NBDHE Head and Neck Anatomy Questions and Answers — Questions and Answers
Question 1: A patient is asked to protrude their mandible forward. Which muscle is the PRIMARY agonist for this action?
- Temporalis muscle
- Masseter muscle
- Lateral pterygoid muscle (Correct answer)
- Medial pterygoid muscle
Correct answer: Lateral pterygoid muscle
The lateral pterygoid muscle, particularly when both sides contract together, is the primary muscle responsible for protruding the mandible. The temporalis muscle primarily elevates and retracts the mandible, the masseter is a powerful elevator, and the medial pterygoid assists with elevation and side-to-side movements.
Question 2: A patient presents with a painful swelling on the floor of the mouth, inferior to the tongue, which worsens just before and during meals. A blockage of which structure is the MOST likely cause of these symptoms?
- Stensen's duct
- Wharton's duct (Correct answer)
- Bartholin's duct
- Ducts of Rivinus
Correct answer: Wharton's duct
Wharton's duct is the main excretory duct for the submandibular salivary gland. A blockage, often by a sialolith (salivary stone), causes saliva to back up, leading to painful swelling in the floor of the mouth that is exacerbated by the increased saliva production associated with eating. Stensen's duct serves the parotid gland, while Bartholin's and Rivinus ducts serve the sublingual gland.
Question 3: During a mandibular block injection, a patient experiences immediate numbness of the lower lip and chin on the injected side. This indicates the anesthetic has effectively reached which terminal nerve branch?
- Lingual nerve
- Buccal nerve
- Infraorbital nerve
- Mental nerve (Correct answer)
Correct answer: Mental nerve
The mental nerve is a terminal branch of the inferior alveolar nerve (which is the target of a mandibular block). It exits the mandible through the mental foramen to provide sensory innervation to the skin of the chin and lower lip. Numbness in this area is a classic sign of a successful inferior alveolar nerve block.
Question 4: An infection originating from a mandibular first molar would MOST likely cause initial tenderness and enlargement in which group of lymph nodes?
- Submental nodes
- Submandibular nodes (Correct answer)
- Deep cervical nodes
- Parotid nodes
Correct answer: Submandibular nodes
The submandibular lymph nodes are the primary drainage site for all mandibular posterior teeth, including the first molar. The submental nodes drain the mandibular incisors and the tip of the tongue. The deep cervical nodes receive drainage from the submandibular nodes later, and the parotid nodes drain the scalp, ear, and parotid gland.
Question 5: Which of the following structures passes through the foramen ovale of the sphenoid bone?
- Maxillary division of the trigeminal nerve (V2)
- Ophthalmic division of the trigeminal nerve (V1)
- Middle meningeal artery
- Mandibular division of the trigeminal nerve (V3) (Correct answer)
Correct answer: Mandibular division of the trigeminal nerve (V3)
The mandibular division of the trigeminal nerve (V3) exits the skull through the foramen ovale. The maxillary division (V2) passes through the foramen rotundum, the ophthalmic division (V1) passes through the superior orbital fissure, and the middle meningeal artery passes through the foramen spinosum.
Question 6: During the initial phase of swallowing (deglutition), which group of muscles is primarily responsible for elevating the hyoid bone and the floor of the mouth?
- Infrahyoid muscles
- Muscles of mastication
- Suprahyoid muscles (Correct answer)
- Muscles of facial expression
Correct answer: Suprahyoid muscles
The suprahyoid muscles (digastric, stylohyoid, mylohyoid, and geniohyoid) are located superior to the hyoid bone and collectively act to elevate the hyoid bone, the floor of the mouth, and the larynx, which is a critical action during swallowing. The infrahyoid muscles primarily depress the hyoid bone.
NBDHE Head and Neck Anatomy Questions and Answers
A patient is asked to protrude their mandible forward.
Which muscle is the PRIMARY agonist for this action?