3D anatomy: muscles of the face and neck

Key points

1. Muscles of facial expression are supplied by the facial nerve (CN VII).
2. Muscles of mastication are supplied by the mandibular division of the trigeminal nerve (CN V3).
3. Sternocleidomastoid and trapezius are supplied by the spinal accessory nerve (CN XI).
4. Platysma is a facial-expression muscle in the neck, so it is supplied by CN VII.
5. The carotid sheath contains the common (then internal) carotid artery, internal jugular vein and vagus nerve.

Image guide

What to look for in each view of this topic.

1. Superficial layer. Platysma and muscles of facial expression from the second pharyngeal arch.
2. Masticatory layer. Masseter, temporalis and the pterygoids from the first arch.
3. Anterior triangle. Bounded by the midline, sternocleidomastoid and mandible; contains the carotid sheath.
4. Posterior triangle. Contains the spinal accessory nerve, which is vulnerable in lymph node biopsy.