Nervous System Ch. 8 PART 2
What does the lingual nerve communicate with?
The submandibular ganglion: located superior to the deep lobe of the submandibular salivary gland. -parasympathetic system
Where is the buccal nerve located?
The surface of the buccinator muscle. It travels posteriorly in the cheek, deep to the masseter muscle
What nerve does the chorda tympani nerve travel with and where?
Travels with the lingual nerve in the floor of the mouth. In the submandibular triangle, the chorda tympani nerve, apprearing as part of the lingual nerve, **has communication with the submandibular ganglion**
The IA nerve is in the canal with...?
IA artery and vein
The incisive nerve will go next to what nerve within the mandibular canal before it exits the mandibular canal?
IA nerve
Infraorbital nerve (IO)
-Afferent nerve (upper lip, the medial part of the cheek, the lower eyelid, and the side of the nose) -IO nerve then passes into the infraorbital foramen of the maxilla
Within the bone, the facial nerve gives off an efferent branch to two larger branches.... what are they?
-Greater petrosal nerve -Chorda tympani nerve both carry parasympathetic fibers
Herpes Zoster and Trigeminal Nerve: Clinical note
-Herpes zoster unilateral facial lesions occurring along the distribution of the maxillary branch of the trigeminal nerve. -Intraoral lesions in the same patient illustrate the unilateral distribution of herpes zoster.
Posterior Superior Alveolar nerve (PSA)
-Joins the IO nerve (or maxillary nerve directly in some cases) in the pterygopalatine fossa -Other afferent nerve branches of the PSA 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 or a nerve network in the maxilla for the region.
Trigeminal Neuralgia (TN): Clinical note
-No known cause but involves the afferent nerves of the trigeminal (5th cranial) nerve. -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 the area blood vessels. Clinically: -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. • Because there are a large number of conditions that can cause facial pain, TN can be difficult to diagnose. • But finding the cause of the pain is important as the treatments 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 caused by TN.
Anterior Superior Alveolar Nerve (ASA)
-Originates from dental branches in the pulp of the teeth that exit through the apical foramina -Receives interdental branches from the surrounding periodontum, forming a dental plexus or nerve network in the maxilla for the region
Where the GP nerve travels
-Posteriorly, the GP nerve enters the greater palatine foramen in the horizontal plate of palatine bone near the maxillary second or third molar to travel within the pterygopalatine canal, along with the greater palatine blood vessels. -GP nerve moves superiorly through the pterygopalatine canal, toward the maxillary nerve in the pterygopalatine fossa
Where does the IO nerve pass through?
-Travels posteriorly through the infraorbital canal, along with the infraorbital blood vessels where it is joined by the anterior superior alveolar nerve
Greater petrosal nerve
A branch off the facial nerve -Efferent nerve fibers, preganglionic parasympathetic fibers to the pterygopalatine ganglion in the pterygopalatine fossa -Afferent nerve fibers for taste sensation in the palate**
Mandibular nerve: small branches
A few small branches arise from the V3 trunk before separating into the ANTERIOR and POSTERIOR trunks: muscular branches, which are efferent nerves for the medial pterygoid, tensor tympani, and tensor veli palatini muscles
What 3 nerves pass through the maxillary sinus?
ASA MSA PSA -numbs it
Branches to muscles of facial expression
Additional efferent nerve branches of the facial nerve originate within the parotid salivary gland and pass to the muscles they innervate.
Lingual nerve
Afferent branches from the body of the tongue that travel along the lateral surface of the tongue -General sensation for the body of the tongue, the floor of the mouth, and the lingual gingiva of the mandibular teeth
Incisive nerve
Afferent nerve composed of dental branches from the mandibular premolar 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
What does the incisive nerve serve?
Afferent nerve for the mandibular: -premolars -anterior teeth Crossover-innervation from the contralateral incisive nerve can also occur
What does the NP serve?
Afferent nerve for: -anterior hard palate -lingual gingiva of the maxillary anterior teeth -nasal septum tissue Communication also occurs with the GP nerve in the area that is located lingual to the maxillary canines.
What does the GP serve?
Afferent nerve for: -posterior hard palate -posterior lingual gingiva
Inferior Alveolar Nerve (IA)
Afferent nerve formed from the merger of the mental and incisive nerves
What does the PSA serve?
Afferent nerve of sensation (including pain) for most parts of the maxillary: -molar teeth and their periodontium and buccal gingiva (maxillary second and third molars and the palatal and distal buccal root of the maxillary first molar), as well as the maxillary sinus.
What does the ASA nerve serve?
Afferent nerve of sensation (including pain) for the maxillary: -central incisors -lateral incisors -canines -and their associated tissue Also innervates the overlying facial gingiva
What does the MSA serve?
Afferent nerve of sensation (including pain) for the maxillary: -premolars -mesiobuccal root of the 1st molar -associated preiodontium and overlying buccal gingiva
PSA: Clinical note
All the internal branches of the PSA nerve exit from several posterior superior alveolar foramina on the maxillary tuberosity of the maxilla, which are landmarks for the posterior superior alveolar block.
Where does the ASA nerve ascend?
Along the anterior wall of the maxillary sinus to join the IO nerve within the IO canal
Where does the NP nerve travel?
Along the nasal septum
Where is the mental foramen located?
Anterolateral surface of the mandible and usually between the apices of the mandibular 1st and 2nd premolar
Buccal Block: Clinical note
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, which is a landmark for the buccal block.
What forms the posterior trunk of the mandibular nerve?
Auriculotemporal, lingual, and inferior alveolar nerves. -both afferent and efferent nerves
What type of nerves does the mandibular nerve have?
Both afferent and efferent nerves. -It contains the entire efferent part of the trigeminal nerve
NP: Clinical note
Both the right and left NP nerves enter the incisive canal by way of the incisive foramen, deep to the incisive papilla, thus exiting the oral cavity, which is a landmark for the nasopalatine block.
Chorda tympani 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)
What forms the anterior trunk of the mandibular nerve?
Buccal nerve and additional muscular nerve branches -it has both afferent and efferent nerves
It is important to note that the MSA nerve is not present in all patients. If it is not, how is the area innervated?
By the ASA and PSA (if it is present, there is communication between the MSA with both the ASA and PSA)
Where does the chorda tympani nerve exit the skull?
By the petrotympanic fissure, located immediately posterior to the TMJ
What joins the IA nerve in forming a dental plexus in that region?
Dental branches such as both interdental and interradicular branches from the mandibular posterior teeth
The facial nerve carries both ____________ &______________ nerves.
Efferent & Afferent -Efferent component for the muscles of facial expression -Preganglionic parasympathetic innervation of the lacrimal gland (relaying in the pterygopalatine ganglion) as well as the submandibular and sublingual salivary glands (relaying in the submandibular ganglion).
Masseteric nerve (muscular branches of anterior trunk of mand. nerve)
Efferent nerve that innervates the masseter muscle -a small sensory branch also goes into the TMJ
What does the mylohyoid nerve serve?
Efferent nerve to the: -Mylohyoid muscle -Anterior belly of the digastric muscle (posterior belly is innervated by a branch from the facial nerve)
The chorda tympani nerve is the parasympathetic efferent nerve for...? And afferent nerve for...?
Efferent: The submandibular and sublingual salivary glands Afferent: The taste sensation for the anterior 2/3 body of the tongue
Facial nerve
Emerges from the brain and enters the internal acoustic meatus in the petrous part of the temporal bone
Lateral pterygoid nerve
Enters the deep surface of the lateral pterygoid muscle for efferent nerve for that muscle
Mental nerve
Enters the mental foramen on the lateral surface of the mandible, usually between the apices of the mandibular 1st and 2nd premolars
The mental nerve is composed of
External branches that serve as an afferent nerve for the: -chin -lower lip -labial mucosa of the mand. premolars and anterior teeth
Maxillary Nerve/V2
Formed in pterygopalatine fossa by many nerves Largest infraorbital nerve •Anterior superior alveolar nerve •Middle superior alveolar nerve •Posterior superior alveolar nerve •Greater palatine nerve •Nasopalatine nerve Pterygopalatine ganglion: just inferior to maxillary nerve in fossa
Where do the internal branches of the PSA nerve exit?
From several posterior superior alveolar foramina on the maxillary tuberosity of the maxilla PSA arteries (from maxillary artery) enter the max. tuberosity through same foramina
Where does the MSA form a dental plexus (nerve network) at?
In the maxilla (like the PSA and ASA)
Where does the MSA ascend?
Joins the IO nerve and runs down the lateral wall of the maxillary sinus
Ophthalmic Nerve/V1
Lacrimal nerve -afferent: eye lid, conjunctiva, lacrimal gland -postganglionic parasympathetic to lacrimal gland
Greater Palatine Nerve (GP)
Located between the mucoperiosteum and bone of the posterior hard palate
What does the IA nerve enter to join the mylohyoid nerve?
Mandibular foramen
What forms the trigeminal ganglion of the trigeminal nerve?
Mandibular nerve Ophthalmic nerve Maxillary nerve
What is the largest division of the trigeminal nerve that innervates ALL muscles of mastecation?
Mandibular nerve (V3) -Found within the infratemporal fossa, foramen ovale of the sphenoid bone
There are several muscular branches that are a part of the anterior trunk of V3- where do they arise from?
Motor root of the trigeminal nerve
What is a small branch of the inferior alveolar nerve after it exits the mandibular foramen?
Mylohyoid nerve
Mandibular foramen
Opening of the mandibular canal on the medial surface of the ramus, within the pterygomandibular space
Nasopalatine Nerve (NP)
Originates in the mucosa of the anterior hard palate, lingual to the maxillary anterior teeth, the maxillary central incisors
After the IO travels through the infraorbital canal and groove, where does it go next?
Passes through the pterygopalatine fossa through the inferior orbital fissure
Mylohyoid nerve
Pierces the sphenomandibular ligament and runs inferiorly and anteriorly in the mylohyoid groove and then onto the inferior surface of the mylohyoid muscle
IA nerve travels to join:
Posterior trunk of V3
GP: Clinical note
Posteriorly, the GP nerve enters the greater palatine foramen in the horizontal plate of palatine bone near the maxillary second or third molar to travel within the pterygopalatine canal, along with the greater palatine blood vessels, which is a landmark for the greater palatine block.
Trigeminal nerve has two roots, what are they?
Sensory root: -Ophthalmic V1: sensory only; superior orbital fissure -Maxillary V2: sensory only; foramen rotundum -Mandibular V3: sensory and motor fun together; foreamen ovale Motor root: efferent nerves for muscles of mastication: foramen ovale
Where is the lingual nerve located?
Slightly medial to the inferior alveolar nerve to join the posterior trunk of V3. -Thus the lingual nerve is also anesthetized when administering an inferior alveolar block through diffusion of the local anesthetic agent.
Where does the main trunk of the facial nerve emerge from?
Stylomastoid foramen
ASA: Clinical note
The ASA nerve also receives interdental branches from the surrounding periodontium, forming a dental plexus or nerve network in the maxilla for the region, which is a landmark for the anterior superior alveolar block that anesthetizes the ASA nerve.
MSA: Clinical note
The MSA nerve, like the posterior superior alveolar and ASA nerves, forms the dental plexus or nerve network in the maxilla, which is a landmark for the middle superior alveolar block which anesthetizes the MSA nerve
Middle Superior Alveolar Nerve (MSA)
The middle superior alveolar nerve- MSA nerve 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.
Once the facial nerve passes into the parotid salivary gland, it divides into numerous branches to supply what?
The muscles of facial expression -but NOT the parotid salivary gland itself
Crossover-innervation
The overlap of terminal nerve fibers from the contralateral side of the dental arch (ASA can provide this in a patient)
After the facial nerve emerges from the Stylomastoid foramen, what does it branch off in to?
Two branches: -Posterior auricular nerve -A branch to the posterior belly of the digastric and stylohyoid muscles
Deep temporal nerves (muscular branches of anterior trunk of mand. nerve)
Usually two, anterior and posterior, are efferent nerves that pass between the sphenoid bone and the superior border of the lateral pterygoid...to terminate in the deep surface of the temporalis muscle that they innervate.
