Neurology- Cranial Nerves Flashcards
Olfactory nerve (I)
-Manages smell sensation
-These cells synapse with neurones that project into the amygdala and temporal lobe
-Can lead to hyposmia, anosmia or parosmia
-May result from URTI, sinus disease, HI, basal skull tumour
Optic (II), Oculomotor (III), Trochlear (IV) and Abducens (VI)
- managed more in visual chapters
Trigeminal (V) nerve- Anatomy
-Trigeminal nerve passes through to the pons
-Pain and temperature pathways descend to C2 in the spine hence facial numbness can occur with cervical cord lesions
Trigeminal nerve-anatomy 3 branches
V1ophthalmic- passes into the cavernous sinus, skin of the upper nose, eyelids and mucous membrane of upper nasal cavity
- V2 maxillary- contains fibres for upper mouth, roof of the pharynx, gums, teeth, palate of the upper jaw and maxillary, sphenoidal and ethmoid sinus
-V3 mandibular- supplies the floor of the mouth, sensation to 2/3 of the tongue, gums and teeth of the lower jaw, mucosa of cheek also allows mastication
Trigeminal nerve- exam
1) Sensory
-ask patient to close there eyes and lightly touch areas V1,2,3
-Compare both sides
-Can do nasal tickle
2) Motor (rare signs)
-Inspect for wasting of mastication muscles
-Clench teeth and feel muscles
3) Corneal reflex
-most of the time this is not necessary
-Touch cornea lightly with a damp cotton dub. Look for both direct and consensual blinking
4) Jaw jerk
-let mouth hang loosely
-place 2nd finger on chin (under lip) and precise with tendon hammer
-no or mild reflex is normal jaw jerk occurs in palsy
Facial (VII) nerve
-Facial nerve supplies the muscles of facial expressions and carries parasympathetic fibres to lacrimal, submandibular and sublingual salivary glands
-It receives taste from the anterior 2/3 of the tongue
-Distinct from facial nerve palsies. PD causes loss of spontaneous facial movements (slow blinking, involuntary facial movements)
Facial nerve (VII)- exam
Motor function
-inspect for asymmetry or difference in eye closure
-Watch for involuntary movements
-Ask the patients to raise their eyebrows and observe for symmetrical wrinkling of the forehead
-Ask patients to shut eyes and resist opening them
-Ask patient to bare teeth
-Ask patients to blow out their cheeks with mouth closed
-Bells palsy- paralysis of this nerve.
The vestibulocochler (VIII) nerve
- see ENT
- Allows hearing
Glossopharyngeal (IX) and Vagus nerve (X) Anatomy
-Both nerves arise as several roots from the lateral medulla and leaves the
-IX nerve passes down and forward to supply the stylopharngeus muscle, mucosa of pharynx, tonsils and the posterior 1/3 of the tongue and send parasympathetic fibres of the parotid gland
Glossopharyngeal (IX) and Vagus nerve (X)- exam
-Assess the patients speech for dysarthria or dysphonia
-Say Ah, both sides of palate elevate symmetrically and uvula is central
-puff out cheeks. If air comes out of mouth palate is not rising
-Assess strength of cough
-IX rarely has lesions
-X lesions can be caused by strokes, skull base # or tumours.
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Accessory (XI) nerve- Anatomy
-2 components
1) A cranial part closely related to the vagus nerve
2) A spinal part that provides fibres to the upper trapezius, responsible for shrugging and elevating the arm above horizontal and the sternomastoid muscle that controls head turning and neck flexion.
Accessory (XI) nerve- Exam
- inspect and palpate sternomastoid and trap muscle for wasting/hypertrophy
-Ask patient to shrug shoulders and apply downward pressure - Ask patient to turn head whilst applying resistance
-Ask patient to flex neck, apply resistance to forehead
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Hypoglossal (XII) nerve-anatomy
Hypoglossal nerve- exam
-Ask the patient to open their mouth. Look at the tongue for wasting, fasciculation and involuntary movement
-Ask patient to put their tongue out, look for involuntary movement
-Ask patient to move tongue side to side
-Assess power of the tongue
Summary
