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NECK ANATOMY
NECK ANATOMY
While the overall anatomy of the neck is complex, the superficial anatomy most commonly addressed by cosmetic procedures includes the skin, subcutaneous fat, superficial cervical fascial system, and the platysma. Neck skin is very thin, only slightly thicker than upper eyelid skin. Subcutaneous fat distribution is variable, though it is thinly layered over the platysmal muscle, but tends to accumulate in the submentum. There is also a deeper submental fat pad.
The plastysma is a thin shield-like muscle. It originates on pectoralis fascia. Its anterior border is the risorius muscle at the oral commissure. Posteriorly, it inserts into the SMAS. The plastysma is innervated by the cervical branch of the facial nerve. Its vascular supply stems from branches of the facial artery. It is not clear what the function of the platysma is. In animals such as horses, contraction of the platysma helps to ward off insects. In humans, it does depress the corners of the mouth, and acts as a stabilizing force.
The sternocleidomastoid (SCM) is a major muscle of the neck, but generally it is not manipulated cosmetically. However, the greater auricular nerve (C2, C3) travels
superficial to the SCM, and is very superficial as it terminates inferior to the auricle around the lobule. It is susceptible to injury during a surgical neck lift. The spinal accessory nerve (CN XI) lies in the posterior triangle, and though less likely to be compromised in many superficial neck rejuvenation procedures, is also susceptible to injury during a neck lift. Anteriorly, the marginal mandibular branch of the facial nerve courses inferior to the angle of the mandible and then runs in the superficial layer of the deep cervical fascia just superficial to the submandibular gland and the anterior facial vein. It continues its course over the mandible where the nerve is very superficial and terminates lateral to the anterior commissure. In a small percentage of individuals, its thin rami anastomose with those of the buccal branch of the facial nerve. Extreme care must be taken in these areas.