10.24.11+-+Trigeminal+Nerve

Trigeminal Nerve - Just want to quickly mention that all of these features are bilateral. It's obvious I guess, but sometimes I'm slow.


 * 1a. Name the three major divisions of the trigeminal nerve.**

Three major divisions of trigeminal: opthalmic, maxillary, and mandibular. Opthalmic exits out of the superior orbital fissure. Maxillary exits out of the foramen rotundum. Mandibular exits out of the foramen ovale.


 * 1b. Name the nerves that arise from each of these major divisions, describe the pathways that these nerves follow, and describe what these nerves innervate in the periphery.**


 * 1) Opthalmic has four branches: tentorial, nasociliary, frontal, and lacrimal.
 * 2) Tentorial branches before the superior orbital fissure and heads up the base of the middle cranial fossa (somatic sensory innervation to the tentorial cerebelli)
 * 3) Sensory branch to ciliary ganglia (somatic sensory of the eye)
 * 4) Posterior ethmoidal (pressure sensation of the ethmoidal air cells and sphenoid sinus)
 * 5) Long ciliary (touch sensation of the eye)
 * 6) Anterior ethmoidal (pressure sensation of the ethmoidal air cells and frontal sinus)
 * 7) External branch of anterior ethmoidal (cutaneous sensation of the superior rim of nose)
 * 8) infraTrochlear (cutaneous sensation of nasion region)
 * 9) Supraorbital (cutaneous sensation of forehead)
 * 10) Supratrochlear (cutaneous sensation of medial forehead)
 * 11) Lacrimal goes to the lacrimal gland (lacrimal gland and cutaneous sensation lateral to eye)
 * 12) Maxillary has 4 branches: meningeal, ganglionic branches to pterygopalatine ganglion, posterior superior alveolar, and its terminal branch: infraorbital. 1 exits in the middle cranial fossa, the other 2 exit in the sphenopalatine fossa, and the infraorbital is the maxillary nerve renamed once it passes through the inferior orbital fissure. I found it very difficult to visualize, but found Rohen's, and N5 P121, 120, 44, and 42 most helpful. It branches from the trigeminal ganglia just superior to foramen rotundum and passes through rotundum to enter the superior sphenopalatine fossa. It drops inferior ganglionic branches to the pterygopalatine ganglia (which will send branches into the nasal and oral cavities) and to form the posterior superior alveolar nerve, continues anteriorly through the inferior orbital fissure to enter the orbit and sends off the zygomatic branch superiorly piercing the orbit wall, the alveolar branches inferiorly through canals in the maxilla, and exits the infraorbital fissure to the skin.
 * 13) Meningeal branches from V2 while still within the middle cranial fossa (pressure sensation to dura mater of ant. and med. cranial fossa)
 * 14) Ganglionic branches to pterygopalatine ganglia drop inferiorly from V2 to join the pteryogopalatine ganglia (also formed by autonomic roots) housed in the superior sphenopalatine fossa. The ganglia sends two branches into the nasal cavity and two branches through canals to the oral cavity.
 * 15) Greater and lesser palatine nerves exit the ganglia and head inferiorly through the greater palatine canal formed by a space created between the maxilla and palatine bones, then pass through the maxilla via the greater/lesser palatine fossa to the surface of the palate (Greater: hard palate general sensation; Lesser: soft palate general sensation)
 * 16) Superior Posterior Lateral Nasal and Nasopalatine (N4P42) pass through the nasopalatine foramen to enter the nasal cavity and innervate the septum walls (nasopalatine) and lateral walls (SPLN) of the nasal cavity
 * 17) Posterior superior alveolar branches branch just posterior to inferior orbital fissure. Heads down the backside of the maxilla and enters the maxilla via the alveolar foramina on the tuberosity of maxilla. Innervates teeth and gums.
 * 18) Infraorbital is the terminal branch of the maxillary nerve, heads through inferior surface of orbit, exits through infraorbital foramen to cutaneous innervation of nose and anterior face.
 * 19) Zygomatic branches while in the orbit and splits into two.
 * 20) Zygomaticotemporal exits the orbit laterally through the maxilla bone via the zygomaticotemporal foramen (cutaneous innervation of superior tempora)
 * 21) Zygomaticofacial exits the orbit anteriorly through the maxilla bone via the zygomaticofacial foramen (cutaneous innervation of inferior tempora)
 * 22) Middle superior alveolar branches from infraorbital nerve within the orbit. It also innervates teeth and gums after entering the maxilla via the middle superior alveolar foramen.
 * 23) Anterior superior alveolar branches from infraorbital nerve at the infraorbital foramen. It also innervates teeth and gums after entering the maxilla via the anterior superior alveolar foramen.
 * 24) Mandibular branching pattern is not nearly as complicated as maxillary. It exits middle cranial fossa via foramen ovale and puts off 4 (MABL) sensory branches and 7 branchial muscular branches to 8 muscles (MDM LT TMD). It terminates as the inferior alveolar n. that enters the mandibular foramen and gets renamed the mental n. as it exits the mental foramen.
 * 25) Meningeal branches from V3 and reenters middle cranial fossa via foramen spinosum to innervate lateral middle cranial fossa dura mater
 * 26) Auriculotemporal exits heading posteriorly and encircles the middle meningeal artery before heading superiorly anterior to the external acoustic meatus. It runs with the superficial temporal artery and provides cutaneous innervation to temporal region
 * 27) Buccal nerve: sensory to inner and outer cheek
 * 28) Lingual nerve: somatic sensory to tongue (but it does pick up the chorda tympani which provides taste sensation to tongue and parasympathetic innervation to submandibular glands)
 * 29) Masseter - branchial motor
 * 30) Deep Temporal - branchial motor
 * 31) Medial Pterygoidal - branchial motor
 * 32) Lateral Pterygoidal - branchial motor
 * 33) Tensor Levator Vili - branchial motor
 * 34) Tensor Tympani - branchial motor
 * 35) Mylohyoid - branchial motor
 * 36) Digastric (Anterior belly, part of mylohyoid nerve)
 * 37) Inferior Alveolar Nerve does inferior gums and teeth, somatic sensory, renamed mandibular nerve once it enters mandibular foramen
 * 38) Mental Nerve termination of inferior alveolar nerve once it exits mental foramen. Somatic cutaneous sensory to chin.


 * 1c. Describe the surface landmarks that form the sensory boundaries of each major division of the trigeminal nerve.**

Opthalmic: The tip of the nose to the top of the lower eyelid, then straight up and over at about the superior temporal line and then straight up and over at the vertex of skull Maxillary: The upper lip to the dimples of the cheek and then straight up and over the zygomatic process until it hits the line formed by the opthalmic nerve Mandibular: Inferior surface of the jaw, follow the jaw line to include tragus of ear and anterior superior portion of pinna up to the vertex of the skull


 * 2. Describe the types of nerve fibers found within the trigeminal nerve. Describe what structures they innervate in the periphery.**

Opthalmic: Somatic sensory Maxillary: Somatic sensory Mandibular: Somatic sensory and branchial motor (MDM LT TMD)


 * 3. Describe the location of the trigeminal ganglion. Name the type of neuronal cell bodies present in this ganglion as well as the types of motor nerve fibers that pass through the ganglion.**

The trigeminal ganglion is in the middle cranial fossa lying in the trigeminal impression of the temporal bone, near the apex of the petrous part.

All the neuronal cell bodies are pseudounipolar for somatic sensory (afferent, no synapses). Also proprioceptive nerve fibers pass through. Branchial motor fibers pass through.