GEN ANA QUIZ 9

• Craniofacial muscles are associated with

  • Scalp and cervical skin
  • Orbital margins and eyelids
  • External nose and nostrils
  • Lips, cheeks and mouth
  • Pinna
• Craniofacial muscles


  Muscles of facial expression
• Craniofacial muscles


  • Produce movements of the facial skin that reflect emotions
  • Act as sphincters and dilators of the facial orifices
  • The function of facial expression has developed secondarily
• Organization of the muscles of the face differs from that of muscles in most other regions of the body

  
• Differences in organization of facial muscles

  • There is no deep membranous fascia beneath the skin of the face
  • Many small slips of muscle that are attached to the facial skeleton insert directly into the skin

  
• Craniofacial muscles are derived from the mesenchyme of the 2nd branchial arch and so are innervated by the facial nerve
• Innervation to the muscles of facial expression are supplied by the Facial nerve
• The two muscles of mastication that relate to the face are innervated by the mandibular division of the trigeminal nerve

  
• Sensory innervation is primarily from the three divisions of the trigeminal nerve, with smaller contributions from the cervical spinal nerves
• Topographical and functional subdivision of craniofacial muscles

  • Epicranial
  • Circumorbital and palpebral
  • Nasal
  • Buccolabial
• Epicranius


  Occipitofrontalis and temporoparietalis
• Occipitofrontalis


  • Musculofibrous tissue that covers the dome of the skull from the highest nuchal lines to the eyebrows
  • Broad layer consisting of 4 thin, muscular quadrilateral parts - 2 occipital and 2 frontal - connected by the epicranial aponeurosis

  
• Occipital part (Occipitalis)


  • Arises by tendinous fibers from the lateral two-thirds of the highest nuchal line of the occipital bone and adjacent region of the mastoid part of the temporal bone
• Frontal part (Frontalis)


  • Adherent to the superficial fascia, particularly of the eyebrows
  • Has no bony attachments of its own
  • Fibers blend with those of adjacent muscles - procerus, corrugator supercilii and orbicularis oculi - and ascend to join the epicranial aponeurosis in front of the coronal suture
• Vascular supply of occipitofrontalis is from branches of the superficial temporal, ophthalmic, posterior auricular and occipital arteries
• Occipital part is innervated by the posterior auricular branch of the facial nerve, and the frontal part is innervated by the temporal branches of the facial nerve
• Actions of occipitofrontalis

  • Frontal parts raise the eyebrows and the skin over the root of the nose
  • Occipital parts draw the scalp backwards
  • Acting alternately, the occipital and frontal parts can move the entire scalp backwards and forwards
• Epicranial aponeurosis


  • Fibrous tissue that covers upper part of the cranium connecting the 2 epicranial muscles
  • Attached posteriorly to the external protuberance and highest nuchal line of the occipital bone
  • Splits anteriorly to enclose the frontal parts and sends a short, narrow prolongation between them
  • Laterally, the anterior and superior auricular muscles are attached to it and it continues over the temporal fascia to the zygomatic arch
  • United to the skin lying over the cranial vault by fibrous superficial fascia and connected more loosely to the underlying pericranium by areolar tissue, allowing it to move freely with the skin of the scalp
• Temporoparietalis


  A variably developed sheet of muscle that lies between the frontal parts of occipitofrontalis and the anterior and superior auricular muscles
• Muscles in the circumorbital and palpebral group

  • Orbicularis oculi
  • Corrugator supercilii
  • Levator palpebrae superioris
• Orbicularis oculi


  • A broad, flat, elliptical muscle that surrounds the circumference of the orbit
  • Has orbital, palpebral and lacrimal parts
  • Spreads into the adjacent regions of the eyelids, anterior temporal region, infraorbital cheek and superciliary region
• Orbital part of orbicularis oculi

  • Arises from the nasal component of the frontal bone, frontal process of the maxilla and medial palpebral ligament
  • Upper orbital fibers blend with the frontal part of occipitofrontalis and corrugator supercilii, and many are inserted into the skin and subcutaneous tissue of the eyebrow constituting the depressor supercilii
  • Inferiorly and medially, the ellipses overlap or blend with adjacent muscles like levator labii superioris alaeque nasi and levator labii superioris
• Palpebral part of orbicularis oculi


  • Arises from the medial palpebral ligament, mainly from its superficial surface, and from the bone immediately above and below the ligament
  • The fibers sweep across the eyelids anterior to the orbital septum, interlacing at the lateral commissure to form the lateral palpebral raphe
  • A small ciliary bundle of fine fibers close to the margin of each eyelid behind the eyelashes
• Lacrimal part of orbicularis oculi


  • Arises from the upper part of the lacrimal crest and adjacent lateral surface of the lacrimal bone
  • Passes laterally behind the nasolacrimal sac where some fibers are inserted into the associated fascia, then divides into upper and lower slips
  • Some fibers are inserted into the tarsi of the eyelids close to the lacrimal canaliculi, while most continue across in front of the tarsi and interlace in the lateral palpebral raphe
• Orbicularis oculi is supplied by branches of the facial, superficial temporal, maxillary and ophthalmic arteries
• Orbicularis oculi is innervated by the temporal and zygomatic branches of the facial nerve
• Actions of orbicularis oculi

  • Sphincter muscle of the eyelids
  • Plays an important role in facial expression and various ocular reflexes
  • Orbital portion is usually activated under voluntary control
  • Contraction of the upper orbital fibers produces vertical furrowing above the bridge of the nose, narrowing of the palpebral fissure (squinting), and bunching and protrusion of the eyebrows
  • Eye closure is largely affected by lowering of the upper eyelid with considerable elevation of the lower eyelid
  • Palpebral portion can be contracted voluntarily (to close the lids gently as in sleep) or reflexly (to close the lids protectively in blinking)
  • Palpebral part has upper depressor fascicles and lower elevator fascicles
  • Lacrimal part draws the eyelids and lacrimal papillae medially, aiding drainage of tears and influencing pressure gradients within the lacrimal gland and ducts
• When the entire orbicularis oculi muscle contracts, the skin is thrown into folds that radiate from the lateral angle of the eyelids, causing permanent 'crow's feet' wrinkles in middle age
• Corrugator supercilii


  • A small pyramidal muscle located at the medial end of each eyebrow, lying deep to the frontal part of occipitofrontalis and orbicularis oculi
  • Arises from bone at the medial end of the superciliary arch and its fibers pass laterally and slightly upwards to exert traction on the skin above the middle of the supraorbital margin
• Corrugator supercilii is supplied by branches from the superficial temporal and ophthalmic arteries, and is innervated by the temporal branches of the facial nerve
• Actions of corrugator supercilii

  • Cooperates with orbicularis oculi to draw the eyebrows medially and downwards, shielding the eyes in bright sunlight
  • Also involved in frowning
  • The combined action of the two muscles produces mainly vertical wrinkles on the supranasal strip of the forehead
• Muscles in the nasal group

  • Procerus
  • Nasalis
  • Depressor septi
• Procerus


  • A small muscle superficial to the nasal bone that is active when an individual frowns
  • Arises from the nasal bone and upper part of the lateral nasal cartilage, inserting into the skin over the lower part of the forehead between the eyebrows
  • May be continuous with the frontal belly of the occipitofrontalis muscle
  • Draws the medial border of the eyebrows downward to produce transverse wrinkles over the bridge of the nose
• Nasalis


  • The largest and best developed of the nasal muscles
  • Consists of a transverse part (compressor naris) that compresses the nares, and an alar part (dilator naris) that opens the nares by drawing the alar cartilages downward and laterally
• Nasalis is supplied by the facial artery and the infraorbital branch of the maxillary artery, and is innervated by the buccal branch of the facial nerve, and possibly also the zygomatic branch
• Actions of nasalis

  • The transverse part compresses the nasal aperture at the junction of the vestibule and the nasal cavity
  • The alar parts draw the alae and posterior part of the columella downwards and laterally, assisting in widening the nares and elongating the nose, being active immediately before inspiration
• Dilator naris anterior


  • Also known as apicis nasi or the small dilator muscle of the nose
  • A very small muscle attached to the upper lateral cartilage, the alar part of nasalis, the caudal margin of the lateral crus and the lateral alar crus
  • Encircles the naris and acts as a primary dilator of the nostril
  • Functions with the alar part of nasalis to prevent collapse of the nasal valve during inspiration
• Depressor septi nasi

  • Lies immediately deep to the mucous membrane of the upper lip, usually attached to the periosteum covering the maxilla
  • Its fibers arise from the maxilla above the central incisor tooth and ascend to insert into the lower part of the nasal septum
  • Pulls the nose inferiorly, assisting the alar part of the nasalis in opening the nares
• Depressor septi nasi is supplied by the superior labial branch of the facial artery, and innervated by the buccal branch, and sometimes the zygomatic branch, of the facial nerve
• Actions of depressor septi nasi

  • Pulls the columella, the tip of the nose and the nasal septum downwards
  • Tenses the nasal septum at the start of nasal inspiration and, with the alar part of nasalis, widens the nasal aperture, as well as causing the nose to 'dip' when some people smile