Anatomy
7 questionsCoronary sinus develops from?
All of the following arteries are branches of the coeliac trunk, EXCEPT which one?
From which ribs does the spleen extend?
Which is derived from Wolffian duct?
Risorius is a muscle of?
Which of the following is an operculated sulcus ?
In walking, gravity tends to tilt pelvis and trunk to the unsupported side, the major factor in preventing this unwanted movement is?
NEET-PG 2012 - Anatomy NEET-PG Practice Questions and MCQs
Question 101: Coronary sinus develops from?
- A. Truncus arteriosus
- B. Conus
- C. Sinus venosus (Correct Answer)
- D. AV canal
Explanation: 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.
Question 102: All of the following arteries are branches of the coeliac trunk, EXCEPT which one?
- A. Splenic artery
- B. Left gastric artery
- C. Common hepatic artery
- D. Right gastric artery (Correct Answer)
Explanation: ***Right gastric artery*** - The **right gastric artery** typically originates from the **proper hepatic artery**, which is a branch of the common hepatic artery. - Therefore, it is not a direct branch of the coeliac trunk itself. *Left gastric artery* - The **left gastric artery** is one of the three main direct branches of the **coeliac trunk**. - It supplies the lesser curvature of the stomach and the abdominal esophagus. *Splenic artery* - The **splenic artery** is another major direct branch of the **coeliac trunk**. - It supplies the spleen, pancreas, and parts of the stomach via various branches. *Common hepatic artery* - The **common hepatic artery** is the third main direct branch of the **coeliac trunk**. - It gives rise to the proper hepatic artery and the gastroduodenal artery, supplying the liver, gallbladder, pylorus, and duodenum.
Question 103: From which ribs does the spleen extend?
- A. 5th to 9th rib
- B. 2nd to 5th rib
- C. 11th to 12th rib
- D. 9th to 11th rib (Correct Answer)
Explanation: ***9th to 11th rib*** - The **spleen** is located in the **left upper quadrant** of the abdomen, deep to the 9th, 10th, and 11th ribs. - Its protected position beneath these ribs makes it vulnerable to injury from trauma to the left lower chest or upper abdomen. *5th to 9th rib* - This range primarily covers the location of the **heart** and the upper part of the **lungs**. - While the spleen is superior to other abdominal organs, it does not extend as high as the 5th rib. *2nd to 5th rib* - This region is mainly associated with the **upper lobes of the lungs** and the **superior mediastinum**. - The spleen is an abdominal organ and is situated much lower in the thoracic cavity. *11th to 12th rib* - This range is too low and posterior for the typical position of the spleen, especially for its superior border. - The 12th rib primarily overlies the **kidneys** and the more inferior aspects of the diaphragm.
Question 104: Which is derived from Wolffian duct?
- A. Appendix of epididymis (Correct Answer)
- B. Appendix of the testis
- C. Uterine structure
- D. Hydatid of Morgagni
Explanation: The **appendix of the epididymis** is a vestigial structure directly derived from the mesonephric (Wolffian) duct in males. It is an embryological remnant of this duct, located at the head of the epididymis. *Appendix of the testis* - The **appendix of the testis** (hydatid of Morgagni) is a remnant of the paramesonephric (Müllerian) duct, not the Wolffian duct. - It is usually found on the upper pole of the testis, typically near the epididymis. *Uterine structure* - **Uterine structures** (uterus, fallopian tubes, and upper vagina) are derived from the paramesonephric (Müllerian) ducts in females [1]. - The Wolffian ducts largely regress in females due to the absence of testosterone. *Hydatid of Morgagni* - The term **hydatid of Morgagni** can refer to the appendix of the testis (Müllerian duct remnant) or, less commonly, to the appendix of the epididymis (Wolffian duct remnant). - However, in common clinical and anatomical usage, it almost exclusively refers to the **appendix of the testis**, which is a Müllerian duct derivative.
Question 105: Risorius is a muscle of?
- A. Mastication
- B. Deglutition
- C. Facial expression (Correct Answer)
- D. Eye movement
Explanation: Facial expression - The **risorius muscle** retracts the **corner of the mouth** laterally, contributing to smiling or grimacing. - It falls under the category of **mimetic muscles**, all of which are innervated by the **facial nerve (cranial nerve VII)**. *Mastication* - Muscles of mastication, such as the **masseter**, **temporalis**, and **pterygoids**, are primarily involved in **chewing** and moving the mandible. - These muscles are innervated by the **trigeminal nerve (cranial nerve V)**, not the facial nerve. *Deglutition* - Deglutition refers to the process of **swallowing**, involving muscles of the **pharynx** and **larynx**. - Examples include the **palatoglossus**, **stylopharyngeus**, and **superior pharyngeal constrictor**. *Eye movement* - Muscles responsible for eye movement are the **extrinsic ocular muscles**, such as the **recti** and **oblique muscles** [1]. - These muscles are innervated by the **oculomotor (III)**, **trochlear (IV)**, and **abducens (VI)** cranial nerves. *Note: No provided references mention the risorius muscle, mimetic muscles, or muscles of mastication; citations are applied only to supported sub-topics.*
Question 106: Which of the following is an operculated sulcus ?
- A. Lunate
- B. Calcarine
- C. Central
- D. Sylvian fissure (lateral sulcus) (Correct Answer)
Explanation: ***Sylvian fissure (lateral sulcus)*** - The **lateral sulcus**, also known as the Sylvian fissure, is a deep groove on the lateral surface of the brain that **separates the frontal and parietal lobes from the temporal lobe**. - It is considered an **operculated sulcus** because its banks contain the insula, which is a buried part of the cerebral cortex covered by the surrounding cortical folds called opercula. *Calcarine* - The **calcarine sulcus** is located on the medial surface of the occipital lobe, forming the primary visual cortex, and is not an operculated sulcus. - It delineates the **upper and lower banks of the visual cortex** and does not involve overlying cortical structures. *Lunate* - The **lunate sulcus** is found on the posterior part of the occipital lobe and is not typically described as an operculated sulcus. - It represents a boundary in the visual cortex, but its banks do not hide a buried cortical region like the insula. *Central* - The **central sulcus** (Rolandic fissure) separates the frontal lobe from the parietal lobe and is a prominent sulcus, but it is not operculated. - Its banks contain the **precentral gyrus** (primary motor cortex) and **postcentral gyrus** (primary somatosensory cortex) directly facing each other.
Question 107: In walking, gravity tends to tilt pelvis and trunk to the unsupported side, the major factor in preventing this unwanted movement is?
- A. Adductor muscles
- B. Quadriceps
- C. Gluteus medius and minimus (Correct Answer)
- D. Gluteus maximus
Explanation: ***Gluteus medius and minimus*** - The **gluteus medius** and **gluteus minimus** are essential **abductors** of the hip, primarily responsible for stabilizing the pelvis during the **single-limb support phase of gait**. - When one leg is lifted during walking, these muscles on the **stance leg side** contract to prevent the pelvis from tilting downwards on the unsupported swing leg side. *Adductor muscles* - **Adductor muscles** (adductor longus, brevis, magnus, pectineus, gracilis) primarily function to bring the thigh toward the midline of the body. - While they play a role in gait stability, their main action is not to prevent the lateral pelvic tilt described. *Quadriceps* - The quadriceps femoris group (rectus femoris, vastus lateralis, medialis, intermedius) are powerful **extensors of the knee**. - They are crucial for weight acceptance and propulsion during walking but do not directly prevent lateral pelvic tilt [1]. *Gluteus maximus* - The **gluteus maximus** is the largest and most powerful muscle of the hip, primarily responsible for **hip extension** and **external rotation**. - It is crucial for activities like climbing stairs or running, but its main role in normal walking is not to prevent lateral pelvic tilt; that function is more specific to the gluteus medius and minimus.
Physiology
3 questionsWhat is the Bohr effect in relation to hemoglobin's affinity for oxygen?
What is the consequence of tibial nerve injury/palsy?
Which of the following statements regarding the lower esophageal sphincter is TRUE?
NEET-PG 2012 - Physiology NEET-PG Practice Questions and MCQs
Question 101: What is the Bohr effect in relation to hemoglobin's affinity for oxygen?
- A. Decrease in CO2 affinity of hemoglobin when the pH of blood falls
- B. Decrease in O2 affinity of hemoglobin when the pH of blood rises
- C. Decrease in O2 affinity of hemoglobin when the pH of blood falls (Correct Answer)
- D. Decrease in CO2 affinity of hemoglobin when the pH of blood rises
Explanation: ***Decrease in O2 affinity of hemoglobin when the pH of blood falls*** - The **Bohr effect** describes how **hemoglobin's affinity for oxygen decreases** in acidic environments (lower pH), leading to increased oxygen release to tissues. - This physiological response is crucial in active tissues, where increased metabolism produces more **carbon dioxide** and **lactic acid**, lowering the local pH. *Decrease in CO2 affinity of hemoglobin when the pH of blood falls* - This statement incorrectly relates the Bohr effect to **CO2 affinity** and its change with pH in this manner. - The Bohr effect primarily concerns oxygen affinity, not CO2 affinity; CO2 and H+ directly influence oxygen binding. *Decrease in O2 affinity of hemoglobin when the pH of blood rises* - An **increase in pH** (alkaline environment) would, in fact, **increase hemoglobin's affinity for oxygen**, promoting oxygen uptake in the lungs. - This describes the opposite of the Bohr effect, which is about oxygen release in acidic conditions. *Decrease in CO2 affinity of hemoglobin when the pH of blood rises* - While pH changes do affect CO2 transport, this statement does not accurately describe the Bohr effect. - The **Haldane effect** is more relevant to the relationship between oxygenation status and hemoglobin's CO2 affinity.
Question 102: What is the consequence of tibial nerve injury/palsy?
- A. Loss of plantar flexion (Correct Answer)
- B. Dorsiflexion of foot at ankle joint
- C. Loss of sensation of dorsum of foot
- D. Paralysis of muscles of anterior compartment of leg
Explanation: **Loss of plantar flexion** - The **tibial nerve** innervates the muscles of the **posterior compartment of the leg**, which are primarily responsible for **plantar flexion** of the foot. - Injury to this nerve directly impairs the function of muscles like the gastrocnemius, soleus, and tibialis posterior, leading to a significant loss of the ability to point the foot downwards. *Dorsiflexion of foot at ankle joint* - **Dorsiflexion** is primarily mediated by muscles in the **anterior compartment of the leg**, such as the tibialis anterior, which are innervated by the **deep fibular nerve**. - Tibial nerve injury would not directly affect these muscles or their function; rather, it leads to issues with the opposing action. *Loss of sensation of dorsum of foot* - Sensation to the **dorsum of the foot** is primarily supplied by the **superficial fibular nerve** (for most of the dorsum) and the **deep fibular nerve** (for the first web space). - While the tibial nerve provides sensation to the sole of the foot, it does not typically innervate the dorsum. *Paralysis of muscles of anterior compartment of leg* - The muscles of the **anterior compartment of the leg** (e.g., tibialis anterior, extensor digitorum longus, extensor hallucis longus) are innervated by the **deep fibular nerve**. - A tibial nerve injury would paralyze muscles in the posterior compartment, not the anterior compartment.
Question 103: Which of the following statements regarding the lower esophageal sphincter is TRUE?
- A. It relaxes in response to swallowing. (Correct Answer)
- B. It remains contracted during swallowing to prevent regurgitation.
- C. Its tone is primarily influenced by the myogenic properties of the smooth muscle.
- D. It contracts in response to gastric distension.
Explanation: ***It relaxes in response to swallowing.*** - The **lower esophageal sphincter (LES)** normally maintains high resting tone to prevent gastroesophageal reflux but **relaxes completely during swallowing** to allow passage of food into the stomach. - This relaxation (called **receptive relaxation**) is mediated by **vagal nerve stimulation** through release of nitric oxide (NO) and vasoactive intestinal peptide (VIP). - The relaxation occurs **before the peristaltic wave arrives**, allowing coordinated transit of the bolus. *It remains contracted during swallowing to prevent regurgitation.* - This is **incorrect** - the LES must **relax during swallowing** to allow food passage into the stomach. - Failure of LES relaxation during swallowing is the pathophysiology of **achalasia**, leading to dysphagia. - The LES only maintains contraction between swallows to prevent reflux. *Its tone is primarily influenced by the myogenic properties of the smooth muscle.* - While the LES contains smooth muscle with intrinsic myogenic properties, its tone is **predominantly regulated by neural and hormonal factors**. - **Neural control:** Vagal cholinergic pathways (increase tone), non-adrenergic non-cholinergic (NANC) pathways with NO and VIP (decrease tone). - **Hormonal factors:** Gastrin increases tone, while progesterone, CCK, and secretin decrease tone. *It contracts in response to gastric distension.* - This is **incorrect** - gastric distension actually triggers **transient LES relaxations (TLESRs)**, which are the primary mechanism of physiological reflux. - TLESRs are vagally mediated reflex responses that allow venting of gastric air. - Increased LES contraction in response to gastric distension would be counterproductive.