Functional Human Anatomy Head & Face Cranial Nerves PDF

Functional Human Anatomy Head & Face – Cranial Nerves D R. D O N AL M U R R AY PH D C O N T R IBU T IO N S BY: D R. E LLE N C O S T E LLO, PT, P H D Overview Cranial Nerve V and its responsibilities Please review on your own: bones and sutures of the cranial vault; foramina and associated structu...

Functional Human Anatomy Head & Face – Cranial Nerves D R. D O N AL M U R R AY PH D C O N T R IBU T IO N S BY: D R. E LLE N C O S T E LLO, PT, P H D Overview Cranial Nerve V and its responsibilities Please review on your own: bones and sutures of the cranial vault; foramina and associated structures that enter and exit the cranial vault with emphasis on Cranial Nerves and large vessels Moore Textbook Summary beginning chapter 8 & 10  Cranial Nerves Like spinal nerves, cranial nerves are bundles of sensory or motor fibers that; innervate muscles or glands carry impulses from sensory receptors have a combination of motor and sensory fibers They are called cranial nerves because they emerge from the cranial cavity via foramina or fissures in the cranium There are 12 pairs of cranial nerves, which are numbered I–XII Cranial Nerve V (Trigeminal) Cell bodies rise from Pons & semilunar (aka trigeminal) ganglion 3 branches  V1-ophthalmic- primarily sensory  V2-maxillary-primarily sensory s  V3-mandibular-sensory p and motor Responsibilities include:  sensation to face, anterior half of scalp, teeth, mouth, nasal cavity  motor supply to muscles of mastication  CN V V1 V2 V3  Exit for frontal n. (supraorbital foramen) Ophthalmic Nerve (V1) exits cranial vault through superior orbital fissure Major branches include: lacrimal n.-innervates lacrimal gland (sensory) sensory to conjunctiva & skin of upper lid frontal n.-divides into supraorbital & Sup orbital supratrochlear ns. fissure Supplies sensation forehead, scalp, upper eyelid, frontal sinus Ophthalmic Nerve branches (V1) cont.  Nasociliary n.-major branches = long & short ciliary nerves  Contains:  afferent sensory fibers from cornea, skin of eyelid & nose, lacrimal sac, & sinuses  responsible for the sensory portion of the corneal reflex  (CN VII responsible for the blink of the eye or the motor response…)  Infratrochlear n.-sensation skin alongside the nose  Ethmoidal n.-sensation nose  FYI sympathetic fibers to dilator pupillae; catch a ride with short ciliary nerves  V1 major branches Video Ophthalmic Nerve branches (V1) Sensory only Passes through superior orbital fissure into 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; and anterior scalp Maxillary Nerve (V2) exits foramen rotundum to inferior orbital fissure major branches include:  infraorbital n.  meningeal n.  alveolar ns.  zygomatic n.- divides into zygomaticotemporal and zygomaticofacial ns. Sensory only: supplies skin of face over maxilla, upper lip, maxillary teeth, nose mucosa, maxillary sinus, and palate V2 Exits Foramen Rotundum Inferior orbital fissure Infraorbital nerve  V2: V2 and Sensory only: its supplies skin of face over maxilla, upper branches lip, maxillary teeth, nose mucosa, maxillary sinus, and palate Maxillary Nerve (V2) Sensory only 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; and skin of lateral external Mandibular Nerve (V3) exits 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 ant 2/3 tongue and oral mucosa ; TMJ & motor supply to ms. of mastication Anterior branch - chiefly motor to mastication: Posterior branch- chiefly sensory  branches include auriculotemporal n, buccal n, lingual n (general tongue sensation), & inferior alveolar n. (ends as mental n.) Temporal fossa V3 and its some of its major branches Mandibular nerve (CN V3) Sensory and motor Passes through foramen ovale into infratemporal fossa Supplies sensory innervation to mucosa of anterior two thirds of tongue, floor of mouth, and posterior and anterior inferior oral vestibule; mandibular teeth; and skin of lower lip, buccal, parotid, and temporal regions of face; and external ear (auricle, upper external acoustic meatus, and tympanic membrane) Supplies motor innervation to four muscles of mastication, mylohyoid, anterior belly of digastric, tensor veli palatini, and tensor tympani 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 Video  Branches we will see exiting the foramen in lab x x x Let’s Recap Can you identify where the cell bodies of CN V arise from? What are the overarching responsibilities of CN V? Can you name the 3 major branches of CN V and their responsibilities? Can you trace CN V’s pathway; V1, V2, and V3? What would happen if there is a lesion of CN V along its pathway? What are the neurological deficits? Who is responsible for general sensation to the tongue (touch, pain, hot, cold)? Who is responsible for special sensation to the tongue (taste)? Overview Cranial Nerves VII & V Cranial Nerve VII and its responsibilities Cranial Nerve V and its responsibilities Muscles of Facial Expression  Cranial Nerve VII-Facial Nerve Cell bodies originate in Pons & geniculate ganglion Travel through Internal acoustic meatus & facial canal in calvarium Exit stylomastoid foramen Responsibilities Include:  Motor supply to the muscles of facial expression  (Bell’s Palsy-paralysis of muscles of facial expression; no apparent etiology/idiopathic; suspect edema 2’ infection)  Motor: stylohyoid and posterior belly of digastric ms.  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 Travel through Internal acoustic meatus & facial canal in calvarium Exit stylomastoid foramen  gl ion gan te CN VII: Cell ul a enic bodies G originate in pons and geniculate ganglion pons Stylomastoid foramen  CN VII Glands CN VII: (tears & saliva); Ms facial Taste expression x Cranial Nerve VII terminal motor branches include: To temporal zygomatic buccal Zanzibar mandibular By cervical Car Motor  T Z B M C Muscles of Facial Expression Orbicularis oculi-closes eyelids x Occipitofrontalis-raises eyebrows & wrinkles skin of x forehead; protracts (pulls back) scalp Corrugator supercilli-draws eyebrows medially & down Procerus-depresses medial eyebrow; makes transverse wrinkle in forehead Nasalis-widens nasal aperture during deep inspiration Muscles of Facial Expression Levator labii superioris alaeque nasi (LLSAN)- everts upper lip and dilates nostrils Levator labii superioris- elevates & everts upper lip Zygomaticus minor and major-elevate upper lip; retract buccal angle Levator Anguli Oris-raise the buccal angle  Occiptofrontalis Procerus Corrugator supercilli Orbicularis oculi (One layer deep & in line with the depressor anguli oris) LLSAN Muscles of Facial Expression Buccinator-compress the cheeks against the teeth &/or expelling air when cheeks distended (not well seen on this slide) Mentalis-wrinkles the chin skin Depressor labii inferioris- depresses the lower lip; assist in lower lip eversion Depressor anguli oris-depresses the buccal angle laterally Orbicularis x oris-closes/purses/protrudes the lips Platysma-depresses mandible and tenses skin of inferior face and neck Platysma Cranial Nerve VII 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 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 & scalp muscles:  inability to close the 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 Videos related to CV VII Cranial Nerve VII exam YouTube - Abnormal Cranial Nerve VII - Sensory, Taste 19/25 YouTube - Bell's Palsy and Me - 1 year Let’s Recap Can you identify where the cell bodies of CN VII arise from? Can you trace CN VII’s pathway? What are the overarching responsibilities of CN VII? Can you name the muscles of facial expression? Can you name the 5 major motor branches of CN VII? What would happen if there is a lesion of CN VII along its pathway? What are the neurological deficits? Extraocular Muscles Innervation and Actions Neurological lesions Cranial Nerves III, IV, VI Cranial Nerve XII and its What are extraocular muscles? Muscles attached to the sclera of the eye and the bony orbit Contraction results in movement of the eyes within the orbit & superior eyelid movement The 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) OR Combination Movements Extraocular Muscles 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-elevate, adducts, med rotates eyeball  CN III Inferior Rectus-depress, adducts, lat rotates eyeball  CN III Extraocular Muscles cont. Superior Oblique-depress, abducts, med rotates eyeball (down & out)  CN IV (trochlear n.) Inferior Oblique-elevate, abducts, lat rotates eyeball (up & out)  CN III (oculomotor n.)  Extraocular Muscles Superior rectus Nerve Lesions Lesion of CN VI  Denervation of lateral rectus ms.  gaze directed which way? Lesion of CN III  Denervation of: levator palpebrae superioris, superior rectus, inferior rectus, medial rectus, inferior oblique  gaze directed down & laterally  Why? b/c only muscles left innervated (LR & SO) produce down and out  Ptosis of the eyelid (droopy eyelid..why?) & consistently dilated pupil may be apparent with CN III lesion  CN III responsible for parasymph 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 muscle  cannot depress the eye when eye adducted (eg during convergence when reading or going down stairs; double vision)  SO assists in depression of the eyeball down  Cranial Nerves III, IV, VI exam Extrinsic Tongue Muscles The tongue is essentially a mass of muscles that is mostly covered by mucosa (mucous membrane) The muscles of the tongue do not act in isolation, and some Intrinsic muscles perform multiple actions - extrinsic muscles alter the position of the tongue, and intrinsic muscles alter its shape. Extrinsi Extrinsic Muscles c  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 opposite side  R genioglossus contraction causes tongue to go to left (b/c the muscle pushes the tongue out to left) stylog Hyoglossus geniog hyogl tongue depression and retraction Styloglossus tongue retraction CN XII Lesion CN XII Paralysis-when asked to stick tongue out in midline…deviates to paralyzed side  (First think of the action: One genioglossus ms. working alone pushes the tongue to the opposite side)  R XII lesion: when you ask the patient to stick out their tongue, it deviates to the right (b/c the left genioglossus is working alone)  Cranial Nerve XII Exam Where is the lesion? Let’s summarize What nerve(s) innervates the extraocular muscles? A drooping eyelid or ptosis … what is the potential problem neurologically? If you can’t close your eyelid..who is the culprit? If you pupil is stuck in a dilated position… what is the potential problem? If it won’t dilate? Who is responsible for the sensory arm of the corneal reflex? Who is responsible for the motor response in the corneal reflex?