Pelvic girdle consists of two coxal bones. Each coxal bone is formed by the fusion of three bones – ilium, ischium and pubis. At the point of fusion of the above bones is a cavity called acetabulum to which the thigh bone articulates. The two halves of the pelvic girdle meet ventrally to form the pubic symphysis containing fibrous cartilage.
Which of the above statements regarding the pectoral and pelvic girdles are NOT correct? S1: Each coxal bone of the pelvic girdle is formed by the fusion of the ilium, ischium, and pubis, contributing to the acetabulum. S2: The pectoral girdle comprises two halves, with each half consisting of a clavicle and a scapula, forming the shoulder joint with the femur. S3: The pubic symphysis, where the two halves of the pelvic girdle meet ventrally, is characterised by the presence of hyaline cartilage, allowing limited movement. S4: The scapula is a large triangular flat bone found on the dorsal part of the thorax, and its glenoid cavity articulates with the head of the humerus. S5: The acromion process, an elevated ridge on the scapula, serves as the articulation point for the clavicle.
Correct answer: B — S2 and S3 only
Let's evaluate each statement to identify the incorrect ones: S1: This statement is correct. According to NCERT, "Each coxal bone is formed by the fusion of three bones – ilium, ischium and pubis. At the point of fusion of the above bones is a cavity called acetabulum to which the thigh bone articulates." (Page 226). S2: This statement is incorrect. While the pectoral girdle consists of two halves, each with a clavicle and a scapula, the shoulder joint is formed by the articulation of the glenoid cavity of the scapula with the head of the humerus, not the femur. The femur articulates with the acetabulum of the pelvic girdle. (Page 226). S3: This statement is incorrect. The two halves of the pelvic girdle meet ventrally to form the pubic symphysis containing fibrous cartilage, not hyaline cartilage. (Page 226). S4: This statement is correct. "Scapula is a large triangular flat bone situated in the dorsal part of the thorax... The glenoid cavity which articulates with the head of the humerus to form the shoulder joint." (Page 226). S5: This statement is correct. "The dorsal, flat, triangular body of scapula has a slightly elevated ridge called the spine which projects as a flat, expanded process called the acromion. The clavicle articulates with this." (Page 226). Therefore, statements S2 and S3 are NOT correct. The question tests detailed knowledge about the structure and articulation of the pectoral and pelvic girdles.
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