Which of the following is a traction epiphysis ?
Renal papilla opens into -
Which of the following is not a neural plate inducer?
Crural index is:
Unilateral lacrimal gland destruction may be caused by?
Which of the following extraocular muscle has the longest tendon?
After trauma, a person cannot move their eye outward beyond the midpoint. Which nerve is injured?
Most common site for medulloblastoma is-
Which arteries supply the talus?
Which nerve is primarily involved in cubital tunnel syndrome?
NEET-PG 2012 - Anatomy NEET-PG Practice Questions and MCQs
Question 81: Which of the following is a traction epiphysis ?
- A. Tibial condyles
- B. Head of femur
- C. Trochanter of femur
- D. Coracoid process of scapula (Correct Answer)
Explanation: ***Coracoid process of scapula*** - A **traction epiphysis** (also called atavistic epiphysis) serves as an attachment site for muscles and tendons, transferring muscle force to the bone without bearing significant weight or forming articular surfaces. - The **coracoid process** is a classic example, anchoring the **pectoralis minor, coracobrachialis, and short head of biceps brachii**, as well as important ligaments (coracoclavicular and coracoacromial). - It develops from a separate ossification center purely for muscle and ligament attachment, not for articulation or weight-bearing. *Tibial condyles* - The **tibial condyles** are **pressure epiphyses** (articular epiphyses) that form the superior articular surface of the tibia. - They articulate with the femoral condyles to form the knee joint and bear significant weight during standing and movement. - Their primary function is joint formation and contribution to longitudinal bone growth. *Trochanter of femur* - The **greater and lesser trochanters** are large bony prominences that serve as muscle attachment sites, but they are better classified as **apophyses** rather than true traction epiphyses. - An **apophysis** is a secondary ossification center that does not contribute to longitudinal bone growth and serves primarily for muscle attachment. - While functionally similar to traction epiphyses, the term "traction epiphysis" is more specifically applied to structures like the coracoid process, tibial tuberosity, and calcaneal tuberosity. *Head of femur* - The **head of femur** is a classic **pressure epiphysis** that articulates with the acetabulum to form the hip joint. - It bears significant body weight and contributes to the longitudinal growth of the femur. - Its primary functions are joint formation and weight transmission, not muscle attachment.
Question 82: Renal papilla opens into -
- A. Cortex
- B. Pyramid
- C. Minor calyx (Correct Answer)
- D. Major calyx
Explanation: ***Minor calyx*** - The **renal papilla** is the apex of the renal pyramid, which drains urine directly into a **minor calyx**. - Minor calyces then merge to form major calyces, eventually leading to the renal pelvis. *Cortex* - The **renal cortex** is the outer layer of the kidney, containing glomeruli and convoluted tubules, and does not directly receive urine from the papilla. - Urine is primarily formed and filtered in the cortex and then flows into the medulla. *Pyramid* - A **renal pyramid** is a conical structure within the renal medulla, and the renal papilla is its tip, but it doesn't open *into* the pyramid itself. - Instead, the pyramid *contains* the structures that contribute to the papilla. *Major calyx* - A **major calyx** is formed by the convergence of several minor calyces. - The renal papilla drains into the minor calyx, which then, in turn, drains into the major calyx.
Question 83: Which of the following is not a neural plate inducer?
- A. FGF upregulation
- B. Prechordal mesoderm
- C. High BMP (Correct Answer)
- D. Notochord appearance
Explanation: High BMP - **Bone Morphogenetic Proteins (BMPs)** are primarily involved in promoting epidermal differentiation in the ectoderm, and actively **inhibiting neural differentiation**. - Therefore, high levels of BMP would **prevent neural plate formation**, rather than induce it. *FGF upregulation* - **Fibroblast Growth Factors (FGFs)** are crucial in the early development of the nervous system. - They play a key role in **inducing neural plate formation** and maintaining its identity. *Prechordal mesoderm* - The **prechordal mesoderm**, located anterior to the notochord, is an important signalling center during early embryonic development. - It contributes to the **induction of the forebrain** and plays a role in patterning the anterior neural plate. *Notochord appearance* - The **notochord**, a transient rod-like structure, is a primary inducer of the neural plate. - It secretes factors like **Sonic Hedgehog (Shh)** which induce the overlying ectoderm to differentiate into neuroectoderm, forming the neural plate.
Question 84: Crural index is:
- A. Length of tibia/femur x 100 (Correct Answer)
- B. Length of radius/humerus x 100
- C. Length of fibula/tibia x 100
- D. Length of radius/ulna x 100
Explanation: ***Length of tibia/femur x 100*** - The **crural index** is a measure used in physical anthropology and comparative anatomy to describe the proportion of the lower leg to the thigh. - It is calculated by dividing the **length of the tibia** (lower leg bone) by the **length of the femur** (thigh bone) and multiplying by 100 to express it as a percentage. *Length of radius/humerus x 100* - This formula describes the **brachial index**, which measures the proportion of the forearm to the upper arm. - It does not represent the crural index, which refers specifically to the **lower limb**. *Length of fibula/tibia x 100* - This ratio compares the two bones within the lower leg but is not the definition of the **crural index**. - The crural index focuses on the relative length of the lower leg to the entire thigh, reflecting overall **limb proportions**. *Length of radius/ulna x 100* - This ratio compares the lengths of the two bones in the forearm and does not correspond to the **crural index**. - The crural index involves the **tibia** and **femur**, which are bones of the lower limb.
Question 85: Unilateral lacrimal gland destruction may be caused by?
- A. Fracture of roof of orbit (Correct Answer)
- B. Inferior orbital fissure fracture
- C. Fracture of lateral wall
- D. Fracture of sphenoid
Explanation: ***Fracture of roof of orbit*** - The **lacrimal gland** is situated in the **lacrimal fossa** on the anterior-lateral part of the **orbital roof**. A fracture in this specific area can directly damage the gland. - Trauma to the **orbital roof** can lead to laceration, avulsion, or compression of the lacrimal gland, resulting in its destruction and impairing tear production. *Inferior orbital fissure fracture* - The **inferior orbital fissure** transmits nerves and vessels to the orbit but is located inferior to the lacrimal gland, making direct injury unlikely. - Fractures here are more associated with **infraorbital nerve damage** or disruption of orbital contents into the maxillary sinus, not lacrimal gland destruction. *Fracture of lateral wall* - The **lateral wall of the orbit** forms the outer boundary and protects structures deeper within the orbit, but the lacrimal gland is situated superiorly and anteriorly. - While significant trauma to the lateral wall can impact orbital contents, it is less likely to directly cause unilateral lacrimal gland destruction compared to a direct roof fracture. *Fracture of sphenoid* - Fractures of the **sphenoid bone** are typically more posterior and central, affecting structures like the **optic canal** or **cavernous sinus**. - While it can indirectly affect orbital function, it is not a direct cause of isolated lacrimal gland destruction due to its anatomical location.
Question 86: Which of the following extraocular muscle has the longest tendon?
- A. Medial rectus
- B. Superior rectus
- C. Superior oblique (Correct Answer)
- D. Inferior oblique
Explanation: ***Superior oblique*** - The superior oblique muscle has the **longest tendon** and overall length of all extraocular muscles because it passes through the **trochlea**, a cartilaginous pulley. - Its long course allows it to have a complex action, primarily **intorsion, depression, and abduction** of the eye [1]. *Superior rectus* - The superior rectus is one of the **straight muscles** (recti) and is not the longest. - Its primary actions are **elevation, adduction, and intorsion** of the eyeball [1]. *Medial rectus* - The medial rectus is another **straight muscle** and is generally considered the **strongest** but not the longest extraocular muscle. - Its main action is **adduction** (moving the eye inward) [1]. *Inferior oblique* - The inferior oblique is the **shortest** of all the extraocular muscles. - Its primary actions are **extorsion, elevation, and abduction** of the eyeball [1].
Question 87: After trauma, a person cannot move their eye outward beyond the midpoint. Which nerve is injured?
- A. 3rd
- B. 4th
- C. 6th (Correct Answer)
- D. 2nd
Explanation: ***6th*** - The **abducens nerve (CN VI)** innervates the **lateral rectus muscle**, which is responsible for moving the eye **outward (abduction)** [1]. - Injury to the abducens nerve would result in an inability to move the eye laterally, causing an **esotropia** (eye turned inward at rest) [1]. *2nd* - The **optic nerve (CN II)** is responsible for **vision**, not eye movement [2]. - Damage to this nerve would cause **visual field defects** or **blindness** [3]. *3rd* - The **oculomotor nerve (CN III)** controls most extraocular muscles, including the **medial, superior, and inferior rectus** and **inferior oblique muscles**, as well as the **levator palpebrae superioris** and **pupillary constriction** [2]. - Injury to CN III would lead to a **down and out deviation of the eye**, **ptosis**, and a **dilated pupil** [2]. *4th* - The **trochlear nerve (CN IV)** innervates the **superior oblique muscle**, which primarily causes **intorsion** (rotation downward and inward) [1]. - Damage to this nerve results in **vertical diplopia**, especially when looking down and in, and a characteristic **head tilt** to compensate [3].
Question 88: Most common site for medulloblastoma is-
- A. Cerebellum (Correct Answer)
- B. Pituitary
- C. Cerebrum
- D. Pineal gland
Explanation: ***Cerebellum*** - **Medulloblastoma** is a highly malignant primary brain tumor that characteristically arises in the **cerebellum** [1]. - It is the most common malignant brain tumor in children, typically originating from the **roof of the fourth ventricle**. *Pituitary* - The **pituitary gland** is mostly associated with **adenomas**, which are benign tumors arising from anterior pituitary cells. - Tumors like **craniopharyngiomas** can also be found in the sellar region, but medulloblastomas do not originate here. *Cerebrum* - The **cerebrum** is the most common site for **gliomas** (e.g., glioblastoma multiforme) and metastatic tumors in adults. - Medulloblastoma specifically originates from primitive neuroectodermal cells in the posterior fossa [1]. *Pineal gland* - The **pineal gland** is associated with **pinealomas** (e.g., pineoblastoma, pineocytoma) and **germinomas** [2]. - These are distinct from medulloblastomas in their cellular origin and typical anatomical location.
Question 89: Which arteries supply the talus?
- A. Peroneal artery
- B. Posterior tibial artery
- C. Anterior tibial artery
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - The **talus** has a tenuous blood supply due to its limited muscular attachments, receiving contributions from multiple surrounding arteries to ensure adequate perfusion. - The **anterior tibial artery**, **posterior tibial artery**, and **peroneal artery** all contribute branches that form an anastomotic network around the talus. *Anterior tibial artery* - The **anterior tibial artery** contributes blood supply to the talus primarily through its **dorsal pedis branch** and ascending branches that supply the neck and head of the talus. - Its major role is in supplying the **anterior and superior talar surfaces**. *Posterior tibial artery* - The **posterior tibial artery** is a significant source of blood supply, particularly to the body and posterior aspect of the talus, via branches like the **artery of the tarsal canal** and the **deltoid branch**. - Its branches contribute to the **posterior talar artery network** which is crucial for the central part of the talus. *Peroneal artery* - The **peroneal artery** provides blood supply to the lateral and posterior parts of the talus through its **communicating branch** and perforating branches. - It contributes to the **tarsal artery network**, ensuring collateral circulation to the talus.
Question 90: Which nerve is primarily involved in cubital tunnel syndrome?
- A. Radial nerve
- B. Ulnar nerve (Correct Answer)
- C. Median nerve
- D. Axillary nerve
Explanation: Ulnar nerve - **Cubital tunnel syndrome** is a condition caused by compression of the **ulnar nerve** as it passes through the cubital tunnel at the medial epicondyle of the elbow. - Symptoms typically include numbness and tingling in the **little finger** and **half of the ring finger**, along with weakness of intrinsic hand muscles [2]. *Radial nerve* - The **radial nerve** is primarily involved in conditions like **radial tunnel syndrome** or radial nerve palsy (**wrist drop**), affecting primarily extensor muscles of the forearm and hand. - Its compression site is typically in the **radial tunnel** near the elbow, distinct from the cubital tunnel. *Median nerve* - The **median nerve** is involved in **carpal tunnel syndrome** at the wrist, causing numbness and tingling in the thumb, index, middle, and radial half of the ring finger [2]. - Compression around the elbow (e.g., pronator teres syndrome) can also affect the median nerve, but this is less common than cubital tunnel syndrome [1]. *Axillary nerve* - The **axillary nerve** is responsible for sensation over the deltoid region and motor function of the deltoid and teres minor muscles. - It is often injured with **shoulder dislocations** or fractures of the surgical neck of the humerus, unrelated to cubital tunnel syndrome.