Systemic Anatomy — MCQs
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Which of the following is the primary mechanical action of the tensor tympani muscle?
Food particles mostly get obstructed in which part of the esophagus?
Which of the following is not a part of the uveal tract?
The squamo-columnar junction is normally located at
Which muscle attaches to the posterior surface of the sacrum?
Which of the following lymph nodes does not drain the stomach wall?
What type of muscles are medial two lumbricals?
Which segment of the liver receives blood supply from both the right and left hepatic arteries and portal veins, and drains directly into the inferior vena cava?
Where does the great cardiac vein lie?
To which segment of the liver is the gallbladder related?
Systemic Anatomy Indian Medical PG Practice Questions and MCQs
Question 191: Which of the following is the primary mechanical action of the tensor tympani muscle?
- A. Dampen very loud sound
- B. Tenses tympanic membrane (Correct Answer)
- C. Tenses pharyngotympanic tube
- D. Prevent noise trauma to the inner ear
Explanation: ***Tenses tympanic membrane*** - The **tensor tympani muscle** contracts to pull the **malleus** medially, thereby **tensing the tympanic membrane** [1]. - This action **reduces the amplitude of vibrations** transmitted from the tympanic membrane to the ossicles, protecting the inner ear from loud sounds [1]. *Dampen very loud sound* - While the tensor tympani does play a role in protecting the ear from loud sounds, its primary physiological action is to **tense the tympanic membrane**, which in turn helps dampen sound. - The **stapedius muscle** also contributes significantly to this dampening effect by stabilizing the **stapes** at the oval window [1]. *Tenses pharyngotympanic tube* - The **pharyngotympanic (auditory) tube** is opened by the action of the **tensor veli palatini** and **levator veli palatini muscles** during swallowing and yawning, not the tensor tympani [1]. - Tensing the pharyngotympanic tube is not a known physiological function of the tensor tympani. *Prevent noise trauma to the inner ear* - This is an outcome of the tensor tympani's action, but not its direct physiological function. The tensor tympani directly **tenses the tympanic membrane** to achieve this protective effect [1]. - The **acoustic reflex**, involving both tensor tympani and stapedius muscles, serves to prevent damage from loud sounds, but the question asks for the specific function of the muscle.
Question 192: Food particles mostly get obstructed in which part of the esophagus?
- A. Crossing of arch of aorta
- B. Cardiac end
- C. Cricopharyngeal sphincter (Correct Answer)
- D. None of the options
Explanation: ***Correct: Cricopharyngeal sphincter*** - The **cricopharyngeal sphincter** (upper esophageal sphincter at C6 level) is the **most common site** of esophageal food bolus impaction, accounting for approximately **68-70%** of cases - This is the **narrowest part** of the esophagus and represents the first physiological narrowing where poorly chewed food boluses commonly lodge - It is particularly prone to obstruction with **meat boluses** (steakhouse syndrome), bones, and large food particles - The sphincter's tight muscular ring and acute angle make it the primary site for food impaction in otherwise healthy individuals *Incorrect: Crossing of arch of aorta* - The **aortic arch crossing** (at T4-T5 level) is the **second most common** site of food impaction, not the most common - This anatomical constriction occurs due to external compression by the aortic arch and left main bronchus - While important clinically, it accounts for fewer cases than the cricopharyngeal region *Incorrect: Cardiac end* - The **cardiac end** (lower esophageal sphincter at T10-T11 level) is the **third physiological narrowing** and the **least common** site for acute food bolus impaction in healthy individuals - Obstruction here is more commonly associated with pathological conditions like **achalasia**, **strictures**, or **Schatzki rings** rather than simple food impaction [1] - This area is more frequently involved in **reflux-related issues** than acute obstruction *Incorrect: None of the options* - This is incorrect because the esophagus has **three well-defined anatomical narrowings** where food particles characteristically become obstructed, and the correct answer is listed among the options
Question 193: Which of the following is not a part of the uveal tract?
- A. Iris
- B. Ciliary body
- C. Retina (Correct Answer)
- D. Choroid
Explanation: ***Retina*** - The **retina** is the light-sensitive layer at the back of the eye, responsible for converting light into neural signals. It is part of the **sensory layer** of the eye, distinct from the uveal tract [1]. - While essential for vision, the retina originates from the **neural ectoderm** and is functionally separate from the uvea, which is primarily vascular and pigmented [2]. *Iris* - The **iris** is the colored part of the eye that surrounds the pupil and regulates the amount of light entering the eye. It is the **anterior-most part** of the uveal tract [3]. - It contains pigmented cells and smooth muscle fibers (sphincter and dilator pupillae) that control pupil size. *Ciliary body* - The **ciliary body** is a ring of tissue behind the iris that produces **aqueous humor** and contains the ciliary muscle, which is involved in accommodating the lens [3]. It is the **middle part** of the uveal tract. - It plays a crucial role in maintaining intraocular pressure and focusing vision [3]. *Choroid* - The **choroid** is the vascular layer of the eye, situated between the retina and the sclera, providing oxygen and nourishment to the outer layers of the retina [1]. It is the **posterior part** of the uveal tract. - Its rich blood supply and pigmentation help absorb excess light, preventing reflections within the eye.
Question 194: The squamo-columnar junction is normally located at
- A. In esophagus more than 3cms proximal to GEJ
- B. Proximal 2-3 cms of stomach
- C. Distal 2-3 cms of esophagus (Correct Answer)
- D. None of the options
Explanation: ***Distal 2-3 cms of esophagus*** - The **squamo-columnar junction** (SCJ), or Z-line, is the visible endoscopic landmark where the pale, shiny stratified squamous epithelium of the esophagus meets the red, velvety columnar epithelium of the stomach. - In normal anatomy, this junction is typically located within the **distal 2-3 cm** of the esophagus, just above the anatomical gastroesophageal junction (GEJ). *Proximal 2-3 cms of stomach* - This location would imply the SCJ is in the stomach, which is incorrect; the stomach lining is entirely composed of **columnar epithelium**. - While there is a transition at the gastroesophageal junction, the term squamo-columnar junction specifically refers to the meeting point of esophageal squamous and gastric-type columnar epithelia. *In esophagus more than 3cms proximal to GEJ* - If the SCJ is located more than 3 cm proximal to the GEJ, it suggests **Barrett's esophagus**, where gastric-type columnar epithelium has replaced the normal esophageal squamous lining due to metaplasia [1]. - This is an abnormal finding and not the physiological location of the squamo-columnar junction. *None of the options* - This option is incorrect because the distal 2-3 cm of the esophagus accurately describes the normal location of the squamo-columnar junction. - The SCJ's position is a critical clinical landmark for identifying conditions like Barrett's esophagus or hiatal hernia [1].
Question 195: Which muscle attaches to the posterior surface of the sacrum?
- A. Multifidus Lumborum (Correct Answer)
- B. Iliacus
- C. Coccygeus
- D. Piriformis
Explanation: ***Multifidus Lumborum*** - The **multifidus lumborum** is a deep back muscle that has attachments to the **posterior surface of the sacrum**, specifically the sacral groove. - Its primary role involves **stabilizing the spine** and performing small, precise movements of the vertebrae. *Iliacus* - The **iliacus muscle** originates from the **iliac fossa** of the pelvic bone, not the sacrum. - It primarily acts as a **hip flexor** by inserting onto the lesser trochanter of the femur. *Coccygeus* - The **coccygeus muscle** (also known as ischiococcygeus) originates from the **ischial spine** and inserts onto the lateral border of the coccyx and the lowest part of the sacrum, but its primary attachment is not the posterior surface of the sacrum. - It forms part of the **pelvic floor**, supporting pelvic organs and flexing the coccyx. *Piriformis* - The **piriformis muscle** originates from the **anterior surface of the sacrum**, specifically the pelvic surface, and runs through the greater sciatic notch. - It is a **hip external rotator** and abductor, inserting onto the greater trochanter of the femur.
Question 196: Which of the following lymph nodes does not drain the stomach wall?
- A. Pyloric nodes
- B. Short gastric vessel nodal group
- C. Right gastroepiploic nodes
- D. Inguinal nodes (Correct Answer)
Explanation: ***Inguinal nodes*** - The **inguinal lymph nodes** primarily drain the lower limbs, perineum, and external genitalia. - They do **not** receive any lymphatic drainage from the **stomach wall**, making this the correct answer. - These nodes are located in the **groin region** and are part of the superficial and deep inguinal lymphatic chains. *Pyloric nodes* - The **pyloric nodes** are located around the pylorus of the stomach [1]. - They **do drain** lymph from the **pyloric region** of the stomach [1]. - These are part of the gastric lymphatic drainage system [1]. *Short gastric vessel nodal group* - The **short gastric vessel nodal group** is found along the short gastric arteries. - These nodes **do drain** the **fundus** and a portion of the **body of the stomach**. - They follow the short gastric vessels from the greater curvature to the splenic hilum. *Right gastroepiploic nodes* - The **right gastroepiploic nodes** are situated along the greater curvature of the stomach, following the right gastroepiploic vessels [1]. - They **do drain** the **inferior half** of the greater curvature of the stomach [1]. - These nodes are part of the gastric and omental lymphatic network [1].
Question 197: What type of muscles are medial two lumbricals?
- A. Multipennate
- B. Bipennate (Correct Answer)
- C. None of the options
- D. Unipennate
Explanation: ***Bipennate*** - The **medial two lumbricals** (third and fourth) are classified as **bipennate muscles** because they originate from two adjacent tendons of the flexor digitorum profundus (FDP). - Each of these lumbricals arises from the **adjacent sides of two FDP tendons**, with muscle fibers converging toward a central insertion, creating a bipennate arrangement. - This dual origin distinguishes them from the lateral two lumbricals, which are unipennate. *Unipennate* - **Unipennate muscles** have fibers that attach obliquely to only one side of a single tendon. - The **lateral two lumbricals** (first and second) are unipennate as they each arise from a single FDP tendon. - This is not the correct classification for the medial two lumbricals. *Multipennate* - **Multipennate muscles** have multiple tendon arrangements with fibers converging at different angles from several directions. - Examples include the **deltoid muscle**, which has a much more complex architecture than lumbricals. *None of the options* - Since **bipennate** accurately describes the structure of the medial two lumbricals based on their dual tendon origins, this option is incorrect. - The architectural classification is well-established in anatomical literature.
Question 198: Which segment of the liver receives blood supply from both the right and left hepatic arteries and portal veins, and drains directly into the inferior vena cava?
- A. Segment I (Caudate Lobe) (Correct Answer)
- B. Segment II
- C. Segment IV
- D. Segment III
Explanation: ***Segment I (Caudate Lobe)*** - The **caudate lobe** is unique in its blood supply and venous drainage. It receives arterial supply from both the right and left hepatic arteries and venous drainage from both the right and left portal veins [1]. - Its venous drainage is also distinct, emptying directly into the **inferior vena cava (IVC)** via several small, independent hepatic veins, rather than through the main right, middle, or left hepatic veins like the other segments [1]. *Segment II* - This segment is part of the **left hepatic lobe** and is supplied by branches of the left hepatic artery and left portal vein [1]. - Its venous drainage primarily flows into the **left hepatic vein**. *Segment IV* - This segment, also known as the **quadrate lobe**, is part of the functional left lobe, though anatomically it's often considered part of the right lobe [1]. - It receives blood primarily from the **left portal vein** and drains into the **middle hepatic vein** [1]. *Segment III* - This segment is part of the **left hepatic lobe** and is located to the left of the falciform ligament [1]. - It receives arterial supply from the **left hepatic artery** and venous supply from the **left portal vein**, draining ultimately into the **left hepatic vein**.
Question 199: Where does the great cardiac vein lie?
- A. Tricuspid valve
- B. Anterior interventricular sulcus (Correct Answer)
- C. Posterior interventricular sulcus
- D. Coronary sulcus
Explanation: ***Anterior interventricular sulcus*** - The **great cardiac vein** runs alongside the **left anterior descending artery** (LAD) within the **anterior interventricular sulcus**. - This anatomical position allows it to drain the areas supplied by the LAD, primarily the **anterior walls** of both ventricles and the interventricular septum. - From the apex, it ascends in this sulcus before continuing around the left border of the heart. *Tricuspid valve* - The **tricuspid valve** is located between the **right atrium** and **right ventricle** and is involved in blood flow regulation, not venous drainage. - This is a valvular structure, not a sulcus or groove where vessels lie. *Posterior interventricular sulcus* - The **posterior interventricular sulcus** houses the **middle cardiac vein** and the **posterior interventricular artery**. - The great cardiac vein is not found in this sulcus; it drains the anterior aspect of the heart. *Coronary sulcus* - The **coronary sulcus** (atrioventricular groove) contains the **coronary sinus** and circumflex vessels. - While the great cardiac vein eventually continues as the coronary sinus in this region, the vein itself specifically lies in the anterior interventricular sulcus during its ascending course.
Question 200: To which segment of the liver is the gallbladder related?
- A. Segment I
- B. Segment II
- C. Segment III
- D. Segment IV (Correct Answer)
Explanation: ***Segment IV*** - The **gallbladder** is anatomically positioned in the **fossa of the gallbladder**, which lies in relation to the **quadrate lobe** of the liver [1]. - The **quadrate lobe** corresponds to **Segment IV** of the Couinaud classification system [1]. *Segment I* - **Segment I** is the **caudate lobe**, which is located posterior to the porta hepatis and is functionally distinct, receiving blood supply from both the right and left hepatic arteries [2]. - It is superior to the gallbladder and not directly related to its fossa [1]. *Segment II* - **Segment II** is located in the **left lateral segment** of the liver, superior and to the left of the falciform ligament [3]. - This segment is far from the anatomical position of the gallbladder. *Segment III* - **Segment III** is also part of the **left lateral segment**, situated anteroinferiorly to Segment II [3]. - Like Segment II, it is anatomically distant from the gallbladder fossa.
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