Lecture 8: Muscles Axial Skeleton

Question 1

Muscles of the anterior neck and throat: swallowing

Give the names and differences of the supra hyoid a d infrahyoid and their actions, innervations, origin and insertions

Answer 1

Suprahyoid

Question 2

Muscles of neck and vertebral column: head movements 
Anterolateral neck muscles 
-sternocleidomastoid
-scalenes (anterior, middle, posterior)
Origin, insertion, action, innervation

Answer 2

Sternocleidomastoid:
ORIGIN: Sternal head: anterior surface of manubrium; Clavicular head: medial third of clavicle
INSERTION: Mastoid process and lateral part of the superior nuchal line
ACTION: Inclines head ipsilaterally, rotates contralaterally
NERVE SUPPLY: Spinal accessory nerve (CN XI), with sensory supply from C2 and C3
ARTERIAL SUPPLY: Sternocleidomastoid branch of the occipital artery….
Scalene anterior:
ORIGIN: Anterior tubercles of transverse processes C3-C6

INSERTION: Scalene tubercle at first rib

ACTION: Elevates the ribs, flexes and inclines cervical spine ipsilaterally

NERVE SUPPLY: Brachial plexus, C5-C7
Scalene middle:
ORIGIN: Posterior tubercles of the transverse process of C2-C7

INSERTION: Upper surface of the first rib behind the subclavian artery

ACTION: Elevates upper ribs, flexes and inclines cervical spine ipsilaterally

NERVE SUPPLY: Brachial plexus, C3-C8
Scalene posterior:
ORIGIN: Posterior tubercles of transverse processes C5-C7

INSERTION: Lateral surface of the second rib

ACTION: Elevates upper ribs, flexes and inclines cervical spine ipsilaterally

NERVE SUPPLY: Brachial plexus, C3-C8

ARTERIAL SUPPLY: Ascending cervical artery

Question 3

Intrinsic muscles of the back:

1. Splenis capitis
2. Splenious cervicis
3. Erector spinae

Answer 3

1. Splenis capitis
   ORIGIN: Ligamentum nuchae and spinous processes of C7-T6 vertebrae

INSERTION: Mastoid process and lateral end of the superior nuchal line

ACTION: Rotates head ipsilaterally, extension and lateral flexion of the cervical spine and head

NERVE SUPPLY: Dorsal primary rami of spinal nerves C2-C6

ARTERIAL SUPPLY: Deep cervical artery, posterior intercostal arteries

2. Splenious cervicis
3. ORIGIN: Ligamentum nuchae and spines of C7-T6 vertebrae

INSERTION: Posterior tubercles of the transverse processes of C1-C3 vertebrae

ACTION: Extension and lateral flexion of head and neck; Ipsilateral rotation of head

NERVE SUPPLY: Dorsal primary rami of spinal nerves C2-C6

ARTERIAL SUPPLY: Deep cervical artery, posterior intercostal arteries
3. Erector spinae

Question 4

4. Iliocostalis
5. Longissimus
6. Spinalis

Answer 4

4. Iliocostalis cervical part
   ORIGIN: Angles of 1st-6th cervical ribs

INSERTION: Transverse processes C4-C6

ACTION: Extension, abduction, and rotation of cervical vertebrae

NERVE SUPPLY: Dorsal branches of upper thoracic nerves

ARTERIAL SUPPLY: Deep cervical artery, posterior intercostal arteries, subcostal arteries
5. Longissimus capitis
ORIGIN: Transverse processes of upper 4th-5th thoracic vertebrae and articular processes of three lower cervical vertebrae

INSERTION: Posterior margin of the mastoid process

ACTION: Bilateral extension and ipsilateral lateral flexion of the head, neck and trunk

NERVE SUPPLY: Dorsal primary rami of spinal nerves (C1-S1)
6. Spinalis capitis
ORIGIN: Spinous processes of C6-C7 cervical vertebrae

INSERTION: Spinous processes of upper cervical vertebrae

ACTION: Extension of cervical spine

NERVE SUPPLY: Dorsal primary rami of spinal nerves C2-C6

Question 5

7. Semispinalis

8. Quadratus lumborum

Answer 5

7. Semispinalis capitis
   ORIGIN: Transverse and articular processes of C3-T6

INSERTION: Posterior occipital bone, below superior nuchal line

ACTION: Extends and laterally flexes the cervical and thoracic spine and head

NERVE SUPPLY: Dorsal primary rami of spinal nerves C1-T12

8. Quadratus lumborum
   ORIGIN: Posterior part of the iliac crest and iliolumbar ligament

INSERTION: 12th rib and transverse processes of L1-L4

ACTION: Bends trunk ipsilaterally, fixes the 12th rib aids in expiration

NERVE SUPPLY: Subcostal nerve, ventral primary rami of spinal nerves (L1-L4, T12)

Question 6

Muscles of the thorax: breathing

1. External intercoastals
2. Internal intercoastals
3. Diaphragm

Answer 6

1. External intercoastals
   ORIGIN: Inferior margin of superior rib

INSERTION: Fibers insert medially downward into superior margin of inferior rib

ACTION: Elevation of ribs; aids in inspiration to keep intercostal space stable

NERVE SUPPLY: Intercostal nerves (T1-T11)

ARTERIAL SUPPLY: Intercostal artery
2. Internal intercoastals
ORIGIN: Lateral edge of costal groove of inferior rib

INSERTION: Fibers insert medially upward into inferior margin of superior rib

ACTION: Depresses ribs; aids in expiration to keep intercostal space stable

NERVE SUPPLY: Intercostal nerves (T1-T11)

ARTERIAL SUPPLY: Intercostal artery

3. Diaphragm
   ORIGIN: Xiphoid process, inner surface of 7th to 12th ribs, anterior surfaces of L1-L3, fascia over the quadratus lumborum and psoas major muscles via medial and lateral arcuate ligaments

INSERTION: Central tendon of the diaphragm

ACTION: Inhalation: contraction, increasing the volume of thoracic cavity; pushes abdominal viscera inferiorly

NERVE SUPPLY: Phrenic nerve (C3-C5)

ARTERIAL SUPPLY: Musculophrenic artery, superior phrenic artery, inferior phrenic artery