Page 98 - Anatomy and Physiology of Farm Animals, 8th Edition

The Skeletal System / 83

are longer, arc craniad, and merge into one angle, and it forms the only true joint
between the scapula and another bone in
another to create the costal arch. Through
VetBooks.ir this conjoined arch of cartilage, these more most domestic animals. Birds and
primates possess a clavicle (collarbone),
caudal ribs, called asternal (false) ribs,
attach indirectly to the sternum. When the which forms a joint with the scapula, but
last rib’s costal cartilage fails to fuse with in most quadrupeds, the clavicle is repre-
the costal arch, this rib is referred to as a sented only by the clavicular tendon, a
floating rib. Whereas the last pair of ribs connective tissue band within the brachi-
in humans, cats, and dogs are typically ocephalicus muscle. The fused clavicles
floating ribs, these are much less com- are called the “wishbone” or furcula, in
monly seen in ungulates. birds (see Chapter 30). Birds have a cora-
The spaces between adjacent ribs are coid as a separate bone in addition to the
the intercostal spaces, numbered to cor- scapula and clavicle. The coracoid in
respond to the number of the rib cranial to humans and domestic mammals has been
the space. reduced to the coracoid process (a bony
prominence), which protrudes mediad
from the scapula near the ventral angle in
Appendicular Skeleton most species.
The lateral face of the scapula has a ridge
The appendicular skeleton is made up of called the spine extending from the ventral
the bones of the limbs. The bones of the angle to the dorsal border. In ruminants, the
thoracic limb are compared to those of distal end of the spine is flattened to form
the pelvic limb by region in Table 4‐5. the acromion process. The spine divides
Prominences of the appendicular skeleton the lateral face into the supraspinous fossa,
close to the skin may be palpated and iden- which is cranial to the spine, and the infras-
tified as clinical landmarks (Fig. 4‐11). pinous fossa, which is caudal to the spine.
The costal (medial or deep) face of the scap-
Thoracic Limbs ula gives attachment to some of the muscles
that connect the limb to the body.
The scapula (shoulder blade) in all ani- The humerus (arm bone) is a long bone
mals is a relatively flat triangular bone that varies only in minor details from one
(Fig. 4‐12). The distal portion is its ventral animal to another. It has a shaft and two

Table 4-5. Comparison of Bones of Thoracic and Pelvic Limbs

Thoracic Limb Pelvic Limb
Part of Limb Bones Part of Limb Bones
Thoracic (shoulder) Scapula, clavicle, Pelvic girdle Sacrum, pelvis (ilium,
girdle coracoid ischium, pubis)
Brachium Humerus Thigh Femur
Antebrachium Radius, ulna Crus Tibia, fibula
(forearm)
Carpus (“knee”) Carpal bones Tarsus (hock) Tarsal bones
Metacarpus Metacarpal bones Metatarsus Metatarsal bones
Phalanges (digit) Proximal, middle, Phalanges (digit) Proximal, middle,
and distal and distal phalanges
phalanges Proximal and distal
Proximal and sesamoid bones
distal sesamoid
bones