DFT-16/09/2025- ANATOMY D2

A 28-year-old male presents to the emergency department with a severe, throbbing left-sided headache, fever, and periorbital edema. Three days prior, he had aggressively squeezed a painful pustule on his left nasal ala. On examination, he has unilateral proptosis, complete ptosis, and diplopia on attempted lateral gaze of the left eye. What is the most likely diagnosis?

• Cavernous sinus thrombosis

• Orbital cellulitis

• Bacterial meningitis

• Acute maxillary sinusitis

Answer explanation

This diagnosis is most likely due to the classic triad of a preceding mid-face infection, ophthalmoplegia (involving CN III, IV, VI), and proptosis. The infection spreads retrogradely via valveless facial and ophthalmic veins.

The "dangerous area of the face" is a concept emphasizing the risk of intracranial septic emboli from superficial facial infections. What is the primary anatomical reason for this direct pathway of infection?

• Valveless communication between the facial vein and the cavernous sinus

•  Abundant anastomoses with the external carotid artery branches

• Extensive lymphatic drainage into the submandibular and deep cervical nodes

• Direct contiguity with the pterygoid plexus of veins via the maxilla

Answer explanation

Valveless communication between the facial vein and the cavernous sinus: The facial vein connects with the cavernous sinus via the superior ophthalmic vein. The absence of valves allows for retrograde flow of septic emboli directly into this intracranial structure.

1. A 55-year-old male undergoes a superficial parotidectomy for a pleomorphic adenoma. Three weeks post-surgery, he complains of numbness specifically over the angle of his mandible and the skin overlying the parotid gland. He denies any facial drooping or difficulty with mastication. Which of the following nerves was most likely iatrogenically injured?

• Great auricular nerve

• Auriculotemporal nerve

• Marginal mandibular nerve

• Supratrochlear nerve

Answer explanation

The great auricular nerve (from cervical plexus C2, C3) provides sensory innervation to the skin over the angle of the mandible and parotid gland. It is the most commonly injured nerve during parotidectomy, leading to this specific sensory deficit.

During mastication, the integrity of which of the following nerves is crucial for preventing the bolus of food from accumulating in the oral vestibule between the teeth and the cheek?

• Buccal branch of the facial nerve

• Mental nerve

• Zygomatic branch of the facial nerve

• Lacrimal nerve

Answer explanation

The buccal branch of the facial nerve (CN VII) provides motor innervation to the buccinator muscle. This muscle's function is to press the cheek against the teeth, preventing food accumulation in the oral vestibule.

A 58-year-old male, one year post-superficial parotidectomy, presents with unilateral facial flushing and sweating in the preauricular region, exclusively triggered during meals. He denies pain but finds the symptom socially bothersome. Which pathophysiological mechanism is responsible for this presentation?

•  Parasympathetic secretomotor fibers aberrantly innervating dermal sweat glands

• Synkinetic reinnervation between motor branches of the facial nerve (CN VII).

• Focal hypersensitivity of denervated sympathetic receptors.

• Neurogenic inflammation from trigeminal nerve sensitization.

Answer explanation

This accurately describes Frey's syndrome, where regenerating parasympathetic fibers intended for salivary secretion misdirect to innervate sympathetic targets like sweat glands and cutaneous vessels, causing gustatory sweating.

1. A patient with a large retropharyngeal abscess develops rapid clinical deterioration with signs of acute mediastinitis. This life-threatening inferior spread of infection is most directly facilitated by extension through which fascial space?

• Danger space

  
  

•  Pre-tracheal space

  
  

• Carotid sheath

  
  

• Retropharyngeal space proper

  
  

Answer explanation

The danger space, located between the alar and prevertebral fascia, is a continuous plane from the skull base to the diaphragm, allowing unimpeded spread of infection to the posterior mediastinum.

During a thyroidectomy, meticulous dissection is required near a ligamentous thickening of the pre-tracheal fascia that tethers the thyroid gland to the cricoid cartilage. This structure is a critical landmark due to its intimate relationship with the recurrent laryngeal nerve. What is this fascial modification?

• Suspensory ligament of Berry

• Axillary sheath

  
  

•  Pharyngobasilar fascia

• Alar fascia

Answer explanation

The suspensory ligament of Berry is a modification of the pre-tracheal fascia that anchors the thyroid gland, making it a crucial landmark for preserving the recurrent laryngeal nerve during surgery.

A 45-year-old male undergoes an excisional biopsy of a firm, palpable lymph node located in the posterior triangle of the neck, superior to the clavicle and posterior to the sternocleidomastoid muscle. Two weeks post-operatively, he complains of a persistent dull ache in his shoulder, difficulty lifting his arm above 90 degrees to comb his hair, and notes that his shoulder blade "sticks out." On examination, there is shoulder droop and weakness in shrugging against resistance. Which anatomical triangle was most likely breached, leading to iatrogenic nerve injury?

• Occipital triangle

• Subclavian (supraclavicular) triangle

•  Carotid triangle

• Submental triangle

Answer explanation

The spinal accessory nerve (CN XI) traverses the occipital triangle superficially. Injury here results in paralysis of the trapezius muscle, causing the characteristic shoulder droop, aching, and weakened abduction above the horizontal plane.

1. A 48-year-old female undergoes a total thyroidectomy for a large multinodular goiter. Twelve hours post-operatively, she develops acute inspiratory stridor and respiratory distress, requiring emergency re-intubation. Laryngoscopy reveals bilateral vocal cords in a paramedian position. Which muscle’s iatrogenic paralysis is the most likely cause of this life-threatening airway compromise?

• Posterior cricoarytenoid

  
  

• Cricothyroid

• Genioglossus

• Cricopharyngeus

Answer explanation

The posterior cricoarytenoid is the sole abductor of the vocal cords. Its bilateral paralysis, a risk in thyroid surgery due to recurrent laryngeal nerve injury, leads to unopposed adduction and catastrophic airway obstruction.

During the interpretation of a lateral cervical spine radiograph for a foreign body ingestion, a radiopaque object is visualized anterior to the vertebral body of C5. Based on standard anatomical relations, within which subdivision of the pharynx is this object most likely located?

• Laryngopharynx

• Oropharynx

• Nasopharynx

• Esophagus

Answer explanation

The laryngopharynx, the most inferior part of the pharynx, extends from the superior border of the epiglottis to the inferior border of the cricoid cartilage, corresponding to vertebral levels C4 to C6.