NEET-PG 2015 - Anatomy Practice Questions

Q: Which of the following statements about the bare area of the liver is false?

It is circular in shape. ***It is circular in shape*** - The bare area of the liver is **triangular** in shape, bordered by the reflections of the **coronary ligaments** and the inferior vena cava. [1] - Its shape is dictated by the anatomical arrangement of these peritoneal folds, making it distinctly non-circular. *Infection can spread from the abdominal to thoracic cavity at this area* - This statement is true because the bare area is the only part of the liver not covered by **peritoneum**, allowing direct contact between the liver and the diaphragm. [1] - This anatomical arrangement facilitates the spread of infections, like **subphrenic abscesses**, from the abdominal cavity to the posterior mediastinum and pleural cavity. [2] *It is not a site of portocaval anastomosis* - This statement is true; there is **no direct portosystemic shunt** at the bare area of the liver that becomes significant in portal hypertension. - While small veins connect the liver capsule to the diaphragm, these do not represent major portocaval anastomoses like those found at the gastroesophageal junction or rectum. *Formed by the reflections of coronary ligaments* - This statement is true; the bare area is specifically demarcated by the points where the **anterior and posterior layers of the coronary ligament** diverge, leaving a triangular region of the liver directly apposed to the diaphragm. [1] - The **coronary ligaments** are reflections of the peritoneum from the diaphragm onto the superior surface of the liver.

Q: Trigone of urinary bladder develops from:

Mesoderm. ***Mesoderm*** - The **trigone** of the urinary bladder develops from the **distal ends of the mesonephric (Wolffian) ducts**, which are **mesodermal in origin**. - These ducts are **absorbed into the posterior wall of the bladder**, forming the smooth triangular area between the two ureteric orifices and the internal urethral orifice [1]. - Although the epithelium of the trigone is later **replaced by endodermal epithelium** from the urogenital sinus, the **structural origin remains mesodermal**. - This is a classic example of **epithelial metaplasia** where endodermal epithelium replaces mesodermal tissue. *Endoderm of urachus* - The **urachus** is the fibrous remnant of the allantois that connects the apex of the bladder to the umbilicus. - It forms the **median umbilical ligament** in adults and does **not contribute to the trigone**. - The **urogenital sinus** (endodermal) forms the majority of the bladder body, but not the trigone. *Ectoderm* - The **ectoderm** forms the nervous system, epidermis, and sensory epithelia. - It does **not contribute** to the development of the urinary bladder or its trigone. - The urinary system is derived from **mesoderm** (kidneys, ureters, trigone) and **endoderm** (bladder body, urethra). *None of the options* - This is incorrect because **mesoderm** is the correct embryological origin of the trigone. - The mesonephric ducts that form the trigone are definitively mesodermal structures.

Q: Foot drop occurs due to the involvement of:

Common peroneal nerve palsy. ***Common peroneal nerve palsy*** - The **common peroneal nerve** (also known as the common fibular nerve) innervates the muscles responsible for **dorsiflexion** and eversion of the foot (tibialis anterior, extensor hallucis longus, extensor digitorum longus, peroneus longus and brevis). - Damage to this nerve leads to weakness or paralysis of these muscles, resulting in **foot drop**, which is the most common neurological cause. - The nerve is vulnerable at the **neck of the fibula** where it is superficial and can be compressed or injured. *Sciatic nerve* - The **sciatic nerve** divides into the tibial and common peroneal nerves. - Proximal sciatic nerve injury can cause foot drop, but it would also cause additional deficits including hamstring weakness, loss of ankle plantarflexion, and sensory loss over a wider distribution. - Isolated foot drop typically indicates **common peroneal nerve** injury, not sciatic nerve injury. *Direct injury to the dorsiflexors* - Direct trauma to the **dorsiflexor muscles** (tibialis anterior, extensor hallucis longus, extensor digitorum longus) can mechanically impair dorsiflexion. - However, the term "foot drop" typically refers to **neurological causes** rather than direct muscle injury, making common peroneal nerve palsy the more specific answer. *Obturator nerve* - The **obturator nerve** innervates the **adductor muscles of the thigh** (adductor longus, adductor brevis, adductor magnus, gracilis). - It does not innervate any muscles responsible for dorsiflexion of the foot and therefore **cannot cause foot drop**.

Q: Which of the following is true about keratinocytes?

Ectoderm derived cell. ***Ectoderm derived cell*** - Keratinocytes originate from the **ectoderm**, one of the three primary germ layers in embryonic development, which gives rise to the epidermis. - This ectodermal origin is fundamental to their role in forming the protective outer layer of the skin. *Differentiate in basal layer* - Keratinocytes in the **basal layer (stratum basale)** are primarily responsible for **proliferation** (cell division) rather than differentiation. - **Differentiation** into flattened, keratin-filled cells occurs as they migrate upwards through the epidermal layers. *Mature in basal layer* - Maturation, which involves the accumulation of **keratin** and the loss of organelles, primarily occurs in the **upper layers** of the epidermis (stratum spinosum, granulosum, corneum). - The basal layer is where new cells are generated, not where they reach their mature, fully keratinized state. *Present only in basal layer* - While keratinocytes originate in the basal layer, they are the **predominant cell type throughout all layers of the epidermis**. - They represent approximately 90% of epidermal cells and are found from the stratum basale to the stratum corneum.

Q: Submucosal plexus is -

Meissner's plexus. ***Meissner's plexus*** - The **submucosal plexus** is also known as **Meissner's plexus**, located in the submucosal layer of the **gastrointestinal tract** [1]. - It primarily controls local **secretions**, **absorption**, and **blood flow** within the gut [2]. *Myenteric plexus* - The **myenteric plexus** is also known as **Auerbach's plexus**, located between the longitudinal and circular muscle layers of the **gastrointestinal tract** [1]. - It primarily controls **gastrointestinal motility**, not local secretions [1]. *Tympanic plexus* - The **tympanic plexus** is a network of nerves in the **middle ear** that provides sensory innervation to the tympanic cavity. - It is unrelated to the gastrointestinal tract or its intrinsic nervous system. *Auerbach's plexus* - **Auerbach's plexus** is another name for the **myenteric plexus**, which is located between the muscle layers [1]. - It is responsible for gut motility and distinct from the submucosal plexus.

Q: Which of the following extraocular muscles is not supplied by oculomotor nerve?

Lateral rectus. ***Lateral rectus*** - The **lateral rectus muscle** is innervated by the **abducens nerve (CN VI)**, not the oculomotor nerve (CN III). [1] - Its primary action is **abduction** of the eye, moving it laterally away from the midline. [1] *Inferior oblique* - The **inferior oblique muscle** is innervated by the **oculomotor nerve (CN III)**. [1] - Its actions include **extorsion**, elevation, and abduction of the eye. [1] *Medial rectus* - The **medial rectus muscle** is innervated by the **oculomotor nerve (CN III)**. [1] - Its primary action is **adduction** of the eye, moving it medially towards the midline. [1] *Inferior rectus* - The **inferior rectus muscle** is innervated by the **oculomotor nerve (CN III)**. [1] - Its actions include **depression**, extorsion, and adduction of the eye. [1]

Q: Extensor carpi radialis longus is

Extensor and radial deviator of the wrist. ***Extensor and radial deviator of the wrist*** - The **extensor carpi radialis longus (ECRL)** is one of the primary muscles responsible for **extension of the wrist**. [1] - Due to its anatomical position on the radial side of the forearm, it also contributes significantly to **radial deviation** (abduction) of the wrist. [1] *Weak extensor of the wrist* - While it is an extensor, the ECRL is considered a **strong extensor** of the wrist, especially when acting with other extensors like the Extensor Carpi Radialis Brevis (ECRB). [1] - Its strength is crucial for tasks requiring **grip and wrist stabilization**. *Extensor and ulnar deviator of the wrist* - The ECRL performs wrist extension but causes **radial deviation**, not ulnar deviation. [1] - **Ulnar deviation** is primarily performed by the **extensor carpi ulnaris** and **flexor carpi ulnaris**. *Injured in Posterior interosseous nerve injury* - The ECRL is innervated by the **radial nerve** **before** it divides into the superficial and deep (posterior interosseous) branches. [2] - Therefore, ECRL function is typically **spared in isolated posterior interosseous nerve injuries**, which mainly affect muscles in the deep compartment of the posterior forearm. [2]

Question 1

Which of the following statements about the bare area of the liver is false?

Accepted Answer

It is circular in shape

Answer

It is not a site of portocaval anastomosis

Answer

Formed by the reflections of coronary ligaments

Answer

Infection can spread from the abdominal to thoracic cavity at this area

Question 2

Trigone of urinary bladder develops from:

Accepted Answer

Mesoderm

Answer

Ectoderm

Answer

None of the options

Answer

Endoderm of urachus

Question 3

Foot drop occurs due to the involvement of:

Accepted Answer

Common peroneal nerve palsy

Answer

Obturator nerve

Answer

Sciatic nerve

Answer

Direct injury to the dorsiflexors

Question 4

Which of the following is true about keratinocytes?

Accepted Answer

Ectoderm derived cell

Answer

Differentiate in basal layer

Answer

Mature in basal layer

Answer

Present only in basal layer

Question 5

Submucosal plexus is -

Accepted Answer

Meissner's plexus

Answer

Myenteric plexus

Answer

Tympanic plexus

Answer

Auerbach's plexus

Question 6

Which of the following extraocular muscles is not supplied by oculomotor nerve?

Accepted Answer

Lateral rectus

Answer

Inferior oblique

Answer

Medial rectus

Answer

Inferior rectus

Question 7

Extensor carpi radialis longus is

Accepted Answer

Extensor and radial deviator of the wrist

Answer

Weak extensor of the wrist

Answer

Extensor and ulnar deviator of the wrist

Answer

Injured in Posterior interosseous nerve injury

NEET-PG 2015 — Anatomy