Page 175 - Anatomy and Physiology of Farm Animals, 8th Edition

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palmar/plantar portion of the distal phalanx.
In this path, it passes superficial to the proxi-
VetBooks.ir mal and distal sesamoid bones.

The superficial digital flexor tendon
passes distad on the cannon bone just
superficial to the deep digital flexor tendon
with which it shares a synovial sheath.
Distal to the fetlock the superficial digital
flexor tendon divides into two branches,
which pass on each side of the deep digital
flexor tendon and insert at the proximal
end of the middle phalanx and the distal
end of the proximal phalanx.
Strain of the flexor tendons can result
in tendonitis, more correctly called
tenosynovitis to acknowledge the role of
inflammation of synovial structures.
The inflammation produces a convex
profile to the normally straight tendons.
This bowed tendon is most commonly
seen in horses used at speed (e.g., race-
horses) (Fig. 7‐12).

Ligaments

Figure 8-9. Chronic laminitis (founder) is char- The ligaments of the foot include the
acterized by loss of congruity between epidermal medial and lateral collateral ligaments
and dermal laminae. The distal phalanx is rotated of fetlock, pastern, and coffin joints. These
away from the hoof wall by the distractive force of are typical collateral ligaments as found in
the deep digital flexor tendon. Top, normal hoof any ginglymus joint. In addition, a special-
in sagittal section. Arrows emphasize the parallel ized structure, the suspensory ligament,
surfaces of the hoof wall and distal phalanx. runs parallel to the cannon bone on its
Bottom, hoof with chronic laminitis and rotation palmar/plantar aspect. In animals with
of the distal phalanx. Source: photo courtesy of A. more than one digit, this structure usually
Fails, Colorado State University, Fort Collins,
Colorado, USA. has a considerable amount of muscle; in
such animals, it lies between adjacent
metacarpals or metatarsals and is therefore
In the thoracic limb, the lateral digital called the interosseous muscle. The sus-
extensor tendon inserts on the proximal pensory ligament of foals often has signifi-
end of the proximal phalanx after pursuing cant muscle tissue that is subsequently
a course lateral to the common digital replaced with connective tissue during
extensor tendon. In the pelvic limb, the maturation.
lateral digital extensor tendon merges with The equine suspensory ligament is
the tendon of the long digital extensor found between the cannon bone and the
muscle and through it inserts on the exten- deep digital flexor tendon. It attaches prox-
sor process of the distal phalanx. imally to the proximal end of the cannon
The tendon of the deep digital flexor mus- bone and to the distal row of carpal or
cle (in both thoracic and pelvic limbs) passes tarsal bones. It passes down between the
down the palmar/plantar side of the cannon splint bones on the palmar/plantar surface
bone and crosses the fetlock; it inserts on the of the cannon bone in the horse (Fig. 8‐10).