Question

Each pectoral girdle is made of,
A. Two innominate
B. Two clavicles and two scapula
C. One clavicle and one scapula
D. Two clavicles and one scapula

Answer 1

Hint: Pectoral girdle also called shoulder girdle. These are set of bones in the human body. It constitutes the upper limbs in the mammalian species.

Complete answer: The pectoral girdle is known to be the set of bones in the appendicular skeleton which connects to the arm on each side. In humans, it consists of one clavicle and one scapula. Some mammalian species like dogs, horses, etc. consist of only one scapula. In humans, the shoulder girdle is the anatomical mechanism that permits for all upper arm and shoulder movements in humans. The five muscles that comprise the function of the shoulder girdle are as follows: the trapezius muscle, levator scapulae muscle, rhomboid muscle, serratus anterior muscle and pectoralis minor muscle. In Dinosaurs, the main bones of the pectoral girdle were the scapula and the coracoid, which were directly articulated with the clavicle. The clavicles were present in the dinosaurs saurischian but largely absent in ornithischian dinosaurs. In primates, chimpanzees are far better at brachiation than humans. Their scapulas also possess a considerably larger supraspinous fossa, allowing for a larger supraspinatus muscle. Due to the process of evolution, humans lack the Altantoclavicuaris muscle, emerging on the atlas of the vertebral column, and inserting into the acromion clavicle and this particular muscle acts to elevate the clavicle.
Hence, the correct answer is option C.

Note: The pelvic girdle is stronger than the pectoral girdle because the pelvic girdle is used for the primary locomotion and bears the weight of the body. The pelvic girdle is composed of the appendicular hip bones (ilium, ischium, and pubis) oriented in a ring, and connects the pelvic region of the spine to the lower limbs. The pelvic spine consists of the sacrum and coccyx.