Karakteristik Morfofungsi Otot-otot bahu dan Lengan atas Orang Uan Kalimanta (Pongo pygmaeus)

Abstract

Orangutans are arboreal primates that have similarities to gorillas and chimpanzees from both anatomical and physiological aspects, although there are distinct behaviors that allow for differentiation in the structure of the locomotor apparatus. This research aims to study the anatomy of the muscles of the shoulders and upper-arm of the Bornean orangutan associated with the type of locomotion and daily behavior. This study was conducted by observing the morphology of the shoulders and upper-arms muscles and watching their behaviors through video observations. The results showed that the rotator cuff muscles in orangutans were relatively thick resulted in well-fixed shoulders. Musculus rhomboideus occipitalis is only observed in orangutans to facilitate them during arboreal activities such as brachiation. The external trunk muscle in orangutans is found to be relatively large compared to chimpanzees and gorillas, due to the lifting of the upper arms while in trees and on the ground. Musculus brachioradialis and musculus biceps brachii were well developed as flexors of the elbow joint and hold the body mass while climbing up the tree. The Bornean orangutans' activities are more arboreal than those in gorillas and chimpanzees, thus their shoulder and upper arm muscles were more developed to support brachiation activities.

Orangutans are arboreal primates that have similarities to gorillas and chimpanzees from both anatomical and physiological aspects, although there are distinct behaviors that allow for differentiation in the structure of the locomotor apparatus. This research aims to study the anatomy of the muscles of the shoulders and upper-arm of the Bornean orangutan associated with the type of locomotion and daily behavior. This study was conducted by observing the morphology of the shoulders and upper-arms muscles and watching their behaviors through video observations. The results showed that the rotator cuff muscles in orangutans were relatively thick resulted in well-fixed shoulders. Musculus rhomboideus occipitalis is only observed in orangutans to facilitate them during arboreal activities such as brachiation. The external trunk muscle in orangutans is found to be relatively large compared to chimpanzees and gorillas, due to the lifting of the upper arms while in trees and on the ground. Musculus brachioradialis and musculus biceps brachii were well developed as flexors of the elbow joint and hold the body mass while climbing up the tree. The Bornean orangutans' activities are more arboreal than those in gorillas and chimpanzees, thus their shoulder and upper arm muscles were more developed to support brachiation activities.