cranial nerves

OLFACTORY NERVE

• Testing: each nostril separately use familiar odors non irritant odors : coffee, peppermint Anosmia: diminished sense of smell Causes: Transient (non-neural): upper respiratory tract infection [local nasal and sinus diseases ] head injury :Fracture of cribriform plate Frontal lobe tumor Purulent meningitis or hydrocephalus Degenerative disease like Parkinson d Hysterical disease


Olfactory Nerves (CN I) parosmia : distorted perverted smell character Causes : temporal lobe seizure or a tumor, olfactory bulb injury from trauma, depression, a local nasopharyngeal condition, such as sinusitis Olfactory hallucinations occur in association with Alzheimer's disease, depression, schizophrenia, alcohol withdrawal, and uncinate seizures

Causes : 1-space ocupying lesion [sol] 2-systmic medical diseases DM hypertension polycythemia pickwickian syndrome 3- central retinal vein occlusion

Optic nerve neuritis

Papilledema
Acute visual loss & decrease VA
No change
Visual acuity
Central scotoma
Enlarged blind spot Concentric constriction of the field
Visual field
Abnormal
Normal
Color vision
Afferent pupillary defect [APD] Marcus gun pupils
Normal
Pupillary light reflex


optic atrophy : pale disk due to loss of optic nerve axons either primary when the disk margin is clear and rounded or secondary when the disk margin is irregular and usually secondary to papilledema .
causes: optic neuritis neuro- syphilis B12 deficiency ischemic optic atrophy

Oculomotor N. (CN III)• Somatic innervation: superior, medial, & inferior rectus, inferior oblique, levator palpebrae• Visceral innervation: constrictor pupillae, ciliary muscle (accommodation)Trochlear N. (CN IV): superior obliqueAbducens N. (CN VI): lateral rectus

Nystagmus: rhythmic ocular oscillation ether slow jerky , rapid fine or penduler

Anisocotia: unequal pupil size
Horner's syndrome; sympathetic nerve of the pupil defect causing ptosis , enophthalmia , amhydrosis and miosis
INTER NUCLEAR OPHTHALMOPLEGIA : lesion involve medial longitudinal fasciculus's which connect 6 th nerve nucleus of one side with the 3 ed nerve nucleus of the other side the lesion leads to slow jerky nystgmus of abducting eye and restricted adduction of the contralatreal eye bilateral INO is pathognomonic of multiple sclerosis

A third cranial nerve palsy may be partial or complete and some

Abducens N. (CN VI)Abducens N. lesions• Causes: aneurysm, inflammation, cavernous sinus lesion, increased intracranial pressure,fourth ventricle lesions, lesions within cavernous sinus or superior orbital fissure, skull base fractures• Effects: strabismus, Diplopia, inability to abduct past midline• Compensation for sixth nerve palsy: turn head contra laterally to align gaze


• Causes OF LESION : aneurysm, inflammation,cavernous sinus lesion, herniation oftemporal lobe• Effect s OF THE LESION : strabismus diplopia, extortion,weakness in depression & abduction of gazeHead tilting (1) rotation in a vertical plane – looking down and up (depression and elevation of the eyeball) (2) rotation in the plane of the face ( in torsion and extortion of the eyeball). TROCHLEAR N. LESIONS FUNCTIONS

Trigeminal N. (CN V)• Clinical testing: facial sensation corresponding to areas innervated by V1 , V2 , &V3 ,motor:massetertemporalismedial pterygoidlateral pterygoid reflexes : jaw jerk reflex corneal reflex

Lower Motor Neuron Lesions(LMNL)• lesion of facial nucleus or more peripheral• Ipsilateral effects on both upper and lower quadrants of faceUpper Motor Neuron Lesion(UMNL)• Supranuclear lesion (e.g.,cortex)• Contra-lateral effects on lower quadrant only• Upper quadrant receives input from both hemispheres whereas lower quadrant only contralateral input


Lower motor neuron lesions
Upper motor neuron lesions
paresis of all mimetic muscles, including the frontalis muscle ---- BELL’SIGN paresis of voluntary movements of lower face with sparing of the frontalis muscle
Emotional involvement
no Emotional
impairment of taste
Preserved taste
Possible abnormality of lacrimation
Normal lacrimation
No
Hyperacusis ---nerve to stapedous

There are a number of functions of the glossopharyngeal nerve: It receives general sensory fibers (ventral trigeminothalamic tract) from the tonsils, the pharynx, the middle ear and the posterior 1/3 of the tongue. It receives special sensory fibers (taste) from the posterior one-third of the tongue. It receives visceral sensory fibers from the carotid bodies, carotid sinus. It supplies parasympathetic fibers to the parotid gland via the otic ganglion.
The vagus nerve : supplies motor parasympathetic fibers to all the organs except the suprarenal (adrenal) glands . The vagus also controls a few skeletal muscles, BULBER AREA

Side bilateral

UMN
LMN
NAME
Pseudobulbar
Bulbar
SPEECH
Spastic [hot potato ] Donald duke
Nasal
NASAL REGURGITATION
_
+
SWALLOWING
Dysphagia
Dysphagia
GAG REFLEX
+++
_



Accessory N. (CN XI)• Motor to sternocleidomastoid & trapezius• Tested by strength of lateral neck rotation & shoulder shrug

Hypoglossal nerves:Innervates all tongue muscles• Lower Motor Neuron Lesion (LMNL) Ipsilateral atrophy fasculation deviation• Upper Motor Neuron Lesion (UMNL) small spastic deviation