Lecture 18: Infratemporal and pterygopalatine fossae

Question 1

What is the Infratemporal fossa?

Answer 1

The infratemporal fossa is a complex area located at the base of the skull, deep to the ramus of the mandible and to the masseter muscle.

Question 2

What bony frameworks make up the BORDERS of the Infratemporal fossa?

Answer 2

Wedge-shaped infratemporal fossa is deep to master muscle and underlying ramus of mandible. It opens to neck postero-inferiorly.

• Medial wall is formed by lateral plate of pterygoid process of the sphenoid (anteriorly), pharynx, muscles of soft palate (tenso veli palatine and levator veli palatine) (posteriorly).
  
  • It contains pterygomaxillary fissure anteriorly, which allows structures to pass between infratemporal and pterygopalatine fossae.
• Lateral wall is formed by medial surface of ramus of mandible (cut).
  
  • It contains opening to mandibular canal.
• Anterior wall is formed by posterior surface of maxilla.
  
  • It contains alveolar foramen, and upper part opens as inferior orbital fissure into orbit.
• Roof is formed by inferior surface of greater wing of sphenoid and temporal bone.
  
  • It contains foramen spinosum, foramen ovale, petrotympanic fissures. It is lateral to infratemporal crest of greater wing of sphenoid. It is open superiorly to temporal fossa.

Parts of frontal and parietal bones are also involved.

Question 3

What are the contents of infratemporal fossa

Answer 3

Contents Of Infratemporal Fossa

Major contents of infratemporal fossa include:

• Sphenomandibular ligament (1)
• Lateral (2) and medial (3) pterygoid muscles
• Maxillary artery (4)
• Mandibular nerve (V3) (5)
• Pterygoid venous plexus of veins (6)
• Glossopharyngeal nerve (IX)
• Branches of facial nerve (VII).

Question 4

What are the movements at the Temporaomandibular Joint

Answer 4

A chewing or grinding motion occurs when movements at joint on one side are coordinated with a reciprocal set of movements at joint on other side. Movements of mandible include depression, elevation, protrusion, and retraction.

• Depression is generated by digastric, geniohyoid, mylohyoid on both sides, also helped by gravity (default position), with some assistance by lateral pterygoid.
• Elevation is generated by temporalis, masseter, medial pterygoid.
• Protraction is achieved by lateral pterygoid, with some assistance by medial pterygoid.
• Retraction is carried out by geniohyoid, digastric, temporalis and masseter muscles.

Note that opening mouth involves both depression and protrusion.

Except for geniohyoid muscle, which is innervated by Cl spinal nerve, all muscles that move temporomandibular joints are innervated by mandibular nerve (V3) by branches that originate in the infratemporal fossa.

Question 5

TMJ is a _________ joint

Answer 5

Atypical Synovial Joint (Articulate surface is not hyaline but covered by Fibrocartilage)

Temporomandibular Joints (Mandibular Movement)

Question 6

Describe the anatomy of the TMJ

Answer 6

Temporomandibular Joints (Mandibular Movement)

Extracapsular Ligament:

Three extracapsular ligaments stabilise the joint, which are _lateral, sphenomandibular and stylomandibular ligamen_t.

• Posteriorly it has a thickening, but this is not part of the capsule (other ligaments that stabilise the TMJ
  
  • 1) sphenomandibular ligament,
  • 2) s_tylomandibular ligament_
• Laterally
  
  • 3) Lateral ligament

The joint is completely divided by a fibrous articular disc into two parts:

· Lower part allows depression and elevation of mandible

· Upper part allows head of mandible to protrude onto articular tubercle and retract into mandibular fossa

Question 7

Describe the composition and action of the temporomandibular joint

Answer 7

The temporomandibular joints allow 1) opening and closing of the mouth and complex 2) c_hewing_ or 3) side-to-side movements of lower jaw.

It is formed between head of mandible, articular fossa and articular tubercle of temporal bone.

Each joint is synovial joint (atypical). Articular surfaces are covered by fibrocartilage (not hyaline cartilage). The joint is completely divided by a fibrous articular disc into two parts:

· Lower part allows depression and elevation of mandible

· Upper part allows head of mandible to protrude onto a_rticular tubercle_ and re_tract into mandibular fossa_

(Don’t need to know which muscle does what movement)

Question 8

What bones make up the Temporomandibular Joint?

Answer 8

It is formed between head of mandible, articular fossa and articular tubercle of temporal bone.

Question 9

Name the muscles of mastication

Where are they found relative to the infratemporal fossa?

Answer 9

Four muscles of mastication (masseter, temporalis, medial pterygoid, and lateral pterygoid) move lower jaw at temporomandibular joint:

• Masseter
  
  • lateral to the infratemporal fossa;
    
    • Masseter muscle is a powerful muscle of mastication that e_levates mandib_le.
• Medial pterygoid
  
  • in the infratemporal fossa
    
    • mainly elevates mandible, also assists lateral pterygoid in protruding lower jaw.
• Lateral pterygoid
  
  • _​_in the infratemporal fossa;
    
    • It is major protruder of lower jaw
• Temporalis
  
  • _​_fills temporal fossa.
    
    • Temporalis muscle fills much of temporal fossa. Its action is to elevate, retract and side-to-side movement of mandible.

All elevate to some extent expt for lateral pterygoid

Question 10

What muscles depress, elevate, protract and retract the Temporomandibular Joint?

Answer 10

A chewing or grinding motion occurs when movements at joint on one side are coordinated with a reciprocal set of movements at joint on other side. Movements of mandible include depression, elevation, protrusion, and retraction.

• Depression is generated by
  
  • digastric,
  • geniohyoid,
  • mylohyoid on both sides,
  • also helped by gravity (default position), with some assistance by lateral pterygoid.
• Elevation is generated by
  
  • temporalis,
  • masseter,
  • medial pterygoid.
• Protraction is achieved by
  
  • lateral pterygoid,
  • some assistance by medial pterygoid.
• Retraction is carried out by
  
  • geniohyoid,
  • digastric,
  • temporalis
  • masseter muscles.

Note that opening mouth involves both depression and protrusion.

Except for geniohyoid muscle, which is innervated by Cl spinal nerve, all muscles that move temporomandibular joints are innervated by mandibular nerve (V3) by branches that originate in the infratemporal fossa.

Question 11

Opening the mouth requires what actions?

Answer 11

Note that opening mouth involves both depression and protrusion (of TMJ).

Question 12

Except for geniohyoid muscle, which is innervated by __________, all muscles that move temporomandibular joints are innervated by ____________

Answer 12

Except for geniohyoid muscle, which is innervated by Cl spinal nerve, all muscles that move temporomandibular joints are innervated by mandibular nerve (V3) by branches that originate in the infratemporal fossa.

Question 13

Label

Answer 13

Major contents of the infratemporal fossa include…

Sphenomandibular ligament (1),

Lateral (2) and medial (3) Pterygoid muscles,

maxillary artery (4),

mandibular nerve (CN V3) (5),

pterygoid venous plexus (6),

glossopharyngeal nerve (CN IX) and branches of the facial nerve (CN VII).

Question 14

What does this show?

Answer 14

Pre-operative x-ray of the skull (lateral view), showing a bullet that has penetrated into the left maxillary sinus and infratemporal fossa.

Question 15

Describe the Temporalis Muscle

Answer 15

Temporalis muscle fills much o_f temporal fossa._

Its action is to elevate, retract and _side-to-side m_ovement of mandible.

Question 16

Describe the Origins and Branches of the Maxillary artery

Answer 16

Maxillary artery is largest branch of external carotid artery in neck.

• Internal carotid directly go up to the skull (cerebral arteries) without branching off in the neck.
• _External carotid gives off two branches in the nec_k, which are maxillary and superficial temporal arteries

Maxillary artery originates within parotid gland, pass between _neck of mandibl_e and sphenomandibular ligament into infratemporal fossa and then enters pterygopalatine fossa, where it gives origin to terminal branches.

Branches Of Maxillary Artery (Know underlined)

Branches of maxillary artery are:

• First part of maxillary artery (between neck of mandible and sphenomandibular ligament) gives origin to two major branches (middle meningeal, inferior alveolar) and smaller branches (deep auricular, anterior tympanic, accessory meningeal).
  
  • Middle meningeal is important to know for traumas
  • Inferior alveolar artery goes through the I.A foramen and may be damaged by the dentist

(DNTK the rest)

• Second part of the maxillary artery (related to lateral pterygoid muscle) gives origin to deep temporal, masseteric, buccal, and pterygoid branches, which course with branches of mandibular nerve (V3).
• Third part of maxillary artery is in pterygopalatine fossa

Question 17

What are the 2 branches of the External Cartoid artery?

Answer 17

External carotid gives off two branches in the neck, which are maxillary and superficial temporal arteries

Question 18

How does the maxillary artery run?

Answer 18

• Maxillary artery originates within parotid gland,
• pass between neck of mandible and sphenomandibular ligament into infratemporal fossa
• then enters pterygopalatine fossa, where it gives origin to terminal branches.

Question 19

What nerves are found in the Infratemporal fossa?

Answer 19

1) CN V3
2) CN VII
3) CN IX

Question 20

Is CN V3 motor, sensory or both?

Answer 20

Both

Question 21

. Note that inferior alveolar artery will be damaged with ____________

Answer 21

. Note that inferior alveolar artery will be damaged with ramus fracture (punch in the face).

+ by a dentist.

Question 22

Describe the

Route

Function

Branches

of the Manidbular nerve

Answer 22

Route and Function

• Mandibular nerve is largest of three divisions of trigeminal nerve (V).
• Unlike the ophthalmic (V1) and maxillary (V2) nerves, which are purely sensory, mandibular nerve (V3) is both sensory (lower face) and motor (mastication).
• Sensory part originates from trigeminal ganglion in middle cranial fossa, goes through foramen ovale with motor root, and enters infratemporal fossa.
  
  • General sensation of teeth, gingivae of mandible, anterior 2/3 tongue, mucosal floor of oral cavity, lower lip, skin over temple and lower face, and part of dura.
  • Motor innervation to most of muscles that move mandible (all muscles of mastication), tensor tympani in middle ear, and tensor veli palatini of soft palate.

Branches Of Mandibular Nerve

• All branches of the mandibular nerve (V3) originate in infratemporal fossa.
• Soon after sensory and motor roots join, mandibular nerve gives rise to meningeal branch and nerve to medial pterygoid, and then divides into anterior and posterior trunks: (know the bolds)
  
  • Branches from anterior trunk (all motor expect buccal) are buccal nerve, masseteric, deep temporal nerves, nerve to lateral pterygoid.
    • Buccal is a sensory nerve to the facce
  • Branches from posterior trunk (all sensory except mylohyoid) are auriculotemporal, lingual, and inferior alveolar nerves (branch into nerve to mylohyoid and others).

Question 23

What would you observe in a lingual nerve injury?

Answer 23

Lingual nerve injury proximal to where chorda tympani joins it in fossa will produce loss of sensation from anterior 2/3 tongue, oral mucosa, gingivae, lower lip, and chin

Lesion distal to the site then salivary glands secretion and taste from anterior 2/3 tongue will also be lost.

CT joins Lingual nerve in the infratemporal fossa

Question 24

Describe the Lesser Petrosal Nerve (how it runs, what it branches into and where)

Answer 24

Lesser petrosal nerve carries mainly parasympathetic fibers for parotid gland.

• Preganglionic parasympathetic fibers are in glossopharyngeal nerve (IX) as it exits jugular foramen, then branches to tympanic nerve.
• Tympanic nerve reenters temporal bone and ascends through inferior tympanic canaliculus to promontory on labyrinthine (medial) wall of middle ear. Here it participates in the formation of tympanic plexus, branching into lesser petrosal nerve.
• Less petrosal nerve leaves middle ear and enters middle cranial fossa, then descends through foramen ovale with mandibular nerve (V3).
• Preganglionic parasympathetic fibers synapse with postganglionic parasympathetic fibers in otic ganglion in fossa. It leaves otic ganglion and join auriculotemporal nerve (branch of V3) in infratemporal fossa, which carries them to parotid gland.

Question 25

How does the Chorda Tympani run?

Answer 25

Chorda Tympani

Chorda tympani carries taste from anterior 2/3 tongue and parasympathetic innervation to all salivary glands below oral fissure.

• Chorda tympani originates from facial nerve (VII) within temporal bone and in association with mastoid wall of middle ear.
  
  • As it continues anterosuperiorly across middle ear, it is separated from tympanic membrane by handle of malleus.
• It leaves middle ear through petrotympanic fissure, enters infratemporal fossa, descends medial to spine of sphenoid and then to lateral pterygoid muscle, and joins lingual nerve in infratemporal fossa.
• Preganglionic parasympathetic fibers carried in chorda tympani synapse with postganglionic parasympathetic fibers in submandibular ganglion.
  
  • The taste of the tongue (ant 2/3) come from the Chorda tympani, so if you damage the Lingual nerve down at the submanidbular gland, you’ll lose the taste to the anterior 2/3 of tongue and general sensation of the oral cavity. But if you damage the lingual nerve up by the infratemporal region, you might j_ust lose the taste function_ but the rest of the general sensation will be fine.

Question 26

What nerve block is often used by dentists?

Answer 26

Inferior alveolar nerve block is widely practiced by dentists as it is one of largest branches of V3.

Question 27

Describe the Pterygoid plexus

Answer 27

Pterygoid plexus is a network of veins between medial and lateral pterygoid muscles, and between lateral pterygoid and temporalis muscles. It is in i_nfratemporal fossa_ (and pterygopalatine fossa).

• Important point: It has a lot of emissaries that go back to the cavernous sinnus. So any infections here can go to the cavernous sinus.

Pterygoid plexus drain nasal cavity, oral cavity, muscles of infratemporal fossa, paranasal sinuses, nasopharynx. In addition, they have connection with:

• Face (facial vein via a deep facial vein) anteriorly
• Neck (retromandibular vein via a short maxillary vein) posteriorly,
• Orbit (inferior ophthalmic vein via inferior orbital fissure) anteriorly;
• Head (small emissary veins via foramen ovale to cavernous sinus) superiorly (danger triangle!).

Clinical: Cavernous Sinus Thrombosis (Danger Triangle)

Middle ear also drains into pterygoid plexus. With middle ear infection or peri-orbital infections, it can drain back into pterygoid plexus and goes to cavernous sinus, which cause cavernous sinus thrombosis, which becomes a urgent medical case

Question 28

How can an infection in the middle ear end up being an emergency situation?

Answer 28

Clinical: Cavernous Sinus Thrombosis (Danger Triangle)

_Middle ea_r also drains into pterygoid plexus.

With middle ear infection or peri-orbital infections, it can drain back into pterygoid plexus and goes to cavernous sinus, which cause cavernous sinus thrombosis, which becomes a urgent medical case

Question 29

Label

Answer 29

CN V2 is purely sensory and enters the pterygopalatine fossa from the middle cranial fossa through the foramen rotundum. In the pterygopalatine fossa the maxillary nerve gives off the following branches:

• 1) the zygomatic nerve (supplies skin on the face and temple)
• 2) the posterior superior alveolar nerve
  
  • (supplies the upper molar teeth, adjacent buccalgingivae and maxillary sinus).

From the pterygopalatine fossa, the CN V2 passes anteriorly through the inferior orbital fissure where it becomes the

• 3) infraorbital nerve.

The infraorbital nerve gives off the

• 4) middle, 5) anterior and superior alveolar nerves; they innervate the upper teeth, maxillary sinus and nasal cavity.

Question 30

What is this?

Describe it

Answer 30

The pterygopalatine fossa lies directly behind the maxilla and orbit, below the middle
cranial fossa and lateral to the posterior nasal cavity.

It contains the maxillary division of the trigeminal nerve (CN V2), continuation of the maxillary artery and autonomic nerves carried by the nerve of the pterygoid canal to the pterygoid (‘hayfever’) ganglion.

From its key location, nerves and vessels are distributed to the orbit, nasal, oral cavities and pharynx.

Question 31

The maxillary artery enters the___________ through the _______fissure after its course through the infratemporal fossa.

It gives off the following branches in the ________e fossa (accompany branches of maxillary nerve and pterygopalatine ganglion):

_______, ___________, ________ and _________

Answer 31

The _maxillary artery e_nters the pterygopalatine fossa through the pterygomaxillary fissure after its course through the infratemporal fossa. It gives off the following branches in the pterygopalatine fossa (accompany branches of maxillary nerve and pterygopalatine ganglion):

• the zygomatic artery.
• the posterior superior alveolar artery.
• the infraorbital artery.
• the anterior superior alveolar arteries.

Question 32

What is this space (red) called?

Answer 32

Pterygopalatine Fossa

Question 33

What are the boarders of Pterygopalatine Fossa

Answer 33

Pterygopalatine fossa lies directly behind maxilla and orbit, below middle cranial fossa and lateral to posterior nasal cavity.

Walls of pterygopalatine fossa are formed by parts of palatine, maxilla, and sphenoid bones

• Anterior wall is posterior surface of maxilla
• Medial wall is lateral surface of palatine bone.
• Posterior wall and roof are parts of sphenoid bone, middle cranial fossa
• Roof: Sphenoid bone

Question 34

In the Pterygopalatine fossa, what nerve and artery are sitting close together?

Answer 34

V2- Maxillary nerve

Internal carotid artery

Question 35

In an ultrasound, how can you tell the diff between an external and internal carotid artery?

Answer 35

External will bificate early

Internal won’t for ages (want to get to the brain)

Question 36

Name 2 important gateways of pterygopalatine fossa

Answer 36

Gateways of Pterygopalatine Fossa (Know Underline)

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

• Foramen rotundum (maxillary nerve V2) communicates with middle cranial fossa (posterior wall of fossa)
• Sphenopalatine foramen (sphenopalatine artery (posterior epistaxis)__) leads to posterior aspect of nasal cavity (medial wall of fossa).
• Inferior orbital fissure opens into floor of the orbit (anterior wall of fossa).
• Pterygoid canal (autonomic nerves) communicates with middle cranial fossa (posterior wall of fossa).
• Palatovaginal canal leads to nasopharynx (posterior wall of fossa).
• Palatine canal leads to roof of oral cavity (hard palate) (inferior aspect of fossa).
• Pterygomaxillary fissure (‘door’ at lateral aspect) continuous with infratemporal fossa (lateral aspect of pterygopalatine fossa)

Question 37

What contents are found in the pterygopalatine fossa?

Answer 37

Pterygopalatine fossa contains:

• Terminal part of maxillary artery;
  
  • Branch to sphenopalatine artery (+ others)
    
    • ​Posterior nasal cavity
    • Posterior epitaxis
• Veins to pterygoid plexus;
• Maxillary nerve (V2);
• Autonomic nerves carried by nerve of the pterygoid canal to synapse with pterygoid (‘hayfever’) ganglion:
  
  • Preganglionic parasympathetic fibers from greater petrosal nerve (VII)
  • Postganglionic sympathetic fibers from deep petrosal branch of carotid plexus (T1)

From its key location, nerves and vessels are distributed to orbit, nasal/oral cavities and pharynx.

Note that all upper teeth receive their innervation and blood supply from maxillary nerve (V2) and terminal part of maxillary artery that pass through pterygopalatine fossa.

Question 38

What arteries do the Maxillary arteries give off in the Pterygopalatine fissure?

Answer 38

Maxillary artery is a major branch of external carotid artery in neck. After its course through infratemporal fossa, it enters pterygopalatine fossa through pterygomaxillary fissure.

Its has 15 branches in total but the third part gives off branches in pterygopalatine fossa (accompany branches of maxillary nerve and pterygopalatine ganglion):

The only one we need to know:

• Sphenopalatine artery (leave through _sphenopalatine forame_n into posterior part of nasal cavity) (middle menangial and infra-alveoli aren’t in here)
• Branches of the maxillary artery contributes to the blood supply of the teeth and skin.

Question 39

What is Posterior epitaxis?

Answer 39

Posterior epistaxis is bleeding from the nose of a posterior origin, usually sphenopalatine artery (supply posterior part of nose). Patient can taste and swallow blood. It is a significant arterial bleed and an emergency.

Posterior epistaxis is not so common (5%), epistaxis is usually anterior origin (95%).

Question 40

Is V2 motor, sensory or both?

Answer 40

Purely sensory

Question 41

What are the 3 significant branches of the Maxilla artery:?

What are the consequences if these are damaged?

Where is the bleeding seen?

Answer 41

1) Middle Meningeal Artery (extradual haematoma)
2) Inferior alveolar artery (pain in teeth)
3) Sphenopalatine artery
- Terminal part of the maxillary
- Posterior nasal cavity
- Posterior Epitaxis

Question 42

Someone punches into ramus of mandible. What structures have been damaged? What symptoms?

Answer 42

Possible damage of ma_xillary artery_ and mandibular nerve (V3)

Symptoms include toothache due to inferior alveolar nerve damage.

Question 43

Describe the clinical importance of the ganglion in the pterygopalatine fossa

Answer 43

The hay fever ganglion sits in the pterygopalatine region = pterygopaltine ganglion

If you have high fever, you have running nose and eyes.

The parasympathetic innervatiion to the nose and eyes are coming from the pterygopalatine fossa.

Pterygopalatine (Hay-Fever) Ganglion (Running Nose & Eyes) (Parasympathetic Ganglion)

Nerve of pterygoid canal passes anteriorly through superior surface of foramen lacerum (cartilage) to enter pterygoid canal, then into pterygopalatine fossa where it joins pterygopalatine ganglion.

Pterygopalatine ganglion is largest parasympathetic ganglion in head.

Postganglionic parasympathetic fibers that originate in pterygopalatine ganglion, together with postganglionic sympathetic fibers passing through ganglion, join fibers from ganglionic branches of maxillary nerve (V2) to form different branches (orbital, palatine, nasal, pharyngeal), which leave the ganglion.

If someone has a very bad hay fever, the surgeon can go to the pterygopalatine fossa and destroy this gangion

Question 44

What is the greater petrosal nerve a branch of?

What does it branch to?

Answer 44

Branch from facial nerve: VII

Nerve Of Pterygoid Canal

Nerve of pterygoid canal is formed in middle cranial fossa under internal carotid artery by union of greater petrosal nerve (branch of facial nerve VII) and deep petrosal nerve (branch of internal carotid plexus).

Nerve of pterygoid canal passes into pterygopalatine fossa and goes to pterygopalatine ganglion. It carries mainly preganglionic parasympathetic and postganglionic sympathetic fibers.

• Greater petrosal nerve carries preganglionic parasympathetic innervation to all glands above oral fissure (mucous glands in nasal cavity, salivary glands in upper half of oral cavity, and lacrimal gland in orbit), joins ganglion, then form postganglionic fibres.
  
  • Greater petrosal nerve also carries some taste (SA) fibers from soft palate in lesser palatine nerve.
• Deep petrosal nerve carries postganglionic sympathetic fibers mainly for blood vessels, pass through ganglion.

Question 45

What is the funcftion of the greater petrosal nerve?

Answer 45

• Greater petrosal nerve carries preganglionic parasympathetic innervation to all glands above oral fissure (mucous glands in nasal cavity, salivary glands in upper half of oral cavity, and lacrimal gland in orbit), joins ganglion, then form postganglionic fibres.
  
  • Greater petrosal nerve also carries some taste (SA) fibers from soft palate in lesser palatine nerve.

Question 46

What are the sympathetic and parasympathetic innervation in the ptergopalatine fossa?

Answer 46

VII

Greater petrosal nerve (parasympathetic)

Deep petrosal nerve (-sympathetic)

• Greater petrosal nerve carries preganglionic parasympathetic innervation to all glands above oral fissure (mucous glands in nasal cavity, salivary glands in upper half of oral cavity, and lacrimal gland in orbit), joins ganglion, then form postganglionic fibres.
  
  • Greater petrosal nerve also carries some taste (SA) fibers from soft palate in lesser palatine nerve.
• Deep petrosal nerve carries postganglionic sympathetic fibers mainly for blood vessels, pass through ganglion.

Question 47

The smpathetic innervation of the mid part of the face and some orbital cavity (to lacrimal gland) is supplied by…

Answer 47

V2 (deep petrosal nerve)- comes from internal carotid plexus

Question 48

If someone comes in with face pain, what should you do first?

Answer 48

Tell them to go to the dentist.

Question 49

What can be damaged after a trip to the dentist?

Answer 49

The needle may have gone into….

Infratemporal fossa

1) Infra-alveolar nerve
2) Lingual nerve
3) Lingual artery (?)

Question 50

What are the symptoms of infection in the cavernous sinus? **

Answer 50

Cavernous sinus thrombosis is usually a late complication of an infection of the central face or paranasal sinuses. Other causes include bacteremia, trauma, and infections of the ear or maxillary teeth.

Cavernous sinus thrombosis (CST) is the formation of a blood clot within the cavernous sinus, a cavity at the base of the brain which drains deoxygenated blood from the brain back to the heart. The cause is usually from a spreading infection in the nose,sinuses, ears, or teeth.

Question 51

_____________nerve block is widely practiced by dentists becuase ___________

Answer 51

Inferior alveolar nerve block is widely practiced by dentists as it is one of l_argest branches of V3._ It is also possible to anaesthetize infra-orbital and buccal nerves, depending on where anaesthesia is needed.