Infratemporal & pterygopalatIne fossae January. 2011 Thursday Structures inside the temporal fossa



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Dr. Kaan Yücel http://yeditepedentistryanatomy.wordpress.com Yeditepe Anatomy


Infratemporal & pterygopalatIne fossae

5.January.2011 Thursday

Structures inside the temporal fossa:

  1. Temporal muscle

  2. Temporal fascia (overlies the temporalis muscle)

  3. Superficial temporal artery (br. of external carotid)

  4. Superficial temporal vein (unites with the maxillary vein to form the retromandibular vein)

  5. Auriculotemporal nerve (br. of mandibular nerve which is a br of the trigeminal nerve)

A knowledge of the anatomy of the infratemporal and pterygopalatine fossae and their contents is essential for understanding the dental region. Many of the nerves and blood vessels supplying the structures of the mouth run through or close to these fossae. In addition, the infratemporal fossa contains the pterygoid muscles which play an important part in movements of the mandible. The posterior boundary of the fossa is occupied by the styloid apparatus and carotid sheath and is closely related the last four cranial nerves.



Infratemporal Fossa

The infratemporal fossa is an irregularly shaped space deep and inferior to the zygomatic arch, deep to the ramus of the mandible and posterior to the maxilla. It communicates with the temporal fossa through the interval between (deep to) the zygomatic arch and (superficial to) the cranial bones.

Temporal fossa is superior to the zygomatic arch, and the infratemporal fossa is inferior to the zygomatic arch. The boundaries of the infratemporal fossa are as follows:


  • Laterally: the ramus of the mandible

  • Medially: the lateral pterygoid plate

  • Anteriorly: the posterior aspect of the maxilla

  • Posteriorly: the tympanic plate and the mastoid and styloid processes of the temporal bone

  • Superiorly: the inferior (infratemporal) surface of the greater wing of the sphenoid

  • Inferiorly: where the medial pterygoid muscle attaches to the mandible near its angle

The infratemporal fossa contains the:

  1. Inferior part of the temporalis muscle

  2. Lateral and medial pterygoid muscles

  3. Maxillary artery

  4. Pterygoid venous plexus

  5. Mandibular, inferior alveolar, lingual, buccal, and chorda tympani nerves

  6. Otic ganglion

Neurovasculature of the infratemporal fossa

The maxillary artery is the larger of the two terminal branches of the external carotid artery. It arises posterior to the neck of the mandible and is divided into three parts based on its relation to the lateral pterygoid muscle.

1st (mandibular) part: Deep to the condyle of mandible

2nd (pterygoid) part: Neighbourhood of lateral pterygoid muscle

3rd (pterygopalatine) part: Inside the infratemporal fossa (extends into the pterygopalatine fossa)

Branches of the 1st part:


  1. Deep auricular (to external acoustic meatus)

  2. Anterior tympanic artery (to the tympanic membrane)

  3. Middle meningeal (to dura mater and calvaria)

  4. Accessory meningeal aa. (to the cranial cavity)

  5. Inferior alveolar artery (to the mandibular gingiva and teeth)

Branches of the 2nd part:

  1. Deep temporal aa. (to the temporal muscle)

  2. Pterygoid aa. (to the pterygoid muscles)

  3. Masseteric artery (to the masseter muscle)

  4. Buccal artery (to the buccinator muscle)

The pterygoid venous plexus is located partly between the temporalis and the pterygoid muscles. It is the venous equivalent of most of the maxillary artery—that is, most of the veins that accompany the branches of the maxillary artery drain into this plexus. It is actually a network of veins formed by the veins following the branches of maxillary artery. The plexus anastomoses with the facial vein via the deep facial vein and with the cavernous sinus via emissary veins. The maxillary vein unites with the superficial temporal vein to form the retromandibular vein.

The mandibular nerve arises from the trigeminal ganglion in the middle cranial fossa. It immediately receives the motor root of the trigeminal nerve and leaves the cranium through the foramen ovale into the infratemporal fossa. The mandibular nerve contains GSA and SVE fibers

Branches of CN V3 supply the four muscles of mastication but not the buccinator, which is supplied by the facial nerve. Branches within the infratemporal fossa is divided into three groups:

1) Branches arising from the trunk



    • Spinous nerve

    • Medial pterygoid nerve

2) Anterior branches

    • Buccal nerve

    • Masseteric nerve

    • Deep temporal nerves

    • Lateral pterygoid nerve

3) Posterior branches

    • Auriculotemporal nerve

    • Lingual nerve

    • Inferior alveolar nerve

The spinous nerve passes through the spinous foramen and enters the cranium. It is a sensory nerve innervating the dura mater.

The medial pterygoid nerve innervates the medial pterygoid muscle, tensor veli palatini muscle and the tensor tympani muscle. Buccal nerve, masseteric nerve, deep temporal nerves, lateral pterygoid nerve innervate the muscles with the same name except the buccal nerve. Buccal nerve is sensory and innervates the inner surface of the cheek.

The auriculotemporal nerve supplies sensory fibers to the auricle and temporal region. The auriculotemporal nerve also sends articular (sensory) fibers to the TMJ. It conveys postsynaptic parasympathetic secretomotor fibers from the otic ganglion to the parotid gland.

The inferior alveolar nerve enters the mandibular foramen and passes through the mandibular canal, forming the inferior dental plexus, which sends branches to all mandibular teeth on its side. Before entering the canal, gives two motor branches that supply the anterior belly of digastric and mylohyoid muscle. The terminal branch of the inferior alveolar nerve is the mental nerve which passes through the mental foramen.

The lingual nerve is sensory to the anterior two thirds of the tongue, the floor of the mouth, and the lingual gingivae.

The chorda tympani nerve, a branch of CN VII carrying taste fibers from the anterior two thirds of the tongue. The chorda tympani joins the lingual nerve in the infratemporal fossa. The chorda tympani also carries secretomotor fibers for the submandibular and sublingual salivary glands.

The otic ganglion (parasympathetic) is located in the infratemporal fossa, just inferior to the foramen ovale. Presynaptic parasympathetic fibers, are located in the glossopharyngeal nerve [IX] as it exits the jugular foramen at the base of the skull. The tympanic nerve, a branch of the CN IX, forms a plexus called tympanic plexus. The lesser petrosal nerve is a branch of this plexus. The presynaptic parasympatic nerves are carried by the lesser petrosal nerve to the otic ganglion. Postsynaptic parasympathetic fibers, which are secretory to the parotid gland, pass from the otic ganglion to this gland through the auriculotemporal nerve.

Pterygopalatine Fossa

The pterygopalatine fossa is a small space behind and below the orbital cavity. The pterygopalatine fossa is an inverted 'tear-drop' shaped space between bones on the lateral side of the skull immediately posterior to the maxilla. Although small in size, the pterygopalatine fossa communicates via fissures and foramina in its walls with:



  1. the middle cranial fossa

  2. infratemporal fossa

  3. floor of the orbit

  4. lateral wall of the nasal cavity

  5. oropharynx

  6. roof of the oral cavity.

Gateways










Seven foramina and fissures provide apertures through which structures enter and leave the pterygopalatine fossa:

  • the foramen rotundum and pterygoid canal communicate with the middle cranial fossa

  • a small palatovaginal canal leads to the nasopharynx;

  • the palatine canal leads to the roof of the oral cavity (hard palate)

  • the sphenopalatine foramen opens in the nasal cavity

  • the pterygopalatine fossa is continuous with the infratemporal fossa via a large gap (the pterygomaxillary fissure) between the posterior surface of the maxilla and pterygoid process of the sphenoid bone;

  • the fossa opens into the floor of the orbit via the inferior orbital fissure

Because of its strategic location, the pterygopalatine fossa is a major site of distribution for the maxillary nerve [V2] and for the terminal part of the maxillary artery. In addition, parasympathetic fibers from the facial nerve [VII] and sympathetic fibers originating from the T1 spinal cord level join branches of the maxillary nerve [V2] in the pterygopalatine fossa. All the upper teeth receive their innervation and blood supply from the maxillary nerve [V2] and the terminal part of the maxillary artery, respectively, that pass through the pterygopalatine fossa.

Skeletal framework



The walls of the pterygopalatine fossa are formed by parts of the palatine, maxilla, and sphenoid bones:

  • the anterior wall is formed by the posterior surface of the maxilla;

  • the medial wall is formed by the lateral surface of the palatine bone;

  • the posterior wall and roof are formed by parts of the sphenoid bone.

The part of the sphenoid bone that contributes to the formation of the pterygopalatine fossa is the anterosuperior surface of the pterygoid process. Opening onto this surface are two large foramina:

  • the maxillary nerve [V2] passes through the foramen rotundum which communicates posteriorly with the middle cranial fossa;

  • the greater petrosal nerve from the facial nerve [VII] and sympathetic fibers from the internal carotid plexus join to form the nerve of the pterygoid canal that passes into the pterygopalatine fossa through the anterior opening of the pterygoid canal.

The pterygoid canal is a bony canal opening onto the posterior surface of the pterygoid process. The pterygoid canal opens into the middle cranial fossa just anteroinferior to the internal carotid artery as the vessel enters the cranial cavity through the carotid canal.

The contents of the pterygopalatine fossa:



  1. Third part (pterygopalatine part) of the maxillary artery

  2. Maxillary nerve

  3. Nerve of the pterygoid canal

  4. Pterygopalatine ganglion

As the pterygopalatine fossa contains the maxillary nerve, the pterygopalatine ganglion and the third part of the maxillary artery, it is intimately concerned with the nerve and blood supply of the upper jaw.

The maxillary nerve [V2] and terminal part of the maxillary artery enter and branch within the pterygopalatine fossa. In addition, the nerve of the pterygoid canal enters the fossa. The preganglionic parasympathetic fibers synapse in the pterygopalatine ganglion and both the sympathetic and postganglionic parasympathetic fibers pass with branches of the maxillary nerve [V2] out of the fossa and into adjacent regions. In addition to nerves and arteries, veins and lymphatics also pass through the pterygopalatine fossa.



Lacrimal Gland

The lacrimal gland consists of a large orbital part and a small palpebral part. It is situated above the eyeball in the anterior and upper part of the orbit posterior to the orbital septum. The gland opens into the lateral part of the superior fornix of the conjunctiva.



Innervation of the lacrimal gland

The parasympathetic secretomotor nerve supply is derived from the lacrimal nucleus of the facial nerve. The preganglionic fibers reach the pterygopalatine ganglion (sphenopalatine ganglion) via the nervus intermedius and its great(er) petrosal branch (and via the nerve of the pterygoid canal; greater petrosal nerve enters the pterygoid canal and becomes the nerve of the pterygoid canal). The postganglionic parasympathetic and sympathetic fibers leave the zygomaticotemoral branch of the zygomatic nerve and form a special autonomic nerve, which joins the lacrimal nerve. The lacrimal nerve is a major general sensory branch of the ophthalmic nerve [V1]. The postganglionic parasympathetic and sympathetic fibers pass with the lacrimal nerve to the lacrimal gland.

Maxillary Nerve (V2)

The maxillary nerve [V2] is purely sensory. It originates from the trigeminal ganglion in the cranial cavity, exits the middle cranial fossa, and enters the pterygopalatine fossa through the foramen rotundum. It exits as the infra-orbital nerve through the inferior orbital fissure.



Branches

V2 gives sensory fibers to the skin of the face and the side of the nose. Within the fossa, the maxillary nerve is attached to the pterygopalatine ganglion by two ganglionic branches. Ganglionic branches, contain sensory fibers that have passed through the ganglion from the nose, the palate, and the pharynx. They also contain postganglionic parasympathetic fibers that are going to the lacrimal gland.

More anteriorly the posterior superior alveolar nerves are given off. Usually two or three in number, these pass downwards and laterally through the pterygopalatine maxillary fissure into the infratemporal fossa. Here they run on the posterior surface of the maxilla and divide into numerous small branches which enter the maxilla through the posterior alveolar foramina and supply the upper molar teeth, the mucous membrane on the buccal surface of the associated alveolar process and the lining of the maxillary sinus. Anesthesia of the upper molar teeth and associated buccal mucosa can be achieved by a posterior superior alveolar block.

As the maxillary nerve is about to enter the inferior orbital fissure it gives rise to the zygomatic nerve. This runs forward through the fissure and along the lateral wall of the orbit where it divides into zygomaticotemporal and zygomaticofacial branches. These nerves leave the orbit through canals in the zygomatic bone, the zygomaticotemporal branch passing into the temporal fossa to supply the skin of the temple, and the zygomaticofacial nerve emerging more anteriorly to supply the skin over the prominence of the cheek. The zygomatic nerve also contains postganglionic parasympathetic fibres from the pterygopalatine ganglion. Within the orbit these pass in a communicating branch from the zygomaticotemporal nerve to the lacrimal nerve and reach the lacrimal gland.



Pterygopalatine Ganglion

The pterygopalatine ganglion is the largest of the four parasympathetic ganglia in the head. It is located deep within the pterygopalatine fossa close to the sphenopalatine foramen. It is a relay station for parasympathetic secremotor fibres derived from the facial nerve and destine for the lacrimal gland and the glands of the mucous membranes of the nose, nasopharnyx, paranasal sinuses, palate, and upper lip. The maxillary branches pass through the ganglion without interruption.

The pterygopalatine ganglion is formed by the cell bodies of the postganglionic neurons associated with preganglionic parasympathetic fibers of the facial nerve [VII] carried by the greater petrosal nerve and the nerve of the pterygoid canal. The first neuron of these preganglionic parasympathetic fibres is superior salivatory nucleus. The postganglionic fibers, together with sympathetic fibers, join fibers from the ganglionic branches of the maxillary nerve [V2]. Postsynaptic fibers arising from the pterygopalatine ganglion supply the lacrimal gland as well as nasal glands and minor salivary glands within the oral cavity. The postsynaptic fibers innervating the lacrimal gland pass to the lacrimal nerve to reach the lacrimal gland.

Branches


  • Orbital branches, which enter the orbit through the inferior orbital fissure. They contribute to the supply of the orbital wall and of the sphenoidal and ethmoidal sinuses.

  • Greater and lesser palatine nerves, supply the palate, the tonsil, and the nasal cavity. The greater palatine nerve originates from the geniculate ganglion of the facial nerve [VII] in the temporal bone. In the palatine canal, the greater palatine nerve gives origin to posterior inferior nasal nerves, which contribute to the innervation of the lateral nasal wall. The greater palatine nerve supplies the mucous membrane and associated glands, of the palate as forwards as the lateral incisor region. Wihin the greater palatine canal the nerve gives rise to nasal branches which pierce the perpendicular plate of the posteroinferior quadrant of the lateral wall of the nose.

  • The lesser palatine nerves also descend in the greater palatine canal but emerge on to the oral surface of the bony palate through the lesser palatine foramina. They supply the mucous membrane of the soft palate and of an area around the palatine tonsil. The taste fibres from this region are believed to pass back to the pterygopalatine ganglion (through which they pass without interruption) and then travel in the nerve of the pterygoid canal and in the greater petrosal nerve to the facial nerve.

  • The pharyngeal nerve (branches) leaves the pterygopalatine ganglion and passes through the palatovaginal canal to be distributed to the mucous membrane of the nasopharynx.

Maxillary Artery

The maxillary artery is a major branch of the external carotid artery in the neck. It passes through the infratemporal fossa, and then enters the pterygopalatine fossa through the pterygomaxillary fissure.

It passes across the fossa and then through the inferior orbital fissure to enter the orbit, where it is known as the infraorbital artery.Branches of the third part of the maxillary artery (i.e., that part of the vessel within the pterygopalatine fossa) include the posterior superior alveolar, infra-orbital, greater palatine, pharyngeal, and sphenopalatine arteries, and the artery of the pterygoid canal. Collectively, these branches supply much of the nasal cavity, the roof of the oral cavity, and all upper teeth. In addition, they contribute to the blood supply of the sinuses, oropharynx, and floor of the orbit.

The maxillary artery gives off the posterior superior alveolar branch as it enters the pterygopalatine fossa. The posterior superior alveolar artery runs with the corresponding branches of the maxillary nerve to suppy the upper posterior teeth and adjacent structures. The posterior superior alveolar artery may give rise to a sizeable buccogingival branch which runs forwards on the posterior and then anterior surface of the maxilla, below the zygomatic process, to reach the infraorbital region where it may anastomose with the infraorbital artery. It is usually accompanied by a vein which is a tributary of the facial vein. The artery and vein lie immediately adjacent to periosteum, and may be at risk of being punctured in injections to obtain anesthesia of the maxillary teeth.



Veins that drain areas supplied by branches of the terminal part of the maxillary artery travel with these branches back into the pterygopalatine fossa. The veins pass through the pterygomaxillary fissure to join the pterygoid plexus of veins in the infratemporal fossa.













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