Nephron is derived from ?
Fibrous stroma of liver is derived from -
Which structure is contained within the femoral canal?
The structure which lies outside the femoral sheath is:
Which structure forms the lateral border of the ischiorectal fossa?
Which artery is primarily responsible for supplying the head and neck of the femur?
Which of the following muscles is not supplied by the femoral nerve?
Superior gluteal nerve does not supply?
A nerve injured during axillary lymph node dissection leads to loss of sensation in the medial side of the arm. Which nerve is injured?
Azygos vein drains into:
NEET-PG 2015 - Anatomy NEET-PG Practice Questions and MCQs
Question 61: Nephron is derived from ?
- A. Ureteric bud
- B. Mesonephric duct
- C. Metanephros (Correct Answer)
- D. Mesonephros
Explanation: ***Metanephros*** - The **metanephric mesenchyme**, also known as the **metanephros**, gives rise to the excretory units of the kidney, which are the nephrons. - This mesenchymal tissue differentiates to form the **glomerulus**, Bowman's capsule, proximal and distal convoluted tubules, and the loop of Henle. *Ureteric bud* - The **ureteric bud** originates from the mesonephric duct and forms the collecting system of the kidney, including the ureter, renal pelvis, calyces, and collecting ducts. - It induces the differentiation of the metanephric mesenchyme but does not directly form the nephron itself. *Mesonephric duct* - The **mesonephric duct** (Wolffian duct) is a primitive embryonic structure that gives rise to the ureteric bud and parts of the male reproductive system. - It does not directly form any part of the nephron. *Mesonephros* - The **mesonephros** is a transient embryonic kidney that functions briefly during fetal development. - It degenerates and does not contribute to the formation of the definitive nephrons in the mature kidney.
Question 62: Fibrous stroma of liver is derived from -
- A. Endoderm from the foregut
- B. Endoderm from the midgut
- C. Endoderm from the hindgut
- D. Mesoderm from the septum transversum (Correct Answer)
Explanation: ***Mesoderm from the septum transversum*** - The **fibrous stroma of the liver**, which provides its structural framework, develops from the **mesoderm** of the **septum transversum** [1]. - The septum transversum is a thick mass of mesoderm that contributes to the formation of the **diaphragm** and the connective tissue elements of the liver [1]. *Endoderm from the foregut* - While the **parenchymal cells (hepatocytes)** of the liver are derived from the **endoderm of the foregut**, this tissue forms the functional units, not the fibrous supporting stroma. - The endoderm forms the glandular tissue, while the mesoderm forms the connective tissue [1]. *Endoderm from the midgut* - The midgut endoderm gives rise to structures like the **small intestine**, cecum, appendix, ascending colon, and part of the transverse colon, but not the liver's stroma [2]. - Its primary role is in forming the epithelial lining of these digestive organs. *Endoderm from the hindgut* - The hindgut endoderm develops into the distal third of the transverse colon, descending colon, sigmoid colon, rectum, and superior part of the anal canal, - It plays no role in the development of the liver's fibrous stroma.
Question 63: Which structure is contained within the femoral canal?
- A. Deep inguinal lymph node (Correct Answer)
- B. Loose areolar tissue and fat
- C. Lymphatic vessels
- D. Femoral vein
Explanation: ***Deep inguinal lymph node*** - The **femoral canal** contains several structures: a **lymph node (of Cloquet or Rosenmüller)**, **lymphatic vessels**, and **loose areolar tissue**. [1] - Among these contents, the **deep inguinal lymph node** (also called the lymph node of Cloquet or Rosenmüller) is the **most clinically significant and specifically named structure**. - This lymph node is an important anatomical landmark, serving as a sentinel node that drains lymph from the lower limb, external genitalia, and perineum. - **Clinically**, it is the structure most commonly referenced when discussing femoral canal contents, particularly in the context of femoral hernias and lymphatic drainage patterns. [1] *Loose areolar tissue and fat* - While **loose areolar tissue and fat** are indeed present within the femoral canal, they are **supporting contents** rather than specifically named anatomical structures. [1] - These tissues fill the space and allow for expansion of adjacent vessels (femoral artery and vein), but they are not the primary structure of anatomical or clinical significance. - When asked about "the structure" in the femoral canal, the named lymph node is the more specific answer. *Lymphatic vessels* - **Lymphatic vessels** do traverse the femoral canal, but they are **conduits** rather than a discrete, named structure. [1] - These vessels drain lymph towards the deep inguinal lymph node (of Cloquet) located within the same canal. - The specifically named lymph node is the more definitive anatomical answer than the unnamed vessels passing through. *Femoral vein* - The **femoral vein** is located in the **intermediate compartment of the femoral sheath**, NOT within the femoral canal. - The femoral sheath has three compartments: lateral (femoral artery), intermediate (femoral vein), and medial (femoral canal). - The femoral vein lies lateral to the femoral canal, making this option clearly incorrect.
Question 64: The structure which lies outside the femoral sheath is:
- A. Genitofemoral nerve
- B. Femoral vein
- C. Femoral artery
- D. Femoral nerve (Correct Answer)
Explanation: ***Femoral nerve*** - The **femoral nerve** lies lateral to the femoral artery and is therefore situated outside the **femoral sheath**, which encloses the femoral artery, femoral vein, and lymphatic vessels [2]. - It originates from the lumbar plexus (L2-L4) and provides motor innervation to the quadriceps femoris and sensory innervation to the anterior thigh and medial leg. *Femoral artery* - The **femoral artery** is a primary content of the **femoral sheath**, occupying the most lateral compartment. - It is a continuation of the external iliac artery and is a major blood supply to the lower limb. *Femoral vein* - The **femoral vein** lies within the **femoral sheath**, positioned medial to the femoral artery. - It is the primary vein responsible for draining blood from the lower limb and eventually becomes the external iliac vein. *Genitofemoral nerve* - The **genitofemoral nerve** typically emerges on the anterior surface of the psoas major muscle and then usually divides into genital and femoral branches [1]. - While its femoral branch supplies sensory innervation to the skin over the femoral triangle, it does not course within the femoral sheath itself but rather anterior to it or outside its immediate vicinity [1].
Question 65: Which structure forms the lateral border of the ischiorectal fossa?
- A. Perineal membrane
- B. Obturator internus muscle (Correct Answer)
- C. Gluteus maximus
- D. Sacrotuberous ligament
Explanation: ***Obturator internus muscle*** - The **ischiorectal fossa** (also known as the **ischioanal fossa**) is a wedge-shaped space in the perineum, and its lateral wall is formed by the **obturator internus muscle** and its covering fascia [1]. - This muscle originates from the inner surface of the **obturator membrane** and the surrounding bone, descending through the lesser sciatic foramen to insert on the greater trochanter of the femur. *Perineal membrane* - The **perineal membrane** is a dense fibrous sheet that forms the inferior boundary of the **deep perineal pouch**. - It does not form a lateral border of the ischiorectal fossa but rather contributes to the floor of the **urogenital triangle**, anterior to the fossa. *Gluteus maximus* - The **gluteus maximus** is a large muscle of the buttock, primarily involved in extension and lateral rotation of the hip. - It lies superficial to the structures of the perineum and therefore does not form a boundary of the **ischiorectal fossa**. *Sacrotuberous ligament* - The **sacrotuberous ligament** is a strong fibrous band connecting the sacrum to the ischial tuberosity. - While it helps to define the boundaries of the **perineum** posteriorly and contributes to the stability of the **sacroiliac joint**, it does not form the lateral wall of the **ischiorectal fossa**.
Question 66: Which artery is primarily responsible for supplying the head and neck of the femur?
- A. Medial circumflex artery (Correct Answer)
- B. Obturator artery
- C. Lateral circumflex artery
- D. Profunda femoris artery
Explanation: ***Medial circumflex artery*** - The **medial circumflex artery** is the primary blood supply to the **femoral head and neck** in adults. - Its branches, particularly the **retinacular arteries**, ascend along the femoral neck to perfuse the head. *Lateral circumflex artery* - The **lateral circumflex artery** supplies the **vastus lateralis muscle** and contributes to the supply of the **greater trochanter**. - While it anastomoses with the medial circumflex artery, its direct contribution to the femoral head is minimal. *Profunda femoris artery* - The **profunda femoris artery**, or deep femoral artery, is the main arterial supply to the **thigh muscles**. - It gives rise to the medial and lateral circumflex femoral arteries but does not directly supply the femoral head. *Obturator artery* - The **obturator artery** primarily supplies the **adductor muscles** of the thigh and contributes branches to the hip joint capsule. - While it has a small branch (artery to the head of the femur) that may contribute to the femoral head in children, it is not the main source in adults.
Question 67: Which of the following muscles is not supplied by the femoral nerve?
- A. Pectineus
- B. Sartorius
- C. Vastus medialis
- D. Obturator externus (Correct Answer)
Explanation: ***Obturator externus*** - The **obturator externus** muscle is primarily supplied by the **obturator nerve** (L3-L4), which arises from the lumbar plexus, not the femoral nerve. - Its main function is the **lateral rotation of the thigh** at the hip joint. *Pectineus* - The **pectineus** muscle receives dual innervation, typically from both the **femoral nerve** (L2-L4) and the obturator nerve. - It aids in **adduction**, **flexion**, and **medial rotation** of the thigh. *Sartorius* - The **sartorius** muscle is entirely supplied by the **femoral nerve** (L2-L3). - It is responsible for **flexing, abducting, and laterally rotating the thigh** at the hip, and flexing the leg at the knee. *Vastus medialis* - The **vastus medialis** is one of the four muscles forming the quadriceps femoris group, all of which are exclusively supplied by the **femoral nerve** (L2-L4). - This muscle is crucial for **extending the leg** at the knee joint.
Question 68: Superior gluteal nerve does not supply?
- A. Tensor fasciae latae
- B. Gluteus medius
- C. Gluteus minimus
- D. Gluteus maximus (Correct Answer)
Explanation: ***Gluteus maximus*** - The **gluteus maximus** muscle is primarily innervated by the **inferior gluteal nerve** (L5, S1, S2), not the superior gluteal nerve. - Its main actions include **extension** and **external rotation** of the hip. *Tensor fasciae latae* - The **tensor fasciae latae** is innervated by the **superior gluteal nerve** (L4, L5, S1). - This muscle helps in **flexion**, **abduction**, and **internal rotation** of the hip. *Gluteus medius* - The **gluteus medius** muscle receives its innervation from the **superior gluteal nerve** (L4, L5, S1). - It is a primary **abductor** and **internal rotator** of the hip, crucial for pelvic stability. *Gluteus minimus* - The **gluteus minimus** is also innervated by the **superior gluteal nerve** (L4, L5, S1). - Its functions are similar to the gluteus medius, including **abduction** and **internal rotation** of the hip.
Question 69: A nerve injured during axillary lymph node dissection leads to loss of sensation in the medial side of the arm. Which nerve is injured?
- A. Long thoracic nerve
- B. Intercostobrachial nerve (Correct Answer)
- C. Medial pectoral nerve
- D. Accessory nerve
Explanation: ***Intercostobrachial nerve*** - The **intercostobrachial nerve** (T2) is the nerve most commonly injured during **axillary lymph node dissection** - It provides **sensory innervation to the medial side of the upper arm**, specifically the skin over the medial and posterior aspects of the arm [1] - This nerve arises from the **lateral cutaneous branch of the second intercostal nerve** and crosses the axilla to reach the arm [1] - Injury during axillary surgery results in **numbness or paresthesia** in the medial upper arm region, which is a well-recognized complication of breast cancer surgery with axillary node dissection [1] - Studies show **30-80% of patients** undergoing axillary dissection experience intercostobrachial nerve injury *Long thoracic nerve* - The **long thoracic nerve** (C5-C7) innervates the **serratus anterior muscle**, which is crucial for scapular protraction and rotation - Damage to this nerve causes **"winged scapula"**, where the scapula protrudes posteriorly - This is a **motor nerve**, not sensory, so injury does not result in sensory deficits in the arm *Medial pectoral nerve* - The **medial pectoral nerve** (C8-T1) primarily innervates the **pectoralis major** and **pectoralis minor** muscles [1] - This is a **motor nerve** playing a role in muscle function rather than sensation [1] - Injury would result in weakness of these muscles, not sensory loss *Accessory nerve* - The **accessory nerve** (cranial nerve XI) innervates the **sternocleidomastoid** and **trapezius muscles** - This nerve is located in the **posterior triangle of the neck**, not in the axilla - Injury would lead to weakness in shrugging the shoulders or turning the head, not sensory loss in the arm during axillary dissection
Question 70: Azygos vein drains into:
- A. Right subcostal vein
- B. Right ascending lumbar vein
- C. Superior vena cava (Correct Answer)
- D. Brachiocephalic
Explanation: ***Superior vena cava*** - The **azygos vein** is a major venous channel that drains the walls of the thorax and abdomen, emptying directly into the **superior vena cava (SVC)**. [1] - This connection is crucial for venous return from the posterior thoracic wall, pericardium, and bronchi, especially bypassing the inferior vena cava if it's obstructed. [1] *Right subcostal vein* - The right subcostal vein is a tributary that helps form the **azygos vein**; it does not receive drainage from the azygos vein. - It contributes to the initial formation of the azygos system, not its termination. *Brachiocephalic* - The **brachiocephalic veins** are formed by the union of the internal jugular and subclavian veins, and they merge to form the **superior vena cava**. - The azygos vein drains into the superior vena cava, not directly into the brachiocephalic veins. *Right ascending lumbar vein* - The **right ascending lumbar vein** is a major tributary that contributes to the formation of the **azygos vein** in the lumbar region. - It drains into the azygos system, illustrating its origin rather than its termination.