Other Muscles That Move The Arm And Pectoral Girdle

Front 1

Teres major

Back 1

* extends from the lower lateral border and inferior angle of the scapula to the medial edge of the intertubercular groove of the humerus
* medially rotates and adducts the humerus

Front 2

Coracobrachialis

Back 2

* a small cylindrical muscle which extends from the tip of the coracoid process of the scapula to the middle of the humerus on the medial side
* adducts and flexes the humerus

Front 3

Trapezius

Back 3

* upwardly rotates the scapula --> elevates the arm
* acts together with the serratus anterior

Front 4

Serratus anterior

Back 4

* forms medial wall of the axilla
* acts together with the trapezius to rotate the scapula upwards --> elevates the arm
* can also rotate the scapula downwards --> lowers the arm

Front 5

Lavator scapulae

Back 5

* extends from the cervical verts to the upper medial border of the scapula
* works together with the rhomboids and pectoralis minor to produce downward rotation of the scapula --> lowers the arm
* works with trapezius to elevate and retract the scapula --> rotates the arm

Front 6

Pectoralis minor

Back 6

* extends from several ribs on the front of the chest to the coracoid process on the scapula
* acts together with the rhomboids and lavator scapulae to produce downward rotation of the scapula --> lowers the arm

Front 7

Rhomboids

Back 7

* extend from the spines of the thoracic verts to the medial border of the scapula
* rhomboid minor is superior to and smaller than rhomboid major
* both act together with the lavator scapulae and pectoralis minor to perform downward rotation of the scapula --> lowers the arm

Front 8

Deltoid

Back 8

* makes up the bulk of the shoulder mass
* originates from the outer lateral part of the clavicle, to the acromion process and around the shoulder to the scapular spine, then inserts into the deltoid tuberosity on tge lateral side of the shaft of the humerus
* principle elevator of the arm
* anterior fibers flex the humerus
* posterior fibers extend the humerus

Front 9

Pectoralis major

Back 9

* extends as 2 branches from the front of the medial half of the clavicle and from the front of the sternum to the crest of the greater tubercle on the humerus
* clavicular fibers act to flex the humerus
* adducts the humerus

Front 10

Latissimus Dorsi

Back 10

* triangular muscle of the lower back which contributes to the posterior wall of the axilla
* extends from the lower thoracic spinous processes and the iliac crest to the intertubercular groove of the humerus
* prime muscle that lowers the arm
* adducts the humerus
* some fibers are active in extension of the humerus
* when arm is fixed, can draw the whole body upwards