Gross anatomical studies on the pelvic limb bones of white cockatoo (Cacatua alba)
A. R. Sreeranjini, N. Ashok, S. Maya, K. M. Lucy, V. R. Indu, N.S. Sunilkumar and K.B. Sumena
The present study was conducted on the pelvic limb bones of a five year old male umbrella cockatoo. The femur was light in weight and presented a straight shaft, two extremities and four surfaces. The proximal extremity had a head with distinct fovea capitis, neck and indistinct trochanter major, while the distal extremity had a trochlea, two condyles and a wide intercondyloid groove. Patella was a small pea-sized sesamoid bone. The tibiotarsus was the largest of the leg bones and was one third longer than femur. It presented a long shaft with distinct fibular crest and two extremities. Both extremities showed medial and lateral condyles. From proximal extremity, the straight cnemial crest extended ventrally. The condyles of distal extremity were separated by intercondyloid fossa and continued caudally to wide grooved trochlea. Instead of extensor canal in other birds, a deep groove was observed. The fibula was with small head and rudimentary shaft and terminated near the middle of the shaft of tibiotarsus. The tarsometatarsus was extremely short. Its shaft presented convex dorsal surface whereas the plantar surface was concave without ridges. The distal extremity presented three articular trochleae. Between the trochlea for third and fourth digits, a bony canal was noticed. The spur core seen in cockerel was not observed in the present study. Four digits from one to four showed zygodactyl type of arrangement and contained two, three, four and five phalanges, respectively. Distal phalanx in each digit was a claw. The light femur and highly reduced fibula in umbrella cockatoo showed adaptations for flight whereas the positioning of the digits showed adaptation for climbing and grasping.
Key words: Gross anatomy, Hind limb, Pelvic limb, Umbrella cockatoo, White cockatoo