Question

What advantages are there to mammals in possessing a flexible connection between the pectoral girdle and the vertebral column?

Answer 1

Hint: Pectoral girdle is a set of bones connecting the arms on each side along the body axis being a part of the appendicular skeleton. It consists of $2$ the main parts – the clavicle and the scapula. The vertebral column is also known as the backbone which encloses the spinal cord and the fluid that surrounds the spinal cord. The vertebral column consists of $5$ parts – cervical, thoracic, lumbar, sacral, and coccygeal.

Complete answer:
The function of the pectoral girdle is the articulation of the arm bones occurring in the shoulder girdle and also provides the attachment of some muscles of the arm. The vertebral column, on the other hand, acts as firm support for the head and the body, and also the intervertebral disc of cartilage acts as a buffer and the curves of the vertebral column give the flexibility of bending without breaking. The main advantage of the flexible connection of the pectoral girdle and the vertebral column is the free movement of the mammalian rib cage. As we know ribcage is connected directly to the vertebral column. The flexibility helps the animal to withstand the shock that is sustained by the forelimbs at the time of landing in a jump. Various forelimb activities such as digging, climbing are also easy due to the presence of the flexible connection.

Note:
There are $126$ bones in the appendicular skeleton. The first cervical vertebrae are the atlas and the second is the axis. The atlas lacks a body and a spinous process whereas the axis has a peg-like process known as the odontoid process. The undivided spinous process is seen in the case of the first seven cranial vertebrates.