gross day 4: muscles of the posterior cervical triangle

Question 1

sternocleidomastoid

Answer 1

Origin: s-head: ant surface of manubrium, c-head: Sup surf of medial 1/3 of clavicle
Insertion: lateral surf of mastoid process, lateral 1/2 of superior nuchal line
Innervation: CN XI (accessory) and C2, C3 (pain, proprio)
Action: ipsilaterally tilts head, rotates face contralaterally and superior; Bi: extends neck at AO joint; cervical flection, protraction of head

Question 2

anterior scalene

Answer 2

Origin: ant tubercles of t-pros of C3-C6
Insertion: scalene tubercle of 1st rib
Innervation: C4-C6
Action: flexes neck laterally, elevates 1st rib in forced inspiration

Question 3

middle scalene

Answer 3

Origin: post tubercles of t-pros of C4-C7
Insertion: superior surf of 1st rib posterior to groove for subclavian A.
Innervation: anterior rami of cervical nerve
Action: flexes neck laterally, elevates 1st rib in forced inspiration

Question 4

posterior scalene

Answer 4

Origin: post tubercles of transverse processes of C4-C6
Insertion: external border of 2nd rib
Innervation: ant rami of C7, C8
Action: flexes neck laterally, elevates 2nd rib in forced inspiration

Question 5

platysma

Answer 5

Origin: inf border of mandible, skin, and subcutaneous tissues of lower face
Insertion: fascia covering superior parts of pectoralis major and deltoid muscles
Innervation: cervical branch of facial nerve (CN VII)
Action: frowning, widening mouth; draws skin of neck superiorly when teeth are clenched indicating tension