A 26-year-old previously healthy man is brought to the emergency department following a motorbike accident. He is found to have a maxillofacial injury. His condition is stabilized, and surgical repair is performed. While recovering, the patient develops difficulty chewing food. On examination, the jaw deviates to the right side when the patient is instructed to open his mouth. The nerve that has been injured in this patient exits the skull through which of the following foramina?

Question

A 26-year-old previously healthy man is brought to the emergency department following a motorbike accident.  He is found to have a maxillofacial injury.  His condition is stabilized, and surgical repair is performed.  While recovering, the patient develops difficulty chewing food.  On examination, the jaw deviates to the right side when the patient is instructed to open his mouth.  The nerve that has been injured in this patient exits the skull through which of the following foramina?

Quizplus · Accepted Answer

11ec160b_35cb_e99c_9249_97889721faa9_MD0001_00 This patient has symptoms consistent with injury of the third division of the trigeminal nerve (cranial nerve [CN] V3, mandibular nerve), which provides sensory innervation to the face and motor innervation to the muscles of mastication. These include the 3 muscles that close the jaw (masseter, medial pterygoid, temporalis) and the single muscle that opens the jaw (lateral pterygoid). Unilateral injury to CN V3 will result in unopposed action of the contralateral pterygoid muscles; because of the plane of action of these muscles, this leads to deviation of the mandible toward the paralyzed side on opening the mouth. Bilateral paralysis would cause mandibular drop and lack of jaw movement. CN V3 exits the skull through the foramen ovale, which also contains the lesser petrosal nerve, the accessory meningeal artery, and the emissary veins. The second division of the trigeminal nerve (CN V2, maxillary nerve) exits the skull via the foramen rotundum (Choice C). The foramen spinosum contains the middle meningeal artery, middle meningeal vein, and the meningeal (recurrent) branch of CN V3, which supplies the dura and contains sympathetic fibers (Choice D). The first branch of the trigeminal nerve (CN V1, ophthalmic nerve) passes through the superior orbital fissure. (Choice A) The foramen lacerum contains only a few small vessels (meningeal branch of ascending pharyngeal artery, emissary veins) and is otherwise occluded by fibrous tissue and cartilage. The internal carotid artery passes along its superior surface but does not traverse it. (Choice E) The jugular foramen contains CNs IX, X, and XI; the inferior petrosal and sigmoid sinuses; and the posterior meningeal artery. Educational objective: The third (mandibular) branch of the trigeminal nerve exits the skull through the foramen ovale and innervates the muscles of mastication, including the masseter, the medial and lateral pterygoids, and the temporalis muscles.

A 26-Year-Old Previously Healthy Man Is Brought to the Emergency