NBDHE Head and Neck Anatomy 2 — Questions and Answers

Question 1: The parotid gland's secretory duct (Stensen's duct) opens into the oral cavity at which landmark?

The parotid papilla opposite the maxillary second molar (Correct answer)
The sublingual caruncle on the floor of the mouth
The posterior wall of the pharynx
Directly behind the upper first molar

Correct answer: The parotid papilla opposite the maxillary second molar

Stensen's duct (parotid duct) opens via the parotid papilla on the buccal mucosa opposite the maxillary second molar.

The parotid gland, the largest salivary gland, produces predominantly serous saliva. Its secretory duct (Stensen's duct) travels anteriorly across the masseter muscle, pierces the buccinator, and opens via the parotid papilla — a small mucosal elevation on the buccal mucosa at the level of the maxillary second molar. The submandibular gland's duct (Wharton's duct) and sublingual ducts (Bartholin's duct and ducts of Rivinus) open via the sublingual caruncles on the floor of the mouth near the midline. Knowing these landmarks is essential for sialography, duct palpation, and management of salivary gland disorders.

Question 2: Which cranial nerve provides sensory innervation to the anterior two-thirds of the tongue?

Lingual nerve (branch of V3 — trigeminal) (Correct answer)
Chorda tympani (branch of VII — facial)
Glossopharyngeal nerve (CN IX)
Hypoglossal nerve (CN XII)

Correct answer: Lingual nerve (branch of V3 — trigeminal)

The lingual nerve (branch of the mandibular division of the trigeminal — V3) provides general somatic sensation (touch, pain, temperature) to the anterior two-thirds of the tongue.

The tongue has a dual sensory supply: (1) General somatic afferent (touch, pain, temperature) — anterior 2/3 via lingual nerve (V3); posterior 1/3 via glossopharyngeal nerve (CN IX). (2) Special sensory (taste) — anterior 2/3 via chorda tympani (branch of facial nerve, CN VII) carried within the lingual nerve; posterior 1/3 via glossopharyngeal (CN IX); epiglottis via vagus (CN X). Motor supply (tongue movements) is provided entirely by the hypoglossal nerve (CN XII), except the palatoglossus (CN X). The chorda tympani also carries secretomotor fibers to the submandibular and sublingual glands.

Question 3: The mental foramen in adults is typically located:

Between the apices of the mandibular first and second premolars, on the buccal aspect (Correct answer)
On the lingual surface of the mandible near the midline
At the inferior border of the mandible near the gonial angle
Immediately inferior to the incisive foramen

Correct answer: Between the apices of the mandibular first and second premolars, on the buccal aspect

The mental foramen transmits the mental nerve and vessels and is located on the buccal (lateral) surface of the mandible, typically between the apices of the first and second premolars.

The mental foramen is the anterior opening of the mandibular canal and transmits the mental nerve (terminal branch of the inferior alveolar nerve — CN V3) and mental vessels. Its typical location is between the apices of the mandibular first and second premolars, approximately midway between the alveolar crest and inferior border of the mandible. Its position varies: it may be below the second premolar or between the first and second premolar apices. Clinically significant for mental nerve block injections and periapical radiograph interpretation (may mimic periapical pathology). With age and tooth loss, the foramen may appear to migrate superiorly as the alveolar bone resorbs.

Question 4: Which muscle depresses the mandible (opens the mouth) and is innervated by the mylohyoid nerve?

Mylohyoid muscle (Correct answer)
Medial pterygoid
Masseter
Temporalis

Correct answer: Mylohyoid muscle

The mylohyoid muscle forms the floor of the mouth and assists in depressing the mandible and elevating the floor of the mouth; it is innervated by the mylohyoid nerve (branch of V3).

The floor of the mouth muscles (suprahyoid group) involved in mouth opening: (1) Mylohyoid — forms the muscular floor; innervated by mylohyoid branch of inferior alveolar nerve (V3). Elevates floor of mouth, depresses mandible. (2) Geniohyoid — elevates hyoid and depresses mandible; innervated by C1 via hypoglossal nerve. (3) Digastric — anterior belly innervated by mylohyoid nerve (V3); posterior belly by facial nerve (CN VII). These muscles depress the mandible when the hyoid is fixed. The masseter, medial pterygoid, and temporalis are elevators (closers) of the mandible; the lateral pterygoid is the primary depressor/protruder.

Question 5: The infraorbital nerve is a branch of which division of the trigeminal nerve, and what structures does it innervate?

Maxillary division (V2) — innervates maxillary anterior teeth, buccal gingiva, upper lip, and cheek skin (Correct answer)
Ophthalmic division (V1) — innervates the orbit and forehead
Mandibular division (V3) — innervates the lower lip and chin
Facial nerve (CN VII) — innervates facial expression muscles

Correct answer: Maxillary division (V2) — innervates maxillary anterior teeth, buccal gingiva, upper lip, and cheek skin

The infraorbital nerve is the terminal branch of V2 (maxillary division), exiting the infraorbital foramen to innervate maxillary anterior teeth, buccal gingiva, upper lip, and skin of the cheek.

The infraorbital nerve is the terminal branch of the maxillary division (V2) of the trigeminal nerve. Before exiting the infraorbital foramen, it gives off: (1) Posterior superior alveolar nerve — maxillary molars and buccal gingiva; (2) Middle superior alveolar nerve (when present) — maxillary premolars; (3) Anterior superior alveolar nerve — maxillary incisors, canines. After emerging from the infraorbital foramen, it distributes into (1) inferior palpebral branches (lower eyelid), (2) external nasal branches (side of nose), and (3) superior labial branches (upper lip). The infraorbital nerve block anesthetizes these terminal distributions and overlying soft tissues.

Question 6: The temporomandibular joint (TMJ) is classified as which type of joint?

Ginglymoarthrodial joint (combination hinge and gliding) (Correct answer)
Simple hinge (ginglymoid) joint only
Ball-and-socket (spheroid) joint
Pivot (trochoid) joint

Correct answer: Ginglymoarthrodial joint (combination hinge and gliding)

The TMJ is a ginglymoarthrodial joint: it combines a hinge motion (rotation in the lower compartment) with a gliding motion (translation in the upper compartment), made possible by the articular disc dividing the joint space.

The TMJ has a unique articular disc (meniscus) that divides the joint into upper and lower compartments. In the lower compartment (between condyle and disc), rotational hinge movement occurs, accounting for initial mouth opening. In the upper compartment (between disc and temporal bone), translatory gliding occurs, as the condyle/disc complex slides forward along the articular eminence during full opening. This dual motion allows the wide range of mandibular movement needed for mastication, speech, and swallowing. The TMJ is lined with fibrocartilage (not hyaline cartilage), which improves its capacity for repair. TMDs affect this joint and associated musculature.

NBDHE Head and Neck Anatomy 2

The parotid gland's secretory duct (Stensen's duct) opens into the oral cavity at which landmark?