neck muscles

Question 1

Sternocleido mastoid (SCM)

Answer 1

origin: clavicle and manubrium
Insertion: temporal bone (mastoid process); occipital bone
Action: unilaterally: ipsilateral lateral flexion, contralateral rotation.
Bilaterally: neck flexion, C1-2 extension
may help elevate manubrium assisting pump-handle action of deep respiration
Innervation : Accessory nerve, C2, C3

Question 2

Platysma

Answer 2

• overlaps SCM
• attaches to fascia covering parts of pec major and deltoid and runs over the clavicle
• *attaches** to the inferior border of mandible
• muscle of facial expressions (sadness, fright) draws corners of mouth inferiorly
• thin & thin muscle
• *-Innervation**: cervical branch of facial nerve

Question 3

trapezius

Answer 3

• *lat attachment**: lateral third of clavicle, acromiom and spine of scapula
• *medial attachment**: superior nuchal line, external occipital protuberance, nuchal ligament, spinous processes of C7-T12
• *action**: stabilizes and moves scapula (elevate, depress and retract scapula)
• *innervation** : spinal accessory nerve

Question 4

anterior scalene

Answer 4

• *superior attachment**: transverse processes of C3-C6
• *inferior attachment**: 1st rib
• *action**: flexes neck laterally and elevates 1st rib during forced respiration
• *innervation:** cervical spinal nerves C4-C6

Question 5

middle scalene

Answer 5

• *sup attachement**: transverse processes of C4-C7
• *inferior attachent**: superior surface of 1st rib, posterior to groove for subclavian artery
• *action**: flex neck laterally and elevates 1st rib during forced respiration
• *innervation**: anterior rami of cervical spinal nerves

Question 6

posterior scalene

Answer 6

• *sup attachment**: transverse processes of C4-C6
• *inferior attachment** : external border of 2nd rib
• *action**: flexes neck laterally and elevates 2nd rib during forced respiration
• *innervation**: anterior rami of cervical spinal nerves C7 and C8