AN2.1-6 | General features of bones & Joints — Gate Quiz

Correct! The scapula is a flat bone that provides a broad surface for muscle attachment.

Bones are classified into five types: long, short, flat, irregular, and sesamoid. Flat bones include the scapula, sternum, and cranial bones.

Incorrect. Flat bones are thin and provide broad surfaces for muscle attachment. The femur is a long bone, talus is a short bone, and pisiform is a sesamoid bone.

Correct! The nutrient artery enters the medullary cavity and supplies the inner two-thirds of the cortex and the bone marrow.

Long bones have three blood supplies: nutrient artery (inner 2/3 cortex + medulla), periosteal arteries (outer 1/3 cortex), and epiphyseal/metaphyseal arteries (bone ends).

Incorrect. The nutrient artery is the main blood supply to the diaphysis — it enters the nutrient foramen and branches to supply the inner cortex and marrow.

Correct! This is a fundamental law of ossification — "the epiphysis that appears first fuses last."

Laws of ossification: (1) Epiphysis first to appear fuses last, (2) Growing end of bone is near the nutrient foramen away-pointing end, (3) Ossification centres appear in a predictable order useful for age estimation.

Incorrect. The law states that the epiphysis first to appear is last to fuse. This is important for estimating bone age in forensic medicine.

Correct! The proximal tibial epiphysis fuses at 18-20 years. Before fusion, the growth plate appears as a radiolucent line on X-ray.

Epiphyseal fusion times are clinically important for distinguishing growth plate fractures from normal anatomy and for medicolegal age estimation.

Incorrect. The proximal tibial epiphysis (an important pressure epiphysis) fuses at approximately 18-20 years.

Correct! The patella is the largest sesamoid bone, developing within the tendon of the quadriceps femoris.

Sesamoid bones develop within tendons where they cross joints. They protect tendons, reduce friction, and modify the direction of pull. The patella increases the leverage of quadriceps by increasing its moment arm.

Incorrect. The patella, located in the quadriceps tendon anterior to the knee, is the largest sesamoid bone in the body.

Correct! Fibrocartilage contains dense bundles of type I collagen fibres within the cartilage matrix, providing both tensile strength and shock absorption.

Three types of cartilage: hyaline (most common — trachea, articular surfaces), elastic (pinna, epiglottis — flexible), fibrocartilage (intervertebral disc, pubic symphysis, menisci — resists compression + tension).

Incorrect. Intervertebral discs contain fibrocartilage — it combines the properties of dense connective tissue (tensile strength) and hyaline cartilage (compressibility).

Correct! The inner two-thirds of the meniscus is avascular — it receives nutrition only by diffusion from synovial fluid. Without blood supply, the inflammatory repair cascade cannot occur.

Cartilage is avascular and receives nutrition by diffusion. This is why cartilage injuries heal poorly. The meniscus has a vascular gradient: outer 1/3 (red zone, vascular, can heal) → inner 2/3 (white zone, avascular, poor healing).

Incorrect. Cartilage heals poorly because it is avascular. The inner meniscus has no blood supply — only the outer one-third (the "red zone") has vascular supply from the periphery.

Correct! The atlantoaxial joint is a pivot (trochoid) joint — the atlas rotates around the dens (odontoid process) of the axis.

Synovial joints are classified by shape: hinge (elbow, knee), pivot (atlantoaxial, proximal radioulnar), ball-and-socket (shoulder, hip), saddle (1st CMC), condyloid (wrist, MCP), plane (intercarpal).

Incorrect. The atlantoaxial joint is a pivot joint. The dens of the axis acts as the pivot around which the atlas (and head) rotates.

Correct! Hilton's law states that a nerve supplying a joint also supplies the muscles that move the joint and the skin overlying the insertions of those muscles.

Hilton's law has clinical significance: joint pain may be referred to the skin territory of the same nerve (referred pain). For example, hip joint disease (obturator nerve) may cause knee pain.

Incorrect. Hilton's law is a fundamental principle: the nerve to a joint also supplies the muscles moving that joint AND the skin over the joint.

Correct! The obturator nerve supplies both the hip joint and the skin on the medial side of the thigh/knee. Hip pathology can cause referred pain along the obturator nerve distribution.

This is a classic clinical application of Hilton's law — hip pathology presenting as knee pain. Always examine the hip in a patient with unexplained knee pain, especially in the elderly.

Incorrect. The obturator nerve supplies the hip joint and sends a cutaneous branch to the medial side of the thigh and knee. By Hilton's law, hip joint pain is referred to this area.