Trigeminal Ganglion

 This is the sensory ganglion of the fifth cranial nerve. It is homologous with the dorsal nerve root ganglia of spinal nerves. 

All such ganglia are made up of pseudounipolar nerve cells, with a 'T'-shaped arrangement of their process; one process arises from the cell body which then divides into a central and a peripheral process

The ganglion is crescentic or semilunar in shape, with its convexity directed anterolaterally. 

The three divisions of the trigeminal nerve emerge from this convexity. 

The posterior concavity of the ganglion receives the sensory root of the nerve

Situation and Meningeal Relations

The ganglion lies on the trigeminal impression, on the anterior surface of the petrous temporal bone near its apex. 

It occupies a special space of dura mater, called the trigeminal or Meckel's cave. 

There are two layers of dura below the ganglion. 

The cave is lined by pia-arachnoid, so that the ganglion along with the motor root of the trigeminal nerve is surrounded by CSF. 

The ganglion lies at a depth of about 5 cm from the preauricular point.

Relations

Medially

1. Internal carotid artery.

2. Posterior part of cavernous sinus.

Laterally

1. Middle meningeal artery.

Superiorly

1. Parahippocampal gyrus.

Inferiorly

1. Motor root of trigeminal nerve.

2. Greater petrosal nerye.

3. Apex of the petrous temporal bone.

4. The foramen lacerum

Associated Root and Branches

The central processes of the ganglion cells form the large sensory root of the trigeminal nerve which is attached to pons at its junction with the middle cerebellar peduncle.

The peripheral processes of the ganglion cells form three divisions of the trigeminal nerve, namely the

ophthalmic, maxillary and mandibular.

The small motor root of the trigeminal nerve is attached to the pons superomedial to the sensory root.

It passes under the ganglion from its medial to the lateral side, and joins the mandibular nerve at the

foramen ovale.

Blood Supply

The ganglion is supplied by twigs from:

1. Internal carotid

2. Middle meningeal

3. Accessory meningeal arteries

4. By the meningeal branch of the ascending pharyngeal artery.

Clinical Anatomy

1. Intractable facial pain due to trigeminal neuralgia or carcinomatosis may be abolished by injecting alcohol into the ganglion. Sometimes cutting of the sensory root is necessary.

2. Congenital cutaneous naevi on the face (port wine stains) map out accurately the areas supplied by one or more divisions of the V cranial nerve.

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5th cranial nerve - Trigeminal nerve | Nucleus| Functional components| Trigeminal ganglion |Branches