2. Trigeminal nerve is the
largest cranial nerve and
contains both sensory
and motor fibers.
It is sensory nerve to the
greater part of the head
and motor nerve to
several muscles
including muscles of
mastication.
3. MAIN SENSORY NUCLEUS:
Lies in posterior part of the pons lateral to
motor nucleus.
Continuous below the spinal nucleus.
SPINAL NUCLEUS:
Continuous superiorly with main sensory
nucleus in the pons,
Extends inferiorly through the whole length of
the medulla oblongata and into the upper part
of the spinal cord as far as the second cervical
segment.
MESENCEPHALIC NUCLEUS:
Situated in the lateral part of the gray matter
around the cerebral aqueduct.
Extends inferiorly into the pons as far as the
main sensory nucleus.
MOTOR NUCLEUS:
Situated
in the pons medial to main sensory nucleus.
4. The sensations of pain ,temperature, touch and pressure from the skin of the face
and mucous membrane travel along axons whose cell bodies are situated in
TRIGEMINAL SENSORY GANGLION.
Central processes of these cells form the large sensory root of the trigeminal nerve.
They then divide into
(a) ascending branches which terminate in the sensory nucleus.
(b) descending branches terminate in spinal nucleus.
The sensations of touch and pressure are conveyed by nerve fibers that terminate in
the sensory nucleus .
The sensations of pain and temperature pass to the spinal nucleus.
The sensory fibers from the ophthalmic division terminate in the inferior part of
spinal nucleus.
Sensory fibers from maxillary division terminates into the middle part of spinal
nucleus
And that of mandibular division terminates into superior part of spinal nucleus.
Proprioceptive impulses from the muscles of mastication and from the facial and the
extraocular muscles are carried by the fibers in the sensory root of trigeminal nerve
that have by passed the trigeminal ganglion.
These fibers arises from the unipolar cells of the mesencephalic nucleus.
5. The axons of the main
sensory nucleus and spinal
nucleus and the central
processes of the cells in the
mesencephalic nucleus now
crosses the medial plane
and now ascend as the
trigeminal lemniscus to
terminate on the nerve cells
of the ventral posteromedial
nucleus of the thalamus.
The axons of these cells
now travel through the
internal capsule to the
postcentral gyrus.
6. The cells of the motor nucleus give rise to the
axons that form the motor root .
The motor nucleus supplies the muscles of
mastication
Tensor tympani
Tensor veil palatine
Mylohyoid
Anterior belly of the
Digastric muscle
7. Leaves the anterior aspect of pons as a small
motor and large sensory root.
Nerve passes forward out of the posterior
cranial fossa and rest on the apex of the
petrous part of the temporal bone in the
middle cranial fossa.
The large sensory now expands to form
TRIGEMINAL GANGLION enclosed in within a
pouch of dura mater called as “MECKEL CAVE”
8. 1.OPTHALMIC NERVE:
Leaves the skull through superior orbital fissure
to enter the orbital cavity.
It has further branches:
(a) Nasocilliary
(b)Anterior ethmoid
(c)Posterior ethmoid
(d)Infratrochlear
(e)Supraorbital
(f) Supratrochlear
(g)Lacrimal
9. 2.MAXILLARY NERVE:
Leaves the skull through foramen rotunda
it has further divisions
In the cranium
Middle meningeal nerve in the meninges
From the pterygopalatine fossa
Infraorbital nerve through Infraorbital canal
Zygomatic nerve (zygomaticotemporal nerve, zygomaticofacial nerve)
through Inferior orbital fissure
Nasal Branches (nasopalatine) through Sphenopalatine foramen
Superior alveolar nerves (Posterior superior alveolar nerve, Middle
superior alveolar nerve, Anterior superior alveolar nerve)
Palatine nerves (Greater palatine nerve, Lesser palatine nerve), including
the Nasopalatine nerve
Pharyngeal nerve
In the infraorbital canal
Anterior superior alveolar nerve
Infraorbital nerve
On the face
Inferior palpebral nerve
Superior labial nerve
Lateral nasal nerve
10. 3.MANDIBULAR NERVE:
Contains both sensory and motor fibers
Leave the skull through foramen ovule
(a)Nerve to mylohyoid
(b)Auric temporal
(c)Lingual
(d)Mental
(e)Buccal
(g) Inferior alveolar
