Biology · Locomotion and Movement · NEET
The pelvic girdle has TWO coxal bones (two halves). But EACH coxal bone is itself formed by the fusion of THREE bones: ilium, ischium and pubis. Students lose marks by mixing these two numbers. Correct answer: 2 coxal bones total, 3 fused bones in each coxal bone.
The femur (thigh bone) articulates with the acetabulum. The rounded head of the femur fits into this cup-shaped cavity to form the hip joint (a ball-and-socket joint). NCERT line: 'a cavity called acetabulum to which the thigh bone articulates.'
The acetabulum lies at the point where the three bones (ilium, ischium, pubis) fuse. So it is not a separate bone; it is the socket formed by all three coming together on the side of the coxal bone.
The two halves meet ventrally (in front) to form the pubic symphysis, which contains fibrous cartilage. NEET often asks the tissue: the answer is FIBROUS cartilage, not hyaline or bone.
No. Both are sockets, but the acetabulum is in the pelvic girdle and holds the femur, while the glenoid cavity is in the pectoral girdle (on the scapula) and holds the humerus. Mixing these is the most common NEET trap for girdles.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Ilium, ischium and pubis fuse together to form each coxal (hip) bone of the pelvic girdle.
The acetabulum is a cup-shaped cavity at the point of fusion of the ilium, ischium and pubis. The head of the femur fits into it to form the hip joint.
A ball-and-socket (synovial) joint is formed where the round head of the femur fits into the acetabulum, allowing movement in many directions.
The two halves of the pelvic girdle meet in front to form the pubic symphysis, which contains fibrous cartilage.
The pelvic girdle has two coxal bones and its socket is the acetabulum (holds the femur). The pectoral girdle has a clavicle and scapula per half, and its socket is the glenoid cavity (holds the humerus).
