NEET-PG 2012 — Anatomy

Q: A patient is found to have a melanoma originating in the skin of the left forearm. After removal of the tumor from the forearm, all axillary lymph nodes lateral to the medial edge of the pectoralis minor muscle are removed. Which axillary nodes would not be removed?

Apical lymph nodes. ***Apical lymph nodes*** - The **apical lymph nodes** are located **medial** to the **medial border of the pectoralis minor muscle**, at the apex of the axilla (Level III) [2]. - Since the removal was restricted to nodes **lateral** to the medial edge of the pectoralis minor, the apical nodes would **not be removed**. - These nodes receive lymph from all other axillary node groups and drain into the subclavian lymphatic trunk. *Central lymph nodes* - **Central lymph nodes** are located **posterior to (deep to)** the pectoralis minor muscle, within the axillary fat (Level II) [1]. - They lie between the medial and lateral borders of the pectoralis minor and are generally considered to be **lateral** to the medial edge of the pectoralis minor, so they would be removed in this dissection. *Lateral lymph nodes* - **Lateral (humeral) lymph nodes** are found along the **lateral border** of the axilla, following the axillary vein (Level I) [1]. - These nodes drain the majority of the upper limb and are clearly **lateral** to the pectoralis minor muscle, so hese would be included in the dissection. *Pectoral lymph nodes* - **Pectoral (anterior) lymph nodes** lie along the **lower border** of the pectoralis minor muscle and the lateral thoracic vessels (Level I). - They receive lymph from the anterior and lateral thoracic walls and much of the breast. - These nodes are located **lateral** to the medial edge of the pectoralis minor and would be removed as part of the surgical procedure. [Practice more Anatomy PYQs on OnCourse]

Q: Deltoid ligament is attached to all, except which structure?

Medial cuneiform. ***Medial cuneiform*** - The **deltoid ligament** is located on the **medial side of the ankle** and primarily connects the **tibia** to several tarsal bones. It does not attach to the medial cuneiform. - The **medial cuneiform** is a midfoot bone primarily involved in the **tarsometatarsal joint** and is not a direct attachment site for the deltoid ligament. *Medial malleolus* - The **medial malleolus**, the distal end of the **tibia**, serves as the **proximal attachment point** for all four parts of the deltoid ligament. - This strong connection is crucial for **stabilizing the ankle joint** medially. *Navicular bone* - The **tibionavicular part** of the deltoid ligament attaches to the **tuberosity of the navicular bone**. - This attachment helps **limit excessive abduction** and **eversion** of the foot. *Sustentaculum tali* - The **tibiocalcaneal part** of the deltoid ligament attaches to the **sustentaculum tali** on the calcaneus. - This attachment provides significant stability to the **subtalar joint**. [Practice more Anatomy PYQs on OnCourse]

Q: What anatomical structures are involved in the closure of the fossa ovalis?

Septum primum + Septum secundum. The septum primum acts as a valve, closing against the septum secundum postnatally due to changes in atrial pressure. This fusion effectively closes the foramen ovale, leading to the formation of the fossa ovalis. The endocardial cushions are important for the formation of the atrial and ventricular septa, as well as the AV valves, but not directly for the closure of the fossa ovalis. The septum primum is directly involved, but its apposition with the endocardial cushions doesn't close the foramen ovale. While both structures contribute to heart development, their direct interaction is not responsible for the closure of the fossa ovalis. The septum secundum forms the muscular rim of the fossa ovalis, and the endocardial cushions are critical for atrial septation, but not the final closure here. This option is incorrect because the specific combination of septum primum and septum secundum is indeed responsible for the closure of the fossa ovalis. [Practice more Anatomy PYQs on OnCourse]

Q: Coronary sinus develops from?

Sinus venosus. 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. [Practice more Anatomy PYQs on OnCourse]

Q: All are derived from ectoderm except for which of the following?

Adrenal cortex. ***Adrenal cortex*** - The adrenal cortex is derived from the **intermediate mesoderm**, specifically from the cells lining the posterior abdominal wall. The cells migrate to develop into the adrenal cortex. - It produces various steroid hormones, including **aldosterone**, **cortisol**, and **androgens**, which regulate diverse bodily functions. *Lens of the eye* - The lens of the eye is derived from the **surface ectoderm**. It forms from an invagination of the surface ectoderm called the lens placode. - Its primary function is to **focus light** onto the retina. *Hair follicles* - Hair follicles develop from the **surface ectoderm** [1]; they are invaginations of the epidermis that extend into the dermis. - They produce hair, which provides **insulation** and **protection** [1]. *Nails* - Nails are also derivatives of the **surface ectoderm**, forming thickened plates on the dorsal surface of the distal phalanges. - They provide **protection** to the fingertips and aid in grasping objects. [Practice more Anatomy PYQs on OnCourse]

98 Previous Year Questions with Answers & Explanations

Questions

A patient is found to have a melanoma originating in the skin of the left forearm. After removal of the tumor from the forearm, all axillary lymph nodes lateral to the medial edge of the pectoralis minor muscle are removed. Which axillary nodes would not be removed?

Deltoid ligament is attached to all, except which structure?

What anatomical structures are involved in the closure of the fossa ovalis?

Coronary sinus develops from?

All are derived from ectoderm except for which of the following?

Which muscle stabilizes the clavicle during movement of the shoulder?

Which of the following is derived from endoderm?

Skeletal derivative of 2nd pharyngeal arch -

Which of the following structures is not derived from the ectoderm?

Q10

Nutrient artery runs ?

NEET-PG 2012 - Anatomy NEET-PG Practice Questions and MCQs

Question 1: A patient is found to have a melanoma originating in the skin of the left forearm. After removal of the tumor from the forearm, all axillary lymph nodes lateral to the medial edge of the pectoralis minor muscle are removed. Which axillary nodes would not be removed?

A. Central lymph nodes
B. Lateral lymph nodes
C. Pectoral lymph nodes
D. Apical lymph nodes (Correct Answer)

Explanation: ***Apical lymph nodes*** - The **apical lymph nodes** are located **medial** to the **medial border of the pectoralis minor muscle**, at the apex of the axilla (Level III) [2]. - Since the removal was restricted to nodes **lateral** to the medial edge of the pectoralis minor, the apical nodes would **not be removed**. - These nodes receive lymph from all other axillary node groups and drain into the subclavian lymphatic trunk. *Central lymph nodes* - **Central lymph nodes** are located **posterior to (deep to)** the pectoralis minor muscle, within the axillary fat (Level II) [1]. - They lie between the medial and lateral borders of the pectoralis minor and are generally considered to be **lateral** to the medial edge of the pectoralis minor, so they would be removed in this dissection. *Lateral lymph nodes* - **Lateral (humeral) lymph nodes** are found along the **lateral border** of the axilla, following the axillary vein (Level I) [1]. - These nodes drain the majority of the upper limb and are clearly **lateral** to the pectoralis minor muscle, so hese would be included in the dissection. *Pectoral lymph nodes* - **Pectoral (anterior) lymph nodes** lie along the **lower border** of the pectoralis minor muscle and the lateral thoracic vessels (Level I). - They receive lymph from the anterior and lateral thoracic walls and much of the breast. - These nodes are located **lateral** to the medial edge of the pectoralis minor and would be removed as part of the surgical procedure.

Question 2: Deltoid ligament is attached to all, except which structure?

A. Sustentaculum tali
B. Medial cuneiform (Correct Answer)
C. Navicular bone
D. Medial malleolus

Explanation: ***Medial cuneiform*** - The **deltoid ligament** is located on the **medial side of the ankle** and primarily connects the **tibia** to several tarsal bones. It does not attach to the medial cuneiform. - The **medial cuneiform** is a midfoot bone primarily involved in the **tarsometatarsal joint** and is not a direct attachment site for the deltoid ligament. *Medial malleolus* - The **medial malleolus**, the distal end of the **tibia**, serves as the **proximal attachment point** for all four parts of the deltoid ligament. - This strong connection is crucial for **stabilizing the ankle joint** medially. *Navicular bone* - The **tibionavicular part** of the deltoid ligament attaches to the **tuberosity of the navicular bone**. - This attachment helps **limit excessive abduction** and **eversion** of the foot. *Sustentaculum tali* - The **tibiocalcaneal part** of the deltoid ligament attaches to the **sustentaculum tali** on the calcaneus. - This attachment provides significant stability to the **subtalar joint**.

Question 3: What anatomical structures are involved in the closure of the fossa ovalis?

A. Septum primum + Endocardial cushion
B. Septum primum + Septum secundum (Correct Answer)
C. Endocardial cushions + Septum secundum
D. None of the options

Explanation: The septum primum acts as a valve, closing against the septum secundum postnatally due to changes in atrial pressure. This fusion effectively closes the foramen ovale, leading to the formation of the fossa ovalis. The endocardial cushions are important for the formation of the atrial and ventricular septa, as well as the AV valves, but not directly for the closure of the fossa ovalis. The septum primum is directly involved, but its apposition with the endocardial cushions doesn't close the foramen ovale. While both structures contribute to heart development, their direct interaction is not responsible for the closure of the fossa ovalis. The septum secundum forms the muscular rim of the fossa ovalis, and the endocardial cushions are critical for atrial septation, but not the final closure here. This option is incorrect because the specific combination of septum primum and septum secundum is indeed responsible for the closure of the fossa ovalis.

Question 4: 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 5: All are derived from ectoderm except for which of the following?

A. Hair follicles
B. Nails
C. Lens of the eye
D. Adrenal cortex (Correct Answer)

Explanation: ***Adrenal cortex*** - The adrenal cortex is derived from the **intermediate mesoderm**, specifically from the cells lining the posterior abdominal wall. The cells migrate to develop into the adrenal cortex. - It produces various steroid hormones, including **aldosterone**, **cortisol**, and **androgens**, which regulate diverse bodily functions. *Lens of the eye* - The lens of the eye is derived from the **surface ectoderm**. It forms from an invagination of the surface ectoderm called the lens placode. - Its primary function is to **focus light** onto the retina. *Hair follicles* - Hair follicles develop from the **surface ectoderm** [1]; they are invaginations of the epidermis that extend into the dermis. - They produce hair, which provides **insulation** and **protection** [1]. *Nails* - Nails are also derivatives of the **surface ectoderm**, forming thickened plates on the dorsal surface of the distal phalanges. - They provide **protection** to the fingertips and aid in grasping objects.

Question 6: Which muscle stabilizes the clavicle during movement of the shoulder?

A. Pectoralis major
B. Latissimus dorsi
C. Subclavius (Correct Answer)
D. Serratus anterior

Explanation: ***Subclavius*** - The **subclavius muscle** originates from the first rib and inserts into the inferior surface of the clavicle, acting to **depress the clavicle** and prevent its displacement, thus enhancing shoulder stability during movement. - It plays a crucial role in protecting the underlying **neurovascular structures** (brachial plexus and subclavian vessels) from external trauma to the shoulder. *Pectoralis major* - This large, fan-shaped muscle primarily functions in **adduction, medial rotation, and flexion of the humerus** at the shoulder joint [1]. - It does not directly stabilize the clavicle but rather acts on the arm. *Latissimus dorsi* - The **latissimus dorsi** is a broad muscle of the back responsible for **extension, adduction, and internal rotation of the humerus** [1]. - Its actions are mainly on the humerus and it does not directly stabilize the clavicle. *Serratus anterior* - The **serratus anterior** muscle primarily **protracts and rotates the scapula**, keeping it pressed against the thoracic wall. - While it's essential for **scapular stability** and overhead arm movements, it does not directly stabilize the clavicle.

Question 7: Which of the following is derived from endoderm?

A. Gall bladder (Correct Answer)
B. Lens
C. Spleen
D. Lymph nodes

Explanation: ***Gall bladder*** - The **gallbladder**, along with other organs of the **gastrointestinal tract** such as the liver, pancreas, and epithelial lining of the digestive and respiratory systems, originates from the **endoderm** [1]. - The endoderm forms the primitive gut tube, from which these accessory digestive organs bud off. *Lens* - The **lens of the eye** is derived from the **surface ectoderm**, which invaginates to form the lens vesicle. - This contrasts with the neural ectoderm, which forms the neural tube and retina. *Spleen* - The **spleen** is derived from the **mesoderm**, specifically from mesenchymal cells in the dorsal mesentery of the stomach. - It is involved in blood filtration and immune responses, making it a lymphoid organ. *Lymph nodes* - **Lymph nodes** are primarily derived from the **mesoderm**, specifically from specialized mesenchymal cells that form their connective tissue capsule and stroma. - The immune cells within the lymph nodes, such as lymphocytes, originate from hematopoietic stem cells that migrate into these developing structures.

Question 8: Skeletal derivative of 2nd pharyngeal arch -

A. Malleus
B. Incus
C. Stapes (Correct Answer)
D. Maxilla

Explanation: ***Stapes*** - The **2nd pharyngeal arch** (also known as the hyoid arch) gives rise to several structures, including Reichert's cartilage, which forms the **stapes** bone, the styloid process, the lesser horn of the hyoid, and the upper part of the hyoid body. - Its muscles include the **stapedius**, stylohyoid, posterior belly of the digastric, and muscles of facial expression. *Malleus* - The **malleus** is derived from the **1st pharyngeal arch** (Meckel's cartilage), along with the incus. - The 1st pharyngeal arch is also responsible for forming the malleus, incus, and mandible. *Incus* - Similar to the malleus, the **incus** also originates from the **1st pharyngeal arch** (Meckel's cartilage). - Both the malleus and incus are crucial components of the middle ear ossicles but are structurally distinct from the stapes. *Maxilla* - The **maxilla** development is primarily from the **maxillary prominence** of the first pharyngeal arch, which is a subdivision of the first arch but does not originate from the 2nd arch. - It forms a significant portion of the midface and upper jaw, contributing to the nasal cavity and orbital floor.

Question 9: Which of the following structures is not derived from the ectoderm?

A. Brain
B. Retina
C. Eustachian tube (Correct Answer)
D. Lens

Explanation: ***Eustachian tube*** - The **Eustachian tube** (auditory tube) is derived from the **endoderm**, specifically from the first pharyngeal pouch. - It connects the nasopharynx to the middle ear and is responsible for equalizing pressure [1]. *Lens* - The **lens** of the eye develops from the surface ectoderm through an invagination called the **lens placode**. - This ectodermal origin is crucial for its transparency and refractive properties. *Brain* - The **brain** is a primary derivative of the ectoderm, specifically the **neural tube**, which forms from the neural plate during neurulation. - This ectodermal origin gives rise to the entire central nervous system. *Retina* - The **retina** of the eye, along with the optic nerve, develops from the **neuroectoderm** (a part of the neural tube). - Its ectodermal origin is essential for its light-sensing function.

Question 10: Nutrient artery runs ?

A. Away from epiphysis (Correct Answer)
B. Towards metaphysis
C. None of the options
D. Away from metaphysis

Explanation: ***Away from epiphysis*** - The **nutrient artery** runs away from the **dominant (faster-growing) epiphysis** towards the non-dominant end of the bone. - This follows the classic anatomical rule: **"To the elbow, from the knee"** - nutrient arteries point towards the elbow in upper limb bones and away from the knee in lower limb bones. - The **nutrient foramen** is directed obliquely away from the more actively growing end, established during bone development. - Examples: In the humerus, it runs towards the elbow (away from proximal epiphysis); in the femur, it runs away from the knee (away from distal epiphysis). *Towards metaphysis* - While the artery does course towards the metaphyseal region of the slower-growing end, this option is less anatomically precise. - The standard teaching emphasizes the relationship with the **dominant epiphysis** rather than the metaphysis. *Away from metaphysis* - This is **incorrect** - the nutrient artery actually runs **towards** the metaphysis of the non-dominant end. - It runs **away from** the dominant epiphysis, not away from the metaphysis. *None of the options* - This is incorrect as **"Away from epiphysis"** correctly describes the direction of the nutrient artery relative to the dominant growing end.