M01.02.025 Maxillary Nerve

The maxillary nerve is the second branch of the trigeminal nerve (cranial nerve V). It originates embryologically from the first pharyngeal arch and serves a primarily sensory role in the mid-third of the face. This article explores the anatomical course, sensory and parasympathetic functions, and clinical relevance of the maxillary nerve.

Anatomy of the Trigeminal Nerve

Origin and Nuclei

The trigeminal nerve arises from four nuclei in the brainstem, which extend from the midbrain to the medulla:

1. Three sensory nuclei:
   • Mesencephalic nucleus
   • Principal sensory nucleus
   • Spinal nucleus
2. Motor nucleus of the trigeminal nerve

Formation of Roots

• Sensory root: Formed by the fusion of sensory nuclei at the pons.
• Motor root: Remains distinct and supplies only the mandibular division (V3).

Trigeminal Ganglion

• Location: In Meckel’s cave (trigeminal cave) lateral to the cavernous sinus.
• The sensory root expands into the trigeminal ganglion, from which the three divisions of the trigeminal nerve arise:
  • Ophthalmic nerve (V1)
  • Maxillary nerve (V2)
  • Mandibular nerve (V3)

Maxillary Nerve (V2)

Anatomical Course

1. Arises from the trigeminal ganglion.
2. Passes through the lateral wall of the cavernous sinus.
3. Exits the skull via the foramen rotundum.
4. Branches extensively to provide sensory innervation.

Branches of the Maxillary Nerve

• Superior alveolar nerves (anterior, middle, and posterior)
• Middle meningeal nerve
• Infraorbital nerve
• Zygomatic nerve
• Inferior palpebral nerve
• Superior labial nerve
• Pharyngeal nerve
• Greater and lesser palatine nerves
• Nasopalatine nerve

Sensory Function

The terminal branches of the maxillary nerve provide sensory innervation to:

• Lower eyelid and its conjunctiva.
• Inferior nasal cavity (posterior region).
• Cheeks and maxillary sinus.
• Lateral nose.
• Upper lip, teeth, and gingiva.
• Superior palate.

Parasympathetic Function

Postganglionic fibers from the pterygopalatine ganglion (associated with the facial nerve) join the maxillary nerve to innervate:

• Lacrimal gland (tear production).
• Mucous glands of the nasal mucosa.

Clinical Relevance: Trigeminal Neuralgia

Trigeminal neuralgia is a chronic pain disorder affecting one or more branches of the trigeminal nerve.

• Symptoms:
  • Hyperalgesia: Increased pain sensitivity.
  • Allodynia: Pain from non-painful stimuli.
• Triggers: Light touch or minor stimuli can cause excruciating facial pain.

Causes

• Possible nerve damage due to:
  • Multiple sclerosis
  • Stroke
  • Trauma

Management

1. Pharmacological:
   • Carbamazepine: Blocks voltage-gated sodium channels to reduce pain transmission.
2. Surgical:
   • Nerve destruction in refractory cases (results in sensory loss).

Points to Remember

1. The maxillary nerve (V2) originates from the trigeminal ganglion and exits the skull via the foramen rotundum.
2. Its branches provide sensory innervation to the mid-third of the face and parasympathetic innervation to lacrimal and nasal mucosal glands.
3. Trigeminal neuralgia is a debilitating condition requiring specialized pharmacological or surgical intervention.

Bibliography

• TeachMeAnatomy. “Maxillary Nerve: Anatomy and Functions.” 2024.
• Neurosurgical Atlas. “Trigeminal Neuralgia Pathophysiology.”