Notes on Trigeminal Nerve

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TRIGEMINAL NERVE

Type: Mixed-general sensory and motory (branchial motor component as the special visceral efferent fibres supply muscles originating from the first branchial arch). Sensory to face/head and supplies muscles of mastication.

Three Sensory Divisions:

1. Ophthalmic (VI).

2. Maxillary (V2).

3. Mandibular (V3).

Nuclei:

1. Motory nucleus - pons, floor of the 4th ventricle.

2. Pontine trigeminal nucleus (chief sensory nucleus): floor of the 4th ventricle.

3. Mesencephalic nucleus (lateral to cerebral midbrain aqueduct).

4. Spinal nucleus (inferior pons and medulla).

Autonomic Ganglia of the Head and Neck:

Are related to and receive input from the trigeminal nerve and are thus briefly discussed here. There are four pairs of autonomic ganglia - ciliary, pterygopalatine, otic and submandibular - sited in the head.

Each ganglion receives 3 roots:

a. Sympathetic root - pass through ganglia.

b. Parasympathetic root (N3, 7, 9, 10) - relay in the ganglia.

c. Sensory root (from trigeminal nerve) - pass through ganglia.

The end organ innervation is as follows:

a. Ciliary ganglion: Pupil sphincter, ciliary muscle (accommodation reflex).

b. Pterygopalatine ganglion: Lacrimal and nasal glands.

c. Submandibular ganglion: Submandibular and sublingual glands.

d. Otic ganglion: Parotid gland.

Elements:

Trigeminal (semilunar) ganglion lodged in the trigeminal cave (depression near the apex of the petrous part of the temporal bone - i.e. dural recess of the middle cranial fossa).

Ophthalmic Nerve or Division (VI):

Sensory.

Areas Supplied:

Scalp, forehead, superior portion of face (eye, lacrimal gland, conjunctiva, nasal cavity, upper eyelid, and nose).

Branches:

1. Lacrimal (to lacrimal gland and conjunctiva).

2. Frontal (br. supratrochlear, supraorbital).

3. Nasociliary (br. Long ciliary, ganglionic to the ciliary ganglion, anterior and posterior ethmoidal and the infratrochlear nerve). Divides into medial and lateral terminal branches that supply the septal mucous membrane, lateral wall of nose, ala and tip of nose (external nasal nerve). Communicates with facial nerve.

Ciliary Ganglion:

Site: Posterior orbit, between optic nerve and the lateral rectus muscle.

Roots:

1. Long (sensory) root from naso-ciliary nerve - eyeball supplied.

2. Short (parasympathetic) motor root - from oculomotor nerve (Edinger - Wesphal nucleus) - relay in ganglion and supply pupillary and ciliary muscle.

3. Sympathetic - cavernous plexus from the sup. Cervical ganglion.

Distribution:

Via short ciliary nerves (inf. and sup.) to ciliary muscle, iris and cornea (i.e. globe of eye).

Maxillary Nerve or Division (V2):

Sensory

Areas Supplied:

Dura, maxillary sinus mucosa, roots of the premolar and maxillary molar teeth, nasal septum, roots of the maxillary central, lateral and canine teeth, lower eyelid, nose and upper lip.

Course of Nerve:

From the trigeminal ganglion passes through the foramen rotundum, pterygopalatine fossa, pterygomaxillary fissure, infratemporal fissure and exits the infraorbital canal and foramen as the infraorbital nerve.

Branches:

1. In Skull: Meningeal (recurrent).

2. In Pterygo-palatine fossa:

a. Zygomatic (br. Zygomatic - temporal and zygomatic - facial).

b. Ganglionic (to spheno-palatine ganglion).

c. Posterior superior alveolar (dental) (br. lat. and med. branch, the latter supplies the molar teeth).

3. In the infra-orbital canal:

a. Middle and anterior superior alveolar (dental) (br. middle - supplies biscuspid teeth if present and anterior - supplies incisor and canine teeth and anterior part of inferior concha.

4. In the Face:

a. Inferior palpebral (lower eye lid).

b. External nasal (side of nose).

c. Superior labial (upper lip, vestibule, gum).

Pterygo-palatine (Spheno-palatine) ganglion

Site:

Pterygo-palatine fossa near spheno-palatine foramen.

Roots:

1. Nervus intermedius (parasympathetic - secret motor) via greater (superficial) petrosal nerve. Postganglionic fibres pass to the lacrimal gland and no other glands of the nasal cavity, palate and Paranasal sinuses (Hay fever ganglion i.e. "allergen stimulus" results in "tears and a running nose").

2. Deep petrosal nerve (via nerve of the pterygoid canal) - carry sympathetic fibres that do not relay but result in vasoconstriction of the nose, palate and Paranasal sinuses).

3. Sensory: From the maxillary branch (trigeminal ganglion).

Distribution:

1. Ascending: to orbital periosteum.

2. Descending:

a. Greater palatine nerve (gums and hard palate mucous and membrane): (br. inferior nasal branches to the mucous membranes of the middle and inferior nasal concha).

b. Lesser palatine nerve: mucous and membrane of the soft palate, uvula and tonsil/soft palate.

3. Medial:

a. Short spheno-palatine - posterior and upper part of the lateral nasal wall.

b. Long spheno-palatine - septum, gums of incisor teeth.

4. Posterior: Pharyngeal to upper naso-pharynx and sphenoidal sinus ostium.

Summary: Mucous membrane of the nasal cavity, naso-pharynx, Paranasal sinuses and palate. Vasoconstrictor sympathetic fibres to the nose, naso-pharynx, Paranasal sinuses and palate.

Mandibular Nerve or Division (V3)

Type:

Mixed sensory and motory.

Course of Nerve:

Exits skull via the foramen ovale and divides into an anterior and posterior division after the motory and sensory roots have united. It is a major nerve of the infratemporal fossa.

Areas Supplied:

Temporal skin, side of face, anterior position of auricle, mandibular and Submental skin, lower lip, teeth, gingiva, muscles of mastication, mucous membrane of part of the tongue and floor of the mouth.

Branches:

1. Meningeal (recurrent: nervus spinosus) - dura.

2. Medial pterygoid (also to lateral pterygoid muscle).

3. Masseteric (motor).

4. Temporal (motor) - temporal muscle.

5. Buccal (sensory) - mucous membrane and skin of cheek.

6. Auriculo - temporal nerve:

Branches:

a. External auditory meatus.

b. Tympanic membrane.

c. Temporal - skin of temple.

d. Parotid (with fibres from N9 via the otic ganglion).

e. Mandibular (to TM joint) - sensory.

7. Inferior alveolar (dental) nerve (molar and bicuspid teeth). Passes through the mental foramen as the mental nerve (supplies skin of chin, mucous membrane and skin of lower lip and labial mandibular gingivae.

Branches:

a. Mylo-hyoid muscle, anterior belly of digastric.

b. Dental (molars and bicuspids).

c. Incisor (canine and incisors).

d. Mental.

8. Lingual nerve (joined by Chordae tympani).

Branches:

Communicating with inferior alveolar nerve.

Supplies:

Sides and of tip of tongue, lingual gums, sublingual and submandibular gland, anterior two-thirds of mucous membrane of dorsum of tongue.

Submandibular Ganglion:

Site: Sited between the hypoglossus muscle and the deep portion of the submandibular gland.

Roots:

1. Sensory: Lingual nerve (trigeminal ganglion).

2. Parasympathetic: N. intermedius and chorda tympani.

3. Sympathetic: Plexus around facial artery (superior cervical ganglion).

Distribution:

1. Submandibular gland and sublingual glands (sympathetic branches).

2. Mucous membrane.

Otic Ganglion:

Site: Medial surface of the mandibular nerve adjacent to the foramen ovale.

Roots:

1. Sensory: from mandibular - auriculo temporal nerve (trigeminal ganglion).

2. Sympathetic: Plexus around middle meningeal artery (superior cervical ganglion).

3. Motor: From mandibular nerve - Nerve to medial pterygoid.

4. Parasympathetic: Lesser petrosal nerve and glossopharyngeal nerve.

Distribution:

1. Communicating to auriculo - temporal and to Chordae tympani.

2. Muscular: tensor tympani and tensor veli palatini

3. Parotid gland via auriculo - temporal.

Summary of Cranial Autonomic Ganglia:

Number: 4 Ganglia.

Names:

1. Ciliary ganglion.

2. Pterygo-palatine (spheno-palatine) ganglion.

3. Submandibular ganglion.

4. Otic ganglion.

Plan of Ganglia:

Afferent branches (3): Motor, sensory, sympathetic.

1. Motor (parasympathetic) root: Via oculomotor nerve (III) - Edinger Wesphal nucleus, nervus intermedius (VII) (superior salivary nucleus) and glossopharyngeal nerve (IX) (inferior salivary nucleus).

2. Sensory root - all from trigeminal ganglion.

3. Sympathetic root - all from superior cervical ganglion on the internal and external carotid arteries.

Distribution of Cranial Autonomic Ganglia:

1. Ciliary ganglion: supplies eyeball.

2. Pterygo-palatine ganglion: palate, nose, naso-pharynx, paranasal sinus, lacrimal gland and labial glands of the upper lip.

3. Submandibular ganglion: Glands of the floor of the mouth (sublingual and submandibular salivary glands).

4. Otic ganglion: Glands that open into the mouth i.e. parotid, buccal, molar and labial glands of the lower lip.

Further Topics on Cranial Nerves:

1. Introduction to Cranial Nerves
2. Notes on Olfactory Nerve CN 1
3. Notes on Optic Nerve CN 2
4. Notes on Oculomotor Nerve CN 3
5. Notes on Trochlear Nerve CN 4
6. Notes on Trigeminal Nerve CN 5
7. Notes on Abducens Nerve CN 6
8. Notes on Facial Nerve CN 7
9. Notes on Vestibulocochlear Nerve CN 8
10. Notes on Glossopharyngeal Nerve CN 9
11. Notes on Vagus Nerve CN 10
12. Notes on Accessory Nerve CN 11
13. Notes on Hypoglossal Nerve CN 12
14. Summary of Cranial Nerve Nuclei
15. Summary of Cranial Nerve Functions

Additional Reading:

Basic Neurology

1. Peripheral Nervous System
2. Central Nervous System
3. The Ventricular System
4. The Spinal Cord
5. The Brain Stem
6. The Cerebellum
7. Visual Pathways
8. Diencephalon
9. Basal Ganglia
10. Cerebral Cortex
11. Sleep Disorders
12. Autonomic Nervous System
13. Cranial Nerves and Parasympathetic Ganglia
14. Cells of the Nervous System
15. Cerebrospinal fluid
16. Additional short notes on Cerebrum
17. Functions and Diseases of Cerebrum
18. Subcortical Grey Matter
19. Notes on The Spinal Cord
20. Regulation of Heart Rate by Autonomic Nervous System
21. Action Potentials, Axon Conduction, and Neuromuscular Junction
22. Types of Seizures
23. What is a Cough Reflex?
24. Notes on Congenital Prosopagnosia
25. Findings in Parkinson's Disease
26. Types of Heat Strokes
27. Types of Strokes
28. What is Benign Intracranial Hypertension?
29. What is Cauda Equina Syndrome?
30. Cranial Nerve Locations in Brain Stem

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1. Video of Neurology Examination in a Clinical Setting

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1. Nervous System Disorders
2. Histology of Nervous Tissue
3. Cranial Nerve Reflexes
4. Motor System Examination

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