Anatomy
One of the intrinsic muscles of the back.
Consists of spinalis capitis, cervicus, thoracis.
Spinalis capitis:
Usually blends with semispinalis capitis.
Spinalis cervicis: (Not always present)
Origin: Ligamentum nuchae and spinous process of C7 (sometimes T1 to T2).
Insertion: Spinous process of axis (C2).
Spinalis thoracis:
Origin: Spinous processes of L2 toT11.
Insertion: Spinous processes of upper thoracic vertebrae.
Key Relations: Most medial muscle of erector spinae group. Interconnects the spinous processes of adjacent vertebrae.
Functions
-Working synergistically and bilaterally with longissimus and illocostalis, acts to extend the vertebral column. If used correctly, responsible for good posture.
-Acting unilaterally with longissimus and iliocostalis acts to laterally flex the spine on the ipsilateral side.
Supply
Nerve Supply:
Dorsal rami of segmental spinal nerves.
Blood Supply:
Lateral sacral artery.
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