CRANIAL NERVE : COMPONENT, ORIGIN, AND INSERTION, FUNCTION AND EXAMINATION: PART 2

CRANIAL NERVE : COMPONENT, ORIGIN, AND INSERTION, FUNCTION AND EXAMINATION: PART 2

CRANIAL NERVE: COMPONENT,ORIGIN, AND INSERTION, FUNCTION AND EXAMINATION: PART 2(oculomotor nerve , trochlear nerve , abducent nerve, and trigeminal nerve)

OCULOMOTOR NERVE- 3rd nerve

COMPONENT: It is a Motor nerve
FUNCTION:-
1.Raises upper eyelid
2.Turns eyeball upward, downward and medially
3. Constricts pupil.
4.Accommodates the eye
• ORIGIN: Anterior surface of the midbrain
• OPENING TO THE SKULL: Superior orbital fissure.
• Examination:- examination of the oculomotor, trochlear and abducent nerve is done together.

TROCHLEAR NERVE- 4th nerve

• COMPONENT: Motor
• FUNCTION: Turns eyeball downward and laterally
• Origin: Posterior surface of the midbrain
• OPENING TO THE SKULL: Superior orbital fissure
• ABDUCENT NERVE:- 6th nerve
• COMPONENT: Motor
• FUNCTION: Lateral rectus muscle turns the eyeball
• ORIGIN: Medulla oblongata
• OPENING TO THE SKULL: Superior orbital fissure.
• EXAMINATION- pupil examination is done.
• OCCULAR MOVEMENT- Steady the patient head and ask him to follow an object held at arm’s length. observe the full range of horizontal and vertical eye movement. Examine eye movement in six different directions of gaze representing maximal individual muscle strength.
• Conjugate movement is checked it is the ability of eyes to move together in horizontal and vertical direction.
• Nystagmus will be checked that is upset in the normal balance of eye control.

TRIGEMINAL NERVE-5th nerve trigeminal nerve is the largest cranial nerve.

COMPONENT – The Trigeminal nerve is a mixed nerve that is motor and sensory
Constitutes 3 nerves:-
1. Ophthalmic nerve
2. Maxillary nerve
3. Mandibular nerve
1.OPHTHALMIC NERVE
• COMPONENT: Sensory
• SUPPLY:
o Cornea
o Skin of forehead
o Scalp
o Eyelids and nose
o The mucous membrane of paranasal sinuses and nasal cavity
• ORIGIN: Anterior aspect of the pons
• OPENING TO THE SKULL: Superior orbital fissure.
2.MAXILLARY NERVE
• COMPONENT: Sensory
• SUPPLY:
o Skin of the face over the maxilla
o Teeth of the upper jaw
o The mucous membrane of the nose, the maxillary sinus, and palate
• ORIGIN: Anterior aspect of the pons
• OPENING TO THE SKULL: Foramen rotundum

MANDIBULAR NERVE:-

• COMPONENT: Sensory
• SUPPLY:
o Skin of the face over the maxilla
o Teeth of the upper jaw
o The mucous membrane of the nose, the maxillary sinus, and palate
• ORIGIN: Anterior aspect of the pons
• OPENING TO THE SKULL: Foramen ovale
• EXAMINATION- for trigeminal nerve examination sensory and motor both examination is done.
• 1.sensation -pain(pinprick)sensation
Temperature (hot and cold test tubes.
Light touch
This test is given before can be done on the whole face. And compare both sides of the face.
Corneal reflex-test the corneal sensation by touching with a wisp of wet cotton wool. a blink response should occur bilaterally.
2.MOTOR EXAMINATION
For a motor, examination observes for wasting and thinning of temporalis muscle –hollowing out’ the temporalis fossa.
Ask the patient to clamp the jaw together. feel temporalis and masseter muscle. Attempt to open the patient’s jaws by applying pressure to the chin. Ask the patient to open mouth. If a pterygoid muscle is weak the jaw will deviate to the weak side, being pushed over by the unopposed pterygoid muscle of good side.
Jaw jerk – ask the patient to relax the jaw.place finger on the chin and tap with a hammer.
Slight jerk is normal
Increased jerk bilateral upper neuron lesion.
In this part, I covered 4 nerves 3rd, 4th, and 6th nerve and 5th nerve. other nerve information is given in the next part.

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