Facial Muscles

Face and Scalp

• The face is the anterior aspect of the head, bounded superiorly by the superciliary arches, inferiorly by the lower edge of the mandible, and posteriorly by the right and left ears.
• The shape of the face reflects an individual's identity and plays a key role in communication.

Bones of the Face

• Seven bones comprise the orbital walls: ethmoid, lacrimal, palatine, maxilla, zygomatic, sphenoid, and frontal.
• The face is composed of multiple bones that articulate with each other.

Scalp

• The scalp consists of hair-bearing skin and subcutaneous tissue covering the neurocranium from the superior nuchal lines on the occipital bone to the supra-orbital margins of the frontal bone.
• The scalp extends laterally over the temporal fascia to the zygomatic arches.
• The scalp is composed of five layers: skin, connective tissue, aponeurosis, loose areolar tissue, and pericranium.

Muscles of the Face and Scalp

• The occipitofrontalis muscle is attached to the aponeurotic layer of the scalp.
• The frontal belly of the occipitofrontalis muscle pulls the scalp anteriorly, wrinkles the forehead, and elevates the eyebrows.
• The occipital belly of the occipitofrontalis muscle pulls the scalp posteriorly, smoothing the skin of the forehead.
• The superior auricular muscle elevates the auricle of the external ear.
• All muscles of facial expression develop from mesoderm in the second pharyngeal arches and are innervated by the facial nerve (CN VII).

Muscles of Facial Expression

• Muscles of facial expression are divided into three groups: orbital, nasal, and oral.
• The orbicularis oculi muscle surrounds each orbital orifice and extends into each eyelid.
• The corrugator supercili muscle is active when frowning and draws the eyebrows toward the midline.
• The nasalis muscle is the largest and best-developed muscle of the nasal group and is active when the nares are flared.
• The procerus muscle is active when an individual frowns and draws the medial border of the eyebrows downward.
• The depressor septi nasi muscle assists in widening the nares.
• The orbicularis oris muscle consists of fibers that completely encircle the mouth and is active when pursing the lips.
• The buccinator muscle resists distension of the cheeks when blowing and protects the inner cheek walls during chewing.

Innervation of the Face and Scalp

• The trigeminal nerve (CN V) provides sensory innervation to the face and scalp, with three paired divisions: V1, V2, and V3.
• The facial nerve (CN VII) provides motor innervation to the muscles of facial expression.
• The trigeminal nerve also provides motor innervation to the muscles of mastication.

Blood Supply of the Face and Scalp

• The facial artery is a branch of the external carotid artery and provides most of the arterial supply to the face.
• The facial vein provides the main superficial drainage of the face.
• The angular vein forms from the supratrochlear and supraorbital veins and drains into the facial vein.

Lymphatic Drainage of the Face

• The face is drained by three groups of superficial lymph nodes: submental, submandibular, and pre-auricular and parotid.
• All lymphatic vessels from the face drain into the deep cervical lymph nodes, which then drain into the jugular lymphatic trunk.