Course
- Formed in the Posterior Cranial Fossa by the union of the Cranial and Spinal (Cervical) roots
- Cranial Root: Merges from the Medulla as a series of rootlets below those of the Vagus between the Olive and the Inferior Cerebellar Peduncle
- Spinal Root: Fibres from cell bodies in the anterior horn of the upper 5 or 6 segments of the cervical cord (mainly 2, 3, 4)
- Nerve occupies the middle compartment in the Jugular Foramen
- Lateral to the Vagus Nerve (with which it shares a meningeal sleeve)
- All fibres of its Cranial root leave the nerve in a branch which joins the Vagus
- Distributed by vagal branches to the striated muscle of the soft palate and larynx
- Nerve (now consisting of Cervical fibres only) runs downwards and backwards on the Internal Jugular Vein
- The nerve crosses laterally (usually) or medial to the vein
- Nerve lies in front of the transverse process of the Atlas (palpable between the Mastoid Process and Mandibular Ramus)
- Passes deep to Styloid Process and Posterior Belly of the Digastric Muscle
- Where it is crossed by the Occipital Artery
- Reaches the Sternocleidomastoid with the upper Sternocleidomastoid Branch of the Occipital Artery
- Enters the substance of Sternocleidomastoid between the upper two quarters of the muscle via the deep surface
- Emerges from the Sternocleidomastoid, about 1/3rd of the way or little lower down its posterior border
- Passes downwards and backwards, with a characteristic wavy course adherent to the inner surface of the fascia of the roof of the triangle
- Disappears beneath the anterior border of Trapezius about 1/3rd of the way from its lower end and 3-5cm above the clavicle
- One or two lymph nodes in the posterior triangle may lie in contact with the nerve