Page 5 of 5
AN14.1-4 | Features of individual bones (Lower Limb) — Gate Quiz
Click any question card to reveal the correct answer.
The acetabulum of the hip bone is formed by the junction of three bones. Which combination is correct?
Correct! The acetabulum is formed at the Y-shaped junction of the ilium (superiorly), ischium (posteroinferiorly), and pubis (anteroinferiorly). The three bones fuse during adolescence.
The os coxae (hip bone) = ilium + ischium + pubis. All three meet at the acetabulum, which articulates with the femoral head.
Incorrect. The three bones that form the hip bone — and meet at the acetabulum — are the ilium, ischium, and pubis.
Click to reveal answer
The anterior superior iliac spine (ASIS) serves as an attachment for which of the following structures?
Correct! The inguinal ligament is attached between the ASIS and the pubic tubercle. Sartorius, the longest muscle in the body, originates from the ASIS.
ASIS landmarks: (1) Lateral end of inguinal ligament, (2) Origin of sartorius, (3) Origin of tensor fasciae latae. The inguinal ligament runs from ASIS to pubic tubercle.
Incorrect. The ASIS is the attachment for the inguinal ligament (lateral end) and sartorius (origin).
Click to reveal answer
In an adult, the primary blood supply to the femoral head is provided by which source?
Correct! In adults, the main blood supply to the femoral head is the retinacular (capsular) branches of the medial circumflex femoral artery, which run along the neck of femur under the capsule. These are torn in displaced intracapsular fractures, causing AVN.
Blood supply to femoral head: (1) Retinacular branches of medial circumflex femoral artery (main — adult), (2) Artery of ligamentum teres/foveal artery from obturator artery (minor in adults, more important in children), (3) Nutrient artery (shaft only). AVN risk in intracapsular fractures.
Incorrect. In adults, the ligament of the head (carrying the obturator artery) is minimal. The main supply is via the medial circumflex femoral artery retinacular branches.
Click to reveal answer
The ossification centre for the lower end of the femur appears at which stage of intrauterine life, and what is its clinical use?
Correct! The lower femoral epiphysis appears at approximately 9 months of intrauterine life and is used radiologically to confirm a term (≥36 weeks) pregnancy. Its presence on X-ray of a neonate indicates term gestation.
Clinically important ossification centres: Lower femur (9 months IU = term marker), Upper tibia (birth), Head of femur (1 year postnatal). Lower femoral epiphysis is the standard radiological marker for term gestation.
Incorrect. The lower femoral epiphysis appears at 9 months (term) of intrauterine life, making it a marker of term pregnancy.
Click to reveal answer
The fibula is said to violate the "law of ossification." What does this mean?
Correct! The law of ossification states: the epiphysis that appears first ossifies (fuses) last. In the fibula, the lower epiphysis appears first (1–2 years) but also fuses first (~16 years), violating the law. The functional demand at the ankle joint is the proposed explanation.
Law of ossification: first to appear = last to fuse. Fibula exception: lower epiphysis appears first (~1–2 years) AND fuses first (~16 years). Upper epiphysis appears later and fuses later (~20 years). Explanation: greater mechanical demand at ankle.
Incorrect. The law states "appears first, fuses last." The fibula breaks this rule because its lower epiphysis appears first AND fuses first.
Click to reveal answer
The ischial tuberosity is clinically important as a pressure point and a muscle origin. Which muscle group originates from it?
Correct! The ischial tuberosity is the origin of the hamstrings: biceps femoris long head, semitendinosus, and semimembranosus. It is also where we sit and a common site for ischial pressure sores in bedridden patients.
Ischial tuberosity: Origin of hamstrings (long head of biceps femoris, semitendinosus, semimembranosus) + adductor magnus (ischial part). Pressure sore site in bedridden patients.
Incorrect. Quadriceps originate from the femur and ilium. The ischial tuberosity is the origin of the hamstrings.
Click to reveal answer
The Achilles tendon (tendo calcaneus) inserts onto which part of the calcaneus?
Correct! The Achilles tendon inserts into the posterior surface of the calcaneus (middle one-third). This is the thickest and strongest tendon in the body; rupture causes inability to plantarflex and a positive Simmond's (Thompson) test.
Calcaneus muscle attachments: Achilles tendon (posterior surface), plantar fascia/intrinsic muscles (medial and lateral tubercles), extensor digitorum brevis (superior/dorsal surface). Sustentaculum tali supports the talus and has the FHL groove.
Incorrect. The Achilles tendon inserts on the posterior surface (middle one-third) of the calcaneus.
Click to reveal answer
A 25-year-old hockey player "turns her ankle" during a game. She has tenderness at the base of the 5th metatarsal and X-ray shows an avulsion fracture at the tuberosity. Which muscle caused this avulsion?
Correct! The peroneus brevis inserts into the tuberosity (styloid process) at the base of the 5th metatarsal. In forceful inversion injuries, the muscle pulls away a fragment — an avulsion fracture. This should be distinguished from a Jones fracture (more proximal, transverse, poor blood supply).
Base of 5th metatarsal: Tuberosity = insertion of peroneus brevis → avulsion in inversion injury. Peroneus longus passes under the cuboid to the plantar foot (inserts on 1st metatarsal and medial cuneiform). Do not confuse with Jones fracture (transverse fracture ~1.5 cm distal to the tuberosity).
Incorrect. Peroneus brevis is the tendon that inserts into the 5th metatarsal tuberosity and is responsible for this avulsion.
Click to reveal answer
The talus is unique among tarsal bones because it has no muscle attachments. Which joints does the talus form?
Correct! The talus forms three joints: (1) Ankle joint — talar trochlea with tibia and fibula, (2) Subtalar (talocalcaneal) joint — inferior surface with calcaneus, (3) Talonavicular joint — head of talus with navicular. All surfaces are articular — no muscle attachments.
Talus = most important tarsal bone clinically. Entirely covered by cartilage or capsule — no muscle attachments. Joints: ankle (trochlea), subtalar (body+calcaneus), talonavicular (head+navicular). Fractures heal slowly due to tenuous blood supply.
Incorrect. The talus forms the ankle joint (with tibia/fibula), subtalar joint (with calcaneus), and talonavicular joint (with navicular).
Click to reveal answer
A 60-year-old man presents with a swelling in the groin. To determine if it is a femoral or inguinal hernia, the clinician palpates the pubic tubercle. Which relationship correctly distinguishes these two hernias?
Correct! The inguinal ligament runs from ASIS to pubic tubercle. Inguinal hernias emerge above and medial to the pubic tubercle (through the superficial inguinal ring). Femoral hernias emerge below and lateral to the pubic tubercle (through the femoral ring, which lies lateral to the pubic tubercle and below the inguinal ligament).
Pubic tubercle as hernia landmark: Inguinal hernia = above and medial (above inguinal ligament, through inguinal canal). Femoral hernia = below and lateral (below inguinal ligament, through femoral ring). Femoral hernias are more common in women and have higher strangulation risk.
Incorrect. Inguinal hernia: above and medial to pubic tubercle. Femoral hernia: below and lateral to pubic tubercle.
Click to reveal answer