Facial Nerves and Muscles
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Questions and Answers

What are the overarching responsibilities of Cranial Nerve VII?

  • Facial expression and taste sensation (correct)
  • Hearing and balance maintenance
  • Vision and eye movement control
  • Blood pressure regulation and digestion

    • Which of the following muscles is NOT considered a muscle of facial expression innervated by CN VII?

  • Orbicularis oris
  • Zygomaticus major
  • Frontalis
  • Masseter (correct)

    • What is the likely outcome if there is a lesion of Cranial Nerve VII along its pathway?

  • Loss of ability to elevate the upper eyelid
  • Loss of sensation in the facial region
  • Weakness in lateral eye movements
  • Inability to produce tears and salivation (correct)

    • Which extraocular muscle is responsible for the movement that depresses, abducts, and medially rotates the eyeball?

    <p>Superior Oblique</p> Signup and view all the answers

    What neurological deficit might occur with a lesion of CN VI?

    <p>Inability to abduct the gaze laterally</p> Signup and view all the answers

    Which cranial nerve is responsible for the sensation of the face and motor supply to the muscles of mastication?

    <p>Cranial Nerve V</p> Signup and view all the answers

    What could be a potential consequence of damage to Cranial Nerve VII?

    <p>Facial asymmetry and impaired muscle function</p> Signup and view all the answers

    Which muscles are primarily innervated by Cranial Nerve VII?

    <p>Muscles of facial expression</p> Signup and view all the answers

    Which function of the extraocular muscles is controlled by Cranial Nerve III primarily, but not by Cranial Nerve VII?

    <p>Elevation of the eyelid</p> Signup and view all the answers

    Neurological deficits resulting from damage to which cranial nerve could lead to significant difficulty in taste sensation?

    <p>Cranial Nerve VII</p> Signup and view all the answers

    What is the primary motor function of Cranial Nerve VII?

    <p>Motor supply to the muscles of facial expression</p> Signup and view all the answers

    Which structures are primarily affected by Bell's Palsy?

    <p>Muscles of facial expression</p> Signup and view all the answers

    Where do the cell bodies of Cranial Nerve VII originate?

    <p>Pons and geniculate ganglion</p> Signup and view all the answers

    Which of the following statements about the innervation of the tongue is true?

    <p>Cranial Nerve VII is responsible for special sensation (taste) in the anterior two-thirds of the tongue.</p> Signup and view all the answers

    Which cranial nerve is primarily associated with the control of the muscles of mastication?

    <p>Cranial Nerve V</p> Signup and view all the answers

    What effect does a lesion of Cranial Nerve VII typically have?

    <p>Paralysis of the muscles of facial expression</p> Signup and view all the answers

    The exit point for Cranial Nerve VII from the cranium is the:

    <p>Stylomastoid foramen</p> Signup and view all the answers

    Which of the following is NOT a responsibility of Cranial Nerve VII?

    <p>Providing sensory perception for the upper limb</p> Signup and view all the answers

    What is the primary function of the mandibular branch (V3) of Cranial Nerve V?

    <p>Motor supply to the muscles of mastication</p> Signup and view all the answers

    What structures do cranial nerves emerge from when exiting the cranial cavity?

    <p>Foramina and fissures</p> Signup and view all the answers

    Which sensory function is primarily associated with the ophthalmic branch (V1) of Cranial Nerve V?

    <p>Sensation from the forehead and scalp</p> Signup and view all the answers

    How many pairs of cranial nerves are there in total?

    <p>12</p> Signup and view all the answers

    Which region is NOT exclusively supplied by the trigeminal nerve?

    <p>Neck</p> Signup and view all the answers

    Which cranial nerve is responsible for the movement of the lateral rectus muscle?

    <p>Cranial Nerve VI</p> Signup and view all the answers

    What is the primary action of the levator palpebrae superioris muscle?

    <p>Elevates the upper eyelid</p> Signup and view all the answers

    With a lesion of Cranial Nerve III, where would the gaze typically be directed?

    <p>Down &amp; laterally</p> Signup and view all the answers

    Which of the following is an action of the superior oblique muscle?

    <p>Depresses, abducts, and medially rotates the eyeball</p> Signup and view all the answers

    In response to a lesion affecting the lateral rectus muscle, how would the gaze be affected?

    <p>Gaze would deviate toward the affected eye</p> Signup and view all the answers

    Which nerve is responsible for the sensory portion of the corneal reflex?

    <p>Nasociliary nerve</p> Signup and view all the answers

    What is the primary role of the maxillary nerve (V2) in the sensory supply?

    <p>Sensation to the skin over maxilla and related structures</p> Signup and view all the answers

    Which branch of the ophthalmic nerve (V1) is responsible for sensation from the skin of the nose?

    <p>Infratrochlear nerve</p> Signup and view all the answers

    The mandibular nerve (V3) provides sensory innervation to which of the following areas?

    <p>Skin over the mandible and anterior 2/3 of the tongue</p> Signup and view all the answers

    Which type of fibers are carried by the short ciliary nerves?

    <p>Both afferent sensory fibers and sympathetic fibers</p> Signup and view all the answers

    What structures does the maxillary nerve (V2) NOT supply?

    <p>Mandibular teeth</p> Signup and view all the answers

    What is the primary function of the nasal ciliary and ethmoidal nerves?

    <p>Sensation to the nose and surrounding areas</p> Signup and view all the answers

    Where does the mandibular nerve (V3) exit the cranial vault?

    <p>Foramen ovale</p> Signup and view all the answers

    What is the primary function of the genioglossus muscle?

    <p>Tongue protrusion</p> Signup and view all the answers

    Which cranial nerve is responsible for the motor innervation of the extrinsic tongue muscles?

    <p>Cranial Nerve XII</p> Signup and view all the answers

    Which of the following is likely to occur with a CN III lesion?

    <p>Ptosis of the eyelid</p> Signup and view all the answers

    What is the expected deviation of the tongue during a CN XII lesion?

    <p>Deviation to the right side</p> Signup and view all the answers

    Which cranial nerve lesions would result in double vision due to an inability to depress the eye?

    <p>Cranial Nerve IV</p> Signup and view all the answers

    Which muscle is primarily responsible for tongue depression and retraction?

    <p>Hyoglossus</p> Signup and view all the answers

    What is the typical outcome for pupillary reflex with a CN III lesion?

    <p>Loss of pupillary reflex</p> Signup and view all the answers

    When the right genioglossus contracts unilaterally, how does the tongue deviate?

    <p>To the left side</p> Signup and view all the answers

    Which of the following is NOT a function attributed to Cranial Nerve VII?

    <p>Regulation of blood pressure</p> Signup and view all the answers

    What is the significance of the stylomastoid foramen in relation to Cranial Nerve VII?

    <p>It serves as the exit point for the nerve from the cranium.</p> Signup and view all the answers

    A person with Bell's palsy typically experiences which of the following symptoms?

    <p>Inability to raise the eyebrows</p> Signup and view all the answers

    Which muscles are primarily responsible for the movements of the eyelids and are innervated by Cranial Nerve VII?

    <p>Orbicularis oculi</p> Signup and view all the answers

    What is the function of the Buccinator muscle?

    <p>Compresses the cheeks against the teeth</p> Signup and view all the answers

    Which of the following statements about sensory functions of Cranial Nerve VII is true?

    <p>It provides taste sensation to the anterior 2/3 of the tongue.</p> Signup and view all the answers

    In the event of a lesion affecting the origin of Cranial Nerve VII, which symptom is likely to occur?

    <p>Difficulty in closing the eyebrows</p> Signup and view all the answers

    Which area of the facial region is primarily affected by the paralysis caused by Bell's palsy?

    <p>The side ipsilateral to the lesion</p> Signup and view all the answers

    Which nerve fiber types are primarily associated with Cranial Nerve VII?

    <p>Motor and sensory fibers</p> Signup and view all the answers

    Which of the following muscles is responsible for elevating the upper lip?

    <p>Zygomaticus major</p> Signup and view all the answers

    Which branch of Cranial Nerve V is primarily responsible for motor innervation?

    <p>V3 - Mandibular</p> Signup and view all the answers

    What is the primary sensory function of the maxillary nerve (V2)?

    <p>Sensory input from the upper lip and cheeks</p> Signup and view all the answers

    Which structure does the ophthalmic nerve (V1) NOT supply sensory innervation to?

    <p>Lower jaw</p> Signup and view all the answers

    Cranial nerve V (Trigeminal) receives sensory input from which area?

    <p>Face and anterior half of scalp</p> Signup and view all the answers

    Which statement about the trigeminal nerve is incorrect?

    <p>It exclusively carries motor fibers.</p> Signup and view all the answers

    What type of fibers do the long and short ciliary nerves primarily carry?

    <p>Afferent sensory fibers from the cornea</p> Signup and view all the answers

    Which nerve is responsible for sensation from the skin along the side of the nose?

    <p>Infratrochlear nerve</p> Signup and view all the answers

    Which structures are NOT supplied by the maxillary nerve (V2)?

    <p>Buccal mucosa</p> Signup and view all the answers

    What is the primary role of the mandibular branch (V3) of the trigeminal nerve?

    <p>General sensation to the anterior 2/3 of the tongue</p> Signup and view all the answers

    Which of the following branches of the maxillary nerve (V2) provides sensation to the maxillary teeth?

    <p>Alveolar nerve</p> Signup and view all the answers

    What is the primary function of the nasociliary nerve?

    <p>Providing sensation for the corneal reflex</p> Signup and view all the answers

    Which nerve exits the cranial vault through foramen ovale?

    <p>Mandibular nerve (V3)</p> Signup and view all the answers

    Which area is NOT supplied by the ophthalmic nerve (V1)?

    <p>Mucosa of the oral cavity</p> Signup and view all the answers

    Which muscle is primarily responsible for elevating the eyelid?

    <p>Levator palpebrae superioris</p> Signup and view all the answers

    What is the expected position of the eye with a lesion of Cranial Nerve IV?

    <p>Down and out</p> Signup and view all the answers

    Which cranial nerve is primarily responsible for the parasympathetic control of pupil constriction?

    <p>Cranial Nerve III</p> Signup and view all the answers

    What mechanism causes the tongue to deviate towards the side of a CN XII lesion?

    <p>Unilateral action of the genioglossus</p> Signup and view all the answers

    What is the clinical significance of pupil dilation in the case of a CN III lesion?

    <p>It reveals an unopposed action of the iris dilator</p> Signup and view all the answers

    What is the role of the superior oblique muscle during eye movement when reading?

    <p>Depression of the eyeball</p> Signup and view all the answers

    Which extrinsic tongue muscle is primarily involved in tongue retraction?

    <p>Styloglossus</p> Signup and view all the answers

    How does a patient typically present with a CN III lesion during a cranial nerve examination?

    <p>Ptosis and dilated pupil</p> Signup and view all the answers

    What is the primary role of the mandibular nerve (CN V3) in relation to oral anatomy?

    <p>Sensory innervation to the mucosa of the anterior two thirds of the tongue</p> Signup and view all the answers

    Which branch of the trigeminal nerve is primarily associated with excruciating pain in trigeminal neuralgia?

    <p>Mandibular nerve (V3)</p> Signup and view all the answers

    What pathological condition is often related to a vasculature anomaly affecting CN V?

    <p>Trigeminal neuralgia</p> Signup and view all the answers

    Which muscle is NOT innervated by the mandibular nerve (CN V3)?

    <p>Buccinator</p> Signup and view all the answers

    What significant anatomical feature allows the mandibular nerve (CN V3) to communicate with the external environment?

    <p>Foramen ovale</p> Signup and view all the answers

    Which of the following statements about the sensory functions of CN V is FALSE?

    <p>It is exclusively responsible for taste sensation in the tongue.</p> Signup and view all the answers

    Which of the following structures does NOT receive sensory innervation from the mandibular nerve (CN V3)?

    <p>Posterior two thirds of the tongue</p> Signup and view all the answers

    What is the expected result of compression of CN V due to a vascular anomaly?

    <p>Excruciating pain along specific nerve distributions</p> Signup and view all the answers

    What is the primary role of the Platysma muscle?

    <p>Depresses the mandible and tenses skin of the neck</p> Signup and view all the answers

    Which cranial nerve is most frequently associated with facial paralysis?

    <p>Cranial Nerve VII</p> Signup and view all the answers

    Which of the following is an effect of a lesion in Cranial Nerve VII?

    <p>Inability to close the eyelids</p> Signup and view all the answers

    Which branch of Cranial Nerve VII is primarily responsible for taste sensation from the anterior two-thirds of the tongue?

    <p>Chorda tympani</p> Signup and view all the answers

    Which muscle is innervated by Cranial Nerve VII and functions to close the eyelids?

    <p>Orbicularis oculi</p> Signup and view all the answers

    What is Bell's palsy primarily caused by?

    <p>Trauma or damage to the facial nerves</p> Signup and view all the answers

    Which muscle is responsible for elevating the upper lip?

    <p>Levator labii superioris</p> Signup and view all the answers

    Which factor is NOT typically a symptom of a lesion to Cranial Nerve VII?

    <p>Forehead wrinkles</p> Signup and view all the answers

    Which structure serves as the exit point for Cranial Nerve VII from the cranium?

    <p>Stylomastoid foramen</p> Signup and view all the answers

    What is one of the primary functions of the Buccinator muscle?

    <p>Compress the cheeks against the teeth</p> Signup and view all the answers

    Study Notes

    Cranial Nerve V (Trigeminal)

    • Cell bodies originate in the Pons and the semilunar (trigeminal) ganglion
    • Supplies sensory and motor innervation to the face, anterior scalp, teeth, mouth, and nasal cavity
    • Has three branches: ophthalmic (V1), maxillary (V2), and mandibular (V3)

    Ophthalmic (V1)

    • Primarily sensory
    • Exits the cranial vault through the superior orbital fissure
    • Branches include:
      • lacrimal nerve: innervates the lacrimal gland and provides sensory innervation to the conjunctiva and upper eyelid
      • frontal nerve: exits through the supraorbital foramen and divides into the supraorbital and supratrochlear nerves, providing sensation to the forehead, scalp, upper eyelid, and frontal sinus

    Maxillary (V2)

    • Primarily sensory
    • Exits the cranial vault through the foramen rotundum

    Mandibular (V3)

    • Supplies both motor and sensory innervation
    • Exits the cranial vault through the foramen ovale

    Cranial Nerve V (Trigeminal)

    • Cell bodies arise from the Pons and semilunar/trigeminal ganglion
    • Three branches:
      • Ophthalmic (V1): sensory, exits cranial vault through superior orbital fissure
      • Maxillary (V2): sensory, exits through foramen rotundum to inferior orbital fissure
      • Mandibular (V3): sensory and motor, exits through foramen ovale to temporal fossa
    • Responsible for:
      • Sensation to the face, anterior scalp, teeth, mouth, and nasal cavity
      • Motor supply to muscles of mastication

    Ophthalmic Nerve (V1)

    • Sensory only
    • Major branches:
      • Lacrimal- innervates lacrimal gland (sensory)
      • Frontal- divides into supraorbital and supratrochlear nerves, supplies sensation to forehead, scalp, upper eyelid, and frontal sinus
      • Nasociliary- contains afferent sensory fibers from cornea, skin of eyelid and nose, lacrimal sac, and sinuses; responsible for sensory portion of corneal reflex
      • Infratrochlear- sensation to skin alongside the nose
      • Ethmoidal- sensation to nose
    • Passes through the superior orbital fissure into the orbit
    • Supplies:
      • Cornea
      • Superior conjunctiva
      • Mucosa of anterosuperior nasal cavity
      • Frontal, ethmoidal, and sphenoidal sinuses
      • Anterior and supratentorial dura mater
      • Skin of dorsum of external nose
      • Superior eyelid
      • Forehead
      • Anterior scalp

    Maxillary Nerve (V2)

    • Sensory only
    • Major branches:
      • Infraorbital
      • Meningeal
      • Alveolar
      • Zygomatic- divides into zygomaticotemporal and zygomaticofacial nerves
    • Passes through foramen rotundum to enter pterygopalatine fossa
    • Supplies:
      • Dura mater of anterior part of middle cranial fossa
      • Conjunctiva of inferior eyelid
      • Mucosa of postero-inferior nasal cavity, maxillary sinus, palate, and anterior part of superior oral vestibule
      • Maxillary teeth
      • Skin of lateral external nose
      • Maxillary teeth
      • Skin of lateral external nose

    Mandibular Nerve (V3)

    • Sensory and motor
    • Exits through foramen ovale to temporal fossa
    • Responsible for:
      • Sensation to skin over mandible, teeth/gums of mandible, skin of temporal region, general sensation of anterior 2/3 of tongue and oral mucosa, and TMJ
      • Motor supply to muscles of mastication
    • Anterior branch- primarily motor to muscles of mastication
    • Posterior branch- primarily sensory
    • Branches include:
      • Auriculotemporal
      • Buccal
      • Lingual (general tongue sensation)
      • Inferior alveolar
    • Parasympathetic innervation provides motor function for:
      • Secretion of tears (lacrimal gland)
      • Secretion of saliva (sublingual and submandibular salivary glands)
    • Special sensory: taste to anterior 2/3 of tongue and palate

    Cranial Nerve VII (Facial)

    • Cell bodies originate in the pons and geniculate ganglion
    • Travels through internal acoustic meatus and facial canal in calvarium
    • Exits stylomastoid foramen
    • Terminal motor branches include:
      • Temporal
      • Zygomatic
      • Buccal
      • Mandibular
      • Cervical
    • Muscles of Facial Expression
      • Orbicularis oculi- Closes eyelids
      • Occipitofrontalis- Raises eyebrows and wrinkles skin of forehead, protracts (pulls back) the scalp
      • Corrugator supercilli- Draws eyebrows medially and down
      • Procerus- Depresses medial eyebrow, makes transverse wrinkle in forehead
      • Nasalis- Widens nasal aperture during deep inspiration
      • Levator labii superioris alaeque nasi (LLSAN): Everts upper lip and dilates nostrils
      • Levator labii superioris- Elevates and everts upper lip
      • Zygomaticus minor and major- Elevate upper lip; retract buccal angle
      • Levator Anguli Oris- Raises the buccal angle
      • Buccinator- Compresses cheeks against the teeth &/or expelling air when cheeks distended
      • Mentalis- Wrinkles chin skin
      • Depressor labii inferioris- Depresses lower lip; assists in lower lip eversion
      • Depressor anguli oris- Depresses the buccal angle laterally
      • Orbicularis oris- Closes/purses/protrudes lips
      • Platysma- Depresses mandible and tenses skin of inferior face & neck

    Cranial Nerve VII Lesions

    • Most frequently paralyzed cranial nerve containing motor fibers
    • Bell’s palsy is a form of temporary facial paralysis that’s caused by damage or trauma to facial nerves
    • Lesion near the origin of the nerve or along its pathway results in:
      • Ipsilateral paralysis of facial and scalp muscles
        • Inability to close eyelids
        • Angle of the mouth droops
        • Forehead does not wrinkle
      • Loss of taste to anterior 2/3 of tongue and palate
      • Impairments in secretion of tears and saliva

    Extraocular Muscles

    • Muscles attached to the sclera of the eye and the bony orbit; contraction results in movement of the eyes and superior eyelid movement
    • Pupil is the reference point for eyeball movement
    • Movements include: — Elevation of the eyelid (levator palpebrae superioris) — Eyeball movements: — Elevation — Depression — Internal/medial rotation (intorsion) — External/lateral rotation (extorsion) — Adduction (towards nose) — Abduction (towards ear) — Combination Movements
    • Levator palpebrae superioris- Elevates upper eyelid; CN III (oculomotor)
    • Medial Rectus- Adduction of eyeball (towards nose); CN III (oculomotor)
    • Lateral Rectus- Abduction of eyeball (towards ear); CN VI (abducens)
    • Superior Rectus- Elevates, adducts, and medially rotates eyeball; CN III
    • Inferior Rectus- Depresses, adducts, and laterally rotates eyeball; CN III
    • Superior Oblique- Depresses, abducts, and medially rotates eyeball; CN IV (trochlear)
    • Inferior Oblique- Elevates, abducts, and laterally rotates eyeball; CN III (oculomotor)

    Nerve Lesions

    • Lesion of CN VI
      • Denervation of lateral rectus muscle
      • Gaze directed medially (towards nose) because lateral rectus is not working
    • Lesion of CN III
      • Denervation of: levator palpebrae superioris; superior rectus; inferior rectus; medial rectus; inferior oblique
      • Gaze directed down and laterally because only LR and SO are innervated and produce down and out movement
      • Ptosis of the eyelid and consistently dilated pupil may be apparent with CN III lesion
        • CN III is responsible for parasympathetic fibers to sphincter of pupil, which would be lost with a CN III lesion
        • Pupillary reflex lost
    • Lesion of CN IV (rarely occurs alone)
      • Denervation of superior oblique
      • Cannot depress the eye when it is adducted (eg. reading or going down stairs)
      • Double vision may occur
        • SO assists in depression of the eyeball

    Extrinsic Tongue Muscles

     - Tongue is essentially a mass of muscles covered by mucosa 
 - Intrinsic muscles alter the shape of the tongue
 - Extrinsic muscles alter the position of the tongue  
 - Extrinsic Muscles: 
     - Genioglossus
     - Hyoglossus
     - Styloglossus

    Extrinsic Tongue Muscles (CN XII)

    • Genioglossus:
      • Tongue protrusion or protraction when working bilaterally (principal muscle)
      • Curls tongue in a circle
      • Unilateral action causes deviation to opposite side
        • Right genioglossus contraction causes tongue to go to the left (because the muscle pushes the tongue out to the left)
    • Hyoglossus:
      • Tongue depression and retraction
    • Styloglossus:
      • Tongue retraction

    CN XII Lesion

    • CN XII Paralysis: When asked to stick tongue out in midline, tongue deviates to the paralyzed side (because one genioglossus muscle working alone pushes the tongue to the opposite side)
      • Ex. Right CN XII lesion: when you ask the patient to stick out their tongue, it deviates to the right (because the left genioglossus is working alone).

    Cranial Nerve V (Trigeminal)

    • Cell bodies originate in the Pons and semilunar (trigeminal) ganglion
    • 3 branches:
      • V1 - Ophthalmic - primarily sensory
      • V2 - Maxillary - primarily sensory
      • V3 - Mandibular - sensory and motor
    • Responsibilities:
      • Sensation to the face, anterior half of scalp, teeth, mouth, and nasal cavity
      • Motor supply to muscles of mastication

    Ophthalmic Nerve (V1)

    • Exits the cranial vault through the superior orbital fissure
    • Major branches:
      • Lacrimal nerve: innervates the lacrimal gland (sensory), supplies sensory input to the conjunctiva and skin of the upper eyelid
      • Frontal nerve: divides into supraorbital and supratrochlear nerves, supplies sensation to the forehead, scalp, upper eyelid, and frontal sinus
      • Nasociliary nerve: major branches include long and short ciliary nerves, responsible for sensory input from the cornea, skin of the eyelid and nose, lacrimal sac, and sinuses, is responsible for the sensory portion of the corneal reflex

    Maxillary Nerve (V2)

    • Exits foramen rotundum to the inferior orbital fissure
    • Major branches:
      • Infraorbital nerve
      • Meningeal nerve
      • Alveolar nerves
      • Zygomatic nerve: divides into zygomaticotemporal and zygomaticofacial nerves
    • Sensory only: supplies skin of the face over maxilla, upper lip, maxillary teeth, nose mucosa, maxillary sinus, and palate

    Mandibular Nerve (V3)

    • Exits the cranial vault through foramen ovale - to temporal fossa
    • Responsibilities:
      • Sensation to skin over mandible, teeth/gums of mandible; skin of temporal region; general sensation to anterior 2/3 tongue and oral mucosa; TMJ
      • Motor supply to muscles of mastication
    • Anterior branch - chiefly motor to mastication:
    • Posterior branch- chiefly sensory
      • Branches include auriculotemporal nerve, buccal nerve, lingual nerve, (general tongue sensation), and inferior alveolar nerve (ends as mental nerve)

    Trigeminal Neuralgia

    • Aka: Tic Douloureux
    • Idiopathic trigeminal neuropathy (usually sensory in nature)
    • Excruciating pain usually along V2 and V3 distribution
    • Cause Unknown: ?Vasculature anomaly that compresses CN V
    • Treatment: nerve block; medication

    Cranial Nerve VII-Facial Nerve

    • Cell bodies originate in the Pons and geniculate ganglion
    • Travel through Internal acoustic meatus and facial canal in the calvarium
    • Exit stylomastoid foramen
    • Responsibilities:
      • Motor supply to the muscles of facial expression
      • Motor: stylohyoid and posterior belly of digastric muscles
      • Parasympathetic innervation (motor): secretion of tears (lacrimal gland) and saliva (sublingual and submandibular salivary glands)
      • Special sensory: taste to anterior 2/3 of tongue and palate

    Muscles of Facial Expression

    • Orbicularis oculi - closes eyelids
    • Occipitofrontalis - raises eyebrows and wrinkles skin of forehead; protracts (pulls back) scalp
    • Corrugator supercilli - draws eyebrows medially and down
    • Procerus - depresses medial eyebrow; makes transverse wrinkle in the forehead
    • Nasalis - widens nasal aperture during deep inspiration
    • Levator labii superioris alaeque nasi (LLSAN) - everts upper lip and dilates nostrils
    • Levator labii superioris - elevates and everts upper lip
    • Zygomaticus minor and major - elevate upper lip; retract buccal angle
    • Levator Anguli Oris - raises the buccal angle
    • Buccinator - compress cheeks against teeth or expelling air when cheeks distended
    • Mentalis - wrinkles chin skin
    • Depressor labii inferioris - depresses lower lip; assists in lower lip eversion
    • Depressor anguli oris - depresses the buccal angle laterally
    • Orbicularis oris - closes/purses/protrudes lips
    • Platysma - depresses mandible and tenses skin of inferior face and neck

    Cranial Nerve VII

    • Most frequently paralyzed cranial nerve containing motor fibers
    • Bell's palsy is a form of temporary facial paralysis caused by damage or trauma to a person's facial nerves
    • If the lesion is near the origin of the nerve or its pathway distally it results in:
      • Ipsilateral paralysis of facial and scalp muscles
        • Inability to close eyelids
        • Angle of the mouth droops
        • Forehead does not wrinkle
      • Loss of taste to anterior 2/3 tongue and palate
      • Impairments in secretion of tears and saliva

    Extrinsic Tongue Muscles

    • The tongue is essentially a mass of muscles covered by mucosa
    • Muscles do not act in isolation, some muscles perform multiple actions
    • Extrinsic muscles alter the position of the tongue, and intrinsic muscles alter its shape
    • Extrinsic Muscles
      • Genioglossus
      • Hyoglossus
      • Styloglossus

    Extrinsic Tongue Musculature (CN XII)

    • Genioglossus:
      • Tongue protrusion or protraction working bilaterally (principal muscle)
      • Curls tongue in a circle
      • Unilateral action causes deviation to the opposite side
    • Hyoglossus:
      • Tongue depression and retraction
    • Styloglossus:
      • Tongue retraction

    CN XII Lesion

    • CN XII Paralysis: when asked to stick tongue out in midline, tongue deviates to the paralyzed side
      • R XII lesion: when you ask the patient to stick out their tongue, it deviates to the right because the left genioglossus is working alone

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    Functional Human Anatomy Head & Face Cranial Nerves PDF

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    Test your knowledge on Cranial Nerve V, also known as the Trigeminal nerve, which is crucial for sensory and motor functions in the face. This quiz covers its anatomy, branches, and innervations, emphasizing the ophthalmic, maxillary, and mandibular components. Dive deep into the details of its functions and pathways.

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