Deep or Intrinsic Muscles of the Back

Question 1

Splenius Capitis and Cervicis (Intrinsic Superficial)

Answer 1

Origin: Ligamentum nuchae, spinous processes of vertebrae C7-T3 (capitis) C7-T6 (cervicis)
Insertion: Mastoid process of temporal and nuchal line of occipital (capitis), transverse process of C2-C4 vertebrae (cervicis)
Action: Extend or hyperextend the head, laterally rotate and flexes head to same side
Innervated by the dorsal rami of cervical spinal nerves

Question 2

Iliocostalis (Intrinsic Intermediate)

Answer 2

Origin: Iliac crest (lumborum); inferior 6 ribs (thoracis), ribs 3-6 (cervicis)
Insertion: Angles of ribs (lumborum and thoracis), transverse processes of cervical vertebrae C4-C6 (cervical)
Action: Extend and laterally flexes vertebral column, extends head and neck, maintain erect posture and acting on one side, bends vertebral column to same side
Innervated by the dorsal rami of spinal nerves

Question 3

Longissimus (Intrinsic Intermediate)

Answer 3

Origin: Transverse process of lumbar through cervical vertebrae
Insertion: Transverse processes of thoracic through cervical vertebrae and to ribs superior origin. Capitis inserts into mastoid processes of temporal bone
Action: Thoracics and cervices act together to extend vertebral column, acting on one side, bend laterally. Capitis extends head and turns face towards same side
Innervated by the dorsal rami of spinal nerves

Question 4

Spinalis (Intrinsic Intermediate)

Answer 4

Origin: Spines of upper lumbar and lower thoracic vertebrae
Insertion: Spines of upper thoracic and cervical vertebrae
Action: Extends vertebral column, extends head and neck
Innervated by the dorsal rami of spinal nerves

Question 5

Multifidus (Intrinsic Deep)

Answer 5

Origin: Posterior sacrum, L1-5 mamillary processes, T1-12 transverse prcoesses, C4-7 articular prcoesses
Insertion: spinous processes (~4 vertebrae above)
Action: Bilaterally extends spine; unilaterally rotates spine to opposite side
Innervated by the dorsal rami of spinal nerves

Question 6

Rotatores (Intrinsic Deep)

Answer 6

Origin: Transverse processes under multifidus
Insertion: Spinous processes (1-2 vertebrae above)
Action: Bilaterally extend spine; unilaterally rotate spine to opposite side
Innervated by the dorsal rami of spinal nerves

Question 7

Serratus Posterior Superior

Answer 7

Origin: Ligamentum nuchae, spinous process of C7-T6
Insertion: Ribs 2-5
Action: Respiratory
Innervated by the intercostal nerves

Question 8

Semispinalis (Intrinsic Deep)

Answer 8

Origin: Transverse process of C7-T12
Insertion: Occipital bone (capitis); spinous processes of cervical (cervicis) and thoracic vertebrae T1-T4 (thoracis)
Action: Bilaterally extends head and spine; Unilaterally rotates head and neck to opposite side
Innervated by spinal nerves (dorsal rami)

Question 9

Serratus Posterior Inferior

Answer 9

Origin: T11-L2
Insertion: Ribs 9-12
Action: Respiratory
Innervated by the intercostal nerves