Muscles of Facial Expression

• The lecture discusses the muscles of facial expression, their functions, and related anatomy and physiology for application in patient management.
• Aims of the lecture is to gain an overview of the muscles involved in facial expressions and their functions.
• Learning outcomes are to list the muscles of facial expression and outline their origin, insertion, action, innervation, and blood supply.
• The muscles helping with facial expressions originate from bone or fascia, inserting into the skin.
• Facial muscles are innervated by the facial nerve and supplied by the facial artery.
• Contraction of facial muscles moves the facial skin to reflect emotions and expressions.
• Functions of facial expression muscles include speech and mastication.
• Facial muscles located in the subcutaneous fascia are subdivided into the mouth, scalp, neck, eyes, nose, and ears.

Muscles of Facial Expression: Mouth

• Orbicularis Oris circles the oral cavity in lip tissue.
• Its origin has some bony attachment, from the anterior nasal spine and midline above the chin.
• Fiber insertion interlaces with muscles around the lips.
• It closes and opens the mouth, compresses the lips, and causes protrusion.
• It is innervated by the facial nerve, buccal branch.
• Blood supply comes from the facial, maxillary, and superficial temporal arteries.
• Levator Labii Superioris originates from the lower rim of the orbit.
• Its insertion is on the fibres of the Orbicularis Oris at the upper lip.
• This muscle elevates the upper lip.
• It is innervated by the facial nerve, zygomatic and buccal branches.
• Blood supply comes from the facial and maxillary arteries.
• Depressor Labii Inferioris originates beneath the lowest portion of the oblique line of the mandible.
• Its insertion is on the Orbicularis Oris in the lower lip and depresses lower lip.
• This muscle is innervated by the facial nerve, mandibular branch, and supplied by facial & maxillary arteries.
• Zygomaticus Minor originates from the zygomatic arch and inserts into the Orbicularis Oris.
• The muscle elevates the upper lip and is innervated by the facial nerve, buccal, and zygomatic branches.
• Blood supply comes from the facial artery.
• The Zygomaticus Major originates from the zygomatic arch.
• The insertion travels downwards and medially to blend with Orbicularis Oris at the angle of the mouth.
• It elevates the corners of the mouth, e.g. during laughter.
• It is innervated by the facial nerve, buccal and zygomatic branches, and supplied by the facial artery.
• Levator Anguli Oris originates from the canine fossa of the Maxilla, below the infra-orbital foramen.
• Its insertion is at the Orbicularis Oris at the corner of the mouth.
• Elevating the corner of the mouth, it is innervated by the facial nerve (buccal & zygomatic branch).
• Blood supply comes from the facial and maxillary arteries.
• Depressor Anguli Oris originates beneath the angle of the mandible.
• Its insertion converges into the angles of the mouth, blending with Orbicularis Oris.
• This muscle depresses the corner of the mouth.
• Innervation is from the facial nerve, buccal, and mandibular branches and the blood supply is from the facial and maxillary arteries.
• Mentalis originates from the anterior surface of the mandible (incisive fossa).
• Insertion is on the skin covering the chin.
• It puckers/pulls skin of the chin up and helps the Orbicularis Oris muscle in clearing food from the labial sulcus.
• Facial nerve, mandibular branch provides nerve supply.
• Blood supply comes from the facial and maxillary arteries.
• Buccinator originates from the pterygomandibular raphae and buccal alveolar bone (in maxillary and mandibular molars regions).
• Its insertion blends with the Orbicularis Oris at the corners of the mouth.
• Action of this muscle pulls the corner of the mouth back and compresses cheek against the buccal surfaces of molars.
• Facilitates mastication by working with the tongue to direct food to the occlusal tooth surfaces.
• Facial nerve, buccal branch provides nerve supply, whilst blood supply is from the facial and maxillary arteries.
• Risorius originates from angle of the mandible.
• Insertion is the corner of the mouth.
• It retracts the angle of the mouth and assists in smiling.
• Facial nerve, buccal branch provides nerve supply, and the blood supply is the facial artery.

Muscles of Facial Expression: Scalp

• Occipitofrontalis consists of Frontalis, Occipitalis, and Galea Aponeurotica parts.
• Frontalis is associated with facial expression, originating from connective tissue of the scalp.
• The insertion is the skin of the frontal regions of the eyebrows.
• It pulls the scalp up and back- elevates eyebrows and wrinkles scalp.
• It is innervated by the facial nerve, temporal branch.
• Blood supply comes from superficial temporal and ophthalmic arteries.

Muscles of Facial Expression: Neck

• Platysma originates from the clavicle and shoulder and its insertion is on the lower border of mandible, skin & muscle of the lower face & mouth.
• This muscle pulls down the corners of the mouth (grimace) and wrinkles the skin of the chin and neck.
• Facial nerve, cervical branch provides nerve supply, while blood supply comes from the facial artery and thyrocervical trunk.

Muscles of Facial Expression: Eyes

• Orbicularis oculi has two parts: Orbital and Palpebrae.
• The Orbital part encircles the eye in a horseshoe shape and originates from the bone of the upper medial orbital margin, closing the eye forcefully.
• Palpebrae part originates from the medial palpebral ligament and arches laterally within the eyelid, acting to close the eyes gently (blinking).
• Facial nerve, zygomatic and temporal branches provide nerve supply.
• Blood supply comes from superficial temporal, facial, and maxillary arteries.
• The Corrugator originates from the bridge of the nose and its insertion is the skin of the lateral part of the eyebrow.
• It pulls eyebrows medially (frown).
• Facial nerve, temporal branch provides nerve supply and the blood supply is from the superficial temporal artery.
• Procerus originates from the bridge of the nose and its insertion is on the medial end of the eyebrows.
• The action of the muscles is pulling the eyebrows down (frown) and wrinkling of the nose.
• Facial nerve, zygomatic branch provides nerve supply and facial artery supplies blood.

Muscles of Facial Expression: Nose

• The nasalis opens and closes the nostrils with two parts: Dilator Naris and Compressor Naris.
• The nerve supply is the facial nerve, buccal branches and blood supply is the facial artery.
• Dilator Naris originates from the nasal margin of the maxilla and insertion is on the skin of the nostril, flaring the nostrils.
• Compressor Naris originates from the top of the maxillary canine ridge.
• Insertion is on the midline over the nasal cartilage, closing the nostrils.

Muscles of Facial Expression: Ears

• Three muscles act on the external ear: Anterior Auricular, Superior Auricular and Posterior Auricular.
• Anterior Auricular originates from the scalp and temporal fascia.
• Insertion is the anterior medial aspect of the helix of the ear.
• It pulls the ear slightly forward.
• Facial nerve, temporal branch provide the nerve supply and the blood supply is posterior auricular artery.
• Superior Auricular originates from the scalp and temporal fascia.
• Insertion point is the superior medial aspect of the ear and raises it.
• Facial nerve, temporal branch provide nerve supply via the posterior auricular artery.
• Posterior Auricular originates from the superior lateral aspect of the mastoid process.
• Insertion point is to the inferior medial aspect of the auricle of the ear and pulls the ear back.
• Nerve supply comes from the facial nerve (temporal branch).
• Posterior auricular artery provides blood.
• Conditions like Bell's Palsy, Stroke, and Surgery can affect the functionality of facial muscles.