Intrinsic Back Muscles - Deep Layer (Transversospinales)

Question 1

Semispinalis (thoracis, cervicis, and capitis)

1O, 2I, 1N, 3A

Answer 1

O:
+ transverse processes of C4-T10

I:
+ occipital bone
+ spinous processes in upper thoracic and cervical regions, span 4-6 segments

N:
+ posterior rami of spinal nerves

A:
+ extends head
+ extends thoracic and cervical regions of the spinal column
+ rotates head, thoracic, and cervical regions contralaterally

Question 2

Multifidus

7O, 1I, 1N, 2A

Answer 2

O:
\+ posterior sacrum
\+ PSIS of ilium
\+ aponeurosis of erector spinae
\+ SI ligaments
\+ mammillary processes of lumbar vertebrae
\+ transverse processes of thoracic vertebrae
\+ articular processes of C4-C7

I:
+ entire length of spinous processes of vertebrae located 2-4 segments superior to origin

N:
+ posterior rami of spinal nerves

A:
+ unilateral contraction: rotates to contralateral side
+ stabilizes the vertebrae during local movements of the vertebral column

Question 3

Rotatores (brevis and longus)

1O, 1I (for each), 1N, 3A

Answer 3

O:
+ transverse processes of vertebrae, best developed in thoracic region

I:
+ junction of lamina and transverse process/spinous process of vertebrae
=> immediately (brevis)
=> two segments superior to vertebra of origin (longus)

N:
+ posterior rami of spinal nerves

A:
+ proprioception
+ stabilize vertebrae
+ assist with local extension and rotator movements of the vertebral column