Free Practice Questions for KROK 1 Dentistry

Explanation: The lingual nerve runs in the lingual soft tissues in close proximity to the medial aspect of the mandibular ramus and third molar alveolar crest, exhibiting variable relationships to the lingual cortical plate (often separated only by periosteum and submucosa). Fractures of the lingual plate or medial surgical instrumentation can sever or crush the nerve. At this level, the nerve carries both general somatic afferents (from CN V3) and hitchhiking special visceral afferents (taste) and preganglionic parasympathetic fibers from the chorda tympani (CN VII), producing concurrent loss of anterior tongue sensation, taste, and submandibular salivation.

Explanation: The mandibular nerve (V3) exits the middle cranial fossa through the foramen ovale located in the greater wing of the sphenoid bone to enter the infratemporal fossa. Foramen rotundum transmits V2, while foramen spinosum transmits the middle meningeal artery.

Explanation: The lateral pterygoid muscle (specifically its inferior head acting bilaterally) protrudes the mandible and depresses the chin to actively open the mouth. The masseter, temporalis, and medial pterygoid muscles are jaw elevators (closers).

Explanation: The inferior head of the lateral pterygoid originates from the lateral surface of the lateral pterygoid plate and inserts into the pterygoid fovea on the anterior aspect of the condylar neck. When a subcondylar fracture occurs, the unopposed contraction of this inferior head pulls the proximal condylar fragment anteromedially. During surgical reduction, the maxillary artery is at high risk of laceration or entrapment because it courses through the infratemporal fossa immediately medial to the condylar neck.

Explanation: The sphenopalatine foramen, situated in the medial wall of the pterygopalatine fossa, opens directly into the posterior part of the superior meatus of the nasal cavity. It transmits the sphenopalatine vessels and nasopalatine nerve.

Explanation: The maxillary sinus drains into the middle nasal meatus via the infundibulum and hiatus semilunaris beneath the middle nasal concha. The nasolacrimal duct drains into the inferior meatus.

Explanation: The facial artery arises from the anterior aspect of the external carotid artery within the carotid triangle and courses superiorly into the submandibular region, typically grooving the posterior and deep surface of the submandibular gland (with an intraparenchymal course recognized as an anatomical variant). It then hooks around the inferior border of the mandible immediately anterior to the insertion of the masseter muscle, where its pulse can be clinically palpated. From this point, it ascends across the face toward the medial canthus of the eye, giving off labial and nasal branches.

Explanation: The mental foramen is situated on the anterolateral aspect of the mandibular body, typically located midway between the alveolar crest and the inferior mandibular border. In the adult permanent dentition, its location most commonly corresponds to the vertical axis of the second premolar or lies between the apices of the first and second premolars. It transmits the mental nerve and vessels, which provide sensory innervation to the skin of the chin and mucous membrane of the lower lip.

Explanation: The marginal mandibular branch of the facial nerve emerges from the lower pole of the parotid gland and courses near the inferior border of the mandible within or deep to the investing layer of deep cervical fascia. Anatomical studies demonstrate that this branch can dip below the inferior border of the mandible along its posterior segment before arching superiorly across the facial vessels to supply the depressor anguli oris and lower lip muscles. Consequently, submandibular extraoral incisions require careful dissection deep to the platysma with attention to this downward trajectory to avoid causing lower lip asymmetry.

Explanation: In the sublingual space, the lingual nerve and Wharton's (submandibular) duct exhibit a crucial spiral crossing relationship. The lingual nerve initially courses lateral and superior to the duct, then loops under the inferior aspect of the duct from lateral to medial, and finally ascends medial to the duct to reach the tongue on the lateral surface of the hyoglossus. Preserving this spatial relationship is critical during transoral sialolithotomy to prevent iatrogenic nerve transection.