Lecture 6: Anatomy of Leg and Tarsus Flashcards
portion of pelvic limb between stifle and hock joints =
leg
tarsus =
ankle
pes =
foot
tarsus definition
region connecting hock to digits of pes/foot
how is movement of leg achieved
muscles that move the stifle joint
arrangement of hock and tarsus: 3 tiers
proximal
middle
distal
arrangement of hock and tarsus: proximal tier
includes talus and calcaneus
arrangement of hock and tarsus: middle tier
includes central tarsal bone
arrangement of hock and tarsus: distal tier
tarsals 1-4 numbered mediolateral
4th tarsal bone deeper than others and intrudes into middle tier
which tarsal bone is constantly present
4th
variations in equine tarsals
1 and 2 fuse
talus: trochlea
proximal surface
articulates with tibia and fibula
talus: head
distal surface
articulates with central tarsal
where is calcaneus located (Relative to talus)
lateral
calcaneus: sustentaculum tali/talar shelf
supports plantar surface of talus
supports tendon of flexor digitorum superficialis
calcaneus: tuber calcanei
attachment for calcaneal tendon
movement at hock
calcaneal tendon analogous to what structure in humans
achilles tendon
calcaneus: head
articulates with fourth tarsal
metatarsals vs metacarpals
metatarsals longer by 20%
more rounded
what is special about metatarsal 1 in dogs
dewclaw
rudimentary/not always present
3 regions of phalanges
proximal
intermediate
distal
what shape are dorsal sesamoid bones
banana
what shape are proximal sesamoid bones
round
what does proximal trochlear surface of talus articulate with in dogs
tibia and fibula
what does head of talus articulate with in dogs
central bone
what allows for free extension and flexion at talo-crural joint in horses
trochlea of talus is fused with cochlea of tibia
result of flat/small talar head: horse
more stability at talar/central articulation
limited movement
what causes horse’s distal limb to be carried laterally when flexion occurs at the hock
obliquity of talo-crural joint
double pully astragulus: arteriodatyls
talus articulates with central and fourth tarsal
in mammals, the talar head only articulates with what bone
central
4 levels of articulation in hock
tarso-crural/talo-crural
proximal intertarsal
distal intertarsal
tasometatarsal
proximal intertarsal joint is between
central tarsal bone and 1st and 2nd tarsal bones
distal intertarsal joint is between
central tarsal bone and 1st, 2nd and 3rd tarsal bones
tarsometatarsal joint is between
tarsals and metatarsals
almost all movement occurs at what hock joint
talocrural joint
how does talocrural joint work as a hinge joint (benefits)
lateral deviation of foot when its carried forward on flexion
pelvic limb will be external to thoracic limb when they overlap during high speed running
which ligaments extend from tibia and fibula to base of the metatarsus
medial and lateral collateral ligaments
medial/lateral collateral ligaments: 2 parts
long superficial part
shorter deeper part
long superficial part of medial/collateral ligaments extend to
full length of ligament
hock: 3 synovial compartments
tarsocrural and proximal intertarsal joints
distal intertarsal joint
tarsometatarsal joint
4 pouches within tarsocrural and proximal intertarsal joints (synovial compartments of hock)
laterodorsal
mediodorsal
medioplantar
lateral plantar
significance of 4 pouches within synovial compartment of hock
weaker parts of joint
swelling may occur due to over distention
2 bones within caudal compartment of leg
tibia
fibula
4 muscles within caudal compartment of leg
gastrocnemius
flexor digitorum superficialis
flexor digitorum profundus
popliteus
3 muscles that make up flexor digitorum profundii
flexor digitorum lateralis
flexor digitorum medialis
tibialis caudalis
caudal compartment of leg: innervation, blood supply, action
tibial nerve
saphenous artery
extend tarsus and flex digits
popliteus: origin, insertion, action
O - lateral condyle of femur
I - medial/proximal tibia
A- medial rotation of tibia relative to femur during flexion or swing phase
5 muscles of craniolateral compartment of leg
tibialis cranialis
extensor digitorum longus
peroneus longus
peroneus brevis
peroneus tertius
craniolateral compartment of leg: artery, nerve, action
cranial tibial artery
fibular/peroneal nerve
flex tarsus and extend digits
what does peroneus/fibularis tertius do at hock
bifurcates into lateral branch and dorsal branch
specific action of peroneus/fibularis tertius
connect actions of stifle and hock so they extend simultaneously
lateral branch of peroneus/fibularis tertius includes what 2 bones
calcaneus and 4th tarsal
dorsal branch of peroneus/fibularis tertius includes what 2 bones
proximal 3rd tarsal and 3rd metatarsal
what species is peroneus/fibularis tertius absent in
carnivorans
sciatic nerve splits into (in thigh)
tibial nerve
fibular nerve
where does tibial nerve enter
between 2 heads of gastrocnemius
how does tibial nerve travel/split
off of sciatic –> enters through gastrocnemius –> caudal sural branch –> enters tarsus between common calcaneal tendon and caudal crural muscles –> splits into medial and lateral plantar nerves
what branches off tibial nerve innervate the pes
medial and lateral plantar nerves
caudal sural branch of tibial nerve innervates what muscle group/compartment
caudal leg muscles
how does fibular nerve travel
enters lateral to gastrocnemius –> lateral sural cutaneous branch –> dorsum of pes
lateral sural cutaneous branch of fibular nerve innervates what muscle group/compartment
craniolateral leg muscles
which hindlimb artery is not present in horse and why
dorsal pedal
fewer toes
saphenous artery in horse vs dog (what does it do)
makes a loop
long plantar ligament
extends from plantar surface of calcaneus over 4th tarsal bone to metatarsus
lateral saphenous vein drains to
popliteal
on lateral leg
medial saphenous vein drains to
femoral vein –> external iliac
on medial leg
cranial tibial artery anastamoses with
saphenous artery
where does sciatic nerve split
thigh
