NEET-PG 2015 - Anatomy Practice Questions

Q: Locking of the knee involves which of the following?

Internal rotation of the femur with the foot on the ground. ***Internal rotation of the femur with the foot on the ground*** - When the foot is on the ground (closed kinematic chain), the **femur rotates internally on the tibia** during the end stages of knee extension. This creates a more stable, "locked" position of the knee. - This **terminal rotation of the femur** increases the contact area and tension in the cruciate ligaments, enhancing joint stability for weight-bearing. *Internal rotation of the tibia with the foot on the ground* - This describes the action of the **popliteus muscle** when "unlocking" the knee from full extension, not the locking mechanism itself. - With the foot on the ground, the tibia is fixed, and internal rotation would typically be a movement for unlocking, not locking. *Contraction of the popliteus muscle* - The **popliteus muscle** is primarily responsible for **unlocking the knee** from full extension, by causing internal rotation of the tibia (or external rotation of the femur). - Its contraction would lead to initial flexion of the knee, releasing the locked position, not establishing it. *External rotation of femur with the foot off the ground* - With the foot off the ground (open kinematic chain), **external rotation of the tibia** occurs during the final degrees of extension to lock the knee, not external rotation of the femur. - The locking mechanism requires specific relative rotation between femur and tibia; external rotation of the femur alone would not achieve the screw-home mechanism necessary for knee locking.

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

Locking of the knee involves which of the following?

Accepted Answer

Internal rotation of the femur with the foot on the ground

Answer

Internal rotation of the tibia with the foot on the ground

Answer

Contraction of the popliteus muscle

Answer

External rotation of femur with the foot off the ground

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