Superficial Muscles of the Neck

Question 1

Sternocleidomastoid

Answer 1

Origin: manubrium of the sternum and medial one third of the clavicle

Insertion: lateral aspect of the mastoid process of temporal bone

Innervation: CN XI

Action: rotates the head opposite the contracted side; laterally flexes the neck to the contracted side; bilaterally flexes the neck

Question 2

Trapezius

Answer 2

Origin: external occipital protuberence of the skull, C1-T12 spinous processes

Insertion: clavicle (upper fibers), acromion (middle fibers), scapular spine (lower fibers)

Innervation: subtrapezial nerve plexus (CN XI and C3 and C4 ventral rami)

Action: moves shoulder girdle

Question 3

Digastric:

Anterior Belly (AB)

Posterior Belly (PB)

Answer 3

Origin: digastric fossa of mandible (AB), mastoid process (PB)

Insertion: digastric tendon to hyoid bone

Innervation: mylohyoid n. (AB), CN VII (PB)

Action: lowers the mandible or raises hyoid (AB), elevates and retracts hyoid (PB)