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Trigeminal nerve Trigeminal nerve Document Transcript

  • TRIGEMINAL NERVE The trigeminal nerve is so called because of its three main divisions i.e. the Optalmic, Maxillary & Mandibular nerves. It is derived from the combination of 2 Latin words, tres meaning three+ geminus meaning twin i.e. three born together (bilaterally) It is the largest of the cranial nerves. It is the fifth cranial nerve It is a mixed nerve and is sensory to the greater part of the scalp, the teeth, and the oral and nasal cavities. Motor supply is to the MOM. Proprioceptive nerve fibres from the masticatory and extra-ocular muscles. Various nuclei associated with the fifth nerve are situated within the pons. They are: Motor nucleus Sensory nucleus Mesencephalic nucleus Spinal nucleus THE TRIGEMINAL GANGLION: here diagram from Hahn s regional anastesia The trigeminal nerve is continuous with the ventral surface of the pons near its upper border by a large sensory and a small motor root. The ganglion occupies a recess (Trigeminal or Meckel’s cave) in the dura mater in front of the apex of the petrous temporal bone. It lies at depth of 4.5 –5 cm from the lateral aspect of the head near the posterior part of the zygomatic arch. It is crescentic or semilunar in shape. Medially it is related to I.C.A & cavernous sinus, inferiorly with the motor root and the greater petrosal nerve & the apex of the petrous temporal bone and for.lacerum. Blood supply to the ganglion is through the ganglionic branches of the IC & the accesory meningeal artery which enters through the for.ovale. MOTOR ROOT It arises separately from the sensory root in the motor nucleus of pons. At the semilunar ganglion it passes inferolaterally under the ganglion towards for.ovale, through which it leaves the middle cranial fossa along with the man.div. After it exits the skull, it unites with the sensory root and forms a single nerve trunk. It supplies the following muscles: 1. Muscles of mastication 2. Mylohyoid 3. Ant belly of the diagastric
  • 4. Tensor tympani 5. Tensor veli palatini Here diagram,, netter 18 & grays 7.224 pg 1106& Hahn s SENSORY ROOT The fibres of the sensory root arise from the cells of the trigeminal ganglion. The branches of the unipolar cells of the trigeminal ganglio are divided into central and peripheral branches. The central branches leave the concave surface to enter the pons. The peripheral branches are grouped to form the ophthalmic and maxillary nerves and sensory part of the mandibular nerve. OPTHALMIC NERVE • It is the superior division of the V nerve & is the smallest. • It is wholly sensory. • It has 3 branches. All 3 of them pass through the sup. orbital fissure into the orbit. They are; 1. Lacrimal nerve: it is the smallest. It supplies the lacrimal gland & the conjuntiva. It pieces the orbital septum and ends in the skin of the upper eyelid. 2. Frontal nerve: it is the smallest branch& appears to be the direct continuation of the ophthalmic division. It enters the orbit through the SOF divides into 2 branches. Here diagram from Hahn cutaneous of supra trochlear… The supra orbital branch: It is larger & more laterally placed. It supplies the skin of the forehead & scalp as far back as the vertex. It also supplies the mucous membrane of the frontal sinus & pericranium The supra trochlear branch: It is smaller & more medially placed. It curves upward on the forehead , close to the bone. It supplies the skin of the upper eyelid & lower part of the forehead. Nasocilliary nerve: It is intermediate in size & runs more deeply. Its branches are divided as following; Branches in the: - Orbit Nasal cavity On the face Branches in the Orbit:
  • Long root of the cilliary ganglion: It is sensory & passes through the ganglion without synapsing andsupplies to the eyeball. Long ciliary nerve: Supplies the Iris & Cornea. Posterior ethmoidal nerve: It enters the post. Ethmoidal canal & supplies to the mucous membrane lining of the Post. Etmoidal & Sphenoidal paranasal air cells. Anterior ethmoidal nerve: It supplies to the Ant. Ethmoidal & frontal paranasal air cells. In the upper part of the nasal cavity, it further divides into: - Internal nasal branches: It has medialseptal branches to the septal membrane. It also has lateral branches, which supply the nasal conchae & the ant. nasal wall External nasal branches: supplies the skin on the tip & ala of the nose. 2) Branches in the nasal cavity: The branches arising here supply the mucous membrane of the nasal cavity. 3) Terminal branches on the face: They supply sensory nerves to the skin of the medial parts of the both eyelids, the lacrimal sac. They also supply skin on the bridge of the nose. Here diagram netter 40 MAXILLLARY NERVE • This is the second & intermediate division of the trigeminal nerve. • It is wholly sensory. • Course: It begins at the middle of the trigeminal ganglion as a flattened, plexiform band, passes horizontally forwards along the lateral wall of the cavernous sinus. It leaves the skull through the foramen rotundum & becomes more cylindrical & firmer in texture. It crosses the upper part of the pterygopalatine fossa, inclines laterally on the posterior part of the orbital process of the maxilla & enters the orbit through the inferior orbital fissure.
  • It is now termed as the infra orbital nerve. It passes through the infra orbital groove & canal in the floor of the orbit & appears on the face through the infra orbital foramen. • The branches of the maxillary nerve can be divided into the following 4 groups: 1. In the cranium: Meningeal 2. In the pterygopalatine fossa: Ganglionic, Zygomatic, Post.superior alveolar. 3. In the infra orbital canal: Middle sup. alveolar, Anterior superior/ Greater alveolar 4. On the face: Palpebral, nasal, superior labial  Meningeal branch: It is given off near the foramen rotundum. It supplies the duramater of the anterior & middle cranial fossae.  The ganglionic branches: They connect the maxillary nerve to the pterygopalatine ganglion. They contain secretomotor fibres to the lacrimal gland. They provide sensory fibres to the orbital periosteum & mucous membrane of the nose, palate & pharynx.  The zygomatic nerve: It arises in the pterygopalatine fosssa from the maxillary nerve.the nerve then enters the zygomatic bone & then divides into 2 branches.. The Zygomaticofacial nerve perforates the facial surfaces & supplies the skin over the zygomatic bone. The Zygomaticotemporal nerve perforates the temporal surface of the zygomatic bone , pierces the temporalis fascia, & supplies the skin over the anterior temporal fossa region.  The superior alveolar(dental) nerves: They arise from the maxillary nerve before it leaves the pterygopalatine fossa. They are: - here grants diagram 7.75 both fig 1) Posterior superior alveolar nerve: It begins in the pterygopalatine fossa but divides into 3 branches which emerge through the pterygomaxillary fissure.2 branches enter the posterior wall of the
  • maxilla above the tuberosity & supply the 3 molar teeth(except the mesiobuccal root of first molar). The third branch pierces the buccinator & supplies the adjoining part of the gingivae & cheek along the 3 molar teeth. 2) Middle superior alveolar nerve: It arises from the Infra orbital nerve & runs downwards & forwards along the infraorbital groove along the lateral wall of the maxillary sinus. It divides into branches which supply the maxillary premolars & mesiobuccal root of the first molar teeth. 3) Anterior superior alveolar nerve: It also arises in the infraorbital canal near the mid point. It runs in the anterior wall of the maxillary antrum. It runs inferiorly & divides into the branches, which supply the canine & incisors. A nasal branch from this nerve, given off from the superior dental plexus supplies the mucous membrane of the anterior part of the lateral wall & floor of the nasal cavity. It ends in the nasal septum. ( The Infraorbital nerve is consisted of the Middle & Superior alveolar dental nerves)  The palpebral branches: They arise deep to the orbicularis oculi.& pierce the muscle, supplying the skin over the lower eyelid& lateral angle of the eye along with the Zygomaticofacial & Facial nerves.  The nasal branches: They supply the skin of the nose & tip of the nasal septum & join the External nasal branch & anterior ethmoidal nerve.  The superior labial branches: These are large & numerous. They supply the skin over the anterior part of the cheek & upper lip including the
  • mucous membrane & labial glands. They are joined by the facial nerve & form the infraorbital plexus. The SphenopalatinePterygopalatine ganglion Here grays 7.220 & 7.223 It is the largest of the peripheral ganglia. It is associated with the greater petrosal nerve.( it is part of the 7th cranial/facial nerve). It acts as arelay staion bn the superior salivatory nucleus in the pons and the lacrimal gland & mucous & serous glands of the palate, nose & paranasal sinuses. It lies in the pterygopalatine fossa, suspended from the maxillary division of the trigeminal nerve by 2 roots.branches from the maxillary nerve through its ganglionic branches. They do not establish any sympathetic connections with its cells. The branches are: - 1. Orbital branches: They are made up of afferent fibres & convey sensory impulses from the periosteum of the orbit. Others supply the mucous membrane of the Post. Ethmoidal & sphenoidal air cells. 2. Palatine branches: they are distributed to the roof of the mouth, soft palate, tonsil & lining membrane of the nasal cavity. It gives of three branches I. Greater palatine nerve: it emerges from the foramen medial to the 3 rd molar, continues forward splitting into number of branches. It is sensory to the mucosa of the hard palate & palatal gingivae. II. Middle palatine nerve: This nerve emerges from a small foramen in the medial aspect of the pyramidal part of the palatine bone. Sensory supply is to the Mucous membrane of the soft palate.
  • III. Posterior palatine nerve: It emerges from a foramen slightly lateral to the median palatine nerve. It contains sensory & secretomotor fibres to the mucous membrane of the Tonsillar area. 3. Nasal branches: They are divided into 2 groups: - I. Posterior superior lateral nerves: they supply they Posterior part of the nasal conchae II. Nasopalatine(Sphenopalatine) nerve: It passes downwards & forwards between the periosteum &mucous membrane in the region of the vomer, continues downwards & forwards, reachs the floor of the nasal cavity. Descends into the incisal canal to appear in the anterior part of the hard palate & supplies the mucous membrane of the premaxilla. 4. Pharyngeal branches: This branch supplies sensory & secretory fibers to the mucous membrane of the nasopharynx, behind the opening of the auditory tube. It arises from the posterior part of the ganglion & passes through the palatovaginal canal along with the pharyngeal branch of the maxillary artery. Here netter 41 MANDIBULAR NERVE It is the third & largest division of the trigeminal nerve.it is made up of 2 roots: a large sensory root which proceeds from the lateral part of the & semilunar ganglion & almost immediately emerges out through the foramen ovale( of the sphenoid) & a small motor root which passes below the ganglion, & unites with the sensory root just outside the foramen.
  • Immediately beyond the junction of the 2 roots, the nerve sends off the meningeal branch & the nerve to the medial pterygoid. Now the main trunk divides into a small anterior & a large posterior trunk. As it descends from the foramen, the mandibular nerve lies at a distance of 4 cm from the surface & a little in front of the neck of the mandible. The various brancnes given off are as follows: - 1) Branches of the undivided nerve. i. Meningeal branch/nervus spinosus. ii. Nerve to the medial pterygoid 2) Branches of the divided nerve: A) Anterior division: i. Buccal nerve ii. Massetric nerve iii. Deep temporal nerve iv. Nerve to the lateral pterygoid. B) Posterior division: i. Auriculotemporal nerve ii. Lingual nerve iii. Inferior alveolar nerve 1) Undivided nerve branches i. Meningeal nerve: • It enters the skull through the foramen spinosum along with MMA. • It has anterior & posterior divisions that supply the dura of the middle & ant.cranial fossae. ii. Nerve to the medial pterygoid:  It is a slender branch that enters the deep surface of the muscle.  It also gives 1-2 filaments to the tensor tympani & the tensor veli palati muscles. 2) Divided nerve branches. A) Anterior division: It has 1 sensory branch. i.e. long buccal nerve &3 branches that are motor
  • to the massetric, deep temporal & lateral pterygoid muscles. i. The buccal nerve: • It passes between the 2 heads of the lateral pterygoid & descendsbeneath or through the temporalis. It emerges from under cover of the ramus & ant. border of the masseter & unites with the buccal branches of he facial nerve. • It supplies the skin over the ant. part of the buccinator & mucous membrane lining the buccal surface of the gum. ii. The massetric nerve: • Passes laterally above the lateral pterygoid in front of the TMJ & behind the tendon of temporalis. • It passes through the mandibular notch to sink into the masseter. • It also gives a branch to the joint. iii. The deep temporal nerves: • They are 2 in number. • They pass above the upper head of the lateral pterygoid, turn above the infra temporal crest & sink into the deep part of the temporalis. iv. The nerve to the lateral pterygoid. • These are also 2 in number one for each head. (2) Posterior division: The posterior trunk is mostly sensory but receives a few filaments from the motor root. i. The Auriculotemporal nerve: • The auriculotemporal nerve arises by a medial & lateral roots, that
  • enclircle theMMA & unite behind it just below the foramen spinosum. • The united nerve passes backwards, deep to the lateral pterygoid muscle & passes between the sphenomandibular ligament & the neck of the condyle. • It then passes laterally behind the TMJ I.r.t. to the upper part of the parotid. It emerges from behind the TMJ, ascends posterior to the superficial temporal vessels & crosses the posterior root of the zygomatic arch. Communications of the nerve:  2 roots of the nerve:- both tghese roots receive communications from he OTIC ganglion. They are postganglionic secretory fibres to the Parotid gland.i.e they control the secretions from the gland  Communicating branches to the postganglionic sympathetic fibres:- These are vasomotor fibres that pass to the parotid through the auriculotemporal nerve.  Communicating branches to the facila nerve: These are purely sensory from the Auriculotemporal nerve. Branches of the nerve: i. Parotid branches ii. Articular branches--- to the TMJ. iii. Auricular branches---to the skin of the helix & tragus.
  • iv. Meatal branches----- Meatus of the tymphanic membrane v. Terminal branches---- Scalp over the temporal region Lingual nerve Here diagram of grants 7.62 pg 584 This is the smaller of the 2 branches of the posterior division, It passes medial to the lateral pterygoid & it lies between the ramus of the mandible & the muscle in the pterygomandibular space. It gives off sensory fibresto the tonsil & the mucous membrane of the posterior part of the oral cavity. In the pterygomandibular space, it lies parallel to the inferior alveolar nerve, but medial & anterior to it. It then passes deep to reach the side of the tongue. Here it lies in the lateral lingual sulcus against the deep surface of the mandible on the medial side of the roots of the third molar tooth where it is covered only by mucous membrane of the gum. From here it passes on to the side of the the side of the tongue where it is crosses the styloglossus & runs on the lateral surface of the hyoglossus & deep to the mylohyoid in close relation to the deep part of the submandibular gland &its duct. Communication of the facial nerve (Chorda tymphani) As the lingual nerve passes medially to the lateral pterygoid, it is joined by the chorda tympani. This nerve conveys secretory fibres from the facial
  • nerve. The parasympathetic secretory fibres control the submandibular & sublingual salivary glands. Inferior alveolar nerve. It is the largest terminal branch of the posterior division of the mandibular nerve. The nerve descends deeep to the lateral pterygoid muscle 7& at the lower border of the muscle, it passes b/n the sphenomandibular ligament & the ramus to enter the mandibular foramen. In the canal the nerve runs alongside the inferior alveolar artery.as far as the mental foramen where it emerges out& gives off the mental & incisive branches. From here the nerve runs in the canal giving of branches to the mandibular teeth as apical fibres & enters the a[pical foramena of the teeth to supply the pulp mainly as well as the periodontium. Branches of the nerve Mental nerve: it supplies to the skin of the chin & the mucous membrane as well as the skin of the lower lip. Incisive branch: continues anteriorly from the mental nerve in the body of the mandibleto form the incisive plexus & supplies the canine & incisors. Mylohyoid nerve: it is given of before the nerve enters the canal & contains both sensory & motor fibres.it pierces the sphenomandibular ligament, descends in a groove in the medial side of the ramus & passes beneath the mylohyoid line supplying the mylohyoid muscle as well as the anterior belly of the digastric. Autonomic ganglia associated with the mandibular division
  • Submandibular ganglion: Here grays 7.219 It is a small ovoid body that is suspendedfrom the lingual nerve above the submandibulat salivary gland. The preganglionic parasympathetic fibres reach the ganglion arising from the superior salivatory nucleus, reaching through the facial, chorda tympani & the lingual nerve. Post ganglionic fibres are conveyed through the submandibular, sublingual & anterior lingual salivary glands. The sensory nerves reach the gangliothrough the lingual nerve. Sympathetic fibres are derived from the plexus around the facial artery & contain post ganglionic fibres arising in the superior cervical ganglion. They provide secretomotor fibres to the submandibular & sublingual galands. Otic ganglion Here grays 7.223 It is aflattened ovoid body located on the medial side of the undivided nerve. It is situated below the for. ovale & the MMA. It has 2 main roots:- 1) Parasympathetic preganglionic (secretory) fibres: they arise from the inferior salivatory nucleus.the efferent fibres pass by way if the glossopharyngeal nerve through the jugular canal.below the canal it passes through the tympanic branch of the glossopharyngeal nerve( Jacobson’s nerve), passing through the tympanic plexus & the lesser petrosal branch to reach the
  • Ganglion.( the lesser superficial petrosal nerve is the parasympathetic root of the otic ganglion) the postganglionic fibres pass through the auriculotemporal nerve. 2) Sympathetic root: It is made up of the postganglionic fibres that have originated in the superior cervical sympathetic ganglion & the plexus of the MMA. The fibres pass through the ganglion uninterrupted. These fibres reach the parotid thru the auriculotemporal nerve. Afferent of sensory nerves come from the parotid through the auriculotenporal nerve.