DEN 110 Cranial nerves part 2

Trigeminal neuralgia (TN or tic douloureux)

has no known cause but involves the afferent nerves of the fifth cranial nerve -it usually involves the maxillary or mandibular nerve branches but NOT the ophthalmic branch. -one theory is that this lesion is caused by pressure on the sensory root of the trigeminal ganglion by area blood vessels. -clincally, the patient feels excruciating short-term pain when facial trigger zones are touched or when speaking or masticating, setting off associated brief muscle spasms in the area. -pain provokes brief muscle spasm of the facial muscles, thus producing the tic. -it can be difficult to diagnose -but finding the cause of the pain is important as tx for different types of pain may differ. -treatment options include medicines such as anticonvulsants and tricyclic antidepressants, surgery and complementary approaches. -typical analgesics and opioids are not usually helpful in treating the sharp recurring pain.

Bell palsy

involves unilateral facial paralysis with no known cause, except that there is a loss of excitability of the involved facial nerve.

Infraorbital block

the IO nerve passes into the infraorbital foramen which is a landmark for the ____________________ _________________, which when given, anesthetizes the IO nerve as well as both the anterior and middle superior alveolar nerves.

Posterior trunk (division)

the _________________ _________________ of the mandibular nerve is formed by the merger of the auriculotemporal, lingual, and inferior alveolar nerves -it has both afferent and efferent nerves.

Anterior trunk (division)

the ___________________ __________________ of the mandibular nerve is formed by the merger of the buccal nerve and additional muscular nerve branches. -they arise from the motor root of the trigeminal nerve. -has both afferent and efferent.

Afferent

the ___________________ nerve branches of the maxillary nerve carry sensory information to the brain from the maxillae and overlying skin, maxillary sinuses, nasal cavity, palate, nasopharynx, and part of the dura mater. -after all these branches come together in the pterygopalatine fossa to form the max nerve they go through the rontudum.

True

a few small branches arise from the V3 trunk before its separation into the anterior and posterior trunks.

Parotid gland cancer

a neoplastic growth in the parotid salivary gland may be painful due to the presence of the facial nerve.

Meningeal branches

afferent nerves for parts of the dura mater of the mandibular nerve.

Mylohyoid nerve

after the inferior alveolar nerve exits the mandibular foramen, a small branch occurs, the _____________________ nerve. -it pierces the sphenomandibular ligament and runs inferiorly and anteriorly in the mylohyoid groove and then onto the inferior surface of the mylohyoid muscle. -it serves as an efferent nerve to the mylohyoid muscle and anterior belly of the diagstric muscle (posterior belly is innervated by a branch from the facial nerve). -it also in some cases may serve as an afferent nerve for the mandibular first molar, which needs to be considered when the inferior alveolar block fails. -if there is concern, this nerve can be additionally anesthetized by giving a supraperiosteal injection at the apex of the mesial root of the mandibular first molar on the medial surface of the mandible.

True

anterior to the trigeminal ganglion, the sensory root arises from three nerves/divisions that pass into the skull by way of three different fissures or foramina, ophthalmic, maxillary and mandibular.

Buccal block

at the level of the occlusal plane of the most distal molar of the mandibular arch, the nerve crosses anteriorly to the anterior border of the ramus.

true

avoiding anesthetic of the facial nerve at its location in the parotid salivary gland is important when administering an IA block because it may result in transient facial paralysis if given incorrectly.

Greater petrosal nerve

is a branch off the facial nerve before it exits the skull. -it carries efferent nerve fibers; preganglionic parasympathetic fibers to the pterygopalatine ganglion. -the postganglionic fibers arising in the pterygopalatine ganglion then join with the branches of the maxillary nerve to be carried to the lacrimal gland, nasal cavity, and minor salivary glands of the hard and soft palate. -the nerve also carries afferent nerve fibers for taste sensation in the palate.

Trigeminal nerve

is a short nerve trunk composed of two closely adapted roots.

Incisive nerve

is an afferent nerve composed of dental branches from the mandibular premolar and and anterior teeth that originate in the pulp, exit the teeth through the apical foramina, and join with interdental branches from the surrounding periodontium, forming a dental plexus in the region. -the nerve then merges with the mental nerve -the nerve serves as an afferent nerve for the mandibular premolars and anterior teeth. -crossover innervation from the contralateral nerve can also occur. -this nerve merges with the mental nerve where it is anesthetized.

Zygomatic nerve

is an afferent nerve composed of the merger of the zygomaticofacial nerve and the zygomatictemporal nerve in the orbit.

inferior alveolar nerve (IA)

is an afferent nerve formed from the merger of the mental and incisive nerves. -after forming, the nerve continues to travel posteriorly through the mandibular canal, along with the inferior alveolar artery and vein. -it is joined by dental branches such as both interdental and interradicular branches from the mandibular posterior teeth forming a dental plexus. -it then exits through the mandibular foramen where it is joined by the mylohyoid nerve -it then travels lateral to the medial pterygoid muscle b/w the sphenomandibular ligament and ramus of the mandible -^this is posterior and slightly lateral to the lingual nerve. -it then joins the posterior trunk of V3. -carries innervation for mandibular teeth.

Greater palatine nerve

is located between the mucoperiosteum and bone of the posterior hard palate. -this nerve enters the greater palatine foramen in the horizontal plate of the palatine bone to travel within the pterygopalatine canal, along with the greater palatine blood vessels.

Buccal nerve (long buccal nerve)

is located on the surface of the buccinator muscle then travels posteriorly in the cheek, deep to masseter muscle. -the nerve crosses anteriorly to the anterior border of the ramus and goes b/w the two heads of the later pterygoid muscle to join the anterior trunk of V3.

Submandibular ganglion

is located superior to the deep lobe of the submandibular salivary gland for which it supplies parasympathetic efferent innervation.

Facial paralysis

is the loss of muscular action of the muscles of facial expression. -this lesion can occur secondary to a brain injury by way of a stroke with other muscles of the head and neck also affected. -it can occur by directly injuring the nerve that supplies the efferent nerves to the muscles of facial expression, the 7th cranial. -can be unilateral or bilateral and transient or permanent depending on the nature of the nerve damage.

Crossover Innervation

is the overlap of terminal nerve fibers from the contralateral side of the dental arch.

Posterior Superior Alveolar Nerve (PSA)

joins the IO nerve (or maxillary nerve directly sometimes) in the pterygopalatine fossa. -other afferent nerve branches of this nerve originate from dental branches in the pulp of each of the maxillary molar teeth that exit the teeth by way of the apical foramina. -these dental branches are then joined by interdental branches and interradicular branches from the periodontium, forming a dental plexus. -they exit from several foramina on the maxillary tuberosity. -but the arteries enter through these same foramina ^. -both the internal and external branches move superiorly together along the max tuberosity which forms the posterolateral wall of the maxillary sinus, to join either the IO nerve or maxillary nerve. -afferent nerve of sensation for most parts of the maxillary molar teeth and their periodontium and buccal gingiva (max 2nd and 3rd molars and the palatal and DB root of the max first molar) as well as the maxillary sinus.

Pterygopalatine ganglion

lies just inferior to the maxillary nerve in the pterygopalatine fossa. -yellow circular structure in the picture.

True

mandibular nerve joints the ophthalmic and maxillary nerve to form the trigeminal ganglion.

Masseteric nerve

muscular branch of the anterior trunk of the mandibular nerve. - is an efferent nerve that passes b/w the sphenoid bone and superior border of the lateral pterygoid muscle. -then accompanies the masseteric blood vessels through the mandibular notch to innervate the masseter muscle. -a small sensory branch also goes to the TMJ.

Lateral pterygoid nerve

muscular branch of the anterior trunk of the mandibular nerve. -enters the deep surface of the lateral pterygoid muscle b/w the muscles two heads of origin and serves as an efferent nerve for that muscle.

Middle Superior Alveolar Nerve (MSA)

originates from dental branches in the pulp that exit the teeth through the apical foramina, as well as interdental and interradicular branches from the periodontium. -forms the dental plexus or nerve network in the maxilla like the other 2. -it ascends to join the IO nerve by running in the lateral wall of the maxillary sinus. -serves as an afferent nerve of sensation (pain) usually for hte maxillary premolar teeth and mesiobuccal root of the maxillary first molar and their assocaited periodontium and overlying buccal gingiva. -is NOT present in all patients! mainly ASA will take over then.

Nasopalatine nerve (NP)

originates in the mucosa of the anterior hard palate, lingual to the maxillary anterior teeth, the maxillary central incisors, as well as the nasal septal tissue. -then travels along the nasal septum. -communicates with the GP nerve. -enter the incisive canal by way of the incisive foramen.

Migraine nerve

research now points to a complex cascade of chemical releases that aggravate the trigeminal nerve so it is being called the ________________ ________________. -it turns out that many sinus headaches are actually migraine; trigeminal nerve fibers course through the tissues over the sinuses.

Greater Palatine nerve

serves as an afferent nerve for the posterior hard palate and posterior lingual gingiva. -communication occurs with the terminal fibers of the nasopalatine nerve in the anterior hard palate.

Zygomaticofacial nerve

serves as an afferent nerve for the skin of the cheek. #3 in the picture.

Zygomaticotemporal nerve

serves as an afferent nerve for the skin of the temporal region.

Lesser palatine nerve

serves as an afferent nerve for the soft palate and palatine tonsils. -enters the lesser palatine foramen nears its junction w/ the pterygoid process of the sphenoid bone, along with the lesser palatine blood vessels. -joins the other palatine nerve within the pterygopalatine canal.

Anterior Superior Alveolar Nerve

serves as an afferent nerve of sensation for the maxillary central incisors, lateral incisors, and canine as well as their associated tissue. -also innervates the overlying facial gingiva. -many times it also provides crossover innervation to the contralateral side in a patient.

Ophthalmic nerve

the first nerve (V1) of the sensory root of the trigeminal nerve. -this smallest division serves as an afferent nerve for the conjunctiva, cornea, eyeball, orbit, forehead, and ethmoid and frontal sinuses, plus a part of the dura mater. -superior orbital fissure

Infraorbital nerve

the largest contributor to the maxillary nerve. -contributes to the zygomatic, anterior, middle and posterior superior alveolar, the greater and lesser palatine, and the nasopalatine nerves. -is an afferent nerve formed from the merger of cutaneous branches from the upper lip, the medial part of the cheek, the lower eyelid, and the side of the nose.

Afferent

the ophthalmic nerve and maxillary of the sensory root carry only _______________ nerves.

Maxillary nerve

the second division (V2) from the sensory root of the trigeminal nerve. -has many branches, the largest is the infraorbital nerve.

Mandibular nerve (V3)

the third nerve division of the trigeminal nerve which is a short main trunk formed by the merger of a smaller anterior trunk and larger posterior trunk. -found within the infratemporal fossa before it passes through the foramen ovale. -the largest division of the three -both afferent and efferent. -contains the entire efferent part of the trigeminal

Zygomatic branches

these branches of the facial nerve supply the inferior part of the orbicularis oculi muscle and zygomatic major and minor muscles.

Temporal branches

these branches of the facial nerve supply the muscles anterior to the ear, frontal belly of the epicranial muscle, superior part of orbicularis oculi muscle, and corrugator supercillii muscle.

Mandibular Branches

these branches of the facial nerve supply the muscles of the lower lip and mentalis muscle.

Buccal branches

these branches of the facial nerve supply the muscles of the upper lip, nose, buccinator, risorius, and orbicularis oris muscle.

Cervical branch

this branch of the facial nerve runs inferior to the mandible to supply the platysma muscle.

Chorda Tympani nerve

this nerve branches off the facial nerve within the petrous part of the temporal bone, and then crosses the medial surface of the tympanic membrane (eardrum). -it exits the skull through the petrotympanic fissure -it then travels with the lingual nerve along the floor of the mouth in the same nerve bundle -has communication with the submandibular ganglion. -serves as an efferent nerve for the submandibular and sublingual salivary glands and also serves as an afferent nerve for taste sensation for the body of the tongue.

Facial nerve

this nerve emerges from the brain and enters the I.A.M. -within the bone, the nerve gives off a small efferent branch to the muscle in the middle ear (stapedius) and two larger branches, the greater petrosal and chorda tympani nerves, both of which carry parasympathetic. -the main trunk of this nerve emerges from the skull through the stylomastoid foramen and gives off two branches, the posterior auricular nerve and a branch of the posterior belly of the digastric and stylohyoid muscles. -it then passes into the parotid salivary gland and divides into numerous branches to supply the muscles of facial expression but NOT the parotid salivary gland itself. -it caries both efferent and afferent nerves. -carries efferent for muscles of facial expression and for the preganglionic parasympathetic innervation of the lacrimal gland submandibular and sublingual gland.

Mental nerve

this nerve enters the mental foramen on the lateral surface of the mandible usually between the apices of the mandible first and second premolars. -after entering this foramen and traveling a distance within the mandibular canal, the nerve merges with the incisive nerve to for the IA nerve within the mandibular canal. -it is composed of external branches that serve as an afferent nerve for the chin, lower lip, and labial mucosa of the mandibular premolars and anterior teeth.

Lingual nerve

this nerve is formed from afferent branches from the body of the tongue that travel along the lateral surface of the tongue. -it passes posteriorly passing from the medial to the lateral side of the duct of the submandibular salivary gland by going inferior to the duct. -it communicates with the submandibular ganglion located superior to the deep lobe of the submandibular salivary gland. -at the base of the tongue, the nerve ascends and runs b/w the medial pterygoid muscle and the mandible, and anterior and slightly medial to the inferior alveolar nerve. -it continues to travel superiorly to join the posterior trunk of V3. -in the picture its the nerve above the ganglion. -serves as an afferent nerve for general sensation for the body of the tongue, the floor of the mouth, and lingual gingiva of the teeth. -location sometimes visible in the oral cavity. -also anesthetized when giving an inferior alveolar block.

Mandibular nerve

this nerve of the sensory root runs together with the motor root and thus carries both afferent and efferent nerves. -it exits the skull at the foramen ovale then travels with the _________________ ________________ of the sensory root of the trigeminal nerve!!

Anterior superior alveolar nerve (ASA)

this nerve originates from dental branches in the pulp of these teeth that exit through the apical foramina. -also receives interdental branches from the surrounding periodontium, forming a dental plexus or nerve network in the maxilla. -it ascends along the anterior wall of the maxillary sinus to join the IO nerve within the infraorbital canal.

Infraorbital nerve

this nerve passes into the infraorbital foramen of the maxilla then travels posteriorly through the infraorbital canal, along along with the infraorbital blood vessels where it is joined by the anterior superior alveolar nerve. -from the infraorbital canal and groove it then passes into the pterygopalatine fossa through the inferior orbital fissure. -while its in there it receives the posterior superior alveolar nerve.

Auriculotemporal nerve

this nerve travels with the superficial temporal artery and veins and serves as an afferent nerve for the external ear and scalp. -it courses deep to the lateral pterygoid muscle and neck of the mandible, then splits to encircle the middle meningeal artery, and finally joins the posterior trunk of V3.

Muscular branches

undivided mandibular nerve branches which are efferent for the medial pterygoid, tensor tympani and tensor veli palatani muscles.

Deep temporal nerves

usually two, anterior and posterior, are efferent and pass b/w the sphenoid bone and superior border of the lateral pterygoid muscle and turn around the infratemporal crest of the sphenoid to terminate in the deep surface of the temporalis muscle that they innervate. -the posterior one may arise in common with the masseteric nerve, and anterior may be associated at its origin with the buccal nerve. -muscular branch of the anterior trunk of the mandibular nerve.

Trigeminal ganglion

within the skull, a bulge can be noted in the sensory root of the trigimenal nerve. This bulge is the ________________ _________________, which is located on the anterior surface of the petrous part of the temporal bone.