Trigeminal nerve

• 5th cranial nerve

Origin

• Three sensory nuclei (mesencephalic, principal sensory, spinal nuclei of trigeminal nerve) One motor nucleus (motor nucleus of the trigeminal nerve)
• Extending from the midbrain to the medulla.
• Merge to form a sensory root. The motor nucleus continues to form a motor root.
• In the middle cranial fossa, the sensory root expands into the trigeminal ganglion.
• The trigeminal ganglion is located lateral to the cavernous sinus, in a depression of the temporal bone. This depression is known as the trigeminal cave.
• The peripheral aspect of the trigeminal ganglion gives rise to 3 divisions: ophthalmic (V1), maxillary (V2) and mandibular (V3).
  • Mandibular is the only root with motor

Divisions

Opthalmic nerve

• Travels lateral to the cavernous sinsus
• Exits the superior orbital fissure
• 3 terminal branches: frontal, lacrimal and nasociliary, which innervate the skin and mucous membrane of derivatives of the frontonasal prominence derivatives:
  • Forehead and scalp
  • Frontal and ethmoidal sinus
  • Upper eyelid and its conjunctiva
  • Cornea
  • Dorsum of the nose
• Give parasympathetic to Lacrimal gland

Maxillary nerve

• Travels lateral to the cavernous sinsus
• Exits the foramen rotundum
• 14 terminal branches, which innervate the skin, mucous membranes and sinuses of derivatives of the maxillary prominence of the 1st pharyngeal arch:
  • Lower eyelid and its conjunctiva
  • Cheeks and maxillary sinus
  • Nasal cavity and lateral nose
  • Upper lip
  • Upper molar, incisor and canine teeth and the associated gingiva
  • Superior palate
• Give parasympathetic to Lacrimal gland and Nasal glands

Mandibular nerve

• Exits via the foramen ovale entering the infra-temporal fossa
• Mandibular nerve gives rise to four terminal branches in the infra-temporal fossa
  • Buccal nerve
  • Inferior alveolar nerve
  • Auriculotemporal nerve
  • Lingual Nerve
• Sensory supply:
  • Mucous membranes and floor of the oral cavity
  • External ear
  • Lower lip
  • Chin
  • Anterior 2/3 of the tongue (only general sensation; special taste sensation supplied by the chorda tympani, a branch of the facial nerve)
  • Lower molar, incisor and canine teeth and the associated gingiva
• Motor Supply
  • Muscles of mastication; medial pterygoid, lateral pterygoid, masseter, temporalis
  • Anterior belly of the digastric muscle and the mylohyoid muscle (these are suprahyoid muscles)
  • Tensor veli palatini
  • Tensor tympani
• Parasympathetic Supply
  • Submandibular gland anatomy and Sublingual Gland
    •  Post-ganglionic fibres from the submandibular ganglion (derived from the facial nerve), travel with the lingual nerve to innervate these glands.
  • Parotid Gland
    • Post-ganglionic fibres from the otic ganglion (derived from the glossopharyngeal nerve, CN IX), travel with the auriculotemporal branch of the V3 to innervate the parotid gland.