2. FACIAL NERVE (VII)
VII nerve emerges medial to VIII nerve , enters internal auditory meatus with VIII nerve.
So lesions of one can affect another. Here it gives a br. to stapedius muscle.
It is joined by chorda tympani (taste fibers from anterior 2/3 of tongue) at Geniculate
Ganglion.
Taste fibers from ant. 2/3 of tongue → Lingual Nr. →Chorda tympani → Facial Nr. →
Nervous Intermedius → Medulla Oblongata → Tractus Solitarius → Nucleus to Tr. Solit. →
Thalamus → Temporal part of post Central Gyrus and to Amygdala.
Tastes fibers from post. 1/3 part of tongue → IX Nr. → medulla oblongata → (same as
above).
Ageusia → Loss of taste sensation
TEST for –
Sweet – Sugar Solution
Salt – Common Salt
Sour – Weak Sol. of Citric Acid
Bitter – Quinine Soln.
5. Facial Nr. Supplies all the facial Ms. except LPS. Affected side of face loses
expression.
TEST –
1. Shut eyes tightly , Bell’s Phenomenon seen on paralytic side.
2. Ask to whistle.
3. Smile / Show teeth.
4. Inflate mouth.
5. Test taste sensations.
SUPRANUCLEAR PALSY – Lower part of contralateral face is affected. Taste not
affected.
INFRANUCLEAR both upper/lower parts of face are equally affected on same side.
If lesion in auditory canal or proximal → Loss of taste sensation in anterior 2/3 of
tongue and Hyperacusis due to nerve to Stapedius.
6. VESTIBULOCOCHLEAR NERVE (VIII)
1. Cochlea – Hearing
2. Labyrinth and Semicircular Canals → Equilibrium , balance and sensation of body
displacement.
TESTS OF HEARING –
1. Rinne Test – 256/512 Hz
Compares hearing by Air Conduction (AC) and Bone Conduction (BC)
AC > BC Rinne +ve (Normal)
Conductive deafness → BC > AC Rinne –ve
2. Weber Test – midline of skull/mandible
Conductive deafness → sound heard better in affected ear.
Sensory neural deafness → better in better hearing ear.
ABC – Absolute Bone Conduction compared from that of examiner (for sensory neural
deafness).
Abnormal Sensation – Hallucinations – Schizophrenia
Tinnitus (Ringing in ears) – rarely due to neurological ds.
Hyperacusis – Sounds heard with painful intensity.
7.
8. GLOSSOPHARYNGEAL NERVE (IX)
Sensory for post. 1/3 of tongue and mucous memb. of pharynx.
Motor to middle pharyngeal sphincter and stylopharyngeus Ms.
Taste from post. 1/3 of tongue
TEST – 1. Taste from post. 1/3 of tongue
2. Tickle the back of pharynx → reflex contraction occurs (palatal reflex)
(This is also test for vagus).
10. VAGUS NERVE (X)
Motor for
a) Soft palate (except Tensor palate muscle)
b) Pharynx and Larynx
Sensory and Motor for –
a) Respiratory passages and heart
b) Through Parasympathetic Ganglia → Abd. viscera
TESTS – Palate – Ask patient if he notices regurgitation of fluids thru nose when he tries to swallow.
Egg – Eng , Rub – Rum
Dysphagia for fluids (liquids) in LMN lesions and more for solids in UML lesions.
Soft palate – Say Ah → both sides of palate arch upwards. Paralyzed side remains flat and immobile. Median raphae
pulled to other (opposite) side.
B/↓ Palsy → Palate remains motionless.
Larynx – Superior Laryngeal Br. → Sensory to larynx above vocal cord.
Motor to Cricothyroid Ms.
Recurrent Laryngeal Nr. Sensory to larynx below level of vocal cord.
Motor to all Laryngeal muscles except Cricothyroid.
Unilateral Rec. Laryngeal Nr. palsy – Blurred , inaffectual speech. Pt. cannot cough clearly.
B/L Palsy – Serious stridor or even respiratory obstruction.
11.
12. ACCESSORY NERVE (XI) (PURELY MOTOR)
Contributing to innervation of pharynx , larynx and sternomastoid and
trapezius muscles.
TEST –
Trapezius – Shrug shoulders.
Sternomastoid – Rotation of chin towards opposite side.
13. HYPOGLOSSAL NERVE (XII)
Purely motor to tongue and depressors of hyoid bone.
TESTS –
1. Put out tongue as far as possible → Pushed over to paralyzed side.
2. Push check on either side , feel the strength.
3. See for wasting / Fasciculations.
4. Tremors in Parkinson’s ds.
