Deep Layers of Intrinsic Back Muscles

Question 1

Transversospinales

Answer 1

Semispinalis, Multifidus, Rotatores (Brevis & Longus)

All innervated by Dorsal Rami of Spinal nerves

Question 2

Semispinalis

Region, Origin, Insertion-2, Action

Answer 2

Regions: Thoracis, Cervicis, and Capitis

Origin: Transverse processes of C4-T10

Insertion:

• Occipital bone
• Spinous processes in cervical and upper thoracic vert.
• Spans 4-6 segments

-Bilaterally:
Extends head, cervical, & thoracic regions
-Unilaterally: Contralateral rotation

Question 3

Multifidis

Origin-7, Insertion, Action

Answer 3

Origin:

• Posterior Sacrum
• PSIS
• Erector Spinae aponeurosis
• SI Ligaments
• Mammilary Processes
• Transverse processes T1-T3
• Articular processes C4-C7

Insertion: Spinous processes 2-4 segments above origin

• Bilaterally: Extension
• Stabilization
• Unilaterally:Contralateral rotation

Question 4

Rotatores

Origin, Insertion, Action

Answer 4

Origin: Transverse processes of vertebra best developed in cervical

Insertion: Junction of lamina & transverse/spinous processes of vertebrae immediately (brevis) or 2 segments (longus) superior to origin

Action: Proprioceptive, stabilization

Question 5

Serratus Posterior Superior

Origin-2, Insertion, Innervation, Action

Answer 5

Origin:

• Nuchal Ligament
• Spinous processes of C7-T3

Insertion: Superior borders of 2nd-4th ribs

Innervation: 2nd-5th Intercostal nerves

Action: Elevates ribs

Question 6

Serratus Posterior Inferior

Origin, Insertion, Innervation, Action

Answer 6

Origin: Spinous processes of T11-L2

Insertion: Inferior borders of 8th-12th ribs near angles

Innervation:
-9th-11th intercostal nerves -Subcostal nerve (T12)

Action: Depress ribs