Anatomy Infratemporal Fossa Oral Cavity
Questions and Answers
- 1.
To drain an abscess (a closed collection of pus) affecting the cheek area, an emergency room physician used local anesthesia for the surgery. Which of the following nerves must be anesthetized because it carries pain sensation from the cheek area?
- A.
Buccal (V3)
- B.
Buccal (VII)
- C.
Inferior alveolar
- D.
Lingual
- E.
Mental
Correct Answer
A. Buccal (V3)Explanation
The buccal nerve is a branch of the mandibular division of the trigeminal nerve that transmits sensory information from the skin of the cheek area and the oral mucosa of the cheek. The buccal nerve is NOT the same as the buccal branches of the facial nerve, which are motor nerves that innervate the buccinator and the facial muscles of the upper lip. The buccal branches of the facial nerve do not have a sensory component!
The inferior alveolar nerve is another branch of V3 that penetrates the mandibular foramen and is the sensory nerve for the mandible and all mandibular teeth. This is the nerve that dentists must anesthesize when they are working on the mandibular teeth. The lingual nerve is also a branch of V3--it transmits general sensation from the tongue. The lingual nerve also receives the chorda tympani, a branch of the facial nerve, which provides the lingual nerve with preganglionic parasympathetic fibers for the submandibular and and sublingual glands, as well as the taste fibers for the anterior 2/3 of the tongue. Finally, the mental nerve is a branch of V3 from the inferior alveolar nerve--it provides sensory innervation to the skin of the chin and lower lip.Rate this question:
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- 2.
A patient who experienced bilateral anterior dislocation of the jaw (temporomandibular joints) could not swallow or talk since the mouth was held open. What is the position of the condyles of the mandible as a result of the dislocation?
- A.
Against the external acoustic meatus
- B.
Against the anterior slope of the articular eminence
- C.
Against the posterior slope of the articular eminence
- D.
In the mandibular fossa
- E.
In the pterygoid fossa
Correct Answer
B. Against the anterior slope of the articular eminenceExplanation
The TMJ may dislocate anteriorly due to excessive contraction of the lateral pterygoids. This could happen if someone yawned too much or took a large bite of food. So, you want to look for the answer here that represents anterior movement of the jaw. Answer B, against the anterior slope of the articular eminence, is anterior to the normal position of the mandible, so that's the correct answer.
The external acoustic meatus is posterior to the normal position of the mandible, so you know that the mandible would not touch this structure if it dislocated anteriorly. In its normal position, the head of the mandible is near the posterior slope of the articular eminence and in the mandibular fossa, so these answers are not correct. Finally, the pterygoid fossa (also known as pterygoid fovea) is a fossa found on the mandible itself; it's not a place where the mandible could move to dislocate. For a better understanding of this, see Netter Plate 10 and 11.Rate this question:
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- 3.
In reducing an ankylosis of the TMJ, a surgeon provoked an intense hemorrhage by lacerating the artery coursing transversely just medial to the neck of the condyle. Which artery was involved in the accident?
- A.
Buccal
- B.
External carotid
- C.
Maxillary
- D.
Middle meningeal
- E.
Superficial temporal
Correct Answer
C. MaxillaryExplanation
The maxillary artery is one of the terminal branches of the external carotid artery which is closely related with the TMJ. It travels medial to the neck of the condyle, so it would be the artery damaged in this scenario. The buccal artery is a branch of the maxillary artery that travels in the cheek. It supplies blood to the cheek mucosa and skin. The external carotid artery is the source of the maxillary artery, but it is not the artery lying medial to the neck of the mandibular condyle. The middle meningeal artery is a branch of the maxillary artery which is deep to the lateral pterygoid muscle. It supplies the calvaria and the dura surrounding the brain. Finally, the superficial temporal artery is the other terminal branch of the external carotid artery. It courses posterior and lateral to the head of the mandible to supply the scalp of the lateral side of the head and lateral face. See Netter Plate 35 for a picture of all of these arteries and their interconnections.Rate this question:
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- 4.
The muscle which separates the submandibular triangle from the paralingual space is the:
- A.
Digastric, posterior belly
- B.
Hyoglossus
- C.
Mylohyoid
- D.
Stylohyoid
- E.
Styloglossus
Correct Answer
C. MylohyoidExplanation
The submandibular triangle is a space bounded by the anterior and posterior bellies of the digastric and the body of the mandible. It is found superficial to the mylohyoid muscle. The submandibular triangle contains the superficial submandibular gland, stylohyoid muscle, facial artery and facial vein.
The paralingual space is a space found deep to the mylohyoid muscle, which makes the mylohyoid the dividing line between these two distinct spaces. It is bounded by the lateral tongue (including the hyoglossus, styloglossus, and genioglossus muscles), hyoid bone, and oral mucosa. It contains the deep portion of the submandibular gland, the submandibular duct and the sublingual caruncle, lingual nerve and submandibular ganglion, hypoglossal nerve, and sublingual gland and fold.Rate this question:
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- 5.
The predominant muscle most associated with retraction of the mandible is the:
- A.
Lateral pterygoid
- B.
Masseter
- C.
Medial pterygoid
- D.
Temporalis
- E.
Mylohyoid
Correct Answer
D. TemporalisExplanation
Temporalis is the one muscle responsible for retracting the mandible--it pulls the mandible backwards. The lateral pterygoid protracts the mandible, or pulls it forward. It is the one jaw muscle that allows for opening the mouth. The masseter is a powerful chewing muscle that elevates the mandible. The medial pterygoid also elevates the mandible; it has a similar position and action to the masseter, but the ramus of the mandible separates the two muscles. Mylohyoid elevates the hyoid bone and the tongue and depresses the mandible.Rate this question:
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- 6.
At the temporomandibular joint (TMJ), hinge movements occur between the:
- A.
Condyle and articular eminence
- B.
Articular disc and articular eminence
- C.
Condyle and articular disc
- D.
Articular disc and articular cavity
- E.
Condyle and articular cavity
Correct Answer
C. Condyle and articular discExplanation
The TMJ joint is a synovial joint with two articular cavities. Each cavity is responsible for a different movement at the joint. An articular disc sits between the condylar process of the mandible on its inferior side and the mandibular fossa and articular eminence of the temporal bone on the superior side. This disc divides the joint into the two articular cavities, with one cavity acting as a hinge component and the other cavity serving as a gliding component. The lower part of the joint, between the condyle and the articular disc, is the hinge component of the joint. When the joint moves, this hinge component of the joint moves first, to initiate mandibular opening. The upper part of the joint, between the articular disc and the mandibular fossa and articular eminence of the temporal bone, creates the gliding component. During joint movement, this gliding cavity moves after the hinge component to terminate mandibular opening.Rate this question:
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- 7.
A 38-year-old patient complained of acute dental pain. The attending dentist found penetrating dental caries (dental decay) affecting one of the mandibular molar teeth. Which nerve would the dentist need to anesthetize to work on that tooth?
- A.
Lingual
- B.
Inferior alveolar
- C.
Buccal
- D.
Mental
- E.
Mylohyoid
Correct Answer
B. Inferior alveolarExplanation
The inferior alveolar nerve is a branch of the mandibular division of the trigeminal nerve (V3). It penetrates the mandibular foramen and is the sensory nerve for the mandible and all mandibular teeth. This is the nerve anesthetized by dentists working on the mandibular teeth. It is anesthetized near the mandibular foramen, so sensory nerves from branches distal to that point would be blocked. The lingual nerve is another branch of V3--it transmits general sensation from the tongue. The lingual nerve also receives the chorda tympani, a branch of the facial nerve. The chorda tympani gives the lingual nerve preganglionic parasympathetic fibers for the submandibular and sublingual glands, as well as the taste fibers for the anterior 2/3 of the tongue. The buccal nerve is a branch of V3 that transmits sensory information from the skin of the cheek area and the oral mucosa of the cheek. Remember: The buccal nerve is NOT the same as the buccal branch of the facial nerve, which is a motor nerve innervating the buccinator and muscles of the upper lip!!!
The mental nerve is a branch of V3 from the inferior alveolar nerve--it provides sensory innervation to the skin of the chin and lower lip. The nerve to mylohyoid is also a branch of V3--it innervates the mylohyoid muscle and the anterior belly of the digastric. All of these branches of the inferior alveolar nerve could end up being anesthetized as a result of the dental work, but these nerves are not the dentist's main target!Rate this question:
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- 8.
Incapacity to protrude the mandible indicates a dysfunction of which muscle?
- A.
Anterior belly of digastric
- B.
Buccinator
- C.
Lateral pterygoid
- D.
Mylohyoid
- E.
Temporalis
Correct Answer
C. Lateral pterygoidExplanation
The lateral pterygoid muscle protrudes the mandible--it pulls the mandible forward to allow for depression of the chin (which is mostly produced by gravity). None of the other muscles help with this function. The anterior belly of the digastric and mylohyoid have similar functions: they both help elevate the hyoid bone and depress the mandible. The buccinator is a muscle in the cheek; it pulls the corner of mouth laterally and presses the cheek against the teeth. Temporalis is important for retracting and elevating the mandible.Rate this question:
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- 9.
Damage to the facial nerve near the stylomastoid foramen would likely cause each of the following motor deficits EXCEPT:
- A.
Paralysis of the buccinator muscle
- B.
Inability to whistle
- C.
Paralysis of the muscles that elevate the mandible
- D.
Inability to close the lips
Correct Answer
C. Paralysis of the muscles that elevate the mandibleExplanation
The masseter, medial pterygoid, and temporalis are all muscles that elevate the mandible. These muscles are innervated by branches of V3, the mandibular division of the trigeminal nerve. So, none of these muscles would be denervated if the facial nerve was injured. The other actions discussed all involve the muscles of facial expression, which are innervated by the facial nerve (CN VII). The buccinator muscle is innervated by the buccal branches of the facial nerve--this muscle pulls the corner of mouth laterally and presses the cheek against the teeth. The orbicularis oris is the muscle that allows for whistling or closing the lips; this muscle is innervated by the buccal branches of the facial nerve.Rate this question:
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- 10.
The lesser petrosal nerve carries preganglionic parasympathetic fibers to the:
- A.
Geniculate ganglion
- B.
Otic ganglion
- C.
Submandibular ganglion
- D.
Ciliary ganglion
Correct Answer
B. Otic ganglionExplanation
The lesser petrosal nerve is a branch of the glossopharyngeal nerve (CN IX). The lesser petrosal nerve carries presynaptic parasympathetic fibers to the otic ganglion. These fibers synapse in the otic ganglion, and the postsynaptic fibers travel on the auriculotemporal nerve to innervate the parotid gland. The geniculate ganglion is the sensory ganglion of the facial nerve--it holds the cell bodies of the neurons that carry taste sensations from the anterior 2/3 of the tongue. The submandibular ganglion receives preganglionic parasympathetic fibers from the chorda tympani; the postsynaptic fibers from the submandibular ganglion go to the sublingual and submandibular glands. Finally, the ciliary ganglion receives preganglionic parasympathetic fibers from the inferior division of the oculomotor nerve. The postganglionic fibers from this ganglion leave via short ciliary nerves and innervate sphincter pupillae and the ciliary muscle of the eye. Also remember that sensory and sympathetic fibers are passing through the ciliary ganglion and distributing on the short ciliary nerves, but these fibers never synapse in that ganglion.Rate this question:
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- 11.
What bony feature of the mandible can be used to find and palpate the facial artery?
- A.
Oblique line
- B.
Mental trigone
- C.
Angle
- D.
Premasseteric notch
Correct Answer
D. Premasseteric notchExplanation
The facial artery arises from the external carotid artery and winds around the inferior border of the mandible deep to the platysma, immediately anterior to the insertion of masseter muscle. This is the area of the premasseteric notch. The notch lies anterior to the angle of the mandible, so angle would not be a landmark to find the facial artery.Rate this question:
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- 12.
Which of the following suprahyoid muscles would be paralyzed if the inferior alveolar nerve were severed at its origin?
- A.
Geniohyoid m.
- B.
Hyoglossus m.
- C.
Mylohyoid m.
- D.
Stylohyoid m.
Correct Answer
C. Mylohyoid m.Explanation
Mylohyoid is innervated by the nerve to mylohyoid, which is a branch of the inferior alveolar nerve. The inferior alveolar nerve is a branch of the mandibular division of the trigeminal nerve. Geniohyoid is a muscle that spans from the mental spines of the mandible to the body of the hyoid bone--it elevates the hyoid and depresses the mandible. It is innervated by the ventral primary ramus of spinal nerve C1 via fibers carried by the hypoglossal nerve. Hyoglossus is a tongue muscle; it is innervated by the hypoglossal nerve (CN XII). Finally, stylohyoid is a muscle that spans from the styloid process to the hyoid bone. It elevates and retracts the hyoid, and it is innervated by the facial nerve.Rate this question:
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- 13.
Which nerve is endangered during surgical removal of an impacted third mandibular molar tooth?
- A.
Hypoglossal n.
- B.
Glossopharyngeal n.
- C.
Inferior alveolar n.
- D.
Lingual n.
Correct Answer
C. Inferior alveolar n.Explanation
The inferior alveolar nerve provides sensory innervation to the mandibular teeth. This nerve runs in the mandibular foramen, near the roots of the teeth. So, it might be endangered when removing an impacted tooth. The hypoglossal nerve travels lateral to the carotid vessels and through the floor of the mouth. The glossopharyngeal nerve consists of pharyngeal branches that provide sensory innervation to the upper pharynx and lingual branches that sweep around the stylopharyngeus muscle and continue to the base of the tongue. Finally, the lingual nerve, which is from the mandibular division of the trigeminal nerve, is found in the floor of the mouth. These three nerves are far from the area of the impacted tooth, so they would not be endangered by the dental procedure.Rate this question:
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- 14.
After the mandibular condyle is moved forward onto the articular eminence (e.g., by opening the mouth widely), what muscle can then retract the mandible?
- A.
Superficial head of masseter m.
- B.
Deep head of masseter m.
- C.
Posterior part of temporalis m.
- D.
Anterior part of temporalis m.
Correct Answer
C. Posterior part of temporalis m.Explanation
The fibers of the posterior part of temporalis retract the mandible; the fibers from the anterior part of temporalis elevate the mandible. The anterior and deep heads of the masseter muscle are both important for elevating the mandible--remember, the masseter is the very powerful chewing muscle!Rate this question:
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- 15.
Two nerves usually emerge from between the two heads of the lateral pterygoid muscle: the anterior deep temporal nerve and the:
- A.
Masseteric n.
- B.
Buccal n.
- C.
Lingual n.
- D.
Inferior alveolar n.
Correct Answer
B. Buccal n.Explanation
The lateral pterygoid muscle has 2 heads: The superior head of the muscle inserts into the disc and capsule of the temporomandibular joint while the inferior head inserts into the neck of the mandible (the pterygoid fovea). There are two nerves coming between the heads of the lateral pterygoid muscle: the anterior deep temporal nerve and the buccal nerve. See Netter Plate 42A for a picture of these nerves. The masseteric nerve courses superior to the 2 heads of the lateral pterygoid, not between the 2 heads. The lingual nerve travels inferior to the two heads of the muscle. The inferior alveolar nerve also travels inferior to the two heads of the lateral pterygoid before it enters the mandibular foramen.Rate this question:
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- 16.
The chorda tympani enters the infratemporal fossa after it exits the:
- A.
Stylomastoid foramen
- B.
Foramen spinosum
- C.
Foramen lacerum
- D.
Petrotympanic fissure
Correct Answer
D. Petrotympanic fissureExplanation
The chorda tympani exits the skull through the petrotympanic fissure. The stylomastoid foramen is the space that the facial nerve travels through to leave the skull--remember, the chorda tympani has already separated away from the facial nerve by this point. Foramen spinosum is a hole in the base of the skull that transmits the middle meningeal artery and vein. Finally, foramen lacerum is a ragged foramen that is an artifact of a dried skull. In life, it is closed by cartilage. Nothing passes directly through foramen lacerum, although both greater and deep petrosal nerve pass through some of the cartilage that fills it, in order to enter the pterygoid canal at the anterior margin of foramen lacerum.Rate this question:
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- 17.
Paralysis of which of the following muscles would impede retraction of the mandible?
- A.
Buccinator
- B.
Lateral pterygoid, lower portion
- C.
Lateral pterygoid, upper (sphenomeniscus) portion
- D.
Medial pterygoid
- E.
Temporalis
Correct Answer
E. TemporalisExplanation
Temporalis is the important muscle for retracting the mandible! Buccinator is a muscle on the side of the face which pulls the corner of mouth laterally and presses the cheek against the teeth. Both portions of the lateral pterygoid protract the mandible and open the mandible. (Remember: lateral pterygoid is the only muscle that opens the mandible!) Finally, the medial pterygoid protracts and elevates the mandible.Rate this question:
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- 18.
A cranial fracture through the foramen ovale that compresses the enclosed nerve, will have an effect on all muscles EXCEPT :
- A.
Tensor tympani
- B.
Masseter
- C.
Buccinator
- D.
Mylohyoid
- E.
Temporalis
Correct Answer
C. BuccinatorExplanation
The mandibular division of the trigeminal nerve (V3) is transmitted through foramen ovale. Branches from this nerve innervate the muscles of mastication, like temporalis and masseter. A branch from V3 also innervates tensor tympani, which is a muscle that dampens the vibrations of the tympanic membrane. Mylohyoid is innervated by a branch of the inferior alveolar nerve which is also from V3--this muscle elevates the hyoid bone and the tongue and depresses the mandible.
Buccinator is a muscle on the side of the cheek which is innervated by the facial nerve (VII). This muscle, which pulls the corner of mouth laterally and presses the cheek against the teeth, would still be functional even after disrupting the mandibular division of the trigeminal nerve.Rate this question:
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- 19.
Which muscle is also known as the sphenomeniscus?
- A.
Inferior head of the lateral pterygoid
- B.
Masseter
- C.
Medial pterygoid
- D.
Superior head of the lateral pterygoid
- E.
Temporalis
Correct Answer
D. Superior head of the lateral pterygoidExplanation
The superior head of lateral pterygoid is sometimes called sphenomeniscus due to its insertion into the disc of the temporomandibular joint. Remember, the superior head of the lateral pterygoid inserts into the disc of the TMJ, while the inferior head of the lateral pterygoid inserts into the neck of the mandible (pterygoid fovea). None of the other listed muscles insert into a joint like the superior head of the lateral pterygoid.Rate this question:
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- 20.
Forward movement of the condyle of the mandible during wide opening of the jaws is accomplished mainly by the:
- A.
Anterior part of temporalis muscle
- B.
Lateral pterygoid muscle
- C.
Masseter muscle
- D.
Medial pterygoid muscle
- E.
Posterior part of the temporalis muscle
Correct Answer
B. Lateral pterygoid muscleExplanation
Remember--the lateral pterygoid muscle is the one muscle of mastication that is responsible for opening the jaw! It also draws the mandible forward. The anterior part of the temporalis muscle elevates the mandible, while the posterior part of temporalis retracts the mandible. Masseter is a powerful chewing muscle that elevates the mandible. The medial pterygoid muscle elevates the mandible and can help to move the mandible forward. But, when the mouth is open, the lateral pterygoid will be the most important muscle for drawing the mandible forward.Rate this question:
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- 21.
To drill a mandibular tooth without causing undue pain, a dentist has injected an anesthetic into the space located between the medial pterygoid muscle and the mandible near the lingula. Given the nerves passing through the immediate vicinity of the injection site, where would one expect anesthesia in addition to the mandibular teeth?
- A.
Back of tongue
- B.
External ear
- C.
Maxillary incisor teeth
- D.
Skin of chin
- E.
Upper lip
Correct Answer
D. Skin of chinExplanation
The dentist would need to numb the inferior alveolar nerve, which is the nerve that runs in the mandibular foramen and provides sensory innervation to the teeth. The inferior alveolar nerve also gives off the mental nerve, which is a sensory nerve innervating the skin of the chin. So, if the inferior alveolar nerve was anesthetized, the mental nerve would be anesthetized, too. Then, the patient would lose sensory innervation to the skin of the chin.
The back of the tongue (posterior 1/3) receives sensory innervation from the glossopharyngeal nerve. This nerve would not be exposed to the anesthetic. The external ear is innervated by the auriculotemporal nerve, which is not near the area of anesthesia. The maxillary incisor teeth are innervated by the superior alveolar nerves, which are branches of the maxillary division of the trigeminal nerve (V2). The skin of the upper lip is also innervated by a branch of V2--the infraorbital nerve. These branches of V2 would not be exposed to the anesthesia.
If too much anesthesic was injected or if the parotid fascia was pierced by the needle, it would be possible for the anesthesic to diffuse through the soft tissue and paralyze the facial nerve. A high dose of anesthesic might also diffuse to paralyze the muscles of mastication.Rate this question:
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- 22.
The middle meningeal artery:
- A.
Enters the skull through the foramen ovale
- B.
Passes through a split in the trunk of the mandibular nerve (V3)
- C.
Is typically a branch of the second part of the maxillary artery
- D.
Supplies blood to the temporal lobe of the brain
- E.
Usually arises deep to the neck of the mandible
Correct Answer
E. Usually arises deep to the neck of the mandibleExplanation
The middle meningeal artery is always found deep to the lateral pterygoid muscle, so it is arising deep to the neck of the mandible. It enters the skull by passing through the foramen spinosum, not through foramen ovale. Remember--foramen ovale transmits the mandibular branch of trigeminal. Although the middle meningeal artery appears to pass through a fork in the auriculotemporal nerve, it does not pass through a split in the trunk of V3. The middle meningeal artery is not a branch of the second part of the maxillary artery--it is a very early branch that separates from the maxillary artery almost immediately. It supplies blood to the dura mater and the bones of the cranial vault, but it does not supply the temporal lobe of the brain. The temporal lobe is supplied by the middle cerebral artery.Rate this question:
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- 23.
The surgical removal of a metastatic tumor in the infratemporal fossa caused an intense hemorrhage. The surgeon clamped the main source of arterial supply to the area, which is the:
- A.
Internal carotid
- B.
Lingual
- C.
Maxillary
- D.
Posterior auricular
- E.
Superficial temporal
Correct Answer
C. MaxillaryExplanation
The maxillary artery is one of the terminal branches of the external carotid artery. It enters the infratemporal fossa and is the major source of blood for that region. The internal carotid artery is the primary blood supply to the brain. The lingual artery is another branch of the external carotid artery--it supplies blood to the tongue and the floor of the mouth. The posterior auricular is a branch of the external carotid artery that supplies the external ear, scalp and the deeper structures posterior to the ear. The superficial temporal artery is the other terminal branch of the external carotid artery -- it supplies blood to the scalp of the lateral side of the head and the lateral face.Rate this question:
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- 24.
In acute inflammation (arthritis) of the TMJ, the muscle most likely to be affected by the inflammatory process is the:
- A.
Temporal
- B.
Medial pterygoid
- C.
Masseter
- D.
Lateral pterygoid
Correct Answer
D. Lateral pterygoidExplanation
The inferior head of the lateral pterygoid inserts into the neck of the mandible, while the superior head of the lateral pterygoid inserts directly into the capsule and articular disk of the temporomandibular joint. So, this muscle would be affected by arthritis of the joint. This muscle is the only one that opens the mandible, so this movement might be weakened if there was inflammation at the TMJ.
Temporalis elevates and retracts the mandible; it inserts on the coronoid process of the mandible and the anterior surface of the ramus of the mandible. The medial pterygoid muscle protracts and elevates the mandible; it inserts on the medial surface of the ramus and angle of the mandible. Finally, the masseter is the muscle that powerfully elevates the mandible--it inserts on the lower half of the ramus of the mandible. None of these other muscles are inserting into the TMJ, so they would not be impaired quite as much as the lateral pterygoid.Rate this question:
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- 25.
In explaining the pain caused by the drilling of a mandibular molar tooth crown to a freshman medical student, a dentist identified the nerve conducting the pain sensations as the:
- A.
Lingual
- B.
Mylohyoid
- C.
Inferior alveolar
- D.
Buccal
Correct Answer
C. Inferior alveolarExplanation
The inferior alveolar nerve is a branch of the mandibular division of the trigeminal nerve (V3). It travels through the mandibular foramen and provides sensory innervation to the mandibular teeth. The lingual nerve is another branch of V3--it travels in the floor of the mouth and provides sensory innervation to the anterior 2/3 of the tongue and the floor of the mouth. The nerve to mylohyoid is a motor branch of V3--it provides motor innervation to mylohyoid and the anterior belly of the digastric. Finally, the buccal nerve is a sensory branch of V3 that supplies the cheek and oral mucosa.Rate this question:
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- 26.
The temporomandibular joint is characterized by all EXCEPT:
- A.
A capsule strengthened by ligaments on its lateral side only
- B.
A completely flat surface for its gliding action
- C.
An articular disc
- D.
Extracapsular ligaments
- E.
Two joint cavities of different shapes
Correct Answer
B. A completely flat surface for its gliding actionExplanation
The TMJ joint is a synovial joint with two articular cavities. Each cavity is responsible for a different movement at the joint. The lower part of the joint is the hinge component of the joint. When the joint moves, this hinge component of the joint initiates mandibular opening. The upper part of the joint is the gliding component. During joint movement, this gliding cavity moves to terminate mandibular opening. The gliding cavity is the space between the articular disc and the mandibular fossa and articular eminence of the temporal bone--it's not a completely flat surface.
There are extracapsular ligaments around the TMJ joint capsule, but these ligaments are on the lateral side only. The lateral ligament reinforces the lateral part of the capsule, while other ligaments (the stylomandibular and sphenomandibular) only have a minor role in stabilizing the joint capsule. There is also an articular disc dividing the two components of the joint, and the two cavities are different shapes. See Netter Plate 11 for a picture of all of these structures.Rate this question:
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- 27.
In dislocation of the jaw, displacement of the articular disc beyond the articular tubercle of the temporomandibular joint results from excessive contraction of which muscle?
- A.
Buccinator
- B.
Lateral pterygoid
- C.
Medial pterygoid
- D.
Masseter
- E.
Temporalis
Correct Answer
B. Lateral pterygoidExplanation
The TMJ may dislocate anteriorly due to excessive contraction of the lateral pterygoids (for example, during excessive opening of the mouth). This could happen if someone yawned too much or took a large bite of food. Posterior dislocations of the TMJ are rare due to resistance from the postglenoid tubercle and the strong lateral ligaments.
The buccinator is an important muscle for mastication because it keeps the cheek taut, so the cheek can press against the molars. However, it is a facial muscle innervated by the facial nerve, and it is not active at the TMJ. The medial pterygoid, masseter and temporalis produce motion at the TMJ, but contracting these muscles does not cause the joint to dislocate.Rate this question:
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- 28.
Sympathetic fibers reach the tongue by way of the:
- A.
Lingual nerve
- B.
Maxillary artery
- C.
Hypoglossal nerve
- D.
Lingual artery
- E.
Glossopharyngeal nerve
Correct Answer
D. Lingual arteryExplanation
Remember--all over the body, the vasculature is the number one target of sympathetic nerves. Sympathetic nerves help to constrict the vasculature, and they are found covering arteries in periarterial plexuses. In the head, sympathetics travel to targets on vessels. So, you know that the sympathetic nerves are coming to the tongue on an artery--now, you just need to determine what artery goes to the tongue. And that artery is the lingual artery.
The lingual artery is the second branch off the anterior side of the external carotid artery. It travels in the floor of the mouth and supplies blood to the tongue, suprahyoid muscles, and the palatine tonsil. This is the artery going to the targeted area, so that's the answer you're looking for. The maxillary artery is one of the 2 terminal branches of the external carotid artery. It supplies blood to the deep face and infratemporal fossa. It is not going to the tongue.
As far as the nerves go... The lingual nerve is a branch of V3, the mandibular division of the trigeminal nerve. It supplies general sensation (touch and temperature) to the anterior 2/3 of the tongue. (Taste sensation for the anterior 2/3 of the tongue arrives at the tongue by way of the lingual nerve, but the original fibers for taste came from the chorda tympani, a branch of CN VII.) The hypoglossal nerve (CN XII) provides motor innervation to the muscles of the tongue. The glossopharyngeal nerve (CN IX) provides taste sensation and general sensation to the posterior 1/3 of the tongue.Rate this question:
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- 29.
After a radiograph revealed a sialolith (stone) in a patient's right submandibular duct, the surgeon exposed the duct via an intraoral approach. In this approach, what tissues or structures must be cut through?
- A.
Mucous membrane only
- B.
Mucous membrane and genioglossus muscle
- C.
Mucous membrane and mylohyoid muscle
- D.
Mucous membrane and hyoglossus muscle
Correct Answer
A. Mucous membrane onlyExplanation
The submandibular duct is found deep to the mucous membrane of the mouth, but superficial to the muscles of the tongue and the muscles on the floor of the mouth. So, genioglossus, mylohyoid, and hyoglossus are deep to the submandibular duct. See Netter Plate 56B for a picture of these relationships.Rate this question:
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- 30.
Damage of the lingual nerve before it is joined by the chorda tympani in the infratemporal fossa would cause loss of:
- A.
General sensation to the anterior two thirds of the tongue
- B.
General sensation to the posterior one third of the tongue
- C.
Secretion of the submandibular gland
- D.
Taste sensation from the anterior two thirds of the tongue
- E.
Taste sensation from the posterior one third of the tongue
Correct Answer
A. General sensation to the anterior two thirds of the tongueExplanation
The lingual nerve is a branch of V3, the mandibular division of the trigeminal nerve. It transmits general sensation from the anterior 2/3 of the tongue. Damaging this nerve anywhere along its course would cause someone to lose general sensation to the anterior 2/3 of the tongue. The chorda tympani is a branch of VII--it carries taste fibers to the anterior 2/3 of the tongue and presynaptic parasympathetic fibers to the submandibular ganglion. The fibers from the chorda tympani join the lingual nerve as they travel to the submandibular ganglion and the anterior tongue. However, if the lingual nerve was damaged before the chorda tympani had joined it, the chorda tympani fibers would still be intact. So, there would still be taste innervation to the anterior 2/3 of the tongue and the submandibular gland would still secrete. If the lingual nerve was disrupted after the chorda tympani had already joined it, there would be no secretomotor innervation to the submandibular and sublingual glands, and there would be no taste or general sensation to the anterior 2/3 of the tongue.
As for the posterior 1/3 of the tongue, it receives taste and general sensation from the glossopharyngeal nerve (CN IX).Rate this question:
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- 31.
The teeth and gums separate the oral cavity proper from the:
- A.
Nasal cavity
- B.
Oral vestibule
- C.
Oropharynx
- D.
Paralingual space
- E.
Submandibular space
Correct Answer
B. Oral vestibuleExplanation
The oral vestibule is the space in the mouth lying between the lips and the teeth. See Netter Plate 45 for an illustration of the mouth--although the vestibule isn't labeled, you can get some idea of where it lies. The nasal cavities are spaces that connect the nasopharynx with the external environment. The roof of the nasal cavity is made of the cribriform plate of the ethmoid bone. The floor of the nasal cavity is made of the hard palate. The medial wall is made by the nasal septum, and the lateral wall is the place where the inferior, superior, and middle conchae project into the nasal cavity.
The oropharynx is the middle part of the pharynx, found behind the mouth. It communicates anteriorly with oral cavity through the palatoglossal arch, superiorly with the nasopharynx through the posterior margin of soft palate, and inferiorly with the laryngopharynx at the superior margin of epiglottis. The oropharynx contains the palatine tonsil, which is located between the palatoglossal arch and the palatopharyngeal arch.
The paralingual space is a space inside the floor of the mouth. It is bounded by the mylohyoid muscle, the lateral tongue, the hyoid bone, and the oral mucosa. The paralingual space contains the deep portion of the submandibular gland, the lingual nerve and submandibular ganglia, the sublingual gland and fold, and the hypoglossal nerve.
Finally, the submandibular space is a space defined by the body of the mandible and the anterior and posterior digastric muscles. It contains the superficial submandibular gland, mylohyoid and stylohyoid muscles, the facial artery, and the facial vein.Rate this question:
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- 32.
The bleeding was seen to be arterial; which of the following arteries was involved?
- A.
Deep lingual
- B.
Dorsal lingual
- C.
Facial
- D.
Sublingual
- E.
Tonsillar
Correct Answer
B. Dorsal lingualExplanation
The dorsal lingual artery runs on the superficial surface of the tongue--it is a branch of the lingual artery that delivers blood to the posterior superficial tongue. So, this artery must be the source of the hemorrhage. The deep lingual artery and sublingual artery are two terminal branches of the lingual artery. These branches run in the floor of the mouth (sublingual) and the deep surface of the tongue (deep lingual). See Netter Plate 53 for a picture. The facial artery is a branch of the external carotid artery that courses across the face. The tonsillar artery is a branch of the facial artery that supplies blood to the palatine tonsil.Rate this question:
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- 33.
The difficulty in swallowing was due to involvement of which muscle that elevates the tongue?
- A.
Genioglossus
- B.
Hyoglossus
- C.
Styloglossus
- D.
Stylohyoid
- E.
Stylopharyngeus
Correct Answer
C. StyloglossusExplanation
Styloglossus retracts and elevates the tongue. Genioglossus is a large, fan shaped muscle with many actions: its inferior fibers protrude the tongue, its middle fibers depress the tongue, and its superior fibers draw the tip back and down. Hyoglossus retracts and depresses the tongue. All of these muscles are innervated by the hypoglossal nerve (CN XII). Stylohyoid elevates and retracts the hyoid bone. It is innervated by the facial nerve (CN VII). Stylopharyngeus elevates the larynx--it is innervated by the glossopharyngeal nerve (IX).Rate this question:
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- 34.
Cutting of the hypoglossal nerve in the hypoglossal canal would not interrupt the nerve supply to the:
- A.
Hyoglossus muscle
- B.
Genioglossus muscle
- C.
Palatoglossus muscle
- D.
Styloglossus muscle
Correct Answer
C. Palatoglossus muscleExplanation
All of the tongue muscles are innervated by the hypoglossal nerve. So, hyoglossus, genioglossus, and styloglossus are all innervated by the hypoglossal nerve. Although palatoglossus sounds like a tongue muscle, it is a palatal muscle, innervated by the vagus nerve. (Palatoglossus is the only "glossus" muscle that is not innervated by the hypoglossal nerve.)Rate this question:
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- 35.
The contents of the paralingual space do NOT include the:
- A.
Hypoglossal nerve
- B.
Lingual artery
- C.
Lingual nerve
- D.
Submandibular gland
- E.
Sublingual gland
Correct Answer
B. Lingual arteryExplanation
The paralingual space is a space inside the floor of the mouth. It is bounded by the mylohyoid muscle, the lateral tongue, the hyoid bone, and the oral mucosa. The paralingual space contains the deep portion of the submandibular gland, the lingual nerve and submandibular ganglion, the sublingual gland and fold, and the hypoglossal nerve. The lingual artery is not in the paralingual space.Rate this question:
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- 36.
A patient is unable to taste a piece of sugar placed on the anterior part of the tongue. Which cranial nerve is most likely to have a lesion?
- A.
Facial nerve
- B.
Glossopharyngeal nerve
- C.
Hypoglossal nerve
- D.
Trigeminal nerve
- E.
Vagus nerve
Correct Answer
A. Facial nerveExplanation
Taste fibers to the anterior 2/3 of the tongue come from the chorda tympani--a branch of the facial nerve. So, if the patient has lost taste sensation to the anterior 2/3 of the tongue, the patient might have a lesion of the facial nerve. The glossopharyngeal nerve (CN IX) carries taste and general sensory fibers to the posterior 1/3 of the tongue. The hypoglossal nerve (CN XII) gives motor innervation to all the muscles of the tongue (ie, all the muscles that end in glossus except for palatoglossus, which is a palate muscle innervated by the vagus). The trigeminal nerve supplies general sensory fibers to the anterior 2/3 of the tongue via the lingual nerve, a branch of V3. Remember, the chorda tympani fibers jump on the lingual nerve to reach the tongue, but the chorda tympani fibers originate from the facial nerve! Finally, the vagus nerve supplies general and taste sensation to a very small part of the posterior tongue, right next to the epiglottis.Rate this question:
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- 37.
The chorda tympani contains which component before it joins the lingual nerve?
- A.
Preganglionic sympathetics
- B.
Postganglionic sympathetics
- C.
Preganglionic parasympathetics
- D.
Postganglionic parasympathetics
- E.
Taste fibers to the posterior third of the tongue
Correct Answer
C. Preganglionic parasympatheticsExplanation
The chorda tympani contains preganglionic parasympathetic nerves that go to the submandibular ganglion. These preganglionic parasympathetics synapse in the submandibular ganglion and then provide secretomotor innervation to the submandibular and sublingual glands. The chorda tympani also contains taste fibers to the anterior 2/3 of the tongue, but not to the posterior 1/3.Rate this question:
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- 38.
The cell bodies of the taste fibers from the anterior two-thirds of the tongue are located in the:
- A.
Geniculate ganglion
- B.
Otic ganglion
- C.
Pterygopalatine ganglion
- D.
Submandibular ganglion
- E.
Trigeminal ganglion
Correct Answer
A. Geniculate ganglionExplanation
The geniculate ganglion is the sensory ganglion of the facial nerve--it holds the cell bodies of the neurons that carry taste sensations from the anterior 2/3 of the tongue. These fibers then travel on the chorda tympani, which carries the fibers to the lingual nerve. The chorda tympani fibers then jump on the lingual nerve so they can reach the tongue and provide taste sensation to the anterior 2/3. The otic ganglion is the ganglion where parasympathetic fibers synapse before innervating the parotid gland. The lesser petrosal nerve is a branch of the glossopharyngeal nerve (CN IX) that carries presynaptic parasympathetic fibers to the otic ganglion. These fibers synapse in the otic ganglion, and the postsynaptic fibers travel on the auriculotemporal nerve to the parotid gland.
The pterygopalatine ganglion is the ganglion that enables secretomotor innervation to the mucous glands of the palate, nasal cavity, and lacrimal gland. Preganglionic fibers arrive at this ganglion from the greater petrosal nerve of the facial nerve. The submandibular ganglion receives preganglionic parasympathetic fibers from the chorda tympani; the postsynaptic fibers from the submandibular ganglion go to provide secretomotor innervation to the sublingual and submandibular glands. Finally, the trigeminal ganglia (also called the semilunar ganglia) is a sensory ganglion equivalent in histological structure and function to a dorsal root ganglion. The cell bodies of the afferent fibers of the trigeminal nerve reside in this ganglion.Rate this question:
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- 39.
Which of the following structures is located in the vestibule of the oral cavity?
- A.
Tongue
- B.
Opening of the parotid duct
- C.
Opening of the submandibular duct
- D.
Sublingual fold
- E.
Uvula
Correct Answer
B. Opening of the parotid ductExplanation
The oral vestibule is the space in the mouth lying between the lips and the teeth. See Netter Plate 45 for an illustration of the mouth and vestibule--although the vestibule isn't labeled, you can get some idea of where it lies. You can also see that the parotid duct is opening into this space . The parotid duct drains the parotid gland; it crosses the masseter to enter the cheek and drain into the oral cavity. The parotid duct drains into the cheek near the upper 2nd molar tooth.
The tongue is not in the vestibule--it's behind the teeth. The submandibular duct opens into the area under the tongue, near the tongue's frenulum. The sublingual fold is also underneath the tongue; this is the fold that contains the openings for the ducts of the sublingual gland to drain into the mouth. The uvula is the "punching bag" hanging from the soft palate at the back of the oral cavity.Rate this question:
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- 40.
When one presses the tongue tip against the anterior (incisor) teeth, which of the following muscles must contract?
- A.
Styloglossus
- B.
Hyoglossus
- C.
Genioglossus
- D.
Superior longitudinal
- E.
Verticalis
Correct Answer
C. GenioglossusExplanation
Genioglossus is a large, fan shaped muscle with many actions: its inferior fibers protrude the tongue, its middle fibers depress the tongue, and its superior fibers draw the tip back and down. So, since the tongue is being protruded, the inferior fibers of genioglossus must be contracting. Styloglossus retracts and elevates the tongue. Hyoglossus depresses the sides of tongue and retracts the tongue. The superior longitudinal and verticalis muscles are intrinsic muscles of the tongue. They help shape the tongue for speech and chewing. All of these muscles are innervated by the hypoglossal nerve!Rate this question:
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- 41.
The muscle responsible for raising the floor of the mouth in the early stages of swallowing is the:
- A.
Genioglossus
- B.
Geniohyoid
- C.
Hyoglossus
- D.
Mylohyoid
- E.
Palatoglossus
Correct Answer
D. MylohyoidExplanation
The mylohyoid muscle elevates the hyoid bone and the tongue and depresses the mandible. It is a muscle in the floor of the mouth that helps elevate the floor of the mouth, so this is the correct answer. The genioglossus is a large, fan shaped tongue muscle that protrudes tongue with its inferior fibers and depresses the tongue with its middle fibers. Geniohyoid is a small muscle in the floor of the mouth that elevates the hyoid and depresses the mandible. Hyoglossus is a tongue muscle that depresses the sides of the tongue and retracts the tongue. Finally, palatoglossus is a palate muscle, innervated by the vagus nerve. It elevates and retracts the tongue.Rate this question:
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- 42.
The cell bodies of the postganglionic parasympathetic neurons innervating the sublingual gland are found in which of the following ganglia?
- A.
Ciliary
- B.
Otic
- C.
Submandibular
- D.
Superior cervical
- E.
Trigeminal
Correct Answer
C. SubmandibularExplanation
The submandibular ganglion contains the cell bodies of the postganglionic parasympathetic neurons that innervate the sublingual and submandibular gland. Preganglionic parasympathetic fibers arrived at the submandibular ganglion via the chorda tympani. These neurons then synapsed with the cell bodies in the submandibular ganglion, and the postganglionic fibers traveled out to provide secretomotor innervation to the sublingual and submandibular glands.
The ciliary ganglion receives preganglionic parasympathetic fibers from the inferior division of the oculomotor nerve. The postganglionic fibers from this ganglion leave via short ciliary nerves and innervate sphincter pupillae and the ciliary muscle of the eye. Also remember that sensory and sympathetic fibers are passing through the ciliary ganglion and distributing on the short ciliary nerves, but these fibers never synapse in that ganglion. The otic ganglion is the ganglion where parasympathetic fibers synapse before innervating the parotid gland. The lesser petrosal nerve is a branch of the glossopharyngeal nerve (CN IX) that carries presynaptic parasympathetic fibers to the otic ganglion. These fibers synapse in the otic ganglion, and the postsynaptic fibers travel on the auriculotemporal nerve to the parotid gland.
The superior cervical ganglia is at the level of the C1 and C2 vertebrae--it is the highest ganglia in the sympathetic chain. Sympathetic nerves from this ganglia go to form the internal carotid sympathetic plexus along the internal carotid artery. Finally, the trigeminal ganglia (also called the semilunar ganglia) a sensory ganglion equivalent in histological structure and function to a dorsal root ganglion. The cell bodies of the afferent fibers of the trigeminal nerve reside in this ganglion.Rate this question:
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- 43.
A 46-year-old female patient comes to the emergency department complaining of pain in the area just below her mandible on the right side of her face. She says that the pain is particularly severe when she eats. The area of the submandibular gland is tender and swollen, as is the area in the floor of her mouth lateral to the tongue. You suspect a stone in the submandibular duct, and a plain film radiograph shows a density in that region consistent with a stone. In order to remove the stone, the duct must be incised in the floor of the mouth. What nerve, that loops around the duct, is in danger in such an incision?
- A.
Chorda Tympani
- B.
Glossopharyngeal
- C.
Hypoglossal
- D.
Internal branch of the superior laryngeal
- E.
Lingual
Correct Answer
E. LingualExplanation
The lingual nerve is found in the floor of the mouth--it wraps around the submandibular duct. So that nerve might be injured as you try to remove the stone from the submandibular duct. The lingual nerve contains general sensory fibers for the anterior 2/3 of the tongue, and fibers from the chorda tympani that provide taste to the anterior 2/3 of the tongue. All of these sensory components might be lost if the lingual nerve was damaged.
At the point where the lingual nerve is wrapping around the submandibular gland, the fibers from chorda tympani have already joined the lingual nerve.This means that fibers from chorda tympani might be damaged, but the chorda tympani itself is not near the submandibular duct. The glossopharyngeal nerve provides sensory and taste innervation to the posterior 1/3 of the tongue and sensory innervation to the pharynx--it is not associated with the submandbular duct. The hypoglossal nerve is in the sublingual space, just like the submandibular duct. However, it is deeper in the sublingual space and does not wrap around the duct. Remember--the lingual nerve is a much more superficial structure in the sublingual space. Finally, the internal branch of the superior laryngeal nerve crosses the thyrohyoid membrane to provide sensory innervation to the mucosa of the pharynx, superior to the vocal folds.Rate this question:
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- 44.
In accessing the submandibular gland in the submandibular triangle, what vessel coursing through the gland and triangle would need to be protected?
- A.
External jugular vein
- B.
Facial artery
- C.
Maxillary artery
- D.
Retromandibular vein
- E.
Superior thyroid artery
Correct Answer
B. Facial arteryExplanation
The submandibular triangle is formed by the lower border of the mandible and the anterior and posterior bellies of the digastric muscle. The facial artery and facial vein course through this triangle. The facial artery lies deep to the superficial part of the submandibular gland and wraps around the mandible. The facial vein is superficial to the gland--see Netter Plate 27 for a picture. The external jugular vein is a superficial vein on the lateral side of the neck. The maxillary artery is a branch of the external carotid artery that is the main source of blood to the infratemporal fossa. The retromandibular vein is a vein that passes through the parotid gland, along with the facial artery and facial nerve. Finally, the superior thyroid artery is a branch of the external carotid that supplies blood to the superior pole of the thyroid.Rate this question:
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- 45.
All of the following may be found in the paralingual space EXCEPT:
- A.
Hypoglossal nerve
- B.
Lingual nerve
- C.
Sublingual gland
- D.
Submandibular gland duct
- E.
Superficial lobe of the submandibular gland
Correct Answer
E. Superficial lobe of the submandibular glandExplanation
The paralingual space is found in the floor of the mouth, deep to the mylohyoid muscle. The space is bounded by the lateral tongue, the hyoid bone, and the oral mucosa. Remember--the submandibular gland has a deep and superficial portion. The deep portion of the submandibular gland is found deep to the mylohyoid muscle, while the superficial portion of the submandibular gland is found superficial to the mylohyoid muscle. So, the deep portion of the submandibular gland is in the paralingual space, while the superficial portion of the submandibular gland is not. See Netter Plate 55 for a picture of this.
The paralingual space also contains the submandibular duct and sublingual caruncle, the lingual nerve and submandibular ganglion, the hypoglossal nerve, and the sublingual gland and fold.Rate this question:
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