Week III Muscles

Question 1

Sternocleidomastoid

Answer 1

O: sternal head- anteromedial manumbium of the sternum
clavicular head- medial (one third of the) clavicle

I: mastoid process of the temporal bone and lateral superior nuchal line of the occipital bone

A: Unilaterally- laterally flexes the head and neck to the same side at the spinal joints, rotates the head and neck to the opposite side (contralaterally rotates) at the spinal joints
Bilaterally- flexes the head and neck at the spinal joints

Question 2

Scalenes

Answer 2

O: as a group- transverse processes (TPs) of C2-C7

I: anterior & middle- first rib (posterior to clavicle)
posterior- second rib (at or above trapezius)

A: Unilaterally- with ribs fixed, laterally flexes the neck to the same side at the spinal joints, rotates the neck to the opposite side (contralaterally rotates) at the spinal joints
Bilaterally- flexes the neck at the spinal joints (anterior and middle scalenes (elevates the ribs during inhalation at the sternocostal and costospinal joints)

Question 3

Splenius Capitis

Answer 3

O: inferior (one half) ligamentum nuchae and spinous processes (SPs) of C7-T4

I: mastoid process of the temporal bone and lateral (one third of the) superior nuchal lines of the occipital bone

A: Unilaterally- laterally flexes the head and neck to the same side as the spinal joints, rotates the head and neck to the same side (ipsilaterally rotates) at the spinal joints
Bilaterally- extends the head and neck at the spinal joints

Question 4

Splenius Cervicis

Answer 4

O: spinous processes (SPs) of T3-T6

I: transverse processes (TPs) of C1-C3

A: Unilaterally- laterally flexes the neck to the same side at the spinal joints, rotates the neck to the same side (ipsilaterally rotates) at the spinal joints
Bilaterally- extends the neck at the spinal joints