The spinalis muscle is part of the erector spinae, which is made up of tendons and muscles and located near the spine. The spinalis is the body's most medial deep back muscle and originates at the spinous processes of the inferior vertebral levels. It inserts there, as well as at the skull's base. It innervates at the dorsal primary rami belonging to spinal nerves C2 to L3. The spinalis is split into three parts: the spinalis dorsi, the spinalis cervicis, and the spinalis capitis. The spinalis dorsi and spinalis capitis are rarely considered as separable distinct muscles; they are connected with the semispinalis capitis. The spinalis cervicus is an inconstant muscle that inserts into the spinosus process of the spine's axis and sometimes into its two lower vertebrae. The spinalis muscle's most medial part is subdivided into cervicis, capitis, and thoracis parts. The spinalis muscle is supplied segmentally by the posterior intercostal arteries, the lumbar arteries, the subcostal arteries, and the deep cervical artery. The function of the spinalis muscle is to extend and laterally bend the neck and trunk.
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In Depth: Spinalis