Comes from a union of the posterior auricular and retromandibular veins and then crosses the sternocleidomastoid and drains into the subclavian vein. One can distinctly see it pulsate especially under high venous pressure.
Bear in mind that there is variability in where these arteries arise from.
Transverse cervical artery: comes from the thyrocervical trunk OR as a separate trunk with the suprascapular artery and supplies the trapezius and levator scapulae. Note that the transverse cervical artery does not run with the transverse cervical nerve. The nerve proceeds anteriorly whereas the artery proceeds posteriorly.
Third part of subclavian artery:The longest portion of the subclavian artery. Supplies blood to the Upper limb.
Suprascapular artery: Comes from the thyrocervical trunk OR from a common trunk with the transverse cervical artery. Supplies Shoulder.
Dorsal scapular artery: Comes directly from the subclavian artery (70%) OR the thyrocervical trunk (30%) and supplies the Medial shoulder.
Innvervation of Posterior Triangle
Sensory: From Cervical Plexus
Motor: Spinal accessory CN XI
Think of the locations of the nerves as if they were hands on a clock...
Great auricular n. (12:00):supplies innervation to the skin over the parotid gland, the posterior aspect of auricle and an area of skin from mandible to mastoid process, runs superficial to sternocleidomastoid and in an anteriosuperior direction.
Lesser occipital n. (1:00): Supplies the skin of neck and scalp posteriosuperior to auricle, and runs posterior to sternocleidomastoid.
Accessory n. (4:00): Supplies SCM from deep aspect, then passes posterior-inferiorly to supply the trapezius.
Supraclavicular n. (6:00): Supplies skin of upper anterior chest wall and adjacent shoulder.
Transverse cervical n. (9:00): Supplies skin of anterior neck
Note: the clock analogy is of the left side. It would be backwards from the other side.
All of these nerves come out from behind the SCM. You can locate them by palpating along the SC< until you reach a point that hurts when pressure is applied. You can think of GLAST (sounds like "blast") if that helps you remember it...
Highlights From the Suboccipital Region:
The four muscles of this triangle serve to anchor the atlas and axis to each other and to the skull.
Obliquus capitis inferior
Ipsilaterally rotates C1 with respect to C2
Obliquus capitis superior
extends the head
rectus capitis posterior major
extend the head backwards, act as fine-tuners, proprioceptors
rectus capitis posterior minor
You should know insertions and origins for all of the deep muscles, as these form the corners of the suboccipital triangle.
In addition to the contents of the suboccipital triangle, know these too:
1) Vertebral artery - compression of this artery due to prolonged rotation can cause dizziness.
2) Suboccipital nerve (dorsal rami of C1)
3) Greater Occipital nerve: Closely associated with this triangle. It emerges below the inferior border (obliquus capitis inferior) and runs superficially to this space to innervate the posterior scalp.
Anterior Triangles of Neck and Cervical Viscera
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The Anterior triangle (Netter 24)
Anterior midline of neck
Inferior edge of mandible
Sub-Triangles of the Anterior Triangle
digastric (ant.-inf.and post.-inf.)
Anterior bellies of digastric (lateral)
superior belly of omohyoid (posterior - superior)
midline; hyoid bone (superior)
posterior belly of digastric (anterior - superior)