Trigeminal Nerve Anatomy It is the fifth and largest cranial nerve, which emerges from the anterolateral surface of the pons as a motor and sensory root. The large sensory root expands to form the “trigeminal ganglion”.

1. CLINICAL ASSESSMENT OF
TRIGEMINAL NERVE
BY:
Haidar Muhammed
Jafar Raheam
Ma Alhussain Shaker
Aboalhassan Ali Abass
Mustafa Smsam

2. Trigeminal
nerve
Nerve
anatomy
Clinical
assessment
Sensory
assessment
Motor
assessment
Reflexes
Clinical
relevance
Objectives:

3. TRIGEMINAL NERVE ANATOMY
Trigeminal Nerve Anatomy It is the fifth and largest
cranial nerve, which emerges from the anterolateral
surface of the pons as a motor and sensory root.The
large sensory root expands to form the “trigeminal
ganglion”.
The motor root of trigeminal is situated below the
sensory ganglion and completely separate from it and
leaves the skull through the foramen ovale and,
immediately below this foramen, joins the mandibular
nerve.

4. The trigeminal nerve has three sub-divisions, each of which has its own broad set of
functions:
1. Ophthalmic (V1): carries sensory information from the scalp and forehead, nose, upper eyelid as
well as the conjunctiva and cornea of the eye.
2. Maxillary (V2): carries sensory information from the lower eyelid, cheek, nares, upper lip,
upper teeth and gums.
3. Mandibular (V3): carries sensory information from the chin, jaw, lower lip, mouth, lower teeth
and gums. Also carries motor information to the muscles of mastication (masseter, temporal
muscle and the medial/lateral pterygoids) as well as the tensor tympani, tensor veli palatini,
mylohyoid and digastric muscles.

5. TRIGEMINAL NERVE

6. CLINICAL ASSESSMENT OF TRIGEMINAL NERVE
Sensory assessment: First, explain the modalities of sensation you are going to assess
(e.g. light touch/pinprick) to the patient by demonstrating on their sternum.This provides
them with a reference of what the sensation should feel like (assuming they have no sensory
deficits in the region overlying the sternum).
Ask the patient to close their eyes and say ‘yes’ each time they feel you touch their face.
Assess the sensory component of V1,V2 and V3 by testing light touch and pinprick sensation
across regions of the face supplied by each branch:
• Forehead (lateral aspect): ophthalmic (V1)

7. • Cheek: maxillary (V2)
• Lower jaw (avoid the angle of the mandible as it is
supplied by C2/C3): mandibular branch (V3)
❖ The same steps are then repeated using a neurotip
to assess for superficial pain. Record the findings,
and interpret any deficits found. Another part of the
sensory test that is not frequently performed is the
nasal tickle test. It includes gently gliding a cotton
wisp inside each nostril.The sensation is rather
unpleasant and the patient readily recognizes it.

8. Motor assessment : Use the muscles of
mastication to assess the motor component of V3:
1. Inspect the temporalis (located in the temple
region) and masseter muscles (located at
the posterior jaw) for evidence of wasting.This is
typically most noticeable in the temporalis
muscles, where a hollowing effect in the temple
region is observed.
2. Palpate the masseter muscle (located at the
posterior jaw) bilaterally whilst asking the
patient to clench their teeth to allow you to assess
and compare muscle bulk.

9. 3. Ask the patient to open their mouth
whilst you apply resistance
underneath the jaw to assess the
lateral pterygoid muscles.
An inability to open the jaw against
resistance or deviation of the jaw
(typically to the side of the lesion) may
occur in trigeminal nerve palsy.

10. Jaw jerk reflex : The jaw jerk reflex is a stretch reflex that involves the
slight jerking of the jaw upwards in response to a downward tap.
This response is exaggerated in patients with an upper motor neuron
lesion. Both afferent and efferent pathways of the jaw jerk reflex involve
the trigeminal nerve.
To assess the jaw jerk reflex:
1. Clearly explain what the procedure will involve to the patient and gain consent to
proceed.
2. Ask the patient to open their mouth.

11. 3. Place your finger horizontally across the patient’s chin.
4. Tap your finger gently with the tendon hammer.
5. In healthy individuals, this should trigger a slight closure of the mouth. In
patients with upper motor neuron lesions, the jaw may briskly move upwards
causing the mouth to close completely.

12. Corneal reflex
The corneal reflex involves involuntary blinking of both eyelids in response to unilateral corneal
stimulation (direct and consensual blinking).The afferent branch of the corneal reflex involves
V1 of the trigeminal nerve whereas the efferent branch is mediated by the temporal and
zygomatic branches of the facial nerve.The corneal reflex test is also an uncomfortable
experience for the patient. Spend enough time to ease any anxiety or concerns the patient may
have regarding this test.
To assess the corneal reflex:
1. Clearly explain what the procedure will involve to the patient and gain consent to proceed.
2.With both eyes open, the patient is asked to look up and away to the left.

13. 3. Approach the right eye with a clean cotton wisp
inferiorly, from the right side.This is to ensure that the
patient doesn’t see the object coming towards their eye
and blink prematurely.
4. While approaching the eye with the cotton wisp, the
free hand should be used to gently depress the lower
lid.
5. Lightly touch the edge of the cornea with the cotton
and observe for bilateral blinking.
❖In healthy individuals, you should observe both direct
and consensual blinking.The absence of a blinking
response suggests pathology involving either the
trigeminal or facial nerve.

14. Examination of the nerve exit points
The rough tenderness of the three peripheral branches of the nerves can be assessed
at their exit points: the supraorbital foramen, the infraorbital foramen and the mental
foramen.The examiner presses the foramen using the thumb or middle finger. Slight
tenderness is a normal finding.

15. CLINICAL RELEVANCE:
INFERIOR ALVEOLAR NERVE BLOCK
The inferior alveolar nerve, a branch of V3, travels through the
mandibular foramen and mandibular canal.Within the mandibular canal,
the inferior alveolar nerve forms the inferior dental plexus, which
innervates the lower teeth. A major branch of this plexus, the mental
nerve, supplies the skin and mucous membranes of the lower lip, skin of
the chin, and the gingiva of the lower teeth.
In some dental procedures which require a local anaesthesia, the
inferior alveolar nerve is blocked before it gives rise to the plexus.

16. The anaesthetic solution is
administered at the mandibular
foramen, causing numbness of
area supplied by the inferior
alveolar nerve.The anaesthetic
fluid also spreads to the lingual
nerve which originates near the
inferior alveolar nerve, causing
numbness of the anterior 2/3 of
the tongue

17. THANK YOU