Nerves Flashcards
Describe the route of the ophthalmic n.
It passes from the trigeminal ganglion through the superior orbital fissure and into the orbit.
It then branches into the lacrimal, nasociliary, and frontal branches. The lacrimal nerve passes through the orbit medially and superiorly to innervate the lacrimal gland after giving off a communicating branch to the zygomaticotemporal branch of the maxillary n..
The nasociliary branch connects to the ciliary ganglion and gives off long and short ciliary sensory branches to the orbit and then continues out through the anterior ethmoidal foramen, where it enters the nasal cavity and provides innervation for much of the anterior nasal mucosa via anterior and posterior ethmoidal nn. which pass medially into the nasal cavity to innervate the lateral nasal walls. It then gives off an infratrochlear sensory branch to the external lateral nose.
The frontal branch courses in the middle, superior aspect of the orbit and divides into supraorbital and supratrochlear branches that supply sensory innervation to the medial forehead (supratrochlear in the midline of the forehead and supraorbital above the orbit)
Describe the route of the maxillary n.
exits through the foramen rotundum, into a space posterior to the orbit, the pterygopalatine fossa. It then re-enters the inferior orbital fissure running inferior to the orbit, and travels to the infraorbital canal, and exits through the infraorbital foramen, and terminates by dividing into palpebral, lateral nasal and labial branches. Branches heavily in the pterygopalatine fossa
What are the branches of the ophthalmic n.?
The ophthalmic nerve divides into three named sensory nerves as it passes through the superior orbital fissure: the frontal, lacrimal and nasociliary nerves.
What are the branches of the frontal nerve?
The frontal nerve enters the roof of the orbit, where it divides into the supraorbital and supratrochlear nerves.
What does the lacrimal n. innervate?
the lateral portion of the upper eye lid, conjunctiva and lacrimal gland.
What are the branches of the nasociliary n.?
The small nasociliary nerve consists of the infratrochlear and external nasal nerves, internal nasal nerve from the anterior nasal cavity, anterior and posterior ethmoidal nerves from the ethmoid air sinuses, and, finally, the short and long ciliary nerves innervating the globe.
Describe the branching the maxillary n.
The maxillary nerve exits the cranium through the foramen rotundum and enters the pterygopalatine fossa. In the fossa, several sensory branches to the teeth and palate are given off. These include the greater and lesser palatine nerves, the nasopalatine nerve, the posterior superior alveolar nerve and communicating branches to the pterygopalatine ganglion.
The maxillary nerve continues into the infraorbital canal as the infraorbital nerve.
The zygomatic nerve emerges from the infraorbital n. before it enter the infraorbital canal and branches into its two major terminal branches, the zygomaticofacial and zygomaticotemporal nerves, which innervate the lateral cheek and side of the forehead, respectively.
As it projects anteriorly, the infraorbital nerve gives off the anterior and middle superior alveolar nerves, innervating the upper teeth. It then exits the canal through the infraorbital foramen to innervate the upper lip, cheek and side of the nose.
Mandibular n.
The mandibular nerve exits the cranium through the foramen ovale to enter the infra temporal fossa and branches into anterior and posterior divisions. The mandibular n. is mixed with motor and sensory parts. It is the only trigeminal branch that has both parts. The motor division originates in the basal plate of the embryonic pons and the sensory division originates from the cranial neural crest. The two combine once the sensory part of the mandibular n. passes through the foramen ovale from the trigeminal ganglion and the motor part follows. You can find the otic ganglion just anterior to this confluence on its deep surface.
From the anterior division (all motor except buccal branch):
The posterior and anterior deep temporal nerves follow the temporal bone superiorly on the under side the zygomatic arch and enter the deep surface of temporalis to innervate it
The buccal nerve innervates the mucosa of the mouth and gums (GSA). Branches anteriorly on top of buccinator
Lateral and medial pterygoid branches and nn. to tensor veli palatini and mastered n (motor)
Posterior division (all sensory except for NMH): The meningeal branch re-enters the skull through the foramen spinosum to distribute with the middle meningeal artery.
The auriculotemporal nerve innervates the external auditory meatus and portions of the external surface of the tympanic membrane. It branches posterior and superior to run between the EAM and mastoid process. Splits the middle meningeal a. from the maxillary a.
The posterior division then splits to the lingual and inferior alveolar nn. The lingual nerve provides general sensation to the anterior 2/3 of the tongue, floor of mouth, and lingual gingiva of the mandible.
The inferior alveolar nerve enters the mandibular canal through the mandibular foramen to innervate the lower teeth and gums (GSA). Its terminal branch exits the mental foramen as the mental nerve, innervating the chin and lower lip. Before entering the mandibular foramen the inferior alveolar n. gives off the NMH
What are the four categories of branches of the maxillary n.?
Its branches may be divided into four groups, depending upon where they branch off: in the cranium, in the pterygopalatine fossa, in the infraorbital canal, or on the face.
In the cranium:
Middle meningeal nerve in the meninges (before exiting through the foramen rotundum)
From the pterygopalatine fossa:
- Infraorbital nerve through Infraorbital canal
- Zygomatic nerve (zygomaticotemporal nerve, zygomaticofacial nerve) through Inferior orbital fissure
- Superior and Inferior Posterior Lateral Nasal Branches and Nasopalatine n. through Sphenopalatine foramen to the lateral nasal wall and septum, respectively
- Posterior superior alveolar nerve- to upper teeth roots
- Palatine nerves (Greater palatine nerve, Lesser palatine nerve) on outside of lateral nasal wall
In the infraorbital canal:
- Anterior and middle superior alveolar nerve- these go the roots of teeth
- Infraorbital nerve continuation
On the face:
- Inferior palpebral nerve
- Superior labial nerve
- Lateral nasal nerve (innervates the vestibule)
Where does the motor part of the facial n. originate?
The motor part of the facial nerve arises from the facial nerve nucleus in the pons
Where do the sensory and parasympathetic parts of the facial n. originate?
the sensory and parasympathetic parts of the facial nerve arise from the intermediate nerve.
From the brain stem, the motor and sensory parts of the facial nerve join together and traverse the posterior cranial fossa before entering the petrous temporal bone via the internal auditory meatus. Upon exiting the internal auditory meatus, the nerve then runs a tortuous course through the facial canal, which is divided into what?
labyrinthine, tympanic, and mastoid segments. These are segments, not branches
Describe the labyrinthine segment of the facial n.
The labyrinthine segment is very short, and ends where the facial nerve forms a bend known as the geniculum of the facial nerve (“genu” meaning knee), which contains the geniculate ganglion for sensory nerve bodies.
What is the first branch of the facial n.?
The first branch of the facial nerve, the greater superficial petrosal nerve, arises from the geniculate ganglion.
What does the greater petrosal nerve run? What does it innervate?
The greater petrosal nerve runs through the pterygoid canal and synapses at the pterygopalatine ganglion. Post synaptic fibers of the greater petrosal nerve innervate the lacrimal gland, nasal gland, palatine gland, and pharyngeal gland. It also provides parasympathetic innervation to the sphenoid sinus, frontal sinus, maxillary sinus, ethmoid sinus and nasal cavity
