Cranial Nerves - 1 - 6

Views:
 
Category: Entertainment
     
 

Presentation Description

No description available.

Comments

Presentation Transcript

CRANIAL NERVES 1 - 6:

CRANIAL NERVES 1 - 6

OLFACTORY NERVE:

OLFACTORY NERVE

Cranial Nerve I:

Cranial Nerve I Bipolar sensory cells Distal portion consists ciliated processes which penetrate the mucus membrane in the upper portion of the nasal cavity Subserve the sense of smell Have their cells of origin in the mucous membrane of the upper and posterior part of the nasal cavity The axons of the mitral cells enter the olfactory tract which course along the olfactory group of the frontal bone to the cerebrum

Cranial Nerve I:

Cranial Nerve I Posteriorly, olfactory tract divides into medial and lateral olfactory striae The medial striae passes to the opposite side through the anterior commissure Fibres in the lateral striae give off collaterals to the anterior perforated substance and terminate in the medial and cortical nuclei of the amygdaloid complex and prepyriform area

How to test:

How to test Use familiar substances Test each nostril separately See whether the patient can appreciate or recognise

Causes :

Causes Acute and Chronic Inflamatary nasal diseases Intracranial tumours Inferior frontal glioma Olfactory glioma / meningioma Atrophy of Olfactory bulbs Basal skull fracture

OPTIC NERVE:

OPTIC NERVE

Cranial Nerve II:

Cranial Nerve II The axons of the ganglion cells of the ganglion layers of the retina constitute optic nerve The rods reacts to dim light, peripheral and night visions The cones are concerned with bright light and colour visions The optic nerve extends from the retina to the optic chiasma through the optic foramena where the fibres from both the nasal side crosses

Cranial Nerve II:

Cranial Nerve II Fibres from the lateral half of the retina are situated in the temporal half of the optic nerve and they pass through the chiasma without crossing Posterior to the chiasma, optic tract consists of Optic tract ends in LGB through which visual fibre enter

Cranial Nerve II:

Cranial Nerve II The neurons from the LGB pass posteriorly as optic radiation, terminate on straite area (area 17) of the occipital cortex The parastraite area (area 18) and the peristraite area (area 19) functions in more complex visual functions such as visual associations and colour vision The fibres subserving light reflex enter the brain stem at superior colliculus

How to test:

How to test Visual Acuity Snellen’s Chart Jaegger’s Chart Field of Vision Colour vision Fundus Pupillary reaction – Direct - Consensual

OCCULOMOTOR NERVE:

OCCULOMOTOR NERVE

Cranial Nerve III:

Cranial Nerve III Occulomotor nuclei consists of several paired groups of nerve cells adjacent to the mid line ventral to the Aqueduct of Sylvius Edinger Westphan Nucleus innervate pupillary sphincters and ciliary bodies The nerve fibres course anteriorly through the mesencephalon medial to the red nucleus, the substantia niagra

Cranial Nerve III:

Cranial Nerve III The nerve emerges from the anterior aspect of the mid brain above the pons. It penetrates the dura lateral and anterior to the posterior clinoid process and enter the lateral wall of cavernous sinus. From there it enters the orbit through the superior orbital fissure and supplies LPS, IO, SR, MR, IR

Slide 21:

THIRD CRANIAL NERVE PALSIES Ptosis of the lid, mydriasis, and an outwardly turned eye during primary gaze. When the patient attempts to turn the eye inward, it moves slowly only to the midline. Upward and downward gaze is compromised in the affected eye. When downward gaze is attempted, the superior oblique muscle causes the eye to rotate inward.

Slide 22:

Causes of 3rd cranial nerve palsies . Intraorbital - lesions producing external ophthalmoplegia and ocular myopathies should be distinguished from cranial nerve disease. Exophthalmos or enophthalmos, a history of severe orbital trauma, or an obviously inflamed orbit suggests restrictive orbital disease, which may impair ocular motility. Myopathies are harder to diagnose but are suggested by a partial 3rd nerve palsy. The pupil is always spared in myopathy.

Slide 23:

Completely non functional parasympathetic fibers (causing fixed dilated pupils) strongly suggest oculomotor nerve compression. Common causes - Aneurysm, (especially of the posterior communicating artery), Trauma, and intracranial mass lesion. Oculomotor paralysis in an unresponsive patient suggests transtentorial herniation and is a major emergency. If the pupil is completely spared but all other muscles innervated by the 3rd nerve are affected (eg, diabetic 3rd nerve paresis), the cause is likely to be an ischemic process of the oculomotor nerve or the midbrain; a demyelinating process is less likely., 5% of posterior communicating artery aneurysms causing oculomotor paralysis spare the pupil. Causes of 3rd cranial nerve palsies

INVESTIGATIONS:

INVESTIGATIONS Third cranial nerve palsies are most indicative of serious disease when associated with severe headache or altered consciousness. CT or MRI is performed. Lumbar puncture is reserved for suspected subarachnoid hemorrhage when CT does not show blood. Cerebral angiography must be performed if aneurysm causing subarachnoid hemorrhage is strongly suspected or when the pupil is clearly affected and no head trauma serious enough to fracture the skull has occurred.

TROCHLEAR NERVE:

TROCHLEAR NERVE

Cranial Nerve IV:

Cranial Nerve IV Smallest of all cranial nerves Situated just anterior to the aqueduct in the mesencephalon just above the pons. It penetrates the dura posterolateral to the posterior clinoid to enter the cavernous signs where it is lateral and inferior to 3 rd nerve. Through the superior orbital fissure enters the orbit to supply SO

IV CRANIAL NERVE PALSY:

IV CRANIAL NERVE PALSY Weakness of the muscle innervated by the 4th (trochlear) nerve (superior oblique muscle). These palsies are often difficult to detect because they affect vertical eye position predominantly when the eye is turned inward. The patient sees double images, one above and slightly to the side of the other. However, by tilting the head to the side opposite the palsied muscle, the patient may achieve full or almost full ocular motility without double vision.

IV CRANIAL NERVE PALSY:

IV CRANIAL NERVE PALSY many are idiopathic. Closed head trauma without skull fracture is a common cause of unilateral and bilateral palsies; Aneurysms, tumors, and multiple sclerosis are rare causes. Evaluation of 4th nerve palsies is similar to that of 3rd nerve palsies.

ABDUCENT NERVE:

ABDUCENT NERVE

Cranial Nerve VI:

Cranial Nerve VI Arises from the lower part of the pons in the floor of the 4 th ventricle The nerve emerges from the brain stem at the pontomedullary junction Has the longest intracranial course Pierces the dura at dorsum sellae to enter the cavernous sinus inferomedial to the 3 rd nerve. Enters the orbit through the superior orbital fissure to supply LR

VI CRANIAL NERVE PALSY:

VI CRANIAL NERVE PALSY Weakness of the muscles innervated by the 6th (abducens) nerve. The eye is turned inward; it moves outward sluggishly, reaching the midline at most. Idiopathic cases are common, although many occur in elderly or diabetic patients in whom small vessel disease may be suspected. In idiopathic cases, no other cranial nerves are involved, and improvement should occur within 2 mo.

CAUSES:

CAUSES Compression of the 6th nerve in the cavernous sinus by a tumor originating in the nasopharynx. Anything that causes the brain to shift may stretch the 6th nerve because of the acute angle it makes before entering Dorello's canal. Large brain tumors remote from the nerve Intracranial pressure, or to lumbar puncture.

CAUSES:

CAUSES Diabetic infarction is one of the more common causes. Basilar skull fracture, infections or tumors affecting the meninges, Wernicke's encephalopathy, aneurysm, and multiple sclerosis. n children without evidence of increased intracranial pressure, these palsies can result from respiratory infection and thus may be recurrent.

CAUSES:

CAUSES Excluding increased intracranial pressure and papilledema (by looking for retinal venous pulsations during funduscopy) is important. MRI or CT can help exclude intracranial mass lesions, hydrocephalus, and direct nerve compression by lesions in the orbit, cavernous sinus, and base of the skull. Lumbar puncture determines the CSF opening pressure and can detect leptomeningeal inflammatory, infectious, or neoplastic infiltrates entrapping the 6th nerve. A collagen vascular screen helps exclude a vasculopathic process. In many cases, 6th nerve palsies resolve once the primary disorder is treated .

Slide 37:

SKELETAL MUSCLES OF THE EYE: MR SO SR LPS LR IR IO RIGHT EYE LR

Slide 38:

CRANIAL NERVES: III OCULOMOTOR, IV TROCHLEAR AND VI ABDUCENT 6 SKELETAL MUSCLES (EYE) 4 RECTI MUSCLES: • SR, IR, MR, LR 2 OBLIQUE MUSCLES • SO, IO EYE MOVEMENTS 1 SKELETAL MUSCLE (UPPER EYELID) LEVATOR PALPEBRAE SUPERIORS (LPS) ELEVATES UPPER EYELID 2 SMOOTH MUSCLES (EYE) SPHINCTER PUPILLAE CILIARY MUSCLE PUPILLARY CONSTRUCTION INCREASES CONVEXITY OF LENS Innervates 7 skeletal muscles and 2 smooth muscles

Slide 39:

III LPS, MR, SR, IO, IR SPHINCTER PUPILLAE CILARY MUSCLE Elevates upper lid Adducts, elevates Depresses and abducts eyeball Constricts pupil (P) Increases convexity of the lens (P) IV SO Depresses eyeballs VI LR Abducts eyeballs LR 6 SO 4 R 3

Slide 40:

RECTI: Right eye MAJOR ACTIONS SR ELEVATES IR DEPRESSES LR ABDUCTS MR ADDUCTS

Slide 41:

SO DEPRESSES THE EYE BY PULLING UP ON THE BACK OF THE EYE IO ELEVATES THE EYE BY PULLING DOWN ON THE BACK OF THE EYE SO IO MAJOR ACTIONS OBLIQUES: Right eye

Slide 42:

ELEVATION OF UPPER LID: LPS is inserted into the cartilage of the upper eyelid Elevates the upper lid and opens the eyes

Slide 43:

SMOOTH MUSCLES OF THE EYE: Sphincter pupillae, arranged in a circular fashion around the pupil; its contraction reduces the size of the pupil, causing pupillary constriction in response to increased light stimuli  Ciliary muscle increases the convexity of the lens during accommodation Sphincter Pupillae Pupillary Constriction

Slide 44:

Ganglion Pre-ganglionic Post-ganglionic Target innervated Motor Nucleus Parasymp. Nucleus Sup. Orb. Fissure Ciliary Ganglion LPS SR MR IR IO Sphincter Pup. Ciliary muscle III BRAIN STEM

Slide 45:

EYE MOVEMENTS Eyes move in a conjugate fashion: Eye muscles work in pairs to produce conjugate movements  RIGHT/LEFT  UP/DOWN  COMBINATIONS (Right and up, right and down, etc.)

Slide 46:

EYES RIGHT : IR LEFT EYE RIGHT EYE LR SR MR IR LR SR MR LR OF THE RIGHT EYE MR OF THE LEFT EYE

Slide 47:

IR LEFT EYE RIGHT EYE LR SR MR IR LR SR MR MR OF THE RIGHT EYE LR OF THE LEFT EYE EYES LEFT:

Slide 48:

III, IV, VI: TESTING SR LR IR IO MR SO ABDUCTED EYE-RECTI ABDUCTED EYE-RECTI IO MR SO ADDUCTED EYE-OBLIQUES SR LR IR ADDUCTED EYE-OBLIQUES Elevators and depressors of the eye

TRIGEMINIAL NERVE:

TRIGEMINIAL NERVE

Cranial Nerve V:

Cranial Nerve V Mixed nerve The cell bodies of the sensory part of the nerve lie in the gasserian ganglion Sensory root arising from this ganglion enters the pons divides into ascending and descending branches Ascending branch is concerned with touch and deep sensation and ends in the mesencephalonic nucleus

Cranial Nerve V:

Cranial Nerve V Descending branch forms the spinal tract of trigeminial nerve concerned with pain and temperature. This tract extends cordially down to the upper cervical cord. From the nucleus of the tract, 2 nd order fibre cross to the opposite thalamus.

Cranial Nerve V:

Cranial Nerve V From the Gasserian ganglion, 3 branches Ophthalmic passes through the superior orbital fissure Maxillary through the foramen rotendum. - Mandibular - foramen ovale. - Trigeminal N has 4 nuclei- SensoryN spinal N mesencephalic N. Motor N Spinal N extends up to the 2 nd cervi cal segment, -Motor N supplies M of mastication

Slide 55:

How to test Pain, Tempt., Light touch in 6 areas Corneal reflex – B/L blink Vth Nerve lesion – No response from either side VIIth lesion – No blink from the side or lesion of the VIIth Early sign of CP Angle tumour Aneurysm and tumours in relation to Cav : sinus and orbital fissur

Motor Functions:

Motor Functions Temporalis Masseter ,Pterygoids, Palpate the musscles while clenching his jaw Note the Symmetry of angle of the jaw Jaw jerk

Slide 57:

TRIGEMINAL NEURALGIA (Tic Douloureux) Disorder of the trigeminal nerve producing bouts of excruciating, lancinating pain, lasting between seconds and 2 min, along the distribution of one or more of its sensory divisions, most often the maxillary.

Slide 58:

At surgery or autopsy, intracranial arterial and, less often, venous loops compressing the trigeminal nerve root where it enters the brain stem have been found, suggesting that the tic is a compressive neuropathy. The disorder usually affects adults, especially the elderly. Pain is often set off by touching a trigger point or by activity (eg, chewing or brushing the teeth). Although each bout of intense pain is brief, successive bouts may be incapacitating. TRIGEMINAL NEURALGIA (Tic Douloureux)

Slide 59:

THANK YOU

authorStream Live Help