Cranial Nerves Flashcards
What fibers are coming out of the spinal nerves?
Sympathetic and parasympathetic (sacral spinal nerves)
Somatic afferent and efferent
What are the parasympathetic cranial nerves?
C3- oculomotor
C7- facial
C9- Glossopharyngeal
C10- Vagus
What are the cranial nerves that move the eye?
C3- oculomotor
C4- trochlear
C6- abducent
C1 (olfactory nerve)
Smell (sensory)
Special Visceral Afferent (SVA)
Originates in the olfactory mucosa
C1/ olfactory pathway
Cells bodies in ethmoidal turbinates –> Cribriform plates –> Olfactory bulbs/synapse
Pathway doesn’t go through the thalamus
Vomernasal Organ (Jacobson’s Organ)
Chemosensory organ at the floor of the nasal cavity
The Flehmen response
Olfactory mechanism identifies the reproductive state of females based on pheromones
Clinical disorders dealing with the olfactory nerve
If they can’t smell, wont eat
Meningitis/ encephalitis: meninges provide routes for infection from nose to cr. cavity and brain
Anosmia and Hyposmia
Lack of ability to smell
Decreased ability to smell
C2 (optic)
Visual perception from the retina to the brain (sensory ganglion in retina)
Special somatic afferent (SSA)
What does C2 enter?
Optic canal, optic chiasm, optic tract, lat. geniculate body and occipital cortices (visual cortex)
Optic neuritis
Inflammation of optic nerve
Swelling and destruction of myelin sheath –> axial damage
Multiple sclerosis
Sudden loss of vision
Optic nerve testing
Menace response test
Pupillary light response (PLR)
Menace response test
Create a threatening gesture
Sensory component –> optic
Motor component –> facial
Air current will stimulate the trigeminal
Pupillary light repsonse (PLR)
Flashing light
Sensory –> optic
Motor (pupil construction)–> oculomotor (parasym.)
C3 (oculomotor)
Pupillary adjustment and lens accommodations
Eye movement (motor)
Parasympathetic
Somatic efferent fibers of C3
Passes through the orbital fissure
Innervates dorsal, medial, and ventral rectus, ventral oblique, and levator palpebral superioris
Parasympathetic efferent fibers of C3
Ciliary m./ lens accommodation
Constrictor pulpillae of the iris (pupillary constriction to light)
C3 deficit
Ptosis: eyelid drooping
Mydriasis: excessive dilation of pupil
Ventrolateral strabismus
Horner’s syndrome (C3)
Miosis of l. eye
Ptosis
Elevation of 3rd eyelid
Enophthalmos
C4 (Trochlear)
Eye movement (somatic efferent) to the dorsal oblique muscle
Passes through the orbital fissure
Dorsolateral strabismus
C5 (Trigeminal)
Sensory to face structures
Motor to muscles of mastication
What are the 3 branches of C5?
Mandibular- muscles of mastication
Ophthalmic- eye (sensory)
Maxillary- face (sensory)
Mandibular nerve of C5
Sensory: Lower lip, tongue mucosa and teeth of lower jaw
Motor: muscles of mastication
Passes through oval foramen
Ophthalmic nerve of C5
Sensory to forehead, medial canthus, eyeball, cornea and nasal mucosa
Passes through orbital fissure
Maxillary n. of C5
Sensory to upper lip, soft and hard palate, teeth of upper jaw
Passes through round foramen and rostral alar foramen
Clinical cases of C5
Mandibular nerve (dropped jaw, loss of sensation)
Ophthalmic abnormal corneal reflex
Maxillary/ loss of sensation in upper lips
C6 (Abducent)
Eye movement (motor)
Passes through orbital fissure
Innervates lateral rectus and retracter bulbi
Medial strabismus
C7 (facial) innervations
Motor to muscles of facial expressions
Taste sensation on rostral 2/3 tongue
Parasympathetic to lacrimal and mandibular salivary glands
Facial nerve paralysis (C7)
Loss of sensation (glands)
Inability to close eye/ no palpebral response (orbicularis occuli)
Food in vestibule (buccinator)
Drop ear (rostral and cd. auricular m.)
C8 (vestibulocochlear)
Hearing and balance
Special somatic afferent (SSA)
Passes through the internal acoustic meatus
2 branches: cochlear (hearing) and vestibular (balance)
Clinical considerations of C8
Head tilt (to affected side)
Ataxia (staggering gait)
Rolling (toward side of lesion)
Nystagmus (eye flicking, vestibulo-ocular reflex)
C9 (Glossopharyngeal)
Pharynx muscles
Taste and sensation cd. 1/3 of tongue
Parotid and zygomatic salivary gland (parasymp.)
Passes through the jugular foramen and tympano-occipital fissure
Clinical considerations of C9
Dysphagia (difficulty swallowing)
Gag reflex
Salivation disorder
C10 (vagus) innervation and what does it pass through?
Passes through the jugular foramen and tympano-occipital fissure
Innervates pharynx, larynx, heart and abdominal viscera
What are the branches of C10?
Cr. laryngeal n., recurrent (cd. laryngeal), cardiac branches, dorsal and ventral vagal trunks
Pharyngeal m. innervations by C10
Motor and sensory
Pharyngeal constrictors
Intrinsic m. innervations by C10
Cr. laryngeal n. to cricothyroideus m.
Cd. (recurrent) laryngeal n. to remainder of laryngeal m.
Clinical considerations of C10
Dysphagia
Gag relfex
Paralysis of intrinsic laryngeal m.
Damage to recurrent laryngeal n.
Roaring especially in horses
C11 (Accessory)
Head and neck movement (motor)
C12 (Hypoglossal)
Tongue muscle and movement (motor)
Passes through the hypoglossal canal
Runs with lingual a.
C12 clinical considerations
Paralysis of extrinsic m. (can’t protrude tongue)
Paralysis of ipsilateral m.
Deviation of tongue toward injured side (LMN) or healthy side (UMN)
Type of innervations by C10
Motor and sensory to pharynx
Parasymp. to thoracic and abdominal viscera
