127. Anatomy | The Orbit and Extraocular Muscles

A 27-year-old male presents after being struck in the face with a baseball. He reports diplopia when looking upward. CT shows inferior displacement of orbital fat into the maxillary sinus. On exam, he cannot elevate the eye when adducted. What structure is entrapped?
A. Superior rectus
B. Inferior oblique
C. Inferior rectus
D. Superior oblique
E. Levator palpebrae superioris

B

A. Superior rectus — ❌

Elevates the abducted eye (not the adducted eye). Not the correct functional deficit.

B. Inferior oblique — ✅

Responsible for elevation of the adducted eye (simple-movement summary slide). Entrapment → inability to elevate when adducted.

C. Inferior rectus — ❌

Depresses the abducted eye; entrapment would impair depression, not elevation.

D. Superior oblique — ❌

Depresses the adducted eye; not involved in elevation loss.

E. Levator palpebrae — ❌

Raises eyelid, not globe movement.

A 34-year-old woman presents with vertical diplopia that worsens when walking downstairs. When asked to tilt her head to the left, her right eye demonstrates excess elevation instead of maintaining level gaze.

Which nerve is most likely affected?

A. Right oculomotor nerve (superior division)
B. Right oculomotor nerve (inferior division)
C. Right trochlear nerve
D. Left trochlear nerve
E. Left abducens nerve

C

• Head-tilt test = Bielschowsky sign ().

• When tilting the head toward the affected side, the eye elevates because the superior oblique fails, leaving unopposed superior rectus elevation.

Here, tilting head left → problem appears in right eye → right trochlear nerve palsy.

A. Right oculomotor (superior division) — ❌

Would affect levator + superior rectus. Does NOT produce Bielschowsky sign.

B. Right oculomotor (inferior division) — ❌

Would affect inferior oblique, medial rectus, inferior rectus. Pattern doesn’t match.

C. Right trochlear nerve — ✅

Superior oblique dysfunctional → cannot counteract superior rectus’s elevation → eye elevates during head tilt toward the opposite side (consistent with transcript description).

D. Left trochlear nerve — ❌

Would affect left eye movements, not right.

E. Left abducens nerve — ❌

Abducting deficit, not torsion deficit.

During an H-test, a clinician asks a patient to look laterally, and then up. The patient is unable to elevate the abducted eye, though other movements appear normal.

Which extraocular muscle is dysfunctional?

A. Inferior oblique
B. Superior oblique
C. Superior rectus
D. Inferior rectus
E. Medial rectus

C

A. Inferior oblique — ❌

Elevates the adducted eye.

B. Superior oblique — ❌

Depresses the adducted eye. Opposite function.

C. Superior rectus — ✅

Primary elevator of the abducted eye → failure to elevate when abducted = SR dysfunction.

D. Inferior rectus — ❌

Depresses abducted eye.

E. Medial rectus — ❌

Only adducts; no elevation role.

A patient tilts their head to the right. The left eye performs appropriate extorsion to maintain level gaze. Which pair of muscles is MOST responsible for producing smooth extorsion without elevation or depression?

A. Inferior rectus + inferior oblique
B. Inferior oblique + medial rectus
C. Superior oblique + superior rectus
D. Superior rectus + inferior oblique
E. Lateral rectus + medial rectus

A

• Extorsion occurs via inferior rectus + inferior oblique (complex torsion slide, extorsion without elevation/depression) ().

• Their elevation/depression effects cancel, leaving pure extorsion.

A. Inferior rectus + inferior oblique — ✅

Correct torsion pair.

B. Inferior oblique + medial rectus — ❌

MR only adducts; no torsion component.

C. Superior oblique + superior rectus — ❌

These both produce intorsion, not extorsion.

D. Superior rectus + inferior oblique — ❌

These form the elevation-without-torsion pair, not extorsion.

E. Lateral + medial rectus — ❌

Horizontal movers only; no torsion.