4/6 Muscles of Posterior Cervical Triangle + Upper Trap and Splenius Capitis

Question 1

Sternocleidomastoid (Sternal head and clavicular head)

2SA, 1IA, 2N, 6A

Answer 1

Superior attachment:
+ lateral surface of the mastoid process of temporal bone
+ lateral half of the superior nuchal line

Inferior attachment:
+ sternal head: anterior surface of manubrium of the sternum
+ clavicular head: superior surface of medial third of the clavicle

N:
+ spinal accessory nerve (XI; motor)
+ C2+C3 nerves (pain and proprioception)

A:
unilaterally:
+ laterally flexes the neck
+ rotates the neck so face is turned superiorly toward opposite side

Bilaterally:
+ extends neck at AO joints
+ flexes cervical vertebrae
+ extends superior cervical vertebrae while flexing the inferior vertebrae so the chin is thrust forward with head kept level
+ with cervical vertebrae fixed, elevate the manubrium+medial end of clavicles, deep respiration

Question 2

anterior scalene

1O, 1I, 1N, 2A

Answer 2

O:
+ anterior tubercles of transverse processes of C3-C6

I:
+ 1st rib

N:
+ Cervical spinal nerves C4-C6

A:
+ flexes neck laterally
+ elevates 1st rib during forced inspiration

Question 3

Middle scalene

Answer 3

O:
+ posterior tubercles of transverse processes of C4-C7

I:
+ superior surface of 1st rib

N:
+ anterior rami of cervical spinal nerves

A:
+ flexes neck laterally
+ elevates 1st rib during forced inspiration

Question 4

Posterior scalene

Answer 4

O:
+ posterior tubercles of transverse processes of C4-C6

I:
+ external border of 2nd rib

N:
+ anterior rami of spinal nerves C7 and C8

A:
+ flexes neck laterally
+ elevates 2nd rib during forced inspiration