The pectoral girdle articulates with the axial skeleton only at the Sternoclavicular ligament<span>. The pectoral girdle connects the upper limbs to the axial skeleton and serves as the attachment site for the muscles of the upper back, chest and neck. The clavicle is the only long bone that lies in a horizontal position in the body. it has three regions; the medial end, the lateral end, and the shaft. The medial end has a triangular shape and articulates with the manubrium portion of the sternum. This forms sternoclavicular joint, which is the only bony articulation between the pectoral girdle of the upper limb and the axial skeleton. </span>
D. sum of all chemical reactions in an organism
The answer is B. Speed up chemical reactions. Hope this helps.
Answer:
a vestigial structure
Explanation:
Vestigial structures are a rudimentary (or even functionless) version of a body part, but they have important functions in a closely correlated or evolutionarily close species, an example of which is the presence of eyes in fish of the genus Astyanax. The existence of these vestigial structures is strong evidence that evolution occurs in organisms, since this structure, today without much apparent function, may in the past have been extremely important to the ancestors of that species.