Avian Anatomy of Poultry skeleton

1. Avian Anatomy I
External features
Integument
Skeleton

2. Origins
• Evolutionally linked to Reptiles
• Adaptations to flight:
– Forelimbs modified as wings
– Bones are exceedingly light
– Bronchi extend outside the lungs as voluminous air
sacs
– Relative weight of heart is greatly increased
– Overall size of the body is reduced to increase the
ratio of surface area to body weight
– A prominent sternum for attachment of fight muscles

3. Terms of orientation
• Dorsal and ventral apply to the upper and
under surface of the wing
• Cranial and caudal apply to the leading and
trailing borders of wings
• Other terms are applied as in mammals

4. External Features and Integument

5. External Features and Integument

10. Ornamental appendages on the head of adult male chicken
• Comb (a)
• Wattles (b) – their edges maybe used for
intradermal injections
• Ricti (c)
• Lobes (d) – below the openings for
external ears

11. Skin
• Thin, dry and white to yellowish-pink in
color
• Relatively avascular compared to
mammals
• Loosely attached to underlying muscles
• Generally unsuitable for S/C injections
except in thicker regions such as back of
neck
• Skin of breast regions is modified to form
an incubation / brood patch
• Brood patches present usually in one sex
(generally female) except in pigeons (both
sexes)
• Brood patches absent in ducks and geese

12. Uropygial / Preen Gland
• Bi-lobed gland
• Ducts open on a median nipple-like papilla
(arrow)
• Main skin gland, lies dorsal to caudal
vertebral near tip of tail (No sweat glands
in poultry)
• Holocrine sebaceous secretion
• keeps feather waterproof
• prevents drying of keratin
• inhibits growth of micro-organisms

14. Avian Skeleton
• Lightness – Contributed by extension of air sacs in bones
In limb bones, air sacs replace bone marrow
Air sacs also extend in skull, vertebral column, pelvic girdle
• Strength
• Rigidity
• Higher calcium phosphate composition
• A prominent sternum for attachment of flight muscles
Achieved by fusion and deletion of components
Fusion
Cranium, Pelvic Girdle
Fusion & Deletion
Wing, Pelvic Limb

15. Axial Skeleton
Skull, Hyoid Apparatus, Vertebral Column, Ribs & Sternum
Appendicular Skeleton
Pectoral and Pelvic Girdles, Limb Bones
Divisions

16. Skull
Characteristic Avian Features
• Vaulted bulbous brain case (A)
• Large bony orbits (B)
• Beak-shaped pyramidal face (C)
• Bones are fused soon after hatching so
boundaries between bones difficult to
identify
• Cranial Kinesis – Movement of the
upper jaw in relation with the brain
case (f)
• Pneumatisation – air spaces within
skull bones communicate with
tympanic and nasal cavities in some
species (adaptation for flight)
AB
C

17. Skull bones

18. Vertebral Column

19. Vertebral Column

20. Vertebral Column

21. Vertebral Column

22. Thoracic Skeleton
• Five or six pairs of ribs
• Each rib consists of a vertebral
(dual articulation with VC)
and a sternal part
• Vertebral rib has an uncinate
process (1) – attachment for
ligaments and muscles
• Sternal ribs correspond to
costal cartilages of mammals
• Last few cervical vertebrae
articulate with floating ribs

23. Sternum
• Well developed Keel (a) is a feature
of Carinates
• In Ratites such as Ostrich, the keel
is flat and raft-like
• Provides attachment for strong
flight muscles

24. Thoracic Girdle
• Consists of scapula (a),
coracoid (b) and clavicle (c)
• Right and left clavicles fuse
ventrally to form the furcula
(wishbone)

26. Humerus

28. Forearm

29. Manus

30. Pelvic Girdle

31. Femur
• Slopes craniolaterally to bring the hind limb close to center of gravity
• Two articulation in the cavity of hip joint
• between head of femur and acetabulum
• between trochanter (arrow) of femur and antitrochanter of ilium
• Movements include protraction, retraction, abduction, adduction and
rotation
• Knee joint (2) is formed between femur, patella (b) and proximal ends
of tibiotarsus (c) and fibula (d). Its main movements are flexion and
extension

32. Crural bones

33. Tarsus

35. Feet