B) The musculocutaneous nerve provides motor innervation for the biceps brachii, coracobrachialis, and brachialis muscle. Its terminal branch is the lateral cutaneous nerve of the forearm. Lesion of the musculocutaneous nerve results in weak flexion of the elbow since the biceps brachii and the brachialis will be paralyzed and this motion will only be performed by the brachioradialis muscle, which is innervated by the radial nerve. Weak supination is caused by the loss of innervation to the biceps brachii, a strong supinator of the forearm. This movement will now be performed only by the small supinator muscle. Anesthesia of the lateral surface of the forearm is due to loss of the lateral antebrachial cutaneous. Loss of the median nerve (choice A) and ulnar nerve (choice E) will result in loss of motor innervation to the flexors of the wrist and fingers. Lesion of the posterior interosseous nerve (choice C) will paralyze extensors of the wrist and fingers, whereas lesion of the radial nerve (choice D) will paralyze the extensor of the elbow as well as those of the wrist and fingers.

Q1) A 50-year-old female has undergone mastectomy for Ca Breast. After mastectomy, patient is not able to extend, adduct and internally rotate the arm. Nerve supply to which of the following muscles is damaged?

Latissimus dorsi •Mastectomy may damage thoracodorsal nerve leading to paralysis of latissimus dorsi. The patient finds difficulty in shoulder extension, medial rotation and adduction.

Q2) A 32-year-old mother complains of serious pain
in the coccygeal area some days after giving birth. To
determine whether the coccyx is involved, a local
anesthetic is fi rst injected in the region of the coccyx
and then dynamic MRI studies are performed. The
MRI reveals coccydynia, which confi rms that her
coccyx dislocates upon sitting. The local anesthetic
is used to interrupt which of the following nerve
pathways?

Q3. A patient presented with acute abdominal pain on clinical suspicion patient underwent cholecystectomy. On histopathological examination the finding is normal. The gallbladder epithelium will be:

Gallbladder is lined by the columnar epithelium with brush border (irregularly placed microvilli).

Q4. An early term embryo spontaneously aborts due to incomplete
lateral body wall folding and failure of the primitive paired
endocardial tubes to merge and form the primitive heart tube.
The endocardial tubes are derived from which of the following
embryonic sources?

Cardiac progenitor cells migrate from the epiblast into the cranial portion of the
splanchnic layer of the lateral plate mesoderm. In the mesoderm,
the progenitor cells ultimately form paired cardiac primordia,
that is, the endocardial tubes. Subsequent lateral and
cephalocaudal folding of the embryo causes merging of the
paired endocardial tubes plus caudal shifting of the primitive
heart tube and pericardial cavity. Choice A (Paraxial mesoderm)
is incorrect. The paraxial mesoderm segments into
somites along the long axis of the body wall. Each somite
ultimately differentiates into three portions: sclerotome, myotome,
and dermatome. Choice B (Intermediate mesoderm)
is incorrect. The intermediate mesoderm is the small portion
of mesoderm that connects the paraxial and lateral plate
mesodermal areas. It differentiates into urogenital organs.
Choice D (Parietal mesoderm) is incorrect. The lateral plate
mesoderm splits into parietal (somatic) and visceral (splanchnic)
parts, separated by the intraembryonic body cavity. The
parietal layer becomes associated with the overlying ectoderm
to form the lateral body wall folds. Choice E (Extraembryonic
mesoderm) is incorrect. This cell population appears outside
the embryonic body proper. It forms a loose connective tissue
zone that eventually results in the chorionic cavity.

Q5 Diagram of fourth ventricle is given with the facial colliculus
marked. Damage to the structure producing the elevation
marked leads to paralysis of which of the following muscle?

• Facial colliculus is a rounded elevation formed by the axons of facial nerve (and not by the abducent nucleus deep to it).
• Damage to the facial nerve axons paralyses muscles of facial expression like risorius.

In this patient, herpes
zoster, or shingles, is a painful skin rash affecting the dermatome
distribution pattern of the left 10th thoracic (T10)
nerve, as evidenced by the involvement of the umbilicus.
Shingles is seen in patients who have had previous exposure
to the varicella zoster virus, which causes chickenpox in children
or young adults. After the initial exposure to chickenpox,
this virus can reside latent in ganglia of an individual for years.
If this individual becomes immunocompromised, the skin (or
dermatomes supplied by the infected ganglia) can develop
shingles, a painful skin rash, which blisters, breaks open,
crusts over, and then disappears. In this patient, the herpetic
lesions were found in the sensory distribution of the left T10
nerve, which means the virus resides in this nerve’s sensory
ganglion, or the spinal ganglion of T10. Remember that two
types of ganglia exist: sensory (afferent) and autonomic. The
sensory ganglia, which are most often affected by shingles, are
equivalent to the spinal (dorsal root) ganglia of spinal nerves
in that they house typical pseudounipolar cell bodies of afferent
neurons and do not contain synapses. If a spinal ganglion
were infected by the varicella zoster virus, shingles may present
in its dermatome distribution patterns when the patient is
immunocompromised. Choice A (Paravertebral ganglion) is
incorrect. The paravertebral (sympathetic) ganglia are located
within the sympathetic trunk. They receive efferent fi bers
from the presynaptic (preganglionic) sympathetic neuro originating in the intermediolateral (IML) cell column of the
thoracic and upper lumbar segments (T1-L2). Due to their
location, these sympathetic ganglia are called paravertebral
ganglia. Before it causes shingles (or herpes zoster), the varicella
zoster virus resides latent in sensory ganglia for many
years. Because the paravertebral ganglia are autonomic ganglia,
it is unlikely they would be responsible for the skin rash
in this patient. Choice B (Prevertebral ganglion) is incorrect.
The prevertebral ganglia are sympathetic ganglia that receive
their name as they are located anterior to the vertebral column,
as distinguished from the ganglia of the sympathetic trunk
(paravertebral ganglia). Prevertebral ganglia exist near major
branches of the abdominal aorta in the abdominopelvic cavity.
These ganglia send postsynaptic (postganglionic) sympathetic
fi bers to the abdominopelvic organs with periarterial plexuses.
Before it causes shingles (or herpes zoster), the varicella zoster
virus resides latent in sensory ganglia for many years. Because
the prevertebral ganglia are autonomic ganglia, it is unlikely
they would be responsible for the skin rash in this patient.
Choice C (Lumbar ganglion) is incorrect. The lumbar ganglia
are paravertebral ganglia located in the abdominopelvic part
of the sympathetic trunk. Before it causes shingles (or herpes
zoster), the varicella zoster virus resides latent in sensory ganglia
for many years. Because the lumbar ganglia are autonomic
ganglia, it is unlikely they would be responsible for the skin
rash in this patient. Choice E (Spinal ganglion of L2) is incorrect.
The spinal (posterior root) ganglion is a sensory ganglion,
so it could be infected by the varicella zoster virus and present
with a painful, skin rash along its dermatome distribution pattern.
The sensory distribution of L2 would extend along the
back, hip, and extend into the anterior and medial aspects of
the thigh. Because this patient presents with a skin rash at the
level of the umbilicus, the spinal ganglion of T10 would be the
source of this painful skin rash

Q7) A 27-year-old man was admitted to the emergency
department after an automobile collision in which he
suffered a fracture of the lateral border of the scapula.
Six weeks after the accident, physical examination reveals
weakness in medial rotation and adduction of the
humerus. Which nerve was most likely injured?