Regarding the triangles of the neck:

• A. the posterior triangle is bound by trapezius, sternocleidomastoid and the middle quarter of clavicle
• B. the anterior triangle is further divided into two smaller triangles, the carotid and submandibular triangles
• C. the posterior belly of digastric (and stylohyoid) separates the carotid and submandibular triangles
• D. the accessory nerve (CNXI) divides the posterior triangle into approximately two halves, and of these the lower contains little of importance
• E. the investing fascia splits to enclose the sternomastoid and trapezius, but the parotia and submandibular glands lie deep to the fascia, in the anterior triangle