1.
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?
Correct Answer
B. Against the anterior slope of the articular eminence
Explanation
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.
2.
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?
Correct Answer
B. Inferior alveolar
Explanation
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.
3.
The lesser petrosal nerve carries preganglionic parasympathetic fibers to the: _______
Correct Answer
B. Otic ganglion
Explanation
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.
4.
Which of the following suprahyoid muscles would be paralyzed if the inferior alveolar nerve were severed at its origin?
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.
5.
Paralysis of which of the following muscles would impede retraction of the mandible?
Correct Answer
E. Temporalis
Explanation
Temporalis is the important muscle for retracting the mandible!
6.
A cranial fracture through the foramen ovale that compresses the enclosed nerve, will have an effect on all muscles EXCEPT : ________
Correct Answer
C. Buccinator
Explanation
Buccinator is a muscle on the side of the cheek which is innervated by the facial nerve (VII).
7.
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: ______
Correct Answer
C. Maxillary
Explanation
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.
8.
In acute inflammation (arthritis) of the TMJ, the muscle most likely to be affected by the inflammatory process is the: __________
Correct Answer
D. Lateral pterygoid
Explanation
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.
9.
Damage of the lingual nerve before it is joined by the chorda tympani in the infratemporal fossa would cause loss of: ________
Correct Answer
A. General sensation to the anterior two thirds of the tongue
Explanation
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.
10.
The difficulty in swallowing was due to involvement of which muscle that elevates the tongue?
Correct Answer
C. Styloglossus
Explanation
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).
11.
Cutting of the hypoglossal nerve in the hypoglossal canal would not interrupt the nerve supply to the: __________
Correct Answer
C. Palatoglossus muscle
Explanation
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.)
12.
The chorda tympani contains which component before it joins the lingual nerve?
Correct Answer
C. Preganglionic parasympathetics
Explanation
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.
13.
The cell bodies of the taste fibers from the anterior two-thirds of the tongue are located in the: _________
Correct Answer
A. Geniculate ganglion
Explanation
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.
14.
When one presses the tongue tip against the anterior (incisor) teeth, which of the following muscles must contract?
Correct Answer
C. Genioglossus
Explanation
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.
15.
The cell bodies of the postganglionic parasympathetic neurons innervating the sublingual gland are found in which of the following ganglia?
Correct Answer
C. Submandibular
Explanation
The submandibular ganglion contains the cell bodies of the postganglionic parasympathetic neurons that innervate the sublingual and submandibular gland.