Complex sentence: The superior region (descending part), which supports the weight of the upper limb, the intermediate region (transverse part), which retracts the scapulae, and the inferior region (ascending part), which medially rotates and depresses the scapulae.
Split into simpler sentences: The superior region (descending part) supports the weight of the upper limb. The inferior region (ascending part) medially rotates and depresses the scapulae.