Muscles of Facial Expression - 300L Anatomy PDF

MUSCLES OF THE FACE/MUSCLES OF FACIAL EXPRESSION Course Lecturer: OVIOSUN, AUGUSTINE Department of Anatomy Faculty of Basic Medical Science January 10th 2022 1 ...

MUSCLES OF THE FACE/MUSCLES OF FACIAL EXPRESSION Course Lecturer: OVIOSUN, AUGUSTINE Department of Anatomy Faculty of Basic Medical Science January 10th 2022 1  LEARNING OUTCOMES At the end of this lecture, each student should be able to- Identify the muscles of facial expression and their location’ Describe the anatomy of Muscles of fascial expression (origin, Insertion, innervation and Action). 2  MUSCLES OF FACIAL EXPRESSION INTRODUCTION The muscles of facial expression are located in the subcutaneous tissue, originating from bone or fascia, and inserting onto the skin. By contracting, the muscles pull on the skin and exert their effects. They are the only group of muscles that insert into skin. These muscles have a common embryonic origin – the 2nd pharyngeal arch. They migrate from the arch, taking their nerve supply with them. As such, all the muscles of facial expression are innervated by the facial nerve. Fig; Muscles of facial expression 3 4 5  MUSCLES OF FACIAL EXPRESSION Contrary to the other skeletal muscles they are not surrounded by a fascia, with the exception of the buccinator muscle. The muscles of facial expression are positioned around facial openings (mouth, eye, nose and ear) or stretch across the skull and neck. Thus, these muscles are categorized into several groups; Muscles of the mouth (buccolabial group) Muscles of the eyelid (orbital group) Muscles of the nose (nasal group) Muscles of the cranium and neck (epicranial group) Muscles of the external ear (auricular group) 6  MUSCLES OF THE MOUTH (BUCCOLABIAL GROUP) A broad group of muscles that form a functional compound that controls the shape and movements of the mouth and lips. Majority of mouth muscles are connected by a fibromuscular hub onto which their fibers insert. This structure is called the MODIOLUS it is located at the angles of the mouth and primarily formed by The buccinator, Orbicularis oris, Risorius, Depressor anguli oris and Zygomaticus major muscles. There are 11 muscles of the mouth Fig; MODIOLUS 7  MUSCLES OF THE MOUTH (BUCCOLABIAL GROUP) 1. ORBICULARIS ORIS A circular composite muscle that surrounds the mouth and forms the majority of lips. Origin; Medial aspects of maxilla and mandible, perioral skin and muscles, modiolus Insertion; Skin and mucous membrane of lips Action; Closes mouth, compresses and protrudes lips Innervation; Buccal branch of facial nerve (CN VII) Blood supply;  Facial artery - Superior and inferior labial arteries  Maxillary artery - Mental and infraorbital arteries Fig; ORBICULARIS ORIS  Superficial temporal artery - Transverse facial artery 8  MUSCLES OF THE MOUTH (BUCCOLABIAL GROUP) 2. BUCCINATOR MUSCLE forms the muscular basis of the cheek, filling the interval between the maxilla and mandible. It is composed of three parts; superior, inferior and posterior. Origin; Superior part: Alveolar process of maxilla Inferior part: Alveolar part of mandible Posterior part: Pterygomandibular raphe, buccinator crest of mandible Fig; BUCCINATOR MUSCLE 9  Insertion; Modiolus, blends with muscles of upper lip Action; Compresses cheek against molar teeth Innervation; Buccal branch of facial nerve (CN VII) Blood supply; Buccal artery (maxillary artery), facial artery 10  MUSCLES OF THE MOUTH (BUCCOLABIAL GROUP) 3. LEVATOR LABII SUPERIORIS MUSCLE; A short triangular muscle Origin; Zygomatic process of maxilla, maxillary process of zygomatic bone Insertion Blends with muscles of upper lip Action Elevates upper lip, exposes maxillary teeth Innervation Zygomatic and buccal branches of facial nerve (CN VII) Blood supply Fig; Levator labii superioris muscle Facial artery, infraorbital branch of maxillary artery 11  MUSCLES OF THE MOUTH (BUCCOLABIAL GROUP) 4. DEPRESSOR LABII INFERIORIS MUSCLE A short quadrangular muscle found in the chin region Origin; Oblique line of mandible (continuous with platysma muscle) Insertion Skin and submucosa of lower lip Action Depresses lower lip inferolaterally Innervation Mandibular branch of facial nerve (CN VII) Blood supply Fig; Depressor labii inferioris muscle Inferior labial branch of facial artery, mental branch of maxillary artery 12  MUSCLES OF THE MOUTH (BUCCOLABIAL GROUP) 5. LEVATOR LABII SUPERIORIS ALAEQUE NASI MUSCLE A slender, strap-like muscle found on both sides of the nose. Origin; from the upper part of the frontal process of the maxilla Insertion Into the perichondrium and the skin over the major alar cartilage of the nose Action elevate and evert the upper lip, as well as to elevate, deepen and increase the curvature of the nasolabial furrow. Innervation; Zygomatic and buccal branches of facial nerve (CN VII) Fig; Levator labii superioris alaeque Blood supply; nasi muscle Facial artery and the infraorbital branch of the maxillary artery. 13  MUSCLES OF THE MOUTH (BUCCOLABIAL GROUP) 6. Mentalis muscle (Musculus mentalis) a paired conical facial muscle located in the chin Origin; Incisive fossa of mandible Insertion Skin of chin (Mentolabial sulcus) Action Elevates, everts and protrudes lower lip, wrinkles skin of chin Innervation Mandibular branch of facial nerve (CN VII) Blood supply Fig; Mentalis muscle Inferior labial branch of facial artery, mental branch of the maxillary artery 14  MUSCLES OF THE MOUTH (BUCCOLABIAL GROUP) 7. RISORIUS MUSCLE A slender and narrow facial muscle It is highly variable and inconsistent where it is believed to be unique to the African apes and humans. It is deemed as the ‘smiling muscle’ as its bilateral contraction pulls the angles of the mouth laterally and slightly superiorly and produces a smile. Origin; Parotid fascia, Buccal skin, zygomatic bone (variable) Insertion Modiolus Action Extends angle of mouth laterally Innervation Buccal branch of facial nerve (CN VII) Blood supply Fig; Risorius muscle Superior labial artery (facial artery) 15  MUSCLES OF THE MOUTH (BUCCOLABIAL GROUP) 8. LEVATOR ANGULI ORIS MUSCLE A paired strap-like muscle of the face Origin; Canine fossa of maxilla Insertion Modiolus Action Elevates angle of mouth Innervation Zygomatic and buccal branches of facial nerve (CN VII Blood supply Fig; Levator anguli oris muscle Superior labial branch of facial artery, infraorbital branch of maxillary artery 16  MUSCLES OF THE MOUTH (BUCCOLABIAL GROUP) 9. Depressor anguli oris muscle A paired triangular muscle Origin; Mental tubercle and oblique line of mandible (continuous with platysma muscle) Insertion Modiolus Action Depresses angle of mouth Innervation Buccal and mandibular branches of facial nerve (CN VII) Blood supply Inferior labial artery (facial artery); mental artery (maxillary Fig; Depressor anguli oris muscle artery) 17  MUSCLES OF THE MOUTH (BUCCOLABIAL GROUP) 10. ZYGOMATICUS MAJOR A thin paired facial muscle. Along with risorius, zygomaticus major contributes to laughing, which is why they are deemed the “laughing muscles”. Origin; (Posterior part of) Lateral aspect of zygomatic bone Insertion Modiolus, blends with muscles of upper lip Action Elevates and everts angle of mouth Innervation Buccal and zygomatic branches of facial nerve (CN VII) Blood supply Fig; Zygomaticus major Superior labial artery (facial artery) 18  MUSCLES OF THE MOUTH (BUCCOLABIAL GROUP) 11. ZYGOMATICUS MINOR A thin paired facial muscle Origin; (Anterior part of) Lateral aspect of zygomatic bone Insertion Blends with muscles of upper lip (medial to zygomaticus major muscle) Action Elevates upper lip, exposes maxillary teeth The function of this movement is to facilitate speech, as well as to enable various facial expressions, such as smiling. Innervation Zygomatic and buccal branches of facial nerve (CN VII) Blood supply Fig; Zygomaticus minor Superior labial branch of the facial artery 19  MUSCLES OF THE MOUTH (BUCCOLABIAL GROUP) APPLIED ANATOMY: Paralysis to the Oral Muscles If the facial nerve is dysfunctional, the oral muscles can become paralysed. The patient may present with difficulty eating, with food collecting between the teeth and cheeks. In addition, the tissue around the mouth and cheeks sags, and is drawn across to the opposite side while smiling. 20  MUSCLES OF THE EYELID (Orbital Group) The orbital group of facial muscles contains two muscles associated with the eye socket. 1. ORBICULARIS OCULI Surrounds the eye socket and extends into the eyelid. It has three distinct parts – palpebral, lacrimal, and orbital. Origin; Nasal part of frontal bone, frontal process of maxilla, medial palpebral ligament, lacrimal bone Insertion: Skin of orbital region, lateral palpebral raphe, superior and Fig; Orbicularis oculi muscle inferior tarsal plates. 21 Actions: Palpebral part – gently closes the eyelids. Lacrimal part – involved in the drainage of tears. Orbital part – tightly closes the eyelids. Innervation – Temporal and zygomatic branches of Facial nerve (CN VII) Blood supply; Maxillary, superficial temporal, facial and ophthalmic arteries 22  MUSCLES OF THE EYELID (Orbital Group) 2. CORRUGATOR SUPERCILII MUSCLE A small, pyramidal muscle that belongs to the circumorbital and palpebral group of facial muscles Origin; Medial end of superciliary arches, Fibers of orbicularis oculi muscle Insertion Skin above middle of supraorbital margin Action Creates vertical wrinkles over glabella, creating a facial expression of frowning. Innervation Temporal branches of facial nerve (CN VII) Fig; Corrugator supercilii muscle Blood supply Ophthalmic artery, superficial temporal artery 23  MUSCLES OF THE EYELID (Orbital Group) APPLIED ANATOMY: Paralysis to the Orbital Muscles If the facial nerve becomes damaged, the orbital muscles will cease to function. As they are the only muscles that can close the eyelids, this has some serious clinical consequences;  The eye cannot shut – this can cause the cornea to dry out. This is known as exposure keratitis.  The lower eyelid droops, called ectropion.  Lacrimal fluid pools in the lower eyelid and cannot be spread across the surface of the eye. This can result in a failure to remove debris, and ulceration of the corneal surface. The test for facial nerve palsy involves raising the eyebrows and closing the eyelids 24  MUSCLES OF THE NOSE (NASAL GROUP) The nasal group of facial muscles are associated with movements of the nose, and the skin around it. They also contribute to respiration. There are three muscles in this group; Fig; The nasal muscles of facial expression 25  MUSCLES OF THE NOSE (NASAL GROUP) 1. NASALIS MUSCLE Found on each side of the midline, respectively. Each muscle is composed of two parts; lateral or transverse part (compressor naris) and  medial or alar part (dilator naris posterior). Origin; Alar part: Frontal process of maxilla (superior to lateral incisor) Transverse part: Maxilla (superolateral to incisive fossa) Insertion Fig; Nasalis muscle Alar part: Skin of ala; Transverse part: Merges with counterpart at dorsum of nose 26  MUSCLES OF THE NOSE (NASAL GROUP)-NASALIS MUSCLE (Contd) Action Alar part: Depresses ala laterally, dilates nostrils Transverse part: Wrinkles skin of dorsum of nose These actions are notable in creating certain facial expressions such as conveying feelings of anger, but also to enhance deep breathing. Innervation Buccal branch of facial nerve (CN VII) Blood supply Superior labial, septal, and lateral nasal branches of facial artery; Infraorbital branch of maxillary artery 27  MUSCLES OF THE NOSE (NASAL GROUP) 2. PROCERUS MUSCLE A small, triangular muscle of the head that occupies the glabella, which is the region located between the eyebrows. Origin Nasal bone, (superior part of) lateral nasal cartilage Insertion Skin of glabella, fibers of frontal belly of occipitofrontalis muscle Action Depresses medial end of eyebrow, wrinkles skin of glabella. This action enables frowning. Innervation Temporal, lower zygomatic or buccal branches of facial nerve (CN VII) Blood supply Fig Procerus muscle Angular and lateral nasal branches of facial artery 28  MUSCLES OF THE NOSE (NASAL GROUP) 3. DEPRESSOR SEPTI NASI Origin; Maxilla above the central incisor. Insertion Cartilaginous nasal septum. Action Works with the alar part of the nasalis to pull the nose inferiorly, widening the nasal openings. Innervation Facial nerve (Cranial nerve VII). Blood supply Fig; Depressor Septi Nasi Lateral nasal and septal branches of the facial artery. 29  MUSCLES OF THE CRANIUM AND NECK (EPICRANIAL GROUP) OCCIPITOFRONTALIS MUSCLE A long and wide muscle of the scalp Consists of frontal and occipital bellies, each containing a pair of quadrangular muscle heads. The bellies are connected by a thick fibrous sheath called epicranial aponeurosis (galea aponeurotica) Fig; Frontal belly of Origin; Occipitofrontalis muscle Frontal belly (frontalis): Skin of eyebrow, Muscle of forehead Occipital belly (occipitalis): (Lateral 2/3 of) superior nuchal line Insertion Epicranial aponeurosis Fig; Occipital belly of Occipitofrontalis muscle 30  Action Frontal belly: Elevates eyebrows, creating an expression of surprise. wrinkles skin of forehead producing a frown Occipital belly: Retracts scalp, moving it anteriorly Innervation Frontal belly: Temporal branches of facial nerve (CN VII) Occipital belly: Posterior auricular nerve (branch of facial nerve (CN VII)) Blood supply Superficial temporal, ophthalmic, posterior auricular and occipital arteries 31  MUSCLES OF THE CRANIUM AND NECK (EPICRANIAL GROUP) PLATYSMA MUSCLE a sheet-like muscle situated within the superficial cervical fascia of the anterior neck. Origin; Skin/fascia of infra- and supraclavicular regions Insertion Lower border of mandible, skin of buccal/cheek region, lower lip, modiolus, orbicularis oris muscle Fig; Platysma muscle 32  PLATYSMA MUSCLE Action Depresses mandible and angle of mouth, tenses skin of lower face and anterior neck Innervation Cervical branch of facial nerve (CN VII) Blood supply submental artery (facial artery), suprascapular artery (thyrocervical trunk) 33  MUSCLES OF THE EXTERNAL EAR (auricular AURICULAR MUSCLES group) Thin, fan-shaped muscles that connect the auricle to the scalp, and move the auricle to a certain extent. These muscles include: Auricularis anterior, Auricularis Posterior, Auricularis superior Fig; Auricularis anterior muscle 1. Auricularis anterior Origin; lateral border of the epicranial aponeurosis Insertion; to the spine of the helix of the auricle. 35  MUSCLES OF THE EXTERNAL EAR (Auricular group) 2. Auricularis Posterior Origin; mastoid process of the temporal bone Insertion; into the ponticulus on the eminentia conchae. Fig; Auricularis Posterior muscle 36  MUSCLES OF THE EXTERNAL EAR (auricular group) AURICULAR MUSCLES 3. Auricularis superior Origin; from the epicranial aponeurosis Insertion; onto the upper part of the auricle Fig; ; Auricularis superior muscle 37  ‘ MUSCLES OF THE EXTERNAL EAR (auricular AURICULAR MUSCLES group) Innervation; auricularis anterior and superior are supplied by temporal branches of facial nerve auricularis posterior by the posterior auricular branch of facial nerve Blood supply posterior auricular artery. Action The auricular muscles are quite rudimentary, their function is mainly insignificant in humans. Most of the movements of the ear produced by these muscles are observed during smiling and yawning, involving pulling the auricle anteriorly, posteriorly or superiorly. 38 39 40  ASSIGNMENT What is Bell’s Palsy. ? 41