Page 538 - Anatomy and Physiology of Farm Animals, 8th Edition

Poultry / 523

Orbit Frontal bone
Scleral bones Temperoral bone
Lacrimal bone
VetBooks.ir Premaxilla Occipital bone Two phalanges of 2nd (major) digit
Nasal bone
Atlas
Zygomatic Axis Two phalanges of
1st (alular) digit
bone
Single phalanx of 3rd (minor) digit
Mandible Radial carpal bone
Quadrate bone Carpometacarpal bone
Ulnar carpal bone
Hyoid apparatus
External acoustic meatus Radius
Ulna
Notarium
6th thoracic vertebra
Ilium Caudal end of synsacrum
Coracoid
Free caudal vertebrae
Furcula
Pygostyle
Floating rib
Obturator
2nd vertebral rib foramen
Uncinate process Thoracic process Ischium
of sternum Pubis
1st sternal rib Patella
Fibula
Caudal lateral process of sternum
Keel of sternum
Tibiotarsal bone

Hypotarsal sesamoid bone
1st metatarsal bone
Five phalanges of 4th digit Two phalanges
of 1st digit Tarsometatarsal bone

Four phalanges of 3rd digit
Three phalanges of 2nd digit

Figure 30-5. The skeleton of the chicken Source: McCracken and Kainer, 1999. Reproduced with
permission of John Wiley & Sons, Inc.

direction. The other three toes fan out in that serve as articulating processes and
a forward direction. Digit one has two sites for muscle attachment.
phalanges, digit two has three, digit three Ten to 14 days prior to the beginning of
has four, and digit four has five. a laying period, chickens develop a type of
The sternum of domestic poultry is bony tissue unique to birds and crocodil-
dramatically modified for flight. As the ians in the shaft of long bones such as the
pectoral muscles of birds are massively femur and humerus. This medullary bone
deve loped, the sternum (their primary consists of interlacing bony spicules, with
attachment site) is correspondingly enlarged. blood sinuses and marrow between the
The large, shield‐like mass of the sternum spicules. Medullary bone may fill the
is further increased for muscle attach- pneumatic cavities of some bones and
ment by the presence of a large midline may replace up to 75% of the hematopoi-
keel or sternal crest. The cranial sternum, etic tissue in laying hens, but it is absent in
especially, is adorned with projections nonlaying hens and males. Medullary bone