Cutaneous & Superficial Muscles of the Neck

Question 0

Insertion of SCM?

Answer 0

Lateral surface of mastoid process of temporal bone and lateral half of superior nuchal line

Question 1

Origin of SCM?

Answer 1

Sternal head: anterior surface of manubrium to sternum

Clavicular Head : superior surface of medial third of clavicle

Question 2

Innervation of SCM?

Answer 2

Spinal Accessory Nerve (CN: XI; motor), C2 and C3 (pain and proprioception)

Question 3

Actions of SCM?

Answer 3

Unilateral contraction: tilts head to the same side (lateral flexion of neck) and rotates it so face is turned superiorly toward opposite side (contralateral rotation)
Bilateral rotation : extends neck at atlanto-occipital joints, flexes cervical vertebrae so chin approaches manubrium, extends superior cervical vertebrae while flexing inferior vertebrae so chin is thrust forward with head kept level.
With cervical vertebrae fixed, may elevate manubrium and medial end of clavicles, assisting pump handle action of deep respiration.

Question 4

Origin of Platysma?

Answer 4

Fascia covering superior parts of pecs major and deltoid muscles

Question 5

Insertion of Platysma?

Answer 5

Inferior border of mandible, skin, subcutaneous tissues of lower face

Question 6

Innvervation of Platysma?

Answer 6

Cervical branch of facial nerve (CN VII)

Question 7

Actions of Platysma?

Answer 7

Draws corner of mouth inferiorly and widens it as in expression of sadness and fright, draws skin of neck superiorly while teeth are clenched, indicating tension