Stay Apparatus, Conformation, Gait Flashcards
horses have two mechanisms to reduce fatigue and prolong ability to remain alert
- Nuchal Ligament
- Stay Apparatus
stay apparatus permits
standing for a long time while minimizing fatigue, with minimal muscular activity
basic principle of stay apparatus is that
if the horse relaxes most of its muscles, the legs will remain in a standing position
three parts to the stay apparatus
-stay apparatus of forelimb (proximal to carpus)
-stay apparatus of hindlimb (proximal to tarsus)
-suspensory apparatus (distal to carpus/tarsus)
two types of sleep in horses
- Slow Wave Sleep (SWS)
- Paradoxical sleep (PS, includes REM)
paradoxical sleep (PS) only occurs
for a few minutes at a time, in lateral recumbency
total sleep required for horses is about
3-4 hours
the stay apparatus is part of a
fibrous support mechanism (FSM)
In the horse, if the muscles of the forelimb relax, ligaments and tendons should hold the leg in normal resting position (4)
-neutral shoulder and elbow
-extended carpus
-over-extended fetlock
-extended pastern and coffin joints
___% of weight in horses is on the thoracic limbs
60%
shoulder stability is done by (3)
-internal (short) tendon of biceps (radial insertion acts as fixed point)
-lacterus fibrosus
-extensor carpi radialis
flexion of elbow is prevented by (3)
-tension of medial head of triceps
-collateral ligaments
-origin of digital flexor muscles (medial humerus)
overextension of the carpus is prevented by
superior check ligament of the SDFT
flexion of the carpus is prevented by
tension of extensor carpi radialis from biceps tendon via lacterus fibrosus
suspensory apparatus of forelimb includes (3)
-suspensory ligament
-proximal sesamoid bones
-ligament from proximal sesamoid bones to cannon bone/phalanges
In the forelimb, fetlock, pastern, and coffin joint stability comes from (3)
-suspensory apparatus
-inferior check ligament of DDFT
-SDFT and DDFT
the hindlimb stay apparatus prevents legs from collapsing by preventing (2)
-flexion of stifle and hock
-overextension of fetlock and phalangeal joints
what links the stifle and hock
reciprocal apparatus
two cords of the reciprocal apparatus
-peroneus tertius
-superficial digital flexor
In the hindlimb, the superior and inferior check ligaments
-superior = nonexistent
-inferior = small
two important parts of the hindlimb passive stay apparatus include
-reciprocal mechanism
-locking of patella
intermittent/permanent upper fixation of the patella is treated via
surgical desmotomy (transection) of medial patellar ligament
reciprocal apparatus (3)
-comprised of two cords (peroneus tertius and SDF)
-mostly tendinous
-aids in both movement and stay apparatus functions
the spring and coil mechanism involves (2)
-deep digital flexor
-superficial digital flexor
SDF and DDF have (2)
-small muscle bellies
-long tendons
natural gaits include (6)
-walk
-trot
-canter
-pace
-gallop
-backing
equal stride gaits include (3)
-walk
-trot
-pace
unequal stride gaits include (3)
-canter
-gallop
-backing
the near side of the horse is the
left side
The Walk is a
four-beat diagonal gait in eight phases, where second half mirrors first half
during a walk, there is no
suspension phase - there is always one fore and one hind foot on the ground at any time
The Trot is a
two beat diagonal gait (opposite fore and hind limbs), with two moments of suspension (no feet on ground)
The Pace (4)
-same as trot except ipsilateral limbs (same fore and hind limbs)
-faster than a trot
-natural gait in some species
-prevents clipping/interference of feet
The Canter is (2)
-eight phase with single suspension phase
-three beat with two feet landing together but other two landing independently of one another
two types of gallop
-transverse (ex. horse, camel, buffalo)
-rotational (ex. dog, deer, antelope)
gallop is ___ than canter
faster
light contact of foot with medial surface of opposite foot is called
brushing
when the toe of forefoot hits above the coronary band of the hind foot it is called
scalping (seen in trotters)
when the inside of the hind foot clips the inside of opposite forefoot it is called
cross-firing (seen in pacers)
when the toe of the hind foot strikes the sole of the fore foot on the same side it is called
forging
when the toe of hind foot hits the fore heel on the same side it is called
over-reaching
over-flexing of the carpus so that the hoof hits the caudal aspect of the elbow is called
elbow-hitting
base wide is when
increased force on inside of hoof (tarsal valgus)
“toe out” conformation is
winging
“toe in” conformation is
paddling
base narrow is when
increased force on outside of hoof (tarsal varus)
Carpal Valgus is (3)
-lateral deviation of the fore limb from the carpus distally
-“knock kneed”
-common angular limb deformity
Carpal Varus (2)
-medial deviation of the forelimb from the carpus distally
-“bow legged”
the hoof should be
level when viewed from dorsal to palmar/plantar
lordosis is also called
swaybacked
foot angle should be the same as
pastern angle
