Neck Muscles

Question 1

Sternocleidomastoid

Answer 1

Origin: sternal head - anterior surface of manubrium, clavicular head - upper surface of medial 1/3 of clavicle

Insertion: lateral surface of mastoid process and lateral 1/2 of superior nuchal line

Innervation: accessory nerve (CN XI)

Blood Supply: SCM branch of superior thyroid and occipital arteries, muscular branch of suprascapular artery, and occipital branch of posterior auricular artery

Action: bilaterally - flex head, raise thorax, unilaterally - turns face toward opposite side

Question 2

Scalenes

Answer 2

Origin:
Anterior: anterior tubercles of transverse processes of C3-C6
Middle: posterior tubercles of transverse processes of C2-C7
Posterior: posterior tubercles of transverse processes of C4-C6

Insertion:
Anterior: scalene tubercle on 1st rib
Middle: upper surface of 1st rib
Posterior: outer surface of 2nd rib

Innervation:
Anterior: anterior rami of C5-C8
Middle: anterior rami of C3-C7
Posterior: anterior rami of lower 4 cervical nerves

Blood Supply:
Anterior: ascending cervical branch or inferior thyroid artery
Middle: muscular branches of ascending cervical artery
Posterior: Muscular branches of ascending cervical division of inferior thyroid artery and superficial branch of transverse cervical artery

Action:
Anterior: elevates 1st rib and bends neck
Middle: elevates 1st rib and bends neck
Posterior: elevates 2nd rib and bends neck

Question 3

Rectus Capitis Anterior

Answer 3

Origin: lateral mass of atlas

Insertion: base of occipital bone in front of foramen magnum

Innervation: ventral rami of C1-C2

Blood Supply: muscular branches of vertebral artery and ascending pharyngeal artery

Action: flexes head

Question 4

Rectus Capitis Lateralis

Answer 4

Origin: upper surface of transverse process of atlas

Insertion: inferior surface of jugular process of occipital bone

Innervation: ventral rami of C1-C2

Blood Supply: muscular branches of vertebral artery, occipital artery, and ascending pharyngeal artery

Action: flexes head laterally to same side

Question 5

Longus Colli

Answer 5

Origin:

• vertical portion: C5-T3 vertebrae
• inferior oblique portion: T1-T3 vertebrae
• superior oblique portion: anterior tubercles of transverse processes of C3-C5 vertebrae

Insertion:

• vertical portion: into C2-C4 vertebrae
• inferior oblique portion: anterior tubercles of transverse processes of C5-C6 vertebrae
• superior oblique portion: tubercle of anterior arch of atlas

Innervation: ventral primary rami of C2-C8

Blood Supply: prevertebral branches of ascending pharyngeal artery, muscular branches of ascending cervical and vertebral arteries

Action:

• bilaterally: flex and assist in rotating cervical vertebrae and head
• unilaterally: flexes vertebral column laterally

Question 6

Longus Capitis

Answer 6

Origin: anterior tubercles of transverse processes of C3-C6

Insertion: inferior surface of basilar part of occipital bone

Innervation: ventral rami of C1-C4

Blood Supply: ascending cervical branch of inferior thyroid artery, ascending pharyngeal artery, and muscular branches of vertebral artery

Action: flexes and assists in rotating cervical vertebrae and head