Block 5 Anat Orbit & Ear From Ta's W Expl
Questions and Answers
- 1.
Mr. Smith presents to your clinic this morning complaining of frequent headaches that he has been having for the past week. After taking a thorough HPI and past medical history, Mr. Smith tells you that he bumped his head last month while skiing with family over the Christmas break. He didn't think much of it until his headaches became more frequent and more severe in intensity. Furthermore, Mr. Smith notices diplopia when reading his favorite book. Concerned for his well-being and given the history of head trauma and recent headaches, you decide that it be best to get an MRI of Mr. Smith's head. But before sending him for imaging, you conduct an H-test. When moving your finger medially, and superiorly, Mr. Smith's left eye is able to move inward towards the nose, but fails to follow your finger upwards. The nerve that is MOST LIKELY damaged carries which modalities?
- A.
GSA, GSE, SVA
- B.
SSA
- C.
GSA, GSE, GVE
- D.
GSE, GVE
- E.
GSE
- F.
SVA
- G.
SSA, GSE, GSA
Correct Answer
D. GSE, GVEExplanation
Remember the action of the extraocculomotor muscles are different than the muscles that you are testing when conducting the H-Test! In this question, when you bring the left eye medially, you are effectively isolating the function of superior and inferior oblique muscles. The questions stem states that when the left eye is placed in the medial position, the patient is UNABLE to move that eye in the UPWARD direction suggesting paralysis/paresis of the inferior oblique muscle (IO). IO is innervated by the occulomotor nerve (CNIII). CNIII carries GSE AND GVE ONLY.Rate this question:
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- 2.
A patient presents to you with presbyopia. You suspect that the lens, due to aging, has become less flexible. The muscle and ganglion responsible for accommodation are:
- A.
Ciliary muscle, otic ganglion
- B.
Sphincter pupillae, ciliary ganglion
- C.
Dilator pupillae, otic ganglion
- D.
Dilator pupillae, pterygopalantine ganglion
- E.
Sphincter pupillae, pterygopalantine ganglion
- F.
Ciliary muscle, ciliary ganglion
Correct Answer
F. Ciliary muscle, ciliary ganglionExplanation
Presbyopia is when the lens has difficulty focusing. When the ciliary muscle contracts, it provides slack to the zonular fibers which allows the lens to form a more convex shape which is necessary for viewing objects up close. The inferior division of the oculomotor nerve synapses in the ciliary ganglion. From there the short ciliary nerves go on to provide parasympathetic innervation to the ciliary muscle and sphincter pupillae muscle.Rate this question:
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- 3.
You are shadowing a general practitioner during a physical exam. You observe the doctor performing the H-test on the patient. You notice that the patient's right eye does not abduct. Which of the following muscles or nerve is most likely damaged?
- A.
Abducens nerve
- B.
Frontal nerve
- C.
Trochlear nerve
- D.
Optic nerve
- E.
Opthalmic nerve
- F.
Medial rectus
Correct Answer
A. Abducens nerveExplanation
H-test or not, the inability to abduct (laterally rotate) the eye involves a lesion to either the lateral rectus muscle itself or the nerve supplying it (abducens nerve, CN VI). So we can pick the abducens nerve. The frontal nerve (Answer B) supplies the eyelid and part of the forehead (sensory). The trochlear nerve (Answer C) supplies the superior oblique and the resting patient will present with the eye adducted and raised due to the predominating occulomotor nerve or will be unable to depress and adduct the eye on an H test (see lecture 3 notes). The optic nerve (Answer D) is responsible for vision and has no motor functions. The opthalmic nerve (Answer E), also known as V1 provides sensation to the upper face and eye, but has no motor function. The medial rectus (Answer F) is responsible for medial rotation, but the stem was speaking of an error in lateral rotation.Rate this question:
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- 4.
Which path correctly displays the innervation of the lacrimal gland?
- A.
CN VII → Lesser Petrosal Nerve → PPG → Nerve of Pterygoid Canal → Zygomatic Nerve → Lacrimal Nerve
- B.
CN IX → Greater Petrosal Nerve → Nerve of Pterygoid Canal → PPG → Zygomatic Nerve → Lacrimal Nerve
- C.
CN VII → Greater Petrosal Nerve → Nerve of Pterygoid Canal → PPG → Zygomatic Nerve → Lacrimal Nerve
- D.
CN IX → Tympanic Nerve → Otic Ganglion → Zygomatic Nerve → Lacrimal Nerve
Correct Answer
C. CN VII → Greater Petrosal Nerve → Nerve of Pterygoid Canal → PPG → Zygomatic Nerve → Lacrimal NerveExplanation
The correct answer is CN VII → Greater Petrosal Nerve → Nerve of Pterygoid Canal → PPG → Zygomatic Nerve → Lacrimal Nerve. This pathway correctly displays the innervation of the lacrimal gland. The lacrimal gland is innervated by the parasympathetic fibers of the greater petrosal nerve, which synapse in the pterygopalatine ganglion (PPG). From there, the postganglionic fibers travel through the nerve of the pterygoid canal and join the zygomatic nerve, which finally innervates the lacrimal gland.Rate this question:
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- 5.
A patient is seen for a physical. The physician performs an H-test for the extrinsic muscles. The patient complains that he sees double like two pictures next to each other horizontally when looking to the side. Which extrinsic muscle is most likely responsible?
- A.
Medial rectus
- B.
Lateral rectus
- C.
Inferior oblique
- D.
Medial rectus and Inferior rectus
Correct Answer
B. Lateral rectusExplanation
The patient is having horizontal diplopia. The medial rectus performs adduction, but superior rectus as well as inferior rectus perform a part of adduction. The lateral rectus is the only one innervated by the abducens nerve, so if there is a lesion then the lateral rectus will cause the pictures to widen and diplopia will occur. The superior oblique muscles contribute to vertical diplopia.Rate this question:
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- 6.
A 42-year-old woman went to see her primary care physician because she was having difficulty blinking while cleaning dusty areas within her home. The physician proceeds to elicit the corneal reflex test using a cotton wisp. Which of the following are the correct nerves associated with the corneal reflex test?
- A.
Afferent via CN V1; efferent via CN V2
- B.
Afferent via CN III; efferent via CN VII
- C.
Afferent via CN V2; efferent via CN VII
- D.
Afferent via CN III; efferent via CN V3
- E.
Afferent via CN V1; efferent via CN VII
Correct Answer
E. Afferent via CN V1; efferent via CN VIIExplanation
The corneal reflex arc utilizes CN V1 as the sensory component while the efferent motors are sent through CN VII to close the eyelid upon detection of a foreign body on the cornea.Rate this question:
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- 7.
An 85-year-old man is found unconscious in his apartment by one of his neighbors; the neighbors proceed to call 9-1-1 and the paramedics soon arrive. The paramedics quickly assess the situation and proceed to shine light into the eyes of the 85-year-old man to elicit which of the following responses?
- A.
Parasympathetic muscle contraction of the sphincter pupillae muscle, innervated by CN III
- B.
Parasympathetic muscle contraction of the sphincter pupillae muscle, innervated by cervical nerve T1
- C.
Parasympathetic muscle dilation of the dilator pupillae muscle innervated, by cervical nerve T1
- D.
Sympathetic muscle contraction of the ciliary muscle for near vision accommodation, innervated by CN III
- E.
Sympathetic muscle contraction of the sphincter pupillae muscle, innervated by CN III
Correct Answer
A. Parasympathetic muscle contraction of the sphincter pupillae muscle, innervated by CN IIIExplanation
The parasympathetic response of light entering the eye elicits pupillary constriction by the sphincter pupillae muscle, which is innervated by CN III.Rate this question:
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- 8.
A 13-year-old boy presents to the emergency room with a fever and deficits in extraocular movements. On exam, the physician notes the patient’s face to show signs of acneiform pustules with inflammation. Which of the following is located near the location to which infection has most likely spread in this patient?
- A.
Parotid gland
- B.
Pituitary gland
- C.
Submandibular gland
- D.
Submental gland
- E.
Confluence of the sinuses
Correct Answer
B. Pituitary glandExplanation
The pituitary gland is located closest to the cavernous sinus, inflammation of which (due to infection spread from the ‘danger triangle’ of the face) has most likely compressed the nerves controlling extraocular muscle movements. None of the other structures, even if enlarged, would present with this set of symptoms.Rate this question:
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- 9.
A medical student is performing an examination of extraocular eye movements on a patient at a community clinic. While performing the H-test, the student notes that the patient cannot depress his left eye following adduction. The student correctly reports to his attending physician that the patient has a possible palsy of which cranial nerve?
- A.
CN III
- B.
CN IV
- C.
CN V
- D.
CN VI
- E.
CN VII
Correct Answer
B. CN IVExplanation
This is a deficit of the superior oblique muscle, innervated by CN IV (trochlear). CN VI (abducens) innervates the lateral rectus muscle, which abducts the eye. CN III innervates all extraocular muscles of the eye not innervated by CN IV or VI, as well as providing parasympathetic branches via the ciliary ganglion to the sphincter pupillae and ciliary muscle, and to the levator palpebrae muscle. CN V (trigeminal) provides sensory innervation to the face and motor innervation to muscles of mastication. CN VII (facial) provides motor innervation to the muscles of facial expression.Rate this question:
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- 10.
A 23-year-old girl had a sudden onset of loss of tear secretion and left-sided hearing loss. A CT scan revealed a mass in the left middle cranial fossa. A neurosurgery resident, amazed that he recognized an extremely rare condition, ran to tell his attending physician. Being well-versed in the pathways of cranial nerves, which of the following did he recognize as the cause of the girl’s symptoms?
- A.
Deep petrosal nerve
- B.
Supraorbital nerve
- C.
Anterior ethmoidal nerve
- D.
Supratrochlear nerve
- E.
Greater petrosal nerve
Correct Answer
E. Greater petrosal nerveExplanation
This was actually a real case (Paulis DD, Cola FD, Marzi S, Ricci A, Coletti G, Galzio RJ. A rare case of greater petrosal nerve schwannoma. Surg Neurol Int 2011;2:60), where a 23-year-old girl developed a schwannoma of the left greater petrosal nerve. (The addition of the excitable neurosurgery resident was my own contribution. I don’t know if that actually happened; probably not.) The greater petrosal nerve, a branch of the facial nerve, contains parasympathetic fibers and receives sympathetic fibers from the deep petrosal nerve (a lesion of which would increase tearing, not decrease it), subsequently proceeding as the nerve of the pterygoid canal to the pterygopalatine ganglion, with the zygomatic nerve and to the lacrimal nerve (a branch of CN V1), finally terminating in the lacrimal gland. The supraorbital and supratrochlear nerves are branches of CN V1 providing sensory innervation to the forehead and anterior scalp. The anterior ethmoidal nerve is a sensory nerve of the nasal cavity.Rate this question:
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- 11.
Rupture of the annulus tendinosus would impair muscles innervated by what nerve(s)?
- A.
Cranial Nerve III
- B.
Cranial Nerve IV
- C.
Cranial Nerve VI
- D.
All of the above
- E.
Cranial Nerves III and VI
Correct Answer
E. Cranial Nerves III and VIExplanation
The annulus tendinosus is the common origin for Superior, Medial, Lateral and Inferior Rectus muscles.Rate this question:
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- 12.
A patient presents to your clinic with suspected extraocular muscle damage. Upon an H-test, the patient is unable to depress his left eye when the eye is adducted. Which of the following pair correctly identifies the damaged muscle and nerve?
- A.
Superior Rectus; Trochlear Nerve
- B.
Superior Rectus; Oculomotor Nerve
- C.
Superior Oblique; Trochlear Nerve
- D.
Superior Oblique; Oculomotor Nerve
- E.
Superior Oblique; Abducens Nerve
Correct Answer
C. Superior Oblique; Trochlear NerveExplanation
Superior oblique is innervated by the trochlear nerve and is responsible for moving the eye inferiorly (depressed) once adductedRate this question:
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- 13.
Which of the following actions/senses would most likely be spared with an occlusion blocking the nerves traveling through the superior orbital fissure?
- A.
Adducting the eye
- B.
Abducting the eye
- C.
Constricting the pupil
- D.
Sensing light
Correct Answer
D. Sensing lightExplanation
The optic nerve, CN II, passes through the optic canal. The rest of the nerves dealing with the eye (CN III, IV, and VI) travel through the superior orbital fissure.Rate this question:
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- 14.
A fracture of the roof of the orbit is most likely to cause damage to which part of the eye FIRST?
- A.
Superior oblique
- B.
Superior rectus
- C.
Levator palpebrae superioris
- D.
Optic nerve
- E.
Ophthalmic artery
Correct Answer
C. Levator palpebrae superiorisExplanation
The levator palebrae superioris lies superior (closer to the roof) than all other structures.Rate this question:
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- 15.
After a physical examination on your patient you realize that he/she has ptosis in the right eye; this is an indication of paralysis of which muscle ?
- A.
Orbicularis oris
- B.
Orbicularis oculi
- C.
Levator palpebrae muscle
- D.
Superior Oblique muscle
Correct Answer
C. Levator palpebrae muscleExplanation
Remember that the Orbicularis oculi is what closes the eyelid and the levator palpebrae muscle is what opens it .Rate this question:
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- 16.
The constriction of the pupil is innervated by parasympathetic nervous system. Which nerve branch carries the parasympathetic innervation and in what ganglion does it synapse?
- A.
Infratrochlear n., ciliary ganglion
- B.
Short ciliary n., ciliary ganglion
- C.
Long ciliary n., otic ganglion
- D.
Short ciliary n., otic ganglion
Correct Answer
B. Short ciliary n., ciliary ganglionExplanation
From the ciliary ganglion, the short ciliary nerves branch to bring parasympathetic innervation to the sphincter muscle of the eye. The long ciliary nerves are responsible for dilation.Rate this question:
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- 17.
You are examining a patient with a Berry aneurysm in the circle of Willis. While performing a preliminary eye exam, you suspect the aneurysm is compressing and causing paralysis of the right oculomotor nerve. When observing the eye, what physical findings would you most likely find?
- A.
Right eye presenting down and out with miosis.
- B.
Left eye presenting up and in with miosis.
- C.
Right eye presenting down and out with mydriasis.
- D.
Left eye presenting up and in with mydriasis.
- E.
Right eye presenting up and in with miosis.
- F.
Left eye presenting down and out with miosis.
- G.
Right eye presenting up and in with mydriasis.
- H.
Left eye presenting down and out with miosis.
Correct Answer
C. Right eye presenting down and out with mydriasis.Explanation
The question is asking about a right occulomotor nerve palsy which would be affecting the right eye only. The occulomotor nerve (CNIII) carries GSA motor fibers to medial rectus, superior rectus, inferior rectus, and inferior oblique. In CNIII palsy this would only leave the right lateral rectus and right superior oblique muscles in tact bringing the right eye down and out. CNIII also carries GVE parasympathetic nerve fibers from the Edinger-Westphal nucleus giving input to constrict the pupil (miosis). In CNIII palsy, the loss of these fibers would limit the eye’s ability to constrict the pupil, causing the eye to be dilated (mydriasis). (B), (D), (F), and (H) are wrong because the question is referring to the right occulomotor nerve. The occulomotor nerve is a LMN and will not decussate and provide innervation to the opposite eye. Therefore, the left eye would observe no change. c(A) is wrong because without GVE fibers from Edinger-Westphal the eye would be dilated not constricted. (E) is wrong because with CNIII palsy you are only left with lateral rectus and superior oblique in-tact bringing the eye down and out. Also, without GVE fibers from Edinger-Westphal, the eye would be dilated not constricted. The right eye would be dilated; however, (G) is wrong because with CNIII palsy you are only left with lateral rectus and superior oblique in-tact bringing the eye down and out.Rate this question:
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- 18.
After reviewing the orbit of the eye and relating it to the branches of the sympathetic nervous system as well as parasympathetic you note that Sympathetic fibers begin from the Superior Cervical Ganglion and then enter the face. When examining the eye of a person what do would you notice if they were taking a sympathetic blocking agent?
- A.
Impaired accommodation reflex
- B.
Exopthalmous and with a dilated iris
- C.
Mydriasis with impaired convergence
- D.
Pin point pupils and Ptosis
- E.
Enopthalmous with dry eyes
Correct Answer
D. Pin point pupils and PtosisExplanation
Think about what the sympathetic nerves innervate first when approaching this question. Sympathetic fibers will dilate the pupil and elevate the eye lid via the superior tarsal muscle. Relate this to a clinical situation such as Horner's Syndrome. Classic presentation is Ptosis, Anhydrosis, and Miosis. Instead of remembering Miosis means pin point pupil, it is easier to think of "MyDriasis" as "Dilated" pupils. The emphasis being on the letter "D." Accommodation is not mediated by the sympathetic system, rather it is under strict parasympathetic control and is a great way of ruling out parasympathetic versus sympathetic agents.Rate this question:
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- 19.
Mr. Smith, a 59 year-old, male presents to your ED with multiple lacerations across the forehead and facial region. History of the present illness reveals head trauma involving an automobile collision 30 minutes prior to hospital arrival. Mr. Smith seems confused and delirious as he screams and curses at hospital and law enforcement personnel. Upon physical examination, you notice that the eyes are misaligned on the vertical axis. Mr. Smith experiences diplopia when attempting to lower his field of vision. In particular, the patient has difficulty walking down stairs. Which nerve is MOST likely damaged?
- A.
CN V
- B.
CN III
- C.
CN VI
- D.
CN VII
- E.
CN IV
Correct Answer
E. CN IVExplanation
The clinical vignette describes a clear case of trochlear nerve palsy. The trochlear nerve innervates only one of the extraoccular muscles (EOM) in the orbit; superior oblique muscle. The remaining 5 EOM muscles remain intact allowing unopposed pull. In particular, the inferior oblique muscle will extort the eye (please review anatomical attachments for a complete understanding of this action) leading to the clinical manifestations otherwise seen in these patients. Furthermore, patients will often complain of difficulty in walking down stairs due to their vertical diplopia (double vision). Patients with trochlear nerve palsy will attempt to correct this type of vertical diplopia by tilting their head.Rate this question:
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- 20.
A 35 year old woman presents to your clinic with a slightly drooping eyelid and miosis. Upon examination, you determine that she is suffering from Horner's Syndrome. Which of the following muscles and associated nerve is responsible for the miosis that the patient is presenting with?
- A.
Dilator Pupillae; Oculomotor N. (CN III)
- B.
Superior Tarsal; Oculomotor N. (CN III)
- C.
Dilator Pupillae; Trochlear N. (CN IV)
- D.
Sphincter Pupillae; Oculomotor N. (CN III)
- E.
Ciliary Muscle; Oculomotor N. (CN III)
Correct Answer
D. Sphincter Pupillae; Oculomotor N. (CN III)Explanation
The sphincter pupillae, innervated by the Oculomotor N. (CN III) is responsible for the miosis seen in this patient since the dilator pupillae is no longer working due to the lesion of the sympathetics (Horner's Syndrome).Rate this question:
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- 21.
A 4 year old female is brought into the pediatrician irritable and holding her right ear. Upon examination, the right tympanic membrane is red, swollen and bulging laterally. Otitis media is diagnosed and antibiotics are ordered. Pain due to the ear infection in this patient is referred from the tympanic membrane by what cranial nerve?
- A.
V
- B.
VII
- C.
IX
- D.
X
Correct Answer
C. IXExplanation
The tympanic membrane has different sensory innervation based on what side is in question. The external portion is innervated by both V3 and X, while the inner portion (facing the middle ear and ossicles) is innervated by the glossopharyngeal (IX) nerve. A middle ear infection is placing pressure on the tympanic membrane from the inside (bulging outward) and therefore is carried by sensory fibers on CN IX.Rate this question:
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- 22.
Following a bar fight, a 43 year old male presents to the emergency room with lacerations and bruises over the right temporal, parietal and mandibular areas. The patient complains of dry mouth and inability to taste over the front of his tongue but denies any sensation loss on the floor of his mouth. What is the possible location of nerve damage?
- A.
Lingual nerve as it branches off of V3
- B.
Auriculotemporal nerve as it leaves the otic ganglion
- C.
Greater petrosal nerve as it enters the pterygopalatine ganglion
- D.
Chorda tympani as it passes between ossicles of the middle ear
Correct Answer
D. Chorda tympani as it passes between ossicles of the middle earExplanation
The patient complains of loss of taste on the front of his tongue and dry mouth, indicating that fibers from the chorda tympani nerve have been damaged (SVA - taste and parasympathetics/GVE - submandibular/sublingual glands). However, he denies losing sensation to the floor of his mouth, innervated by fibers from the lingual nerve. Chorda tympani has been damaged before passing its fibers to the lingual nerve, indicating the lesion was somewhere proximal to that point. (A) if the lingual nerve was damaged where it branches off of V3, the patient would have also lost GSA sensory innervation to the floor of his mouth. (B) the auriculotemporal nerve carries postsynaptic fibers from the otic ganglion to the parotid gland and would not present with loss of taste sensation if damaged. (C) the greater petrosal nerve brings presynaptic parasympathetic fibers innervating the lacrimal gland to the pterygopalatine ganglion and, if damaged, would not present with any of the above symptoms.Rate this question:
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- 23.
While listening to his favorite song by Frankie Valli and the Four Seasons, an anatomy TA was impressed that Frankie could sing so well despite being nearly unable to hear himself in the late 1970s. This was due to otosclerosis, which impaired the proper function of his stapes. Assuming his case only affected his left ear initially, a Rinne’s test performed on his right ear would have demonstrated which of the following?
- A.
Air conduction greater than bone conduction
- B.
Bone conduction greater than air conduction
- C.
Equal conduction by bone and air
- D.
Only air conduction
- E.
Only bone conduction
Correct Answer
A. Air conduction greater than bone conductionExplanation
On his unaffected ear, Frankie would have air conduction greater than bone conduction; the reverse (option B) would be true on his left, affected ear. Both are normally present, but air conduction is greater in unaffected ears. It is, actually, true that Frankie Valli sang nearly entirely from memory in the latter half of the 1970s (his conductive hearing loss was bilateral), but his hearing was surgically restored, to the joy of the world, by the 1980s.Rate this question:
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