Anatomy-7

A 4-month-old male infant is brought to the
clinic because of excessive noisy respiration.
On examination, the infant is within the normal
range of growth, appears healthy, and does not
show respiratory distress. Phonation is normal,
along with head and neck examination findings.
However, the child displays stridor (highpitched
breathing sound) on inspiration,
accentuated in the supine position. The parents
report that the same stridor is heard
during feeding or when the child is agitated.
The attending physician places the child in the
prone position and the stridor is relieved. To
confirm, she holds the child in a neck extended
position, which also relieves the stridor. An
endoscopic laryngeal examination reveals
bulky arytenoids cartilages and the diagnosis
of laryngomalacia is established. During development,
the arytenoids cartilages arise from
which of the following?
(A) first pharyngeal arch
(B) second pharyngeal arch
(C) third pharyngeal arch
(D) fifth pharyngeal arch
(E) sixth pharyngeal arch

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Anatomy-5

A10-year boy is examined because his parents
noticed that “his eyes never seem to look in
the right direction.” On examination, the left
eye of the child is unable to move laterally
(abduction) and when asked to look toward
the nose (adduction), the eyeball retracts into
the socket and the eye opening narrows.
Sometimes, the eye also moves superiorly. The
child is diagnosed with Duane syndrome, a
congenital ocular motility disorder characterized
by limited abduction of the affected eye.
This is due to absence of the abducens (fifth
cranial) nerve with aberrant innervation by the
oculomotor (third cranial) nerve. Which of the
following muscles is normally innervated by
the abducens nerve?
(A) inferior oblique
(B) lateral rectus
(C) medial rectus
(D) superior oblique
(E) superior rectus

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Anatomy-3

The third week of development is characterized
by the appearance of the branchial apparatus,
the embryonic primordium from which head
and neck structures will be derived. The apparatus
consists of five branchial arches, numbered
1, 2, 3, 4 and 6. Second arch anomalies
represent 95% of all branchial anomalies and
are classified into four types with types I–III
being the most common. The anomalies manifest
as cysts or fistulae in the lateral neck,
located anterior and deep to the sternocleidomastoid
muscle. Which of the following structures
develop from the second branchial arch?
(A) anterior digastric muscle
(B) posterior cricoarytenoideus muscle
(C) posterior digastric muscle
(D) stylopharyngeus muscle
(E) superior constrictor muscle

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Anatomy-2

An 8-year-old boy is referred to a neurologist
by his family physician because he has developed
progressive slow and clumsy walking.
On examination, the patient has difficulty with
standing and running. While standing, he
adopts a wide-based gait with constant shifting
of position to maintain his balance. Sitting or
standing, he also displays a constant tremor of
the head and trunk. When asked to walk, his
feet strike the ground in an uneven and irregular
rhythm; if he attempts to correct his imbalance,
he displays wild and abrupt movements.
A magnetic resonance image (MRI) reveals
demyelination in the dorsal columns, corticospinal
and spinocerebellar tracts. The child is
diagnosed with Friedreich’s ataxia, an autosomal
recessive neurological disorder resulting
from mutation of a gene locus on chromosome 9.
Second-order neurons of the dorsal (posterior)
spinocerebellar tracts are located in which of
the following?
(A) deep cerebellar nuclei
(B) dorsal root ganglion
(C) nucleus cuneatus
(D) nucleus dorsalis (Clarke’s column)
(E) Rexed’s lamina IX of the spinal cord

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Anatomy-1

A 2-year-old male patient develops progressive
generalized weakness and muscle atrophy.
The impairment first began with the muscles of
the hips, and then progressed to the pelvic area,
thigh, and shoulder muscles. The patient is
diagnosed with Duchenne’s muscular dystrophy,
a congenital disorder where the protein
dystrophin is deficient. Which of the following
describes the role of dystrophin in muscle
tissue?
(A) anchors actin to the sarcolemma
(B) endows the myosin filaments with elastic
recoil properties
(C) extends from Z disk to Zdisk, forming a
supportive network
(D) inhibits the binding of myosin to actin
(E) protects desmin filaments from stressinduced
damage

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