Which chamber of the heart forms the posterior surface?
Which chamber of the heart is located anterior to the sternum?
Which of the following statements is false about the right bronchus?
Which type of collagen is primarily responsible for forming the basement membrane sheets?
Type of collagen found in space of Disse in liver is -
Which is the earliest secondary ossification center to develop chronologically?
In current medical practice, cephalic index is primarily used for
What anatomical structure is formed after the obliteration of the umbilical vein?
T cells in lymph node are present in:
What is the approximate length of the tibia in centimeters for an average adult?
NEET-PG 2013 - Anatomy NEET-PG Practice Questions and MCQs
Question 71: Which chamber of the heart forms the posterior surface?
- A. Right Atrium (RA)
- B. Left Atrium (LA) (Correct Answer)
- C. Left Ventricle (LV)
- D. Right Ventricle (RV)
Explanation: ***Left Atrium (LA)*** - The **left atrium** forms the posterior surface of the heart, lying in front of the esophagus and thoracic aorta [1]. - Its posterior position makes it susceptible to enlargement, which can compress the **esophagus** and cause dysphagia [1]. *Right Atrium (RA)* - The **right atrium** primarily forms the right border of the heart and receives deoxygenated blood from the systemic circulation. - It lies anteriorly and to the right, behind the sternum and costal cartilages. *Left Ventricle (LV)* - The **left ventricle** forms the apex of the heart and part of the left border. - It is positioned *inferiorly* and *anteriorly*, contributing significantly to the *diaphragmatic surface* of the heart. *Right Ventricle (RV)* - The **right ventricle** forms the majority of the anterior surface of the heart, directly behind the sternum. - It also contributes to the *inferior surface* of the heart, resting on the diaphragm.
Question 72: Which chamber of the heart is located anterior to the sternum?
- A. Left ventricle
- B. Right atrium
- C. Right ventricle (Correct Answer)
- D. Left atrium
Explanation: ***Right ventricle*** - The **right ventricle** forms the majority of the **anterior surface of the heart** and is the chamber closest to the sternum [2]. - This anatomical position is important clinically, for instance, in cases of **pericardial effusion** or **chest trauma**. *Left atrium* - The **left atrium** is located most **posteriorly** in the heart, adjacent to the esophagus [1], [2]. - Due to its posterior position, an enlarged left atrium can compress the esophagus, causing **dysphagia**. *Left ventricle* - The **left ventricle** forms the **apex of the heart** and is located more on the left and posterior aspect compared to the right ventricle [2]. - While it contributes to the anterior surface, the **right ventricle** is more directly anterior to the sternum [2]. *Right atrium* - The **right atrium** is positioned to the right and slightly posterior to the right ventricle. - It receives venous blood from the body and forms the **right border of the heart**.
Question 73: Which of the following statements is false about the right bronchus?
- A. Shorter
- B. More horizontal (Correct Answer)
- C. In the line of trachea
- D. Wider
Explanation: ***More horizontal*** - The right bronchus is traditionally described as **more vertical** or **more directly in line with the trachea** compared to the left bronchus. - This anatomical orientation makes it more susceptible to the aspiration of foreign bodies. *Shorter* - The **right main bronchus** is indeed shorter than the left main bronchus. - Its length is typically 2-3 cm, while the left main bronchus is about 5 cm long. *Wider* - The **right main bronchus** has a larger diameter than the left main bronchus. - This wider lumen contributes to the ease with which foreign bodies can enter it. *In the line of trachea* - The right main bronchus diverges from the trachea at a **less acute angle** (approximately 25 degrees) compared to the left (approximately 45 degrees). - This makes it appear more as a **direct continuation of the trachea**, facilitating aspiration into the right lung.
Question 74: Which type of collagen is primarily responsible for forming the basement membrane sheets?
- A. Type I
- B. Type II
- C. Type IV (Correct Answer)
- D. Type VI
Explanation: ***Type IV*** - **Type IV collagen** is unique as it forms a **two-dimensional network** that constitutes the structural foundation of **basement membranes**. - Its structure, with **non-fibrillar domains**, allows for assembly into sheets rather than fibrils, providing essential support and filtration properties. *Type I* - **Type I collagen** is the most abundant type in the human body, providing **tensile strength** to tissues like **skin, bone, tendons**, and ligaments. - It forms **thick, striated fibrils** and does not primarily associate with basement membranes [1]. *Type II* - **Type II collagen** is the main collagen found in **cartilage**, providing **resilience and shock absorption**. - It forms thin fibrils within the cartilage matrix and is not a component of basement membranes. *Type VI* - **Type VI collagen** is a minor fibrillar collagen that associates with **interstitial connective tissues**, often forming a **microfibrillar network**. - It links cells to the surrounding matrix and is not a primary component of basement membrane sheets.
Question 75: Type of collagen found in space of Disse in liver is -
- A. Collagen I & II
- B. Collagen III & IV (Correct Answer)
- C. Collagen II
- D. Collagen II & V
Explanation: ***Collagen III & IV*** - The **space of Disse** in the liver contains a delicate extracellular matrix predominantly composed of **collagen type III (reticular fibers)**, which provides structural support, and **collagen type IV**, a major component of basement membranes. - This specific collagen composition is crucial for regulating the exchange of solutes between **sinusoidal blood** and **hepatocytes**, as well as for the functional integrity of the liver [1]. *Collagen I & II* - **Collagen type I** is the most abundant collagen in the human body, found in connective tissues like **bone, skin, tendons, and ligaments**, but is not primary in the space of Disse. - **Collagen type II** is characteristic of **hyaline cartilage** and vitreous humor, and is not a significant component of the liver's extracellular matrix in the space of Disse. *Collagen II* - As mentioned, **collagen type II** is primarily found in **cartilage** and vitreous humor, which are distinct from the architectural requirements of the liver sinusoidal space. - Its presence in the space of Disse would not provide the necessary structural flexibility and support for the metabolic functions of the liver. *Collagen II & V* - While **collagen type V** is a minor fibrillar collagen that associates with collagen type I in many tissues, it is not a primary component of the space of Disse. - **Collagen type II** is, again, largely confined to cartilaginous structures, making this an unlikely combination for the liver microenvironment.
Question 76: Which is the earliest secondary ossification center to develop chronologically?
- A. Lower end of femur (Correct Answer)
- B. Upper end of humerus
- C. Lower end of fibula
- D. Upper end of tibia
Explanation: ***Lower end of femur*** - The **distal femoral epiphysis** is typically the first secondary ossification center to appear, often present at birth or shortly before [1]. - Its presence at birth is an indicator of **fetal maturity**, making it a key developmental landmark [1]. *Upper end of humerus* - The **proximal humeral epiphysis** typically ossifies around 6 months of age, significantly later than the distal femur. - This center contributes to the growth of the humeral head and greater tubercle. *Lower end of fibula* - The **distal fibular epiphysis** appears around the first year of life, after both the distal femur and proximal humerus. - It forms part of the ankle joint and contributes to its stability. *Upper end of tibia* - The **proximal tibial epiphysis** typically ossifies around 6-12 months of age, well after the distal femur. - This center is crucial for the growth of the upper tibia and knee joint development.
Question 77: In current medical practice, cephalic index is primarily used for
- A. Evaluation of skull deformities
- B. Assessment of craniosynostosis (Correct Answer)
- C. Clinical documentation of head shape
- D. Neurosurgical planning
Explanation: ***Assessment of craniosynostosis*** - The **cephalic index** (ratio of maximum head width to maximum head length × 100) provides a quantitative measure of head shape that can help characterize types of **craniosynostosis** [1]. - It helps differentiate patterns: **scaphocephaly** (dolichocephaly, CI <76), **brachycephaly** (CI >81), and **normocephaly** (CI 76-81). - In current practice, while **CT imaging** is the gold standard for diagnosing craniosynostosis, the cephalic index remains a useful **anthropometric measurement** in clinical assessment and documentation of cranial deformities. - It is particularly helpful in distinguishing **positional plagiocephaly** from **true craniosynostosis** when combined with clinical examination. *Evaluation of skull deformities* - The cephalic index can be used to evaluate various skull deformities, but this is too broad a description. - Its most specific clinical utility is in the context of **craniosynostosis assessment** where quantitative head shape measurements are diagnostically relevant [1]. - Many other skull deformities are assessed through direct clinical observation or specialized imaging rather than anthropometric indices. *Clinical documentation of head shape* - While the cephalic index does provide objective documentation of head shape, this describes its function rather than its primary **clinical indication**. - Documentation alone lacks the diagnostic and therapeutic implications that make cephalic index measurement clinically valuable. - In modern practice, simple descriptive terms (dolichocephaly, brachycephaly) are often used without calculating the precise index. *Neurosurgical planning* - Neurosurgical planning for craniosynostosis repair relies primarily on **CT scans with 3D reconstruction** to visualize suture fusion patterns, bone thickness, and intracranial anatomy. - The cephalic index provides diagnostic context but does not directly guide surgical technique, approach, or reconstruction planning. - Surgical decisions are based on imaging findings, age of the patient, and specific suture involvement rather than the numerical cephalic index value.
Question 78: What anatomical structure is formed after the obliteration of the umbilical vein?
- A. Ligamentum venosum
- B. Ligamentum arteriosum
- C. Medial umbilical ligament
- D. Round ligament of the liver (ligamentum teres) (Correct Answer)
Explanation: ***Round ligament of the liver (ligamentum teres)*** - The **umbilical vein** carries oxygenated blood from the placenta to the fetus during development [1]. - After birth, the umbilical vein obliterates and forms the **round ligament of the liver**, also known as the **ligamentum teres hepatis**. *Ligamentum venosum* - This structure is the obliterated remnant of the **ductus venosus**, which shunted blood from the umbilical vein to the inferior vena cava, bypassing the fetal liver [1]. - It is located in a fissure on the posterior surface of the liver, separate from the round ligament. *Ligamentum arteriosum* - This ligament is the remnant of the **ductus arteriosus**, a fetal blood vessel connecting the pulmonary artery to the aorta. - Its obliteration allows blood to flow through the lungs after birth. *Medial umbilical ligament* - This ligament is formed from the obliterated **umbilical arteries**, which carry deoxygenated blood from the fetus back to the placenta. - There are two medial umbilical ligaments, one from each umbilical artery.
Question 79: T cells in lymph node are present in:
- A. Paracortical area (Correct Answer)
- B. Mantle layer
- C. Medullary cords
- D. Cortical follicles
Explanation: ***Paracortical area*** - The **paracortical area** contains a high concentration of **T cells**, particularly activated T cells in response to antigenic stimulation [1]. - It plays a crucial role in **immune responses**, bridging the cortex and medulla of the lymph node [1]. *Mantle layer* - The **mantle layer** surrounds the follicles and primarily consists of **B cells**, not T cells. - It is involved in the initial immune response but does not contain a significant number of T lymphocytes. *Medullary cords* - **Medullary cords** mainly contain **plasma cells** and macrophages, with very few T cells present. - Their primary function is the secretion of antibodies rather than T cell activation or response. *Cortical follicles* - **Cortical follicles** are primarily sites for **B cell activation and proliferation**. - While they may have some T cells at their periphery, the majority of T cells are located in the paracortical area.
Question 80: What is the approximate length of the tibia in centimeters for an average adult?
- A. 30 cm
- B. 35 cm (Correct Answer)
- C. 40 cm
- D. 45 cm
Explanation: ***35 cm*** - The **tibia**, or shin bone, is the larger of the two bones in the lower leg and plays a crucial role in supporting body weight. - Its average length in adults is approximately **36-38 cm**, with **35 cm** being well within the normal range for an average adult. - Females typically have tibiae measuring **36-37 cm**, while males average **38-39 cm**. *30 cm* - A length of **30 cm** would be unusually short for an adult tibia, falling well below the normal range for average adults. - Such a short length might be associated with specific medical conditions or skeletal dysplasias. *40 cm* - A length of **40 cm** would be at the upper end or slightly above the typical average for an adult tibia. - This measurement might be seen in taller individuals, but it exceeds the average for most adults. *45 cm* - A length of **45 cm** would be comparatively long for an average adult tibia. - This measurement is significantly above average and would only be seen in very tall individuals.