Trigeminal nerve (part 1): overview of branches, motor & sensory root, and ganglion.

 INTRODUCTION:

• Largest cranial nerve.
• Consist of large sensory and small motor root.
• Motor root- supplies muscles of mastication.
• Sensory root- supplies skin of entire face, mucous membrane of cranial viscera and oral cavity.(except pharynx and base of tongue)

Motor root:

Sensory root:

It comprise central processes of ganglion cells located in trigeminal (semilunar or gasserian) ganglion.

Three sensory division: 

• Ophthalmic division
• maxillary division
• mandibular division.
  
  
  
  
  
  

Gasserian or semilunar ganglion:

1. Two ganglia, one innervating two side of face.
2. Location: Meckel's cavity, on the anterior surface of petrous portion of the temporal bone.
   
   
   
3. They are flat & cresent shaped, apprx 1*2cm.
4. Convexities faces anteriorly and downward.
5. Sensory fibre enter concave portion of each cresent.
6. Three sensory divisions( ophthalmic, maxillary, mandible) exit from convexity.

Ophthalmic division:

• First branch, sensory in nature, smallest of three branches.
• Exits the cranium, enters orbit through superior orbital fissure(SOF).
• Nerve trunk supplies eyeball, conjunctiva, lacrimal gland, parts of mucous membrane of nose and paranasal sinus, skin of forehead, eyelid and nose.

Before ophthalmic nerve passes through the SOF it divides into three branches.

Maxillary division:

Arises from middle of trigeminal ganglion. Purely sensory.

Leaves the cranium through foramen rotundum.

Mandibular division:

• Largest branch of trigeminal nerve.
• Mixed in nature, contains both sensory(large) and motor(small).
• Two roots emerges from cranium through foramen ovale.

Branches: gives off branches in three area, undivided, anterior and posterior(divided nerve).

Undivided nerve	Divided nerve
Nervus spinosus  Nerve to medial pterygoid muscle.	a. anterior division:  nerve to the lateral pterygoid muscle, masseter muscle, temporal muscle, buccal nerve. b. posterior division: auriculotemporal nerve Lingual nerve Mylohyoid nerve Inferior alveolar nerve:dental branches Incisive branch: dental branches. Mental nerve.

Commentary: The above content covers short description of trigeminal nerve divisions and their branches.

In our subsequent blogs detailed notes of each branch will be discussed.

Kindly report in comment section if you have any doubts or if you find any error.