Unit 4 - Head and Neck: Superficial Neck Muscles (Ex. III)

Question 1

sternal head of sternocleidomastoid

Answer 1

O: manubrium of sternum
I: mastoid process of T bone; S nuchal line of O bone
Inn: accessory n. (CN XI); C plexus (C2, C3)
A: ipsilaterally laterally flexes head and contralaterally rotates; bilaterally extends head and aids in respiration w/ head fixed

Question 2

clavicular head of sterncleidomastoid

Answer 2

O: M 1/3 of clavicle
I: mastoid process of T bone; S nuchal line of O bone
Inn: accessory n. (CN XI); C plexus (C2, C3)
A: ipsilaterally laterally flexes head and contralaterally rotates; bilaterally extends head and aids in respiration w/ head fixed

Question 3

descending trapezius

Answer 3

O: EOP; nuchal ligament
I: L 1/3 of clavicle
Inn: accessory n. (CN XI); C plexus (C2, C3)
A: L rotates scapula; rotates glenoid cavity S

Question 4

platysma

Answer 4

O: skin over lower neck and upper L thorax
I: I border of mandible; skin over lower face and angle of mouth
Inn: C branch of facial n. (CN VII)
A: depresses and wrinkles skin of lower face and mouth; tenses skin of neck; forced depression of mandible