Which of the following statements provides the MOST COMPLETE description of sclerotome function during vertebral development?
Which statement accurately describes a characteristic of synovial joints?
Skeletal derivative of 2nd pharyngeal arch -
Which of the following is derived from endoderm?
What is the lower limit of the retropharyngeal space?
Maxillary bone does not articulate with:
The thyrocervical trunk is a branch of which part of subclavian artery?
What is the typical length of a human sperm cell?
Which structure(s) passes behind the inguinal ligament:
Azygos vein drains into:
NEET-PG 2012 - Anatomy NEET-PG Practice Questions and MCQs
Question 11: Which of the following statements provides the MOST COMPLETE description of sclerotome function during vertebral development?
- A. The notochord forms the nucleus pulposus.
- B. The sclerotome contributes to the formation of vertebral bodies.
- C. The sclerotome surrounds the notochord and the neural tube during development. (Correct Answer)
- D. The sclerotome surrounds the notochord.
Explanation: ***The sclerotome surrounds the notochord and the neural tube during development.*** - The **sclerotome** is the part of the somite that differentiates into mesenchymal cells and migrates to surround both the developing **notochord** (which gives rise to the nucleus pulposus) and the **neural tube** (which forms the spinal cord). - This encirclement is crucial for the formation of the **vertebral column**, providing protection and a structural framework. *The notochord forms the nucleus pulposus.* - While true that the **notochord** contributes to the **nucleus pulposus**, this statement describes the fate of the notochord itself, not the function of the sclerotome. - The question asks for the function of the sclerotome, and this option only details one specific derivative. *The sclerotome contributes to the formation of vertebral bodies.* - This statement is partially true, as the **sclerotome** does indeed form the **vertebral bodies**, arches, and intervertebral discs. - However, it is not the *most complete* description of its function during development, as it omits the crucial aspect of surrounding the neural tube. *The sclerotome surrounds the notochord.* - This statement is correct but **incomplete** as it only mentions the notochord. - The **sclerotome** also surrounds the **neural tube**, which is a vital part of its developmental role in forming the vertebral canal.
Question 12: Which statement accurately describes a characteristic of synovial joints?
- A. Hyaline cartilage covers the articular surfaces of synovial joints. (Correct Answer)
- B. The metacarpo-phalangeal joint is a condyloid joint.
- C. Cartilage can sometimes divide the joint into two cavities.
- D. Stability is inversely proportional to mobility in synovial joints.
Explanation: ***Hyaline cartilage covers the articular surfaces of synovial joints.*** - The articular surfaces of bones within a **synovial joint** are covered by a thin layer of **hyaline cartilage**, providing a smooth, low-friction surface for movement [1]. - This **articular cartilage** absorbs shock and protects the underlying bone from wear and tear [1]. - This is a **universal structural characteristic** of all synovial joints, making it the most accurate answer. *The metacarpo-phalangeal joint is a condyloid joint.* - While this statement is factually true (MCP joints are indeed **condyloid/ellipsoid joints** allowing movement in two planes), it describes a **specific type** of synovial joint, not a general characteristic of all synovial joints. - The question asks for a characteristic that describes synovial joints as a category, not an example of one specific joint classification. - This makes it incorrect as the best answer to this question. *Cartilage can sometimes divide the joint into two cavities.* - This statement refers to an **articular disc** or **meniscus**, which is a fibrocartilaginous structure that can partially or completely divide a synovial joint cavity. - This feature is present in **some** synovial joints (like the knee or temporomandibular joint) but is **not universal**. - Since it's not a characteristic of all synovial joints, it's not the best answer. *Stability is inversely proportional to mobility in synovial joints.* - Generally, there is an **inverse relationship** between **stability** and **mobility** in joints; joints designed for great mobility (e.g., shoulder) tend to be less stable, and vice-versa (e.g., hip). - However, this describes a **functional principle** or trade-off rather than a **structural characteristic** that defines synovial joints. - While true, it's not the defining characteristic being asked for in this question.
Question 13: Skeletal derivative of 2nd pharyngeal arch -
- A. Malleus
- B. Incus
- C. Stapes (Correct Answer)
- D. Maxilla
Explanation: ***Stapes*** - The **2nd pharyngeal arch** (also known as the hyoid arch) gives rise to several structures, including Reichert's cartilage, which forms the **stapes** bone, the styloid process, the lesser horn of the hyoid, and the upper part of the hyoid body. - Its muscles include the **stapedius**, stylohyoid, posterior belly of the digastric, and muscles of facial expression. *Malleus* - The **malleus** is derived from the **1st pharyngeal arch** (Meckel's cartilage), along with the incus. - The 1st pharyngeal arch is also responsible for forming the malleus, incus, and mandible. *Incus* - Similar to the malleus, the **incus** also originates from the **1st pharyngeal arch** (Meckel's cartilage). - Both the malleus and incus are crucial components of the middle ear ossicles but are structurally distinct from the stapes. *Maxilla* - The **maxilla** development is primarily from the **maxillary prominence** of the first pharyngeal arch, which is a subdivision of the first arch but does not originate from the 2nd arch. - It forms a significant portion of the midface and upper jaw, contributing to the nasal cavity and orbital floor.
Question 14: Which of the following is derived from endoderm?
- A. Gall bladder (Correct Answer)
- B. Lens
- C. Spleen
- D. Lymph nodes
Explanation: ***Gall bladder*** - The **gallbladder**, along with other organs of the **gastrointestinal tract** such as the liver, pancreas, and epithelial lining of the digestive and respiratory systems, originates from the **endoderm** [1]. - The endoderm forms the primitive gut tube, from which these accessory digestive organs bud off. *Lens* - The **lens of the eye** is derived from the **surface ectoderm**, which invaginates to form the lens vesicle. - This contrasts with the neural ectoderm, which forms the neural tube and retina. *Spleen* - The **spleen** is derived from the **mesoderm**, specifically from mesenchymal cells in the dorsal mesentery of the stomach. - It is involved in blood filtration and immune responses, making it a lymphoid organ. *Lymph nodes* - **Lymph nodes** are primarily derived from the **mesoderm**, specifically from specialized mesenchymal cells that form their connective tissue capsule and stroma. - The immune cells within the lymph nodes, such as lymphocytes, originate from hematopoietic stem cells that migrate into these developing structures.
Question 15: What is the lower limit of the retropharyngeal space?
- A. Bifurcation of trachea (Correct Answer)
- B. 4th esophageal constriction
- C. C7
- D. None of the options
Explanation: Bifurcation of trachea - The retropharyngeal space extends inferiorly to approximately the level of T4-T5 vertebrae, corresponding to the bifurcation of the trachea and the superior mediastinum. - This space lies between the buccopharyngeal fascia (posterior to pharynx) and the alar layer of prevertebral fascia. - Clinically, infections or abscesses in this space can descend into the posterior mediastinum, making knowledge of this inferior extent crucial for surgical management. - Note: Some anatomical texts describe the space ending at T1-T2, but for clinical and surgical purposes, the functional inferior limit extends to the bifurcation of the trachea. C7 - While some texts describe the retropharyngeal space as terminating around C7 (level of the lower border of cricoid cartilage), this represents the narrower definition. - The clinical and surgical definition extends the space further inferiorly to allow for tracking of infections into the chest. - C7 alone does not represent the accepted lower limit for examination purposes. 4th esophageal constriction - The fourth esophageal constriction is not a standard anatomical landmark (esophagus has 3-4 constrictions depending on classification). - Esophageal constrictions are luminal narrowings within the esophagus itself and do not define the boundaries of the retropharyngeal space, which is a fascial space posterior to both pharynx and esophagus. None of the options - This is incorrect because bifurcation of the trachea is the recognized lower limit of the retropharyngeal space for clinical and examination purposes. - Understanding this anatomical boundary is essential for predicting the spread of deep neck space infections.
Question 16: Maxillary bone does not articulate with:
- A. Frontal
- B. Lacrimal
- C. Sphenoid
- D. Ethmoid (Correct Answer)
Explanation: ***Ethmoid (Marked Correct - PYQ 2012)*** - This question reflects traditional teaching where the **maxilla-ethmoid articulation** was considered minimal or indirect. - In modern anatomy, the **maxilla DOES articulate with the ethmoid bone** via the uncinate process of the ethmoid and the medial wall of the maxillary sinus. - However, per the **NEET-PG 2012 answer key**, ethmoid was accepted as the correct answer, likely because this articulation is small and often not emphasized in basic anatomy teaching. - The maxilla has major articulations with: frontal, zygomatic, nasal, lacrimal, palatine, inferior nasal concha, vomer, and contralateral maxilla. *Sphenoid* - The **maxilla clearly articulates** with the **greater wing of the sphenoid bone** at the inferior orbital fissure. - This articulation is substantial and forms the posterolateral floor of the orbit. - The sphenoid-maxillary articulation contributes to the boundaries of the **pterygopalatine fossa**. *Frontal* - The **maxilla articulates extensively** with the **frontal bone** at the frontomaxillary suture. - This articulation forms the medial orbital rim and part of the anterior cranial floor interface. - This is one of the most prominent maxillary articulations. *Lacrimal* - The **maxilla articulates directly** with the **lacrimal bone**, forming the anterior part of the medial orbital wall. - Together they form the **lacrimal groove** which houses the lacrimal sac. - This articulation is essential for the nasolacrimal drainage pathway.
Question 17: The thyrocervical trunk is a branch of which part of subclavian artery?
- A. 1st part (Correct Answer)
- B. 2nd part
- C. 3rd part
- D. 4th part
Explanation: ***1st part*** - The **thyrocervical trunk** is one of the three primary branches arising from the **first part** of the subclavian artery. - The first part lies medial to the **anterior scalene muscle**. *2nd part* - The **second part** of the subclavian artery gives rise to the **costocervical trunk**. - This part lies posterior to the **anterior scalene muscle**. *3rd part* - The **third part** of the subclavian artery typically has no branches or may give off the **dorsal scapular artery**. - This part lies lateral to the **anterior scalene muscle**. *4th part* - This option is incorrect as the **subclavian artery has only three parts**, divided by their relationship to the anterior scalene muscle. - There is no anatomical fourth part of the subclavian artery.
Question 18: What is the typical length of a human sperm cell?
- A. 55 micrometers (Correct Answer)
- B. 50 micrometers
- C. 100 micrometers
- D. 65 micrometers
Explanation: ***55 micrometers*** - A typical **human sperm cell** measures approximately **55 micrometers** from the head to the tip of the tail [1]. - This length allows for efficient motility and navigation within the female reproductive tract to reach the ovum [1]. *100 micrometers* - This length is significantly **longer** than the average size of a human sperm cell. - While some cells can achieve this size, it is not typical for **spermatozoa**. *65 micrometers* - Although closer to the actual size, **65 micrometers** is generally considered slightly larger than the average human sperm cell length. - Sperm length is critical for understanding their **mobility** and **fertility** [1]. *50 micrometers* - This measurement is slightly **shorter** than the typical length of a human sperm cell. - The precise length, including the **head** and **flagellum**, contributes to its function.
Question 19: Which structure(s) passes behind the inguinal ligament:
- A. Femoral branch of genitofemoral nerve
- B. Femoral vein
- C. Psoas major
- D. All of the options (Correct Answer)
Explanation: ***Correct: All of the options*** All three structures pass deep to (behind) the inguinal ligament as they transition from the pelvis/abdomen into the thigh [1]. The inguinal ligament forms the superior border of the femoral triangle [1]. ***Femoral branch of genitofemoral nerve (Correct)*** - Pierces the **psoas major** muscle and descends along its anterior surface - Passes through the **lacuna musculorum** (lateral compartment) deep to the inguinal ligament - Lies **lateral to the femoral artery** - Provides sensory innervation to the skin over the femoral triangle ***Femoral vein (Correct)*** - Continuation of the popliteal vein from the lower limb - Passes through the **lacuna vasorum** (medial compartment/femoral canal) within the **femoral sheath** - Located **medial to the femoral artery** behind the inguinal ligament [1] - Carries deoxygenated blood back to the heart via the external iliac vein ***Psoas major (Correct)*** - Major hip flexor muscle originating from lumbar vertebrae (T12-L5) - Passes through the **lacuna musculorum** deep to the inguinal ligament - Located **lateral to the femoral vessels** - Combines with iliacus to form iliopsoas, inserting on the lesser trochanter of femur
Question 20: Azygos vein drains into:
- A. Left brachiocephalic vein
- B. Inferior vena cava
- C. Superior vena cava (Correct Answer)
- D. Right brachiocephalic vein
Explanation: Wait, what? Azygos vein drains into: ***Superior vena cava*** - The **azygos vein** ascends along the right side of the vertebral column and typically arches over the root of the right lung before draining into the **superior vena cava (SVC)**. - This anatomical arrangement allows the azygos system to collect venous blood from the posterior thoracic and abdominal walls, as well as the bronchi and esophagus, ultimately returning it to the systemic circulation via the SVC [1]. *Left brachiocephalic vein* - The **left brachiocephalic vein** drains blood from the upper left limb and left side of the head and neck. - It merges with the right brachiocephalic vein to form the SVC; the azygos vein does not directly drain into it. *Inferior vena cava* - The **inferior vena cava (IVC)** collects deoxygenated blood from the lower body. - The azygos system primarily drains structures above the diaphragm, distinct from the IVC's drainage area. *Right brachiocephalic vein* - The **right brachiocephalic vein** drains blood from the upper right limb and right side of the head and neck. - While it contributes to the formation of the SVC, the azygos vein's direct connection is to the SVC itself, not the right brachiocephalic vein.