Discuss the contents, structure, relationships, innervation (sensory and motor), vasculature, and lymphatics of the suboccipital triangle.

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Contents – Vertebral artery, suboccipital nerve and vessels Suboccipital nerve is derived from the dorsal ramus of C1 and emerges b/n the vertebral artery above and the posterior arch of the atlas below. Supplies the muscles of the suboccipital triangle and semispinalis capitis. Contains skeletal motor fibers, but NO cutaneous sensory fibers. Vertebral artery – branch of the subclavian artery and ascends thru the transverse formanina of the upper 6 cervical vertebra. Winds behind the lateral mass of the atlas, running in a groove on the superior surface of the posterior arch of the atlas, pierces the dura mater to enter the vertebral canal, and ascends into the cranial cavity thru the foramen magnum, gives off an anterior spinal and 2 posterior spinal arteries (vascularize the spinal cord). Vertebral veins – formed in the SOT by union of the tributaries from the venous plexus around the forament magnum, the suboccipital venous plexus, the intervertebral veins, and internal and the external vertebral venous plexus Greater occipital nerve – posterior ramus of C2

Structure – triangle is formed by the rectus capitis posterior major, obliquus capitis superior, obliquus capitis inferior Rectus captitis posterior major – origin = spinous process of C2, insertion = inferior nuchal line, innervation = suboccipital nerve (C1), blood supply = vertebral and occipital arteries, action = extends and rotates the head Obliquus capitis superior – origin – transverse process of C1, insertion = occipital bone b/n nuchal lines, innervation = suboccipital nerve (C1), blood supply = vertebral and occipital arteries, action = lateral flexion Obliquus capitis inferior – origin – spinous process of C2, insertion = transverse process of C1, innervation = suboccipital nerve (C1), blood supply = vertebral and occipital arteries, action = rotates C1 and head

These muscles connect the axis and the axis to each other and to the skull, and are specialized for rotating and extending the head.

The vertebral artery emerges from the transverse foramen of the atlas and crosses the triangle, running medially along the posterior arch of the atlas before entering the foramen magnum to supply the brain.

Greater occipital nerve – appears at the lower border of the obliquus capitis inferior and, after giving off a few muscular branches, crosses over the triangle to reach the scalp.

R/ships – Anterior: semispinalis capitis, longisimus capitus, posterior: posterior arch of the atlas, posterior atlanto-occipital membrane, Inferior: obliquus capitis inferior muscle, Medially: rectus capitis posterior major muscle, laterally: obliquus capitis superior muscle

Innervation – sensory = greater occipital nerve (C2), motor = suboccipital nerve (C1) Vasculature – vertebral and occipital arteries Lymphatics - ?

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