Gross anatomical investigation on the fore limb skeleton of the helmeted guinea fowl (Numida meleagridis)

Abstract

This study on the forelimb skeletal gross anatomy was conducted on the helmeted guinea fowl to document its distinctive morphological features. Eight (8) Helmeted guinea fowls (4 females and 4 males) with an average weight of 3.0kg were sacrificed via jugular vein severance with bone preparation achieved by use of insect larvae. The horizontally oriented scapula was an elongated flattened dorsoventrally curved bone having two extremities and a shaft but lacked the muscular tubercle on the cranial third of the ventral border present in other avian species. The obliquely oriented coracoid presented a thick bone with a hook-like acrocoracoid process that formed a shallow supracoracoid groove at its proximal extremity. It however, lacked the rough surface for muscular attachment and the pneumatic foramen on the dorsal surface. The proximal fossa was absent on the dorsal surface of the humerus while the ulna and radius were joined at their extremities creating an extensive interosseous space. The radius was the thinner of the two bones lying dorsal to the larger ulna in the folded wing. Two carpal bones were present on the wings while the carpometacarpal consisted of the 2nd (stub-like projection), 3rd (large straight long) and 4th (curved) metacarpals with the 3rd and 4th fusing at their extremities giving rise to an extensive D-shaped interosseous space. The digits were three in number (digits II, III and IV) that articulated proximally with carpometacarpals II, III and IV respectively. Digit III had two phalanges while digits II and IV had one. In conclusion, bones of the forelimb of the guinea fowl (Numida meleagridis) lacked some common features visible in its closest relative, the domestic fowl (Gallus domesticus).