Anatomy
6 questionsInferior parathyroid develops from which pharyngeal pouch?
Pancreas divisum indicates which of the following?
Which of the following is NOT an anterior relation of the right kidney?
Which cranial nerve is not associated with the nucleus ambiguus?
In which region of the human spine is the number of vertebrae usually constant?
Nucleus gracilis and nucleus cuneatus are seen in?
NEET-PG 2012 - Anatomy NEET-PG Practice Questions and MCQs
Question 391: Inferior parathyroid develops from which pharyngeal pouch?
- A. 1st
- B. 2nd
- C. 3rd (Correct Answer)
- D. 4th
Explanation: The inferior parathyroid glands develop from the dorsal wing of the third pharyngeal pouch. Due to their origin, they often migrate further caudally than the superior parathyroid glands, sometimes even locating within the thymus which also develops from the third pouch. *1st* - The first pharyngeal pouch contributes to the formation of the eustachian tube, tympanic cavity, and mastoid air cells. - It has no role in the development of the parathyroid glands. *2nd* - The second pharyngeal pouch mainly gives rise to the palatine tonsils and their crypts. - It is not involved in the development of parathyroid tissue. *4th* - The fourth pharyngeal pouch gives rise to the superior parathyroid glands and the parafollicular cells (C cells) of the thyroid, which produce calcitonin. - While it forms parathyroid tissue, it is for the superior glands, not the inferior ones.
Question 392: Pancreas divisum indicates which of the following?
- A. Duplication of the pancreas
- B. Formation of more than two pancreatic buds
- C. Formation of only one pancreatic bud
- D. Failure of fusion of dorsal & ventral pancreatic buds (Correct Answer)
Explanation: ***Failure of fusion of dorsal & ventral pancreatic buds*** - **Pancreas divisum** is a congenital anomaly where the **dorsal and ventral pancreatic buds fail to fuse** during embryonic development [1]. - This results in the **bulk of the pancreas (dorsal bud)** draining through the **accessory pancreatic duct** into the minor duodenal papilla, while the ventral bud drains via the main pancreatic duct [1]. *Duplication of the pancreas* - This condition involves the presence of **multiple, distinct pancreatic tissues**, which is different from pancreas divisum where the existing buds simply do not fuse. - Pancreas divisum is a failure of fusion of two normally formed buds, not the formation of extra pancreatic tissue. *Formation of more than two pancreatic buds* - Normal embryonic development typically involves two pancreatic buds (dorsal and ventral), not more than two [1]. - The issue in pancreas divisum is with the **fusion process**, not the number of initial buds [1]. *Formation of only one pancreatic bud* - Pancreatic development normally involves **two distinct buds (dorsal and ventral)** [1]. - The formation of only one bud would lead to pancreatic agenesis or severe hypoplasia, which is a different anomaly than pancreas divisum.
Question 393: Which of the following is NOT an anterior relation of the right kidney?
- A. Hepatic flexure
- B. Liver
- C. 4th part of duodenum (Correct Answer)
- D. 2nd part of duodenum
Explanation: ***4th part of duodenum*** - The **4th part of the duodenum** is located to the **left of the vertebral column** and is related to the **left kidney**, not the right kidney. - This segment passes superiorly along the left side of the aorta to become continuous with the jejunum at the duodenojejunal flexure. *Liver* - The **right kidney's superior part** is in direct contact with the **right lobe of the liver**, often separated only by the peritoneum [1]. - This is a significant anterior relation, explaining why liver enlargement can sometimes displace the right kidney. *Hepatic flexure* - The **hepatic flexure** (right colic flexure) of the colon lies immediately inferior to the liver and anterior to the **lower part of the right kidney**. - This anatomical relationship means that the right kidney can be affected by diseases of the colon in this region. *2nd part of duodenum* - The **descending (2nd) part of the duodenum** lies anterior to the **hilum and medial part of the right kidney** [1]. - Its retroperitoneal position places it in close proximity to the renal structures, making it a key anterior relation.
Question 394: Which cranial nerve is not associated with the nucleus ambiguus?
- A. Cranial Nerve X (Vagus)
- B. Cranial Nerve XI (Accessory)
- C. Cranial Nerve IX (Glossopharyngeal)
- D. Cranial Nerve XII (Hypoglossal) (Correct Answer)
Explanation: ***Cranial Nerve XII (Hypoglossal)*** - The **hypoglossal nucleus** in the medulla is the origin for CN XII, which primarily controls **tongue movements** [1]. - It does not receive motor fibers from the nucleus ambiguus, as its function is unrelated to the pharyngeal or laryngeal musculature. *Cranial Nerve X (Vagus)* - Motor fibers for the muscles of the **pharynx** and **larynx** from the nucleus ambiguus contribute to the vagus nerve. - The vagus nerve also provides parasympathetic innervation to the **thoracic and abdominal viscera**. *Cranial Nerve XI (Accessory)* - Cranial root contributions from the nucleus ambiguus exit with the vagus nerve to innervate the **laryngeal muscles**. - The **spinal root** of the accessory nerve, originating from the cervical spinal cord, innervates the **sternocleidomastoid** and **trapezius muscles**. *Cranial Nerve IX (Glossopharyngeal)* - The nucleus ambiguus provides motor innervation for the **stylopharyngeus muscle** via the glossopharyngeal nerve. - This muscle plays a role in **swallowing** and elevates the pharynx.
Question 395: In which region of the human spine is the number of vertebrae usually constant?
- A. Cervical (Correct Answer)
- B. Thoracic
- C. Lumbar
- D. Sacral
Explanation: ***Cervical*** - The human cervical spine almost universally consists of **seven vertebrae (C1-C7)**, making it the most constant region in terms of vertebral number. - This consistent number is crucial for normal neck movement and protection of vital neurological structures. *Thoracic* - While typically having **12 vertebrae**, variations in the thoracic region can occur, with some individuals having 11 or 13 due to transitional vertebrae. - These variations are less common but indicate that the number is not as strictly constant as in the cervical spine. *Lumbar* - The lumbar spine commonly has **five vertebrae (L1-L5)**, but variations such as four or six lumbar vertebrae can be seen due to lumbarization or sacralization. - **Lumbarization** involves the first sacral segment detaching, while **sacralization** involves the fifth lumbar vertebra fusing with the sacrum. *Sacral* - The sacrum is formed by the fusion of **five sacral vertebrae (S1-S5)**, but the number of *individual identifiable* vertebrae before fusion, or in cases of incomplete fusion, can vary. - The sacral region itself is a fused structure, and while it originates from five segments, the concept of "number of vertebrae" can be ambiguous due to its characteristic fusion.
Question 396: Nucleus gracilis and nucleus cuneatus are seen in?
- A. Medulla (Correct Answer)
- B. Temporal lobe
- C. Midbrain
- D. Pons
Explanation: ***Medulla*** - The **nucleus gracilis** and **nucleus cuneatus** are located in the **dorsal medulla** and are crucial for processing **conscious proprioception**, **vibration**, and **fine touch**. - These nuclei receive input from the fasciculus gracilis and fasciculus cuneatus (dorsal column tracts) and are part of the dorsal column-medial lemniscus pathway. - They give rise to the **internal arcuate fibers** which decussate and form the **medial lemniscus**. *Pons* - The pons contains several important nuclei, including the **pontine nuclei** (involved in motor coordination), nuclei of cranial nerves V, VI, VII, and VIII, and the **locus coeruleus**. - The dorsal column nuclei are not located in the pons. *Temporal lobe* - The **temporal lobe** is part of the cerebral cortex and is primarily involved in **auditory processing**, memory formation, and language comprehension. - It contains structures like the hippocampus and amygdala, but not the dorsal column nuclei. *Midbrain* - The **midbrain** contains nuclei such as the **red nucleus**, **substantia nigra**, and nuclei of cranial nerves III and IV, involved in motor control and eye movements. - The nucleus gracilis and nucleus cuneatus are not found in the midbrain.
Biochemistry
2 questionsWhich glycogen storage disease also presents as a lysosomal storage disease?
Type of inhibition of aconitase by trans-aconitate is?
NEET-PG 2012 - Biochemistry NEET-PG Practice Questions and MCQs
Question 391: Which glycogen storage disease also presents as a lysosomal storage disease?
- A. Von Gierke's disease
- B. McArdle's disease
- C. Andersen's disease
- D. Pompe's disease (Correct Answer)
Explanation: ***Pompe's disease*** - Also known as **glycogen storage disease type II**, it is caused by a deficiency of **acid alpha-glucosidase (GAA)**, a *lysosomal enzyme*. - This deficiency leads to the accumulation of **glycogen in lysosomes**, particularly affecting muscle tissue, thereby earning its classification as both a glycogen storage disease and a lysosomal storage disease. *Von Gierke's disease* - This is **glycogen storage disease type I** and is due to a deficiency in **glucose-6-phosphatase**. - It primarily affects the **liver and kidneys**, causing severe **hypoglycemia** and **lactic acidosis**, but it is not classified as a lysosomal storage disease. *McArdle's disease* - This is **glycogen storage disease type V**, caused by a deficiency in **muscle glycogen phosphorylase (myophosphorylase)**. - It manifests as **exercise intolerance** and muscle pain, but it does not involve lysosomal enzyme defects or glycogen accumulation in lysosomes. *Andersen's disease* - This is **glycogen storage disease type IV**, caused by a deficiency in the **glycogen branching enzyme**. - It leads to the formation of **abnormal glycogen structures**, primarily affecting the liver and causing early liver failure, but it is not a lysosomal storage disorder.
Question 392: Type of inhibition of aconitase by trans-aconitate is?
- A. Competitive (Correct Answer)
- B. Non-competitive
- C. Allosteric
- D. None of the options
Explanation: ***Competitive*** - **Competitive inhibition** occurs when the inhibitor (trans-aconitate) structurally resembles the enzyme's natural substrate (cis-aconitate) and binds to the **active site**, preventing the substrate from binding. - This type of inhibition can be overcome by increasing the concentration of the **substrate**. *Non-competitive* - **Non-competitive inhibitors** bind to a site on the enzyme other than the active site, causing a conformational change that reduces the enzyme's efficiency, regardless of substrate concentration. - Trans-aconitate's structural similarity to aconitate's substrate points away from a non-competitive mechanism. *Allosteric* - **Allosteric inhibition** involves an inhibitor binding to a regulatory site (allosteric site) on the enzyme, which is distinct from the active site, to alter enzyme activity. - While allosteric regulation is a type of non-competitive inhibition, trans-aconitate's direct structural resemblance to the substrate makes competitive inhibition the more specific and accurate description. *None of the options* - This option is incorrect because **competitive inhibition** accurately describes the mechanism by which trans-aconitate inhibits aconitase, given its structural similarity to the natural substrate. - The other options are less fitting due to the specific characteristics of trans-aconitate's action.
Obstetrics and Gynecology
1 questionsWhich structure do cytotrophoblasts invade during implantation?
NEET-PG 2012 - Obstetrics and Gynecology NEET-PG Practice Questions and MCQs
Question 391: Which structure do cytotrophoblasts invade during implantation?
- A. Decidua capsularis
- B. Decidua vera
- C. Decidua basalis (Correct Answer)
- D. Decidua parietalis
Explanation: ***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.
Surgery
1 questionsDuring incision and drainage of ischiorectal abscess, which nerve is most likely to be injured?
NEET-PG 2012 - Surgery NEET-PG Practice Questions and MCQs
Question 391: During incision and drainage of ischiorectal abscess, which nerve is most likely to be injured?
- A. Superior rectal nerve
- B. Inferior rectal nerve (Correct Answer)
- C. Superior gluteal nerve
- D. Inferior gluteal nerve
Explanation: ***Inferior rectal nerve*** - The **inferior rectal nerve** innervates the **external anal sphincter** and the skin around the anus, making it vulnerable during an incision and drainage of an **ischiorectal abscess** due to its anatomical proximity. - Injury to this nerve can lead to **fecal incontinence** or altered sensation in the perianal region. *Superior rectal nerve* - The **superior rectal nerve** is primarily involved in the innervation of the **rectum** and is not directly located in the area of an **ischiorectal abscess**. - This nerve supplies the smooth muscle of the rectum and is not anatomically vulnerable during incision and drainage of an abscess in the ischiorectal fossa. *Superior gluteal nerve* - The **superior gluteal nerve** supplies the **gluteus medius**, **gluteus minimus**, and **tensor fasciae latae muscles**, which are typically located much more superior and lateral to an **ischiorectal abscess**. - Damage to this nerve causes a characteristic **Trendelenburg gait**, which is unrelated to perianal surgery. *Inferior gluteal nerve* - The **inferior gluteal nerve** innervates the **gluteus maximus muscle**, which is also located more superiorly and laterally relative to the **ischiorectal fossa**. - Injury to this nerve would primarily affect hip extension and is not a common complication of **ischiorectal abscess** drainage.