Unit 2 - Upper Limb: SCM, Scalenes, and Omohyoid (Ex. II)

Question 1

clavicular head of sternocleidomastoid

Answer 1

O: M 1/3 of clavicle
I: mastoid process of T bone; S nuchal line of O bone
Inn: motor - spinal accessory N (CN XI); pain and proprioception - C plexus (C2, C3)
A: ipsilaterally laterally flexes head and contralaterally rotates; together extends head and aids in respiration when head is fixed

Question 2

omohyoid

Answer 2

O: S borer of scapula
I: body of hyoid bone
Inn: ansa cervicalis of C plexus (C1-C3)
A: depresses (fixes) hyoid; depresses larynx and hyoid for phonation and terminal phases of swallowing; also tenses cervical fascia w/ an intermediate tendon

Question 3

A scalene

Answer 3

O: A tubercles of transverse processes of C3-C6
I: scalene tubercle of rib 1
Inn: direct branches from C and B plexuses (C3-C8)
A: w/ ribs mobile - elevates upper ribs (forced inspiration); w/ ribs fixed - ipsilaterally laterally flexes C spine and together flexes neck

Question 4

middle scalene

Answer 4

O: transverse processes of C1-C2; P tubercles of transverse processes of C3-C7
I: on rib 1 P to groove for subclavian a.
Inn: direct branches from C and B plexuses (C3-C8)
A: w/ ribs mobile - elevates upper ribs (forced inspiration); w/ ribs fixed - ipsilaterally laterally flexes C spine and together flexes neck

Question 5

P scalene

Answer 5

O: P tubercles of transverse processes of C5-C7
I: outer surface of rib 2
Inn: direct branches from C and B plexuses (C3-C8)
A: w/ ribs mobile - elevates upper ribs (forced inspiration); w/ ribs fixed - ipsilaterally laterally flexes C spine and together flexes neck

Question 6

sternal head of sternocleidomastoid

Answer 6

O: manubrium of sternum
I: mastoid process of T bone; S nuchal line of O bone
Inn: motor - spinal accessory N (CN XI); pain and proprioception - C plexus (C2, C3)
A: ipsilaterally laterally flexes head and contralaterally rotates; together extends head and aids in respiration when head is fixed