rotate the shoulder.

Nerve: Lower subscapular

Trapezius

Origin: External occipital protuberance, medial portion of superior nuchal line of the occiput, ligamentum nuchae, and spinous processes of C-7 through T-12

Insertion: Lateraly 1/3rd of clavicle, acromion, and spine of the scapula

Action: Upper fibers elevate the scapula and upwardly rotate the scapula. Middle fibers retract the scapula and stabilize the scapula. Lower fibers depress the scapula and upwardly rotate the scapula.

Nerve: Spinal portion of cranial nerve XI and ventral ramus.

Rhomboid Major

Origin: Spinous process of T2 through T5.

Insertion: Medial border of the scapula between the spine of the scapula and inferior angle.

Action: Adduct the scapula, elevate the scapula, downwardly rotate the scapula.

Nerve: Dorsal scapular

Rhomboid Minor

Origin: Spinous process of C7 and T1

Insertion: Upper portion of medial border of the scapula, across from spine of the scapula

Action: Adduct the scapula, elevate the scapula, downwardly rotate the scapula

Nerve: Dorsal Scapular

Teres Minor

Origin: Upper 2/3rds of lateral border of the scapula

Insertion: Greater tubercle of the humerus

Action: laterally rotate the shoulder, adduct the shoulder, stabilize the head of humerus in glenoid cavity

Nerve: Axillary

Group: Rotator Cuff

Levator Scapulae

Origin: Transverse processes of the first through fourth cervical vertebrae

Insertion: Medial border of scapula, between superior angle and superior portion of spine of scapula

Action: Elevate the scapula, downwardly rotate the scapula

Nerve: Cervical and dorsal scapular

Coracobrachialis

Origin: Coracoid process of the scapula

Insertion: Medial surface of mid-humeral shaft

Action: Flex the shoulder, adduct the shoulder

Nerve: Musculocutaneous

Supraspinatus

Origin: Supraspinous fossa of the scapula

Insertion: Greater tubercle of the humerus

Action: Abduct the shoulder, stablize the head of the humerus in the glenoid cavity

Nerve: Suprascapular

Group: Rotator Cuff

Infraspinatus

Origin: Infraspinous fossa of the scapula

Insertion: Greater tubercle of the humerus

Action: Laterally rotate the shoulder, adduct the shoulder, stabilize the head of the humerus in the glenoid cavity

Nerve: Suprascapular

Group: Rotator Cuff

Subscapularis

Origin: Subscapular fossa of the scapula

Insertion: Lesser tubercle of the humerus

Action: Medially rotate the shoulder, stabilize the humerus in the the glenoid cavity

Nerve: Upper and lower subscapular

Group: Rotator Cuff

Serratus Anterior

Origin: External surfaces of upper eight or nine ribs.

Insertion: Anterior surface of medial border of the scapula

Action: With the origin fixed, abduct the scapula, upwardly rotate the scapula, depress the scapula, hold the medial border of the scapula against the rib cage. With the scapula fixed, elevate the thorax during forced inhalation.

Nerve: Long thoracic

Triceps Long Head

Origin: Infraglenoid tubercle of the scapula

Insertion: Olecranon process of the ulna

Action: Extend the elbow, extend the shoulder, adduct the shoulder

Nerve: Radial