_a_, _a′_, Superficial flexor tendon; _b_, tendon to large pad; _c_,
lumbricales muscles; _d_, interossei muscles; _e_, _f_, annular
ligaments at metatarsophalangeal joints; _g_, suspensory ligament of
large pad; _h_, digital annular ligaments; _i_, deep flexor tendon;
_k_, distal sesamoid; _l_, suspensory ligament of _k_; _m_,
suspensory ligament of digital pad; _n_, digital pads.
(Ellenberger-Baum, Anat. d. Haustiere.)
]
The suspensory or superior sesamoidean ligament is more distinctly
muscular than in the horse—indeed in the young animal it consists almost
entirely of muscular tissue. At the distal third of the metacarpus it
divides into three branches. These give rise to five subdivisions,
either by bifurcation of the lateral branches or trifurcation of the
middle branch. The four lateral bands end on the sesamoid bones and the
distal end of the large metacarpal bone, and detach slips to the
extensor tendons. The middle band passes through the groove between the
two divisions of the distal end of the metacarpus, and divides into two
branches which join the tendons of the proper extensors of the digits;
it sends fibers also to the interdigital lateral ligaments and to the
central sesamoids. About the middle of the metacarpus the suspensory
ligament detaches a band which unites lower down with the superficial
flexor tendon, thus inclosing the tendon of the deep flexor of the
digit; it also blends with the thick fascia of the region. The latter
gives off a band on either side to the accessory digits, and a tendinous
band descends from each accessory digit to the third phalanx and
sesamoid bone, blending with the tendon of the corresponding proper
extensor.
=Pig.=—There are four metacarpo-phalangeal joints, each of which has a
capsule, lateral, intersesamoidean, and crucial sesamoidean ligaments.
Since distinct interosseous muscles are present, there are, of course,
no suspensory ligaments.
=Dog.=—There are five metacarpo-phalangeal joints, each having its own
capsule and indistinct lateral ligaments. A small sesamoid bone occurs
in the anterior part of each capsule, over which the corresponding
extensor tendon plays. The intersesamoidean ligaments do not extend
above the sesamoids. The cruciate ligaments are present, as well as a
fibrous layer which attaches the distal margins of the sesamoids to the
posterior surface of the proximal end of the first phalanx.