NEET-PG 2012 - Anatomy Practice Questions

Q: Which of the following is derived from endoderm?

Gall bladder. ***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.

Q: Which of the following is a traction epiphysis ?

Coracoid process of scapula. ***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.

Q: Renal papilla opens into -

Minor calyx. ***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.

Q: Which of the following structures is not derived from the ectoderm?

Eustachian tube. ***Eustachian tube*** - The **Eustachian tube** (auditory tube) is derived from the **endoderm**, specifically from the first pharyngeal pouch. - It connects the nasopharynx to the middle ear and is responsible for equalizing pressure [1]. *Lens* - The **lens** of the eye develops from the surface ectoderm through an invagination called the **lens placode**. - This ectodermal origin is crucial for its transparency and refractive properties. *Brain* - The **brain** is a primary derivative of the ectoderm, specifically the **neural tube**, which forms from the neural plate during neurulation. - This ectodermal origin gives rise to the entire central nervous system. *Retina* - The **retina** of the eye, along with the optic nerve, develops from the **neuroectoderm** (a part of the neural tube). - Its ectodermal origin is essential for its light-sensing function.

Q: Nutrient artery runs ?

Away from epiphysis. ***Away from epiphysis*** - The **nutrient artery** runs away from the **dominant (faster-growing) epiphysis** towards the non-dominant end of the bone. - This follows the classic anatomical rule: **"To the elbow, from the knee"** - nutrient arteries point towards the elbow in upper limb bones and away from the knee in lower limb bones. - The **nutrient foramen** is directed obliquely away from the more actively growing end, established during bone development. - Examples: In the humerus, it runs towards the elbow (away from proximal epiphysis); in the femur, it runs away from the knee (away from distal epiphysis). *Towards metaphysis* - While the artery does course towards the metaphyseal region of the slower-growing end, this option is less anatomically precise. - The standard teaching emphasizes the relationship with the **dominant epiphysis** rather than the metaphysis. *Away from metaphysis* - This is **incorrect** - the nutrient artery actually runs **towards** the metaphysis of the non-dominant end. - It runs **away from** the dominant epiphysis, not away from the metaphysis. *None of the options* - This is incorrect as **"Away from epiphysis"** correctly describes the direction of the nutrient artery relative to the dominant growing end.

Q: Which structure do cytotrophoblasts invade during implantation?

Decidua basalis. ***Decidua basalis*** - The **cytotrophoblasts** invade the maternal **decidua basalis**, which is the portion of the **endometrium** directly underlying the implanted embryo, forming the maternal component of the **placenta**. - This invasion is crucial for establishing the **placenta** and allowing for nutrient and waste exchange between the mother and the fetus. *Decidua parietalis* - The **decidua parietalis** is the portion of the **endometrium** lining the rest of the **uterine cavity**, not directly involved in the immediate implantation site. - It plays a role later in pregnancy, fusing with the **decidua capsularis** as the **embryo** grows. *Decidua capsularis* - The **decidua capsularis** is the portion of the endometrium that overlies the implanted embryo, separating it from the uterine lumen. - It does not undergo invasion by the **cytotrophoblasts** in the same way the **decidua basalis** does. *Decidua vera* - The **decidua vera** is another term for the **decidua parietalis**, referring to the endometrial lining of the uterine cavity that is not involved in the implantation site. - It is not directly invaded by **cytotrophoblasts** during implantation.

Q: All are derived from ectoderm except for which of the following?

Adrenal cortex. ***Adrenal cortex*** - The adrenal cortex is derived from the **intermediate mesoderm**, specifically from the cells lining the posterior abdominal wall. The cells migrate to develop into the adrenal cortex. - It produces various steroid hormones, including **aldosterone**, **cortisol**, and **androgens**, which regulate diverse bodily functions. *Lens of the eye* - The lens of the eye is derived from the **surface ectoderm**. It forms from an invagination of the surface ectoderm called the lens placode. - Its primary function is to **focus light** onto the retina. *Hair follicles* - Hair follicles develop from the **surface ectoderm** [1]; they are invaginations of the epidermis that extend into the dermis. - They produce hair, which provides **insulation** and **protection** [1]. *Nails* - Nails are also derivatives of the **surface ectoderm**, forming thickened plates on the dorsal surface of the distal phalanges. - They provide **protection** to the fingertips and aid in grasping objects.

Q: Blastocyst makes contact with endometrium on ?

5 - 7 days. ***5-7 days*** - The **blastocyst makes initial contact** (apposition) with the **endometrium** around **day 5-6 after fertilization**. - **Implantation**, which includes adhesion and invasion, typically begins around day 6 and is complete by day 10. - This timeframe allows the blastocyst to travel from the fallopian tube to the uterus and for the uterine lining to be optimally prepared. *< 3 days* - Within the first few days after fertilization, the zygote is still undergoing **cleavage** and development into a **morula**, then a young blastocyst, while traveling down the fallopian tube. - It has not yet reached the uterus or developed sufficiently to interact with the endometrium. *8-11 days* - By 8-11 days, the process of implantation is usually **well underway or completed**, with the blastocyst already invading the endometrial wall. - Initial contact and attachment occur prior to this period. *15-16 days* - This timeframe is well beyond the typical window for initial blastocyst contact and implantation. - By 15-16 days post-fertilization, the embryo would be undergoing **gastrulation** and early organogenesis, assuming successful implantation.

Q: Coronary sinus develops from?

Sinus venosus. Sinus venosus - The sinus venosus is a primordial cardiac chamber that receives venous blood from the body and placenta in the early embryonic heart. - The left horn of the sinus venosus loses its connection with the systemic venous circulation and becomes the coronary sinus, which drains most of the cardiac veins into the right atrium [1, 4]. Truncus arteriosus - The truncus arteriosus is the embryonic precursor to the ascending aorta and pulmonary trunk. - It does not contribute to the development of the coronary sinus. Conus - The conus (or conus cordis) is the outflow portion of the primitive ventricle and differentiates into the outflow tracts of the right (infundibulum) and left (aortic vestibule) ventricles. - It is not involved in the formation of the coronary sinus. AV canal - The atrioventricular (AV) canal connects the primitive atrium and ventricle and is crucial for the formation of the AV valves and septation of the heart chambers. - It does not directly develop into the coronary sinus.

Q: What anatomical structures are involved in the closure of the fossa ovalis?

Septum primum + Septum secundum. The septum primum acts as a valve, closing against the septum secundum postnatally due to changes in atrial pressure. This fusion effectively closes the foramen ovale, leading to the formation of the fossa ovalis. The endocardial cushions are important for the formation of the atrial and ventricular septa, as well as the AV valves, but not directly for the closure of the fossa ovalis. The septum primum is directly involved, but its apposition with the endocardial cushions doesn't close the foramen ovale. While both structures contribute to heart development, their direct interaction is not responsible for the closure of the fossa ovalis. The septum secundum forms the muscular rim of the fossa ovalis, and the endocardial cushions are critical for atrial septation, but not the final closure here. This option is incorrect because the specific combination of septum primum and septum secundum is indeed responsible for the closure of the fossa ovalis.

Question 1

Which of the following is derived from endoderm?

Accepted Answer

Gall bladder

Answer

Lens

Answer

Spleen

Answer

Lymph nodes

Question 2

Which of the following is a traction epiphysis ?

Accepted Answer

Coracoid process of scapula

Answer

Tibial condyles

Answer

Head of femur

Answer

Trochanter of femur

Question 3

Renal papilla opens into -

Accepted Answer

Minor calyx

Answer

Cortex

Answer

Pyramid

Answer

Major calyx

Question 4

Which of the following structures is not derived from the ectoderm?

Accepted Answer

Eustachian tube

Answer

Brain

Answer

Retina

Answer

Lens

Question 5

Nutrient artery runs ?

Accepted Answer

Away from epiphysis

Answer

Towards metaphysis

Answer

None of the options

Answer

Away from metaphysis

Question 6

Which structure do cytotrophoblasts invade during implantation?

Accepted Answer

Decidua basalis

Answer

Decidua capsularis

Answer

Decidua vera

Answer

Decidua parietalis

Question 7

All are derived from ectoderm except for which of the following?

Accepted Answer

Adrenal cortex

Answer

Hair follicles

Answer

Nails

Answer

Lens of the eye

Question 8

Blastocyst makes contact with endometrium on ?

Accepted Answer

5 - 7 days

Answer

< 3 days

Answer

8 - 11 days

Answer

15-16 days

Question 9

Coronary sinus develops from?

Accepted Answer

Sinus venosus

Answer

Truncus arteriosus

Answer

Conus

Answer

AV canal

Question 10

What anatomical structures are involved in the closure of the fossa ovalis?

Accepted Answer

Septum primum + Septum secundum

Answer

Septum primum + Endocardial cushion

Answer

Endocardial cushions + Septum secundum

Answer

None of the options

NEET-PG 2012 — Anatomy