LAB EXERCISE 11 CRANIAL NERVES

Cranial Nerves Twelve pairs of cranial nerves That arise from the brain Each nerve is identified by a Roman number I through XII and a name

Cranial Nerves Four Classifications of Cranial Nerves Sensory nerves **Carry somatic sensory information, including touch, pressure, vibration, temperature, and pain Special sensory nerves **Carry sensations such as smell, sight, hearing, balance Motor nerves: **Axons of somatic motor neurons Mixed nerves: **Mixture of motor and sensory fibers

Summary of Function of Cranial Nerves Figure 13.5b

Cranial Nerves Four cranial nerves carry parasympathetic fibers that serve muscles and glands Occulomotor (III) Facial (VII) Glossopharyngeal (IX) Vagus (X)

Cranial Nerves Cranial Nerves The 12 cranial nerve groups are identified by: Primary function Origin Pathway Destination

Cranial Nerves Olfactory Nerves (I) Primary function: Origin: Special sensory (smell) Origin: Receptors of olfactory epithelium

Cranial Nerves Olfactory Nerves (I) Pathway: Olfactory foramina in cribriform plate of ethmoid bone Destination: Olfactory bulbs To the olfactory tract

Cranial Nerve I - Olfactory Nerve Assesment Have patient smell different items Damage to the ethmoid bone Can cause anosmia Loss of smell

Cranial Nerves Optic Nerves (II) Primary function: Special sensory (vision) Origin: Retina of eyes

Cranial Nerves Optic Nerves (II) Pathway: Optic Canal of sphenoid bone

Cranial Nerves Optic Nerves (II) Destination: Diencephalon via optic chiasm Optic tracts Leading to lateral geniculate nuclei Olfactory Lobe

Cranial Nerve II - Optic Nerve Assessment Test visual Acuity one eye at a time Snellen eye chart Test peripheral vision one eye at a time Cover one eye and have the patient look at your nose. Move your finger to check superior and inferior fields Damage to the orbits or diseases in the nervous system can cause a loss of vision. Anopia Ipsilateral blindness due to sensory loss in the nerve

Cranial Nerves Oculomotor Nerves (III) Primary function: Motor (eye movements) Controls four of six eye-movement muscles Origin: Midbrain Pathway: Superior orbital fissures of sphenoid

Cranial Nerves Oculomotor Nerves (III) Destination: Somatic motor Superior, inferior, and medial rectus muscles Inferior oblique muscle Levator palpebrae superioris muscle

Cranial Nerves Oculomotor Nerves (III) Visceral motor Parasympathetic Function Ciliary ganglion

Cranial Nerves Oculomotor Nerves (III) Destination: Visceral motor (Parasympathetic) Intrinsic eye muscles Cilliary Muscle **Accommodation of the lens Circular Muscles **Constriction of iris Radial Muscles **Dilation of iris

Cranial Nerve III - Oculomotor Assessment - To test the patients pupils *Use a penlight and mm ruler - Check to see where eyelid falls on the pupil Damages *Causes Ptosis – Drooping of eyelid *Causes diplopia – Double vision *Trouble with eye movements

Cranial Nerves The Trochlear Nerves (IV) Primary function: Motor (eye movements) Origin: Midbrain

Cranial Nerves The Trochlear Nerves (IV) Pathway: Destination: Superior orbital fissure of sphenoid Destination: Superior oblique muscle

Cranial Nerve IV - Trochlear Nerve Assessment -Have patient follow your finger while moving it to the nose Damages *Causes  Diplopia  Paralysis  Strabismus *Lazy Eye

Cranial Nerves The Trigeminal Nerves (V) Primary function: Mixed Nerve Sensory Functions in touch, pain, & temperature receptors of the face Motor Innervates the muscles of mastication

Cranial Nerves The Trigeminal Nerves (V) Largest cranial nerves With three major branches Ophthalmic Maxillary Mandibular

Cranial Nerves The Trigeminal Nerves (V) Sensory Innervation Semilunar ganglion Contains cell bodies of sensory neurons

Cranial Nerves The Trigeminal Nerves (V) Ophthalmic Branch (V1) Sensory innervation to: Orbital structures Nasal cavity Skin of forehead Upper eyelid Eyebrow Part of nose

Cranial Nerves The Trigeminal Nerves (V) Pathway: Ophthalmic Branch (V1) Superior Orbital Fissure

Cranial Nerves Maxillary Branch (V2) The Trigeminal Nerves (V) Origin: Sensory innervation to Lower eyelid Upper Lip Gums Teeth Cheek and nose Palate and part of pharynx

Cranial Nerves The Trigeminal Nerves (V) Pathway: Maxillary branch (V2) Foramen Rotundum

Cranial Nerves The Trigeminal Nerves (V) Mandibular Branch (V3) Sensory innervation to: Lower Gums Teeth Lips Palate Part of tongue Lingual Nerve

Cranial Nerves The Trigeminal Nerves (V) Origin: Mandibular branch (V3) Motor innervation From Motor nuclei of pons

Cranial Nerves The Trigeminal Nerves (V) Destination: Motor nerves of Mandibular Branch Muscles of mastication Chewing

Cranial Nerves The Trigeminal Nerves (V) Pathway: Mandibular branch Foramen Ovale

Cranial Nerve V - Trigeminal Assessment *To test for pain, touch & tempersture -Safety pin & hot and cold objects *Corneal reflex - Cotton wisk *To test motor function -Clench teeth and move jaw side to side

Cranial Nerve V - Trigeminal Damages *Cause problems in chewing *Loss of sensations of pain and temperature *Tic Douloureux  Trigeminal Neuralgia *Severe pain from damage of maxillary and mandibular nerves

Cranial Nerves The Abducens Nerves (VI) Primary function: Origin: Motor (eye movements) Origin: Pons

Cranial Nerves The Abducens Nerves (VI) Pathway: Superior orbital fissures of sphenoid Destination: Lateral rectus muscle Moves eye laterally

Cranial Nerve VI - Abducens Assessment Make a big x in the air and draw a line through it. **Observe for twitching or nystagmus Damages *Cannot move eyeball laterally *Nystagmus – “Dancing Eyes”

Cranial Nerves Mixed The Facial Nerves (VII) Sensory Motor Origin: Taste receptors on anterior 2/3 of tongue Destination: Sensory nuclei of pons

Cranial Nerves The Facial Nerves (VII) Sensory Innervation Geniculate Ganglion Contains cell bodies of sensory neurons

Cranial Nerves Origin: Motor Motor nuclei of pons Destination The Facial Nerves (VII) Origin: Motor Motor nuclei of pons Destination Somatic Motor Muscles of facial expression

Cranial Nerves Somatic Motor Facial nerve branches Temporal Zygomatic Buccal Mandibular Cervical branches

Cranial Nerves The Facial Nerves (VII) Destination Visceral motor Parasympathetic Function Pterygopalatine Ganglion  Lacrimal gland  Mucous Glands Submandibular Ganglion Submandibular Glands Sublingual Glands

SUBLINGUAL SUBMANDIBULAR

Cranial Nerves The Facial Nerves (VII) Pathway: Internal acoustic meatus to facial canals Then through the stylomastoid foramina

Cranial Nerve VII - Facial Nerve Assessment -- To test for taste **Place sugar(sweet) salt, vinegar(sour) & quinine(bitter) on anterior 2/3 of tounge -- To test for tearing **Place ammonia near the eyes -- To test for facial symmetry **Have patient close eyes, smile, whistle and blow

Cranial Nerve VII - Facial Nerve Damages *Shingles * Lyme disease * Loss of taste * Decreased saliva * Bell’s Palsy.

Cranial Nerves The Vestibulocochlear Nerves (VIII) Primary function: Special sensory Vestibular branch Balance and equilibrium Originates at receptors of vestibule (balance) Connects to vestibular nuclei of pons and medulla oblongata

Cranial Nerves The Vestibulocochlear Nerves (VIII) Primary function: Special sensory Cochlear branch Hearing Originates at sensors of cochlea (hearing) Connects with cochlear nuclei of pons and medulla oblongata

Cranial Nerves The Vestibulocochlear Nerves (VIII) Origin: Pathway: Receptors of inner ear Pathway: Internal acoustic meatus of temporal bones

Cranial Nerve VIII - Vestibulocochlear Assessment **Tuning Fork Damages Vertigo  Rotating Ataxia  Lack of coordination Tinnitus  Ringing of ears

*From motor nuclei of medulla oblongata Cranial Nerves The Glossopharyngeal Nerves (IX) Primary function: Mixed to head and neck Origins: Motor *From motor nuclei of medulla oblongata Sensory Posterior 1/3 of tongue Part of pharynx and palate Carotid arteries

Cranial Nerves Superior and inferior ganglion Sensory neurons of tongue and pharynx FIGURE 14-25

Cranial Nerves The Glossopharyngeal Nerves (IX) Pathway: Jugular foramina Between occipital and temporal bones

Cranial Nerves The Glossopharyngeal Nerves (IX) Destination: Sensory Sensory nuclei of medulla oblongata Somatic motor Nerves involved in swallowing

Cranial Nerves The Glossopharyngeal Nerves (IX) Destination: Visceral motor Parasympathetic Function Otic Ganglion Parotid salivary gland

Cranial Nerve - IX Glossophary-ngeal Assessment Test for taste on posterior 2/3 Test position of uvula Test swallowing and gag reflex Damages Difficulty in Swallowing Digestion Loss of taste Loss of sensation in throat Reduced saliva production

Cranial Nerves The Vagus Nerves (X) “The Vagabond” The only cranial nerve that extends beyond the head and neck Primary function: Mixed 90% of parasympathetic function Thorax and abdomen

Cranial Nerves The Vagus Nerves (X) Origins: Sensory Part of pharynx Auricle and external acoustic meatus Diaphragm Visceral organs of thoracic and abdominopelvic cavities Motor Motor nuclei in medulla oblongata

Cranial Nerves The Vagus Nerves (X) Pathway: Jugular foramina Between occipital and temporal bones

Cranial Nerves Sensory Neurons located in Superior Ganglion Jugular ganglion Inferior Ganglion Nodose ganglion

Cranial Nerves The Vagus Nerves (X) Destination: Sensory Sensory nuclei and autonomic centers of medulla oblongata Visceral motor Parasympathetic Muscles of the palate and pharynx Muscles of the digestive, respiratory, and cardiovascular systems in thoracic and abdominal cavities

Cranial Nerve X - Vagus Assessment **Same as IX Damages Loss of sensations to organs Interfere with swallowing, digestion and vocal cords Increase blood pressure

Cranial Nerves The Accessory Nerves (XI) Primary function: Origin: Motor to muscles of neck and upper back Origin: Motor nuclei of spinal cord and medulla oblongata

Cranial Nerves Accessory Nerve Structures Spinal root Motor fibers that originate in anterior gray horns of first five cervical segments of spinal cord Cranial root Motor fibers that originate in medulla oblongata

Cranial Nerves The Accessory Nerves (XI) Pathway: Jugular foramina between occipital and temporal bones

Cranial Nerves The Accessory Nerves (XI) Destination: Internal branch Voluntary muscles of palate, pharynx, and larynx Figure 14-27

Cranial Nerves The Accessory Nerves (XI) Destination: External branch Sternocleidomastoid and trapezius muscles

Cranial Nerve XI - Accessory Assessment Have patient rotate head Have patient cough Damages Ipsilateral paralysis of sternocleidimastoid and trapezius So you can’t raise your shoulders or turn your head Difficulty in swallowing

Cranial Nerves The Hypoglossal Nerves (XII) Primary function: Origin: Motor (tongue movements) Origin: Motor nuclei of medulla oblongata

Cranial Nerves The Hypoglossal Nerves (XII) Pathway: Destination: Hypoglossal canals of occipital bone Destination: Muscles of tongue

Cranial Nerve XII - Hypoglossal Assessment **Have patient protrude and retract tongue Damages Atrophy of ipsilateral tongue Difficulty Swallowing Chewing Speaking

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Cranial Reflexes Cranial Reflexes Monosynaptic and polysynaptic reflex arcs Involve sensory and motor fibers of cranial nerves Clinically useful to check cranial nerve for brain damage

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CEREBRUM - I - Olfactory –smell l - II - Optic - vision BRAINSTEM MIDBRAIN III - Oculomoter - movement of eye IV - Trochlear – movement of eye PONS V - Trigeminal – chewing, touch, pain & temperature receptors VI - Abducens – movement of eyeball VII - Facial – facial expressions, tears, saliva & taste VIII - Vestibulocochlear (vestibular branch only). - equilibrium Medulla Oblongata VIII – Vestibulocohlear – hearing & equilibrium IX - Glossopharyngeal – swallowing, taste, saliva production, blood pressure and monitor breathing X - Vagus – swallowing, coughing, voice, blood pressure, monitor breathing, control digestive secretions & organs of heart, stomachand G, I tract XI - Accessory – swallowing, movement of head and shoulders XII - Hypoglossal – swallowing, chewing & speaking