The anatomy of the head and neck is rich in complexity as it is populated with motor and sensory organs, cranial nerves, and major arterial and venous structures in a compact three-dimensional space. This chapter provides a broad and concise overview to familiarize the novice and yet is detailed enough to serve as a reference for the more knowledgeable clinician.
The muscles of facial expression develop from the second branchial arch and lie within the skin of the scalp, face, and neck (Figure 1–1).
A. Occipitofrontalis Muscle
The occipitofrontalis muscle, which lies in the scalp, extends from the superior nuchal line in the back to the skin of the eyebrows in the front. It allows for the movement of the scalp against the periosteum of the skull and also serves to raise the eyebrows.
B. Orbicularis Oculi Muscle
The orbicularis oculi muscle lies in the eyelids and also encircles the eyes. It helps to close the eye in the gentle movements of blinking or in more forceful movements, such as squinting. These movements help express tears and move them across the conjunctival sac to keep the cornea moist.
C. Orbicularis Oris Muscle
The orbicularis oris muscle encircles the opening of the mouth and helps to bring the lips together to keep the mouth closed.
The buccinator muscle arises from the pterygomandibular raphe in the back and courses forward in the cheek to blend into the orbicularis oris muscle in the lips. It helps to compress the cheek against the teeth and thus empties food from the vestibule of the mouth during chewing. In addition, it is used while playing musical instruments and performing other actions that require the controlled expression of air from the mouth.
The platysma muscle extends from the skin over the mandible through the superficial fascia of the neck into the skin of the upper chest, helping to tighten this skin and also to depress the angles of the mouth. Although lying primarily in the neck, it is grouped with the muscles of facial expression.
The blood supply of the face is through branches of the facial artery (Figure 1–2). After arising from the external carotid artery in the neck, the facial artery passes deep to the submandibular gland and crosses the mandible in front of the attachment of the masseter muscle. It takes a tortuous course across the face and travels up to the medial angle of the eye, where it ...