NEET-PG 2013 — Anatomy
111 Previous Year Questions with Answers & Explanations
Terminal branches of the internal carotid artery are all except?
Boundaries of the anatomical snuff box are all except
Attachment of the vitreous is strongest at?
Follicles are present in which part of lymph nodes?
The cardiac jelly formed around the heart tube during early development contributes to the formation of:
Arch of Aorta develops from which aortic arch artery?
Which muscle is derived from the third pharyngeal arch?
At which level do the somites initially form?
Sinus venosus receives blood from all EXCEPT:
Collecting part of kidney develops from ?
NEET-PG 2013 - Anatomy NEET-PG Practice Questions and MCQs
Question 1: Terminal branches of the internal carotid artery are all except?
- A. Anterior cerebral artery
- B. Ophthalmic artery (Correct Answer)
- C. Middle cerebral artery
- D. Posterior communicating artery
Explanation: ***Ophthalmic artery*** - The **ophthalmic artery** is a **branch** (not a terminal branch) of the internal carotid artery that arises shortly after the ICA emerges from the cavernous sinus. - It enters the orbit through the optic canal to supply the eye, orbit, and surrounding structures. - Terminal branches are the **final divisions** of a vessel, not branches that arise earlier in its course. *Anterior cerebral artery* - The **anterior cerebral artery (ACA)** is one of the **two terminal branches** of the internal carotid artery. - It supplies the medial surfaces of the frontal and parietal lobes. - It arises at the terminal bifurcation of the ICA in the supraclinoid region. *Middle cerebral artery* - The **middle cerebral artery (MCA)** is the other **terminal branch** of the internal carotid artery. - It is the larger of the two terminal branches and supplies the lateral surfaces of the cerebral hemispheres. - It supplies critical areas including the motor and sensory cotices. *Posterior communicating artery* - The **posterior communicating artery (PCoA)** arises near the terminal bifurcation of the ICA and connects it to the posterior cerebral artery. - While technically a branch (not terminal), it arises very close to the terminal bifurcation point. - It is part of the circle of Willis, providing collateral circulation between anterior and posterior cerebral circulation.
Question 2: Boundaries of the anatomical snuff box are all except
- A. ECU (Correct Answer)
- B. APL
- C. EPL
- D. EPB
Explanation: ***ECU*** - The **extensor carpi ulnaris (ECU)** is not a boundary of the anatomical snuff box. Its tendon inserts into the base of the 5th metacarpal, medial to the snuffbox [1][2]. - The ECU's function is **wrist extension** and **ulnar deviation**, and it does not form part of the snuffbox's borders [1]. *APL* - The **abductor pollicis longus (APL)** tendon forms the **anterior (radial) boundary** of the anatomical snuff box [1][2]. - It inserts into the base of the 1st metacarpal and is responsible for **abducting the thumb** [1]. *EPL* - The **extensor pollicis longus (EPL)** tendon forms the **posterior (ulnar) boundary** of the anatomical snuff box [1][2]. - It inserts into the distal phalanx of the thumb and is responsible for **extending the thumb interphalangeal joint**. *EPB* - The **extensor pollicis brevis (EPB)** tendon forms part of the **anterior (radial) boundary** along with the APL [1][2]. - It inserts into the proximal phalanx of the thumb and aids in **extending the thumb metacarpophalangeal joint** [1].
Question 3: Attachment of the vitreous is strongest at?
- A. Foveal region
- B. Back of lens
- C. Across ora serrata (Correct Answer)
- D. Margin of optic disc
Explanation: ***Across ora serrata*** - The **vitreous base** is a 3-4 mm wide circumferential band extending approximately 2 mm anterior and 2 mm posterior to the **ora serrata**, where the vitreous firmly adheres to the **non-pigmented ciliary epithelium** and the **peripheral retina**. - This strong adhesion makes the **vitreous base** the primary point of vitreous attachment, often remaining attached even during significant vitreous detachments. *Foveal region* - While there is some attachment, the vitreous is typically **less firmly adherent** to the foveal region compared to the vitreous base. - Vitreous detachment from the fovea is a common event, rarely leading to significant tearing or strong adherence. *Back of lens* - The vitreous has a weak attachment to the posterior capsule of the lens, known as the **Wieger's ligament** or **hyaloideocapsular ligament**. - This attachment typically **loses strength with age** and is not the strongest overall point of attachment. *Margin of optic disc* - The vitreous attaches to the margin of the optic disc, forming a circular adhesion called the **peripapillary ring**. - This attachment is **less strong** than the vitreous base and is often the first region from which the vitreous detaches during a **posterior vitreous detachment (PVD)**.
Question 4: Follicles are present in which part of lymph nodes?
- A. Red pulp
- B. White pulp
- C. Medulla
- D. Cortex (Correct Answer)
Explanation: ***Cortex*** - The **cortex** of a lymph node contains lymphoid follicles, which are sites of **B cell proliferation** and differentiation. - These follicles can be primary (inactive) or secondary (active, with a **germinal center**) based on ongoing immune responses. *Red pulp* - The **red pulp** is a component of the **spleen**, not lymph nodes. - It is primarily involved in filtering blood, removing old or damaged red blood cells, and storing monocytes. *White pulp* - The **white pulp** is also a component of the **spleen**, organized around central arterioles. - It contains periarteriolar lymphoid sheaths (PALS) with T cells and lymphoid follicles with B cells. *Medulla* - The **medulla** of a lymph node is the central region, rich in **medullary cords** (containing plasma cells, macrophages, and B cells) and **medullary sinuses**. - While lymphocytes are present, the organized structures of follicles are characteristic of the cortex.
Question 5: The cardiac jelly formed around the heart tube during early development contributes to the formation of:
- A. Pericardium
- B. Mesocardium
- C. Myocardium
- D. Endocardium (Correct Answer)
Explanation: Endocardium (Endocardial Cushions/Valves/Septa) - The **cardiac jelly** is an acellular, gelatinous matrix rich in **hyaluronic acid** that lies between the endocardium and the primordial myocardium during early heart development. - It undergoes **endothelial-to-mesenchymal transformation (EMT)** to form the **endocardial cushions** [1]. - These cushions are critical for forming: - **Atrioventricular (AV) valves** (mitral and tricuspid) [1] - **Semilunar valves** (aortic and pulmonary) [1] - **Cardiac septa** (portions of atrial, ventricular, and AV septa) [1] - While cardiac jelly doesn't form the endocardial lining itself (which is already present as endothelium), it forms the endocardial cushions that are essential endocardial derivatives. *Pericardium* - The **pericardium** develops from the **pleuropericardial folds** and **somatic and splanchnic mesoderm**, forming the fibrous and serous outer coverings of the heart. - It is completely distinct from cardiac jelly, which is an intra-cardiac structure. *Mesocardium* - The **dorsal mesocardium** is a transient mesentery that temporarily connects the developing heart tube to the dorsal wall of the pericardial cavity. - It rapidly degenerates by **day 22-23** to form the **transverse pericardial sinus**. - It does not contribute to cardiac jelly or any heart wall structures. *Myocardium* - The **myocardium** differentiates directly from the **splanchnic mesoderm** surrounding the endocardial tube. - It forms the muscular contractile layer of the heart wall. - Cardiac jelly lies between the endocardium and myocardium but does not form myocardial tissue.
Question 6: Arch of Aorta develops from which aortic arch artery?
- A. Right 3rd
- B. Left 4th (Correct Answer)
- C. Left 3rd
- D. Right Truncus arteriosus
Explanation: ***Left 4th*** - The **arch of the aorta** develops from the **fourth left aortic arch artery**. [1] - This artery connects the **aortic sac** to the **dorsal aorta** on the left side during embryonic development. *Right Truncus arteriosus* - The **truncus arteriosus** gives rise to the **ascending aorta** and the **pulmonary artery**, not the arch of the aorta. - The term "right truncus arteriosus" is not standard in describing normal aortic arch development. *Right 3rd* - The **third aortic arch arteries** primarily contribute to the development of the **common carotid arteries** and the proximal part of the **internal carotid arteries**. - The right third aortic arch forms the proximal part of the right common carotid artery. *Left 3rd* - The **left third aortic arch artery** forms the proximal part of the **left common carotid artery** and the proximal part of the left internal carotid artery. - It does not directly form the arch of the aorta itself.
Question 7: Which muscle is derived from the third pharyngeal arch?
- A. Tensor tympani
- B. Stylopharyngeus (Correct Answer)
- C. Cricothyroid
- D. Stapedius
Explanation: ***Stylopharyngeus*** - The **stylopharyngeus muscle** is uniquely derived from the **third pharyngeal arch**. - It is innervated by the **glossopharyngeal nerve (CN IX)** and plays a role in elevating the pharynx and larynx during swallowing. - This is the **only muscle** derived from the third pharyngeal arch, making it a key anatomical landmark. *Tensor tympani* - The **tensor tympani muscle** is derived from the **first pharyngeal arch**. - It is innervated by the **mandibular nerve (V3)** and dampens sound by tensing the tympanic membrane. *Cricothyroid* - The **cricothyroid muscle** is derived from the **fourth and sixth pharyngeal arches**. - It is innervated by the **external branch of the superior laryngeal nerve (CN X)** and tenses the vocal cords. *Stapedius* - The **stapedius muscle** is derived from the **second pharyngeal arch**. - It is innervated by the **facial nerve (CN VII)** and dampens sound by stabilizing the stapes bone.
Question 8: At which level do the somites initially form?
- A. Lumbar level
- B. Sacral level
- C. Cervical level (Correct Answer)
- D. Thoracic level
Explanation: Cervical level - Somites, which are segmented blocks of paraxial mesoderm, initially appear in the **occipital/cranial cervical region** of the developing embryo around day 20 of development. - The first somite pair forms at the **occipital level**, and subsequent somites develop in a **cranio-caudal sequence**. - Development proceeds both cranially (forming occipital somites) and caudally (forming cervical, thoracic, lumbar, and sacral somites) from this initial formation. - By the end of the 5th week, approximately **42-44 somite pairs** are present. *Thoracic level* - Thoracic somites form subsequent to the initial occipital/cervical somites, as the segmentation process extends caudally. - The formation of somites is a sequential process along the **cranio-caudal axis**. *Lumbar level* - Lumbar somites develop later in the embryological timeline, after the cervical and thoracic regions have undergone somite formation. - The **caudal regions** receive somites progressively as development continues. *Sacral level* - Sacral somites are among the last to form, representing the caudal extent of somite development. - Their formation follows the cranio-caudal progression of somite appearance.
Question 9: Sinus venosus receives blood from all EXCEPT:
- A. Vitelline vein
- B. Umbilical vein
- C. Common cardinal vein
- D. Subcardinal vein (Correct Answer)
Explanation: Sinus venosus receives blood from all EXCEPT: ***Subcardinal vein*** - The **subcardinal vein** is primarily involved in draining the developing **kidneys** and gonads during embryonic development. - While it contributes to the formation of the **inferior vena cava**, it does not directly empty into the sinus venosus. - The subcardinal veins are part of a different venous drainage system that develops independently from the sinus venosus tributaries. *Vitelline vein* - The **vitelline veins** drain blood from the **yolk sac**, which is the primary site of early hematopoiesis. - These veins directly empty into the **sinus venosus** in the early embryo. - They eventually give rise to the **hepatic portal system** and hepatic sinusoids. *Umbilical vein* - The **umbilical vein** carries **oxygenated and nutrient-rich blood** from the placenta to the fetus [1]. - In the early embryo, the umbilical veins drain directly into the **sinus venosus**. - Later in development, the left umbilical vein bypasses the liver via the **ductus venosus** to enter the inferior vena cava [1], [2]. *Common cardinal vein* - The **common cardinal veins** collect blood from the entire embryo, draining both the anterior (from the cephalic region) and posterior (from the trunk and lower limbs) parts. - These veins represent the main drainage system of the developing embryo and directly empty into the sinus venosus. - They are the primary tributaries of the sinus venosus during early cardiac development.
Question 10: Collecting part of kidney develops from ?
- A. Mesonephros
- B. Metanephros
- C. Ureteric bud (Correct Answer)
- D. Pronephros
Explanation: ***Ureteric bud*** - The **ureteric bud** (also known as the metanephric diverticulum) is an outgrowth of the **mesonephric duct** that develops into the collecting system of the kidney. - It gives rise to the **ureter**, **renal pelvis**, major and minor calyces, and all collecting ducts. *Pronephros* - **Pronephros** is the earliest, most rudimentary, and transient excretory structure that appears in human embryos. - It is non-functional in humans and **degenerates completely** by the fourth week of gestation. *Mesonephros* - The **mesonephros** develops after the pronephros and functions as a temporary kidney during the early fetal period (weeks 4-8). - Its tubules primarily contribute to the **male reproductive system** (e.g., epididymis, ductus deferens) and **degenerate** in females. *Metanephros* - The **metanephros** is the definitive kidney in mammals and gives rise to the **nephrons** (glomeruli, Bowman's capsule, proximal and distal convoluted tubules, loop of Henle). - While it's crucial for kidney development, the **collecting part** specifically originates from the ureteric bud, which interacts with the metanephric mesenchyme.