MUSCLES OF THE SHOULDER (PECTORAL) GIRDLE
TRAPEZIUS
Medial Attachment of upper fibers:
External occipital protuberance, superior nuchal line (base of skull), and ligamentum nuchae (posterior ligaments of the neck).
Medial Attachment of middle fibers:
Spinous processes of C7 and T1-T3.
Medial Attachment of lower fibers:
Spinous processes of T4-T12.
Lateral Attachment of upper fibers:
Posterior aspect, lateral one-third of clavicle.
Lateral Attachment of middle fibers:
Medial margin of acromion process and superior lip (upper border) of spine of scapula.
Lateral Attachment of lower fibers:
Tubercle at apex (triangular space at the base) of the scapular spine.
Action:
With the medial attachment or trunk fixed: adduction of the scapula, performed chiefly by the middle fibers with stabilization by the upper and lower fibers. Upward Rotation of the scapula performed chiefly by the upper and lower fibers. In addition, the upper fibers elevate and the lower fibers depress the scapula.
With the Lateral Attachment or scapula fixed:
Acting unilaterally, the upper fibers extend, laterally flex, and rotate the head and joints of the cervical vertebrae so that the face turns toward the opposite side. Acting bilaterally, the upper trapezius extends the neck.
Nerve:
Spinal portion of Cranial Nerve XI (Spinal Accessory), and ventral ramus, C3, 4.
RHOMBOID MAJOR
Medial Attachment:
Spinous processes of second through fifth thoracic vertebrae (T2-T5).
Lateral Attachment:
Medial border of scapula between the spine and inferior angle.
Action:
Adduct and elevate and downward rotation of the scapula.
Nerve:
Dorsal scapular.
RHOMBOID MINOR
Medial Attachment:
Spinous processes of seventh cervical and first thoracic vertebrae (C7 & T1).
Lateral Attachment: Medial border at root or base of spine of scapula.
Action:
Adduct and elevate and downward rotation of the scapula.
Nerve:
Dorsal scapular.
LEVATOR SCAPULAE
Medial Attachment:
Transverse processes of first four cervical vertebrae (C1-C4).
Lateral Attachment: Medial border of scapula between superior angle and root of spine.
Action: With the Medial Attachment or trunk fixed: Elevates the scapula.
With the Lateral Attachment fixed: Acting unilaterally, laterally flexes the cervical vertebrae and rotates their spines toward the same side. Acting bilaterally, the Levator scapulae may assist in extension of the cervical spine.
Nerve: Cervical plexus C3, C4 and Dorsal scapular.
SERRATUS ANTERIOR
Lateral Attachment:
Outer surfaces of upper nine ribs.
Medial Attachment: Costal (anterior) surface of medial border of scapula.
Action: Abducts the scapula and performs upward rotation of the scapula.
Nerve: Long thoracic.
PECTORALIS MINOR
Inferior Attachment:
Anterior surfaces of third, fourth, and fifth ribs near the cartilages.
Superior Attachment: Medial border, superior surface of coracoid process of scapula.
Action: Tilts the scapula anteriorly, i.e., rotates the scapula about a mediolateral axis so that the coracoid process moves anteriorly and inferiorly, while the inferior angle moves posteriorly and medially.
With the scapula stabilized, the Pectoralis Minor assists in forced inspiration.
Nerve: Medial pectoral.