Comparative Morphology and Morphometry of the Scapula in Humans (Homo sapiens) and Sclater’s Monkey (Cercopithecus sclateri)

The scapula is a key anatomical structure reflecting locomotor adaptation in primates. Humans exhibit bipedalism with non-weight-bearing upper limbs, whereas arboreal primates such as Cercopithecus sclateri rely on forelimbassisted locomotion. Forty adult dry scapulae (20 humans, 20 Sclater’s monkeys) were analyzed. Morphological features were assessed qualitatively, while morphometric parameters including spine length, acromion length and width, glenoid diameter, and coracoid process length were measured using digital calipers. Data were recounted as mean ± standard deviation and assessed by an independent t-test (p < 0.05). All parameters were significantly higher in humans: spine length (13.02 ± 0.62 cm vs. 6.35 ± 0.48 cm), acromion width (4.62 ± 0.41 cm vs. 0.52 ± 0.09 cm), glenoid diameter (2.01 ± 0.15 cm vs. 0.81 ± 0.07 cm), and coracoid length (4.38 ± 0.27 cm vs. 1.52 ± 0.12 cm) (p < 0.001). The suprascapular notch was present in all human specimens but absent in monkeys. The scapula demonstrates significant structural divergence between species, reflecting functional adaptation to mobility in humans and stability in arboreal primates.

Key Words: scapula, morphometry, primate anatomy, locomotor adaptation, shoulder biomechanics