A 19-year-old college student squeezes a boil on his upper lip. Four days later he has high fever, headache, swelling of both eyelids and proptosis of the right eye. Along which venous route did the infection most likely reach the cranial cavity?

Angular and superior ophthalmic veins

Retromandibular and external jugular veins

Diploic veins of the frontal bone

Orbit, cavernous sinus and skull foramina

8 NEET-PG practice questions on Orbit, cavernous sinus and skull foramina, part of Anatomy. The first 8 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Hard
A 22-year-old man was punched in the right eye at a wedding. CT shows a fracture of the floor of the right orbit with orbital fat and muscle herniating into the maxillary sinus. The doctor considers four findings: 1. Numbness of the right cheek and upper lip. 2. Double vision on looking up. 3. Enophthalmos once the swelling settles. 4. Loss of the right corneal reflex. Which findings are expected from this injury?
1. A1, 2, 3 and 4
2. B1 and 4 only
3. C1, 2 and 3 only
4. D2 and 3 only
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Answer: C · 1, 2 and 3 only
Statements 1, 2 and 3 are correct. In a blow-out fracture the thin orbital floor gives way; the infraorbital nerve, which runs in the groove and canal of the floor, is damaged and numbs the cheek and upper lip. The inferior rectus and surrounding tissue can be trapped in the fracture, restricting upward gaze (positive forced duction test), and loss of orbital volume causes enophthalmos. The cornea is supplied by the ophthalmic division of the trigeminal nerve, which is not in the floor, so the corneal reflex is preserved.
- A: Includes loss of the corneal reflex; the ophthalmic nerve is not in the orbital floor.
- B: Includes loss of the corneal reflex and omits restricted upgaze and enophthalmos.
- D: Omits numbness from injury to the infraorbital nerve in the orbital floor.
Question 2 · Medium
After a fall from a terrace, a 44-year-old man has a fracture of the sphenoid bone near the right orbit on CT. His right upper eyelid droops completely, the right eye cannot move in any direction, the right pupil is dilated and the forehead is numb. Visual acuity is 6/6, and light shone into the right eye makes the left pupil constrict briskly. Where is the lesion?
1. AOptic canal
2. BSuperior orbital fissure
3. CInferior orbital fissure
4. DOrbital apex
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Answer: B · Superior orbital fissure
Involvement of the oculomotor, trochlear and abducens nerves with the ophthalmic division of the trigeminal nerve and normal vision is the superior orbital fissure syndrome. These nerves, with the superior ophthalmic vein, enter the orbit through the fissure, while the optic nerve passes separately through the optic canal. If vision is also lost, the lesion has extended to the orbital apex. Normal sensation of the cheek also helps, as the maxillary nerve leaves the skull through the foramen rotundum, not the fissure.
- A: An optic canal lesion causes visual loss without ophthalmoplegia.
- C: The inferior orbital fissure carries the infraorbital nerve and vessels, not the nerves to the eye muscles.
- D: Orbital apex syndrome includes the optic nerve, so vision would be reduced.
Question 3 · Hard
A 58-year-old woman has had headache for 3 months. Her right eyelid droops completely and the right eye does not move in any direction. She has numbness over the right forehead and over the right cheek and upper lip, but sensation of the chin and the power of chewing are normal. Visual acuity is 6/6 and the visual fields are full. Where is the lesion most likely?
1. ARight cavernous sinus
2. BRight orbital apex
3. CRight trigeminal ganglion
4. DRight superior orbital fissure
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Answer: A · Right cavernous sinus
Paralysis of all the nerves to the eye muscles with numbness in the ophthalmic and maxillary areas, but sparing of the mandibular division and of vision, localises to the cavernous sinus. The oculomotor, trochlear, ophthalmic and maxillary nerves lie in its lateral wall and the abducens nerve runs through it, while the mandibular nerve leaves the ganglion directly through the foramen ovale without entering the sinus. The superior orbital fissure does not carry the maxillary nerve, and an apex lesion would affect vision. Causes include pituitary tumours extending laterally, meningiomas and aneurysms, so MRI is the next step.
- B: An orbital apex lesion would involve the optic nerve and reduce vision.
- C: A lesion of the ganglion would also numb the chin and weaken chewing, and spare eye movements.
- D: A superior orbital fissure lesion would spare the maxillary nerve and the cheek.
Question 4 · Easy
A 25-year-old man is hit on the side of the head by a cricket ball. He is lucid for a few hours and then becomes drowsy; CT shows a biconvex hyperdense collection beneath a fracture of the squamous temporal bone. The torn artery entered the skull through the:
1. AForamen ovale
2. BForamen lacerum
3. CForamen rotundum
4. DForamen spinosum
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Answer: D · Foramen spinosum
A lucid interval followed by deterioration and a biconvex collection is an extradural haematoma, most often from tearing of the middle meningeal artery under the thin bone at the pterion. The middle meningeal artery, a branch of the maxillary artery, enters the middle cranial fossa through the foramen spinosum. It runs in a groove on the inner surface of the squamous temporal and parietal bones, where fractures tear it. Urgent craniotomy and evacuation saves life.
- A: The foramen ovale transmits the mandibular nerve and the accessory meningeal artery.
- B: The foramen lacerum is closed by cartilage in life; the internal carotid artery passes over it.
- C: The foramen rotundum transmits the maxillary nerve.
Question 5 · Easy
A 19-year-old college student squeezes a boil on his upper lip. Four days later he has high fever, headache, swelling of both eyelids and proptosis of the right eye. Along which venous route did the infection most likely reach the cranial cavity?
1. ARetromandibular and external jugular veins
2. BParietal emissary veins
3. CAngular and superior ophthalmic veins
4. DDiploic veins of the frontal bone
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Answer: C · Angular and superior ophthalmic veins
The upper lip and side of the nose drain to the facial vein, which communicates at the medial angle of the eye through the angular vein with the superior ophthalmic vein, a tributary of the cavernous sinus. Infection can spread along this route to cause septic cavernous sinus thrombosis, which is why this region is called the danger area of the face. Fever, chemosis, proptosis and ophthalmoplegia, soon on both sides, are typical. Treatment is urgent intravenous antibiotics, and boils in this area should never be squeezed.
- A: The retromandibular and external jugular veins drain away from the cranial cavity.
- B: Parietal emissary veins link the scalp, not the lip, to the superior sagittal sinus.
- D: Frontal diploic veins drain the frontal bone and are not linked to the lip.
Question 6 · Medium
Six weeks after a road traffic accident with a skull base fracture, a 28-year-old man notices that his right eye is bulging and red. The eye pulsates, he hears a whooshing noise in his head, and a bruit is heard with the stethoscope over the closed right eye. There are dilated, tortuous conjunctival vessels and chemosis. What is the most likely diagnosis?
1. ACarotid-cavernous fistula
2. BRetrobulbar haemorrhage
3. COrbital cellulitis
4. DCavernous sinus thrombosis
Answer and explanation in LearnFree account
Question 7 · Medium
A 68-year-old woman with trigeminal neuralgia affecting her lower jaw and cheek has not responded to carbamazepine and is unfit for open surgery. A neurosurgeon plans percutaneous radiofrequency treatment of the trigeminal ganglion, passing a needle through the cheek towards the skull base. Through which foramen does the needle reach Meckel's cave?
1. AForamen lacerum
2. BForamen spinosum
3. CForamen rotundum
4. DForamen ovale
Answer and explanation in LearnFree account
Question 8 · Medium
A 62-year-old woman has a large aneurysm of the cavernous part of the left internal carotid artery. Her first and only symptom so far is horizontal double vision; her left eye cannot abduct, while other eye movements, pupils and facial sensation are normal. Why is this nerve affected first?
1. AIt runs through the sinus beside the artery
2. BIt is the lowest nerve in the lateral wall
3. CIt lies in the lateral wall above the oculomotor nerve
4. DIt lies in the medial wall next to the sphenoid sinus
Answer and explanation in LearnFree account

Orbit, cavernous sinus and skull foramina

A 25-year-old man is hit on the side of the head by a cricket ball. He is lucid for a few hours and then becomes drowsy; CT shows a biconvex hyperdense collection beneath a fracture of the squamous temporal bone. The torn artery entered the skull through the:

A 19-year-old college student squeezes a boil on his upper lip. Four days later he has high fever, headache, swelling of both eyelids and proptosis of the right eye. Along which venous route did the infection most likely reach the cranial cavity?

A 62-year-old woman has a large aneurysm of the cavernous part of the left internal carotid artery. Her first and only symptom so far is horizontal double vision; her left eye cannot abduct, while other eye movements, pupils and facial sensation are normal. Why is this nerve affected first?