Question

A cup-like cavity located on each side of the pectoral girdle of a frog is
(a) Thorax cavity
(b) Acetabulum
(c) Glenoid cavity
(d) Sigmoid arc

Answer 1

A cup-like cavity on either side of the frog's pectoral girdle is a shallow pyriform articular surface that is directed laterally and forward and articulates with the humerus head to form the shoulder joint.

Complete step by step answer:
- Pectoral girdle or the shoulder girdle has two halves. Supra scapula (calcified cartilage) scapula, coracoid, pre- coracoid, epicoracoid, and paraglenoid cartilage are produced every half, lateral scapula forms a deep cup- like the glenoid cavity's depressing shape.
- A part of the shoulder is the glenoid cavity or glenoid fossa of the scapula. It is a shallow, pyriform articular surface that is situated at the scapula's lateral angle. It is guided laterally and forward and articulates with the humerus head; it is wider below than above, the longest being its vertical diameter.
- The glenohumeral joint along with the humerus forms this cavity. This joint form is known as a joint of the synovial, ball, and socket. By means of the long head of the biceps tendon, the humerus is fixed in place inside the glenoid cavity. This tendon originates from the glenoid cavity's upper margin and coils over the shoulder, bracing the humerus against the cavity. In order to hold the head of the humerus in the glenoid cavity, the rotator cuff also protects this joint more precisely with the supraspinatus tendon.

So, the correct answer is, ‘Glenoid cavity’.

Note: There are two halves in the pectoral girdle of frogs, each adjacent to a forming humerus. In each, as a single foci of condensed chondrocytes that fuse, the scapula and coracoid form, forming a cartilaginous glenoid bridge articulating with the humerus.