Muscles that Act on the Scapula

Trapezius

Trapezoid-shaped muscle of the upper back responsible for scapular elevation, adduction/retraction, upward rotation, and depression. It also extends the neck.

Trapezius Origin

Nuchal line of the occipital bone and spinous processes of cervical and thoracic vertebrae

Trapezius Insertion

clavicle, acromion, spine of scapula

rhomboid major

Mid back muscle that lies underneath the trapezius and is inferior to the rhomboid minor.

rhomboid major and minor function

Assist the trapezius in downward rotation of the scapula and also in adduction or retraction of the scapula

rhomboid major origin and insertion

Origin: T2-T5

Insertion: Lower medial border of the scapula

rhomboid minor

Mid back muscle that lies underneath the trapezius and is superior to the rhomboid major.

rhomboid minor origin and insertion

Origin: C7-T1

Insertion: The medial border of the scapula at the level of the scapular spine.

serratus anterior

A large muscle that runs along the rib cage, also known as the "boxer's muscle." Helps in upward rotation and abduction or protraction of the scapula.

serratus anterior origin

ribs 1-8

serratus anterior insertion

anterior surface of medial border of scapula

levator scapulae

Muscle that lies along the back and side of the neck that elevates the scapula and rotates the scapula downward.

levator scapulae origin and insertion

Origin: transverse process of C1-c4;

Insertion: Upper medial border of scapula (superior angle)

Pectoralis minor

Chest muscle deep to the pectoralis major. Generally classified as a muscle of respiration during sub- maximal and maximal work.

pectoralis minor (action)

Action: Elevates the ribs and depresses and protracts the scapula.

Deltoid

Triangular-shaped shoulder muscle, consisting of an anterior, lateral, and posterior head.

Deltoid insertion

deltoid tuberosity of humerus

Anterior deltoid origin and action

Origin: clavicle

Action: head flexes and medially rotates the shoulder joint.

Lateral deltoid origin and action

Origin: acromion

Action: Abducts the arm.

Posterior deltoid origin and action

Origin: spine of scapula

Action: extends and laterally rotates the arm.

Coracobrachialis (origin, insertion, and action)

Origin: coracoid process

Insertion: medial aspect of humerus

Action: flexes the shoulder; adducts the arm

Teres major ( action)

Action: extension, adduction, and medial rotation of humerus