Page 94 - Adams and Stashak's Lameness in Horses, 7th Edition

60 Chapter 1

fibularis tertius and, caudally, superficial digital flexor), AXIAL COMPONENTS
the tarsus is correspondingly locked in extension. Even Vertebral Column
VetBooks.ir ceps muscle assures stability of this locked configuration, The vertebral formula of the horse is 7 cervical, 18
during sleep, small amount of muscular tone in the quadri­
preventing flexion of the stifle and tarsocrural joints.
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Distal to the hock the elements of the stay apparatus thoracic, 6 lumbar, 5 sacral, and an inconsistent number
of caudal vertebrae (ranging from 15 to 21). There is
are analogous to those of the thoracic limb. The superficial some individual variation in numbers of other vertebrae,
digital flexor is connected proximally to the calcaneal most commonly in the number of lumbar vertebrae
tuber (effectively, its “check ligament”), and the deep digi­ where five or seven are sometimes seen (there is an
tal flexor is anchored via its accessory (tarsal check) liga­ increased incidence of five lumbar vertebrae in Arabian
ment to the thick plantar part of the tarsal fibrous joint horses ). The typical vertebra possesses a ventrally
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capsule. Prevention of overextension of the fetlock and placed, roughly cylindrical body whose cranial and cau­
interphalangeal joints during the fixed, resting position is dal ends articulate with adjacent vertebrae at the
accomplished through the support rendered by the digital intervertebral disc (Figure 1.53). A bony vertebral arch
flexor tendons and the suspensory apparatus (suspensory attaches to the body and surrounds the spinal cord. The
ligament, proximal sesamoid bones, and their ligaments). aperture created within a given vertebrae by the dorsal

Alar foramen Spinous process

Ala (wing) Dens

Transverse
foramen

Atlas Axis

Spinous process

Articular Transverse
Lamina
process process
Pedicle

Spinous
process Vertebral foramen
Vertebral body
Lumbar vertebra
Spinous processes
Transverse
process

Ala (wing)

Vertebral Costal fovea
foramen
Auricular
face
Vertebral Dorsal sacral
body foramina
Sacrum
Thoracic vertebra
Figure 1.53. Vertebrae.