TOPIC 30A. Statics of the forelimbs in horses, the phases of the step on the distal end of the forelimb Flashcards
What are statics
describe the maintenance of equilibrium in state of rest/motion
statics of forelimb
main supporters of trunk (55%)
elastic spring like apparatus
shock absorber system
Proximal buffers
- biceps tendons and lacertus fibrosus
- triceps long head
- m ext carpi radial
- m flex carpi ulnaris
distal supports
- sesamoid ligaments
- SDF and DDF tendons (check ligs)
- M interosseus medius (Tractus Apposticus)
what ability in eq aid in standing w/o tiring
passive stay apparatus (locking ability)
name the most important suspensory muscle of the trunk
m serratus ventralis (pars cervicis and pars thoracis)
how is the shoulder joint prevented from collapsing
collateral ligaments medial and lateral - m infraspinati and m subscapularis
what structure plays major role in preventing shoulder joint from buckliing
lacertus fibrosus - from biceps to radial carpal extensor
How is the elbow prevented from buckling forward
m triceps and SDF
How is overextension of the carpal joint prevented
palmar liggs,
carpal liggs,
accessory bone,
interosseus and SDF + DDF
what locks the fetlock joint
sesamoidal liggs, suspensory liggs,
what protects the pastern joint from hyperextension
has a weak palmar lig - so SDF and DDF help
what protects the coffin joint from hyperextension
navicular bone and liggs (same as fetlock - sesamoidal and suspensory)
List the elements of the passive stay apparatus of EQ in FL
- lacertus fibrosus
- m. interosseous medius + tractus appositus
- supf. + deep dig. flexor with lig. accessorium
(proximal, distal check ligaments) - suspensory apparatus (fetlock) (sesamoid and suspensory ligaments
- m serratus ventralis
variation in phases of step in FL
varies only in intensity and rhythm - never in order.
Thoracic and pelvic limbs 4 phases of movement
- lift
- swing
- support
- thrust
the hanging limb stage includes
the lift and swing phases
the supporting limb stages
support and thrust phase
one lift phase to the next is the
step
the distance covered between the two phases is
the step-length
types of walk
quick, normal, slow/shortened
step length of the walk
1.3 - 1.8m
speed of walk
6-7 km/hr
which limb moves first
HL moves before ipsilateral FL (same side)
RH RF LH LF
head movements during walk
lowered during swing
lifted during support
what happens in shortened walk
swing phase is shortened - hoof brought to ground quicker, can walk backwards but requires more energy
what is the stance phase
time the limb is in contact with the ground
what is the swing phase
time limb is not in contact with the ground
what is the FL support limb
the one supporting the trunk while being propelled forwards by HL
how is the thoracic limb raised off the ground
by shoulder girdle muscles and flexion of joints by all flexor muscles
in the swing phase, what protracts the limb
brachiocephalic, omo and trap
at end of swing phase what extends the joints again
triceps, ext carpi radialis and distal extensors
what does the biceps extend
the shoulder and carpus via lacertus fibrosus
what joint gets hyperextended
fetlock
what happens before the limb is lifted again
the SDF and suspensory lig relax,
DDF and accessory lig tense - so that coffin flexes once foot is lifted again
