Trigeminal nerve Flashcards
Where are the cell bodies of the motor root of the trigeminal nerve located?
Pons
Where are the cell bodies of the sensory root of the trigeminal nerve located?
Trigeminal ganglion
Describe the trigeminal ganglion in terms of:
- Which cell bodies are located there
- Where it’s located
- Its divisions
· Location of cell bodies of sensory root
· Located in middle cranial fossa “Meckel’s cave”
· Sensory root divides into three divisions: opthalmic, maxillary, mandibular
Where do the divisions of the trigeminal nerve pass through before the trigeminal ganglion?
Ophthalmic: superior orbital fissure
Maxillary: foramen rotundum
Mandibular: foramen ovale
What are the 3 main branches of the opthalmic nerve?
Fontal, naso-ciliary, lacrimal
What sensations does the opthalmic nerve provide?
○ upper eyelid, forehead up to vertex, lacrimal gland
○ tip and dorsum of nose, cornea, orbit,
○ meninges of anterior cranial fossa
○ frontal, ethmoid +/- sphenoid sinuses
What are the four main categories for the branches of the maxillary nerve?
Posterior superior alveolar
Infra Orbital
Pterygopalatine
Zygomatic
What are the sub-branches of the pterygopalatine fossa? (maxillary)
(3)
- Nasopalatine nerve: supplies anterior palate
- Greater and lesser palatine nerves: posterior palate = supplied by greater and lesser palatine nerve.
- Hard palate: greater/ soft palate: branches of lesser palatine nerve
What are the sub-branches of the infraorbital canal? (maxillary)
(2)
- Infraorbital nerve: sensory to lower eyelid, ala of nose and upper lip
- ASA: It branches away from the infraorbital nerve, leaving from the floor of the orbit to innervate the pulp of teeth, travelling in the anterior wall of the maxillary sinus. It supplies the buccal gingivae, and supplies anterior floor of nose and part of nasal septum
- MSA if it’s there
What are the sub-branches of the zygomatic? (maxillary)
2
Zygomaticotemporal: Skin of temples
Zygomaticofacial: Skin of cheek
What are the two divisions of the mandibular nerve?
Anterior division: • Buccal • Masseteric • Lateral and medial pterygoid • Deep temporal
- mostly motor except for the long buccal nerve
Posterior division: • Lingual • Mylohyoid • Dental branches • Incisive • Mental • Auriculotemporal
- mostly sensory, except for mylohyoid nerve
What are the branches of the mandibular nerve?
Long buccal nerve
Lingual nerve
Inferior alveolar nerve
Auriculo-temporal nerve
Anterior: Muscles of mastication
Where does the long buccal nerve come from? What does it innervate?
- It passes in between the two heads of the lateral pterygoid muscles, branching inferiorly towards the buccinator
- Innervates skin of the cheek and oral mucosa near parotid duct opening
- Innervates gingivae over retromolar trigone and buccal gingivae of mandibular teeth
Where does the lingual nerve come from?
- Branches away from the mandibular nerve at the infratemporal fossa
- It lies anterior to the inferior alveolar nerve
- Supplies sensory innervation to the anterior 2/3 of tongue
- It joins with the chorda tympani which is a branch of the facial nerve that carries taste fibres
Where does the inferior alveolar bone come from?
- Sensory and motor
- Lies below the inferior head of the lateral pterygoid
- It enters the mandible through the mandibular foramen
- It branches into the mental and incisive nerves
- It supplies the chin, lower lip and lower teeth
Where does the auriculo-temporal nerve come from?
- It originates from the back of the mandibular nerve, travelling alongside the superficial temporal vein
- Innervates part of the auricle of the ear, and temporal region
- It supplies the sides of the head
What is the motor function of the trigeminal nerve?
· Muscles of mastication: masseter, temporalis, medial and lateral pterygoid, mylohyoid, anterior belly of digastric, tensor veli palatini, tensor tympani
· Motor root runs under the mandibular division and passes through foramen ovale with it
What are the branches of the motor root? (7)
· Masseter
· Medial and lateral pterygoids
· Temporalis
· Tensor tympani:Dampens sounds, such as those created by chewing, by stabilizing the malleus bone in the middle ear
· Tensor veli palatini:helps elevate the soft palate to prevent regurgitation of food and liquid into the nasopharynx.
· Anterior belly of digastric:a suprahyoid muscle involved in elevation of the hyoid bone during swallowing
· Mylohyoid:a suprahyoid muscle involved in elevation of the hyoid bone during swallowing
What is the relationship between trigeminal nerves and the PNS?
Parasympathetic fibres originating from cranial nerves ‘hitch-hike’ with branches of the trigeminal nerve to reach PNS ganglia
For the parasympathetic pterygopalatine ganglion, state:
· Trigeminal nerve
· Hitch- hiking nerve
· Function
Trigeminal nerve:
Maxillary
Hitch hiking nerve
Facial nerve
Function:
Secreto-motor: lacrimal gland, nasal glands, maxillary sinus
For the parasympathetic submandibular ganglion, state:
· Trigeminal nerve
· Hitch- hiking nerve
· Function
Trigeminal nerve:
Mandibular
Hitch hiking nerve:
Facial nerve –> follows lingual nerve
Function:
Secreto- motor for submandibular and sublingual glands
For the parasympathetic nasociliary ganglion, state:
· Trigeminal nerve
· Hitch- hiking nerve
· Function
Trigeminal nerve:
Opthalmic
Hitch hiking nerve:
Nasocilliary nerve
Function:
Controls pupil size
For the parasympathetic otic ganglion, state:
· Trigeminal nerve
· Hitch- hiking nerve
· Function
Trigeminal nerve:
Mandibular
Hitch hiking nerve:
Glosso-pharyngeal–> follows auriculotemporal nerve
Function:
Innervates parotid gland
