CRANIAL NERVE: COMPONENT, ORIGIN, AND INSERTION, FUNCTION AND EXAMINATION: PART 4

CRANIAL NERVE: COMPONENT, ORIGIN, AND INSERTION, FUNCTION AND EXAMINATION: PART 4

CRANIAL NERVE: COMPONENT, ORIGIN, AND INSERTION, FUNCTION AND EXAMINATION: PART 4( In this part glossopharyngeal nerve, vagus nerve, accessory nerve, hypoglossal nerve description is given. This is the last part of cranial nerve topic

GLOSSOPHARYNGEAL NERVE- 9th nerve

• COMPONENT: Glossopharyngeal nerve is a Mixed nerve that is the motor and sensory both components is there.
FUNCTION: the function of the glossopharyngeal nerve is following-
o MOTOR: muscle supplying by glossopharyngeal nerve:-
 Stylopharyngeus muscle
 Assists swallowing
o SENSORY:
 General sensation and taste from posterior 1/2 of tongue and pharynx
 Carotid sinus and carotid body
o SECRETOMOTOR
 Parotid gland
• ORIGIN: originated from Medulla oblongata
• OPENING TO THE SKULL: Glossopharyngeal nerve enters in Jugular foramen through the opening of the skull.
• Examination- examination of the glossopharyngeal nerve is described with vagus nerve examination.

VAGUS NERVE- 10th nerve

• COMPONENT: the component of the vagus nerve is Motor.it supplies so many structures that are given below.
• SUPPLY: vagus nerve is supplying following-
o Heart and great thoracic blood vessels
o Larynx, trachea, bronchi, and lungs
o Alimentary tract from the pharynx to splenic flexure of the colon
o Liver, kidney-pancreas
• ORIGIN: originated from Medulla oblongata
• OPENING TO THE SKULL: enter into Jugular foramen
• EXAMINATION -note if there is any swallowing difficulty or nasal regurgitation of fluids.
• For vagus nerve palsy examination or vagus nerve checking ask the patient to open the mouth and say ‘ah’. note any asymmetry in palatal movement. (vagus nerve palsy).
• Gag reflex- Gag reflex is examined by Depress the patient’s tongue and touch the palate, pharynx or tonsil on one side until the ‘patient gags’. Compare sensitivity on each side(afferent route glossopharyngeal nerve) and observe symmetry of palatal contraction(efferent route – vagus nerve).
Absent gag reflex= loss of sensation or loss of motor power. (taste in the posterior third of the tongue(9th nerve) is impractical to test

ACCESSORY NERVE – 11th nerve

• COMPONENT: accessory nerve is a Motor nerve.
• SUPPLY: supply of accessory nerve is following-
o CRANIAL ROOT:
o Muscles of a soft palate
o Muscles of pharynx
o Muscles of larynx
o SPINAL ROOT
o Sternocleidomastoid and trapezius muscles
• ORIGIN: Medulla oblongata
• OPENING TO THE SKULL: Jugular foramen
• EXAMINATION – for examination of accessory nerve doctor use following:-
For sternocleidomastoid -ask the patient to rotate head against resistance. compare power and muscle bulk on each side. Also, compare each side with patient pulling the head forward against resistance.
For the left sternocleidomastoid turns the to the right and vice-versa.
Trapezius – for trapezius muscle ask the patient to shrug the shoulder and hold during shrug against the resistance. compare power on each side. The patient should resist efforts to depress the shoulder.

HYPOGLOSSAL NERVE- 12th nerve

• COMPONENT: it is a Motor nerve. Supplying muscle of tongue mainly.
• FUNCTION: Muscles of the tongue, controlling its shape and movement
• ORIGIN: Medulla oblongata
• OPENING TO THE SKULL: Hypoglossal canal
EXAMINATION: for examination of hypoglossal nerve ask the patient to open mouth, and protrude tongue. If Any difficulty or deviation is there it should be noted(deviation occur with facial weakness).
Protruded tongue deviates towards the side of weakness.

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