Equine Hindlimb

Question 1

Regions of hindlimb (6)

Answer 1

• thigh
• crus/leg
• hock/tarsus
• fetlock
• pastern
• coffin

Question 2

General joints (6)

Answer 2

• hip
• stifle (2)
• hock (4)
• fetlock

-pastern

• coffin

Question 3

Hip joint

Answer 3

• articulation between acetabulum and femur head
• ligaments prevent hip subluxations

Question 4

Stifle joint

Answer 4

• femoropatellar: articulation between femur and patella
• femoro-tibial: articulation between femur and tibia

Question 5

Hock/tarsus joint

Answer 5

• tibiotarsal: articulation between distal end of tibia and proximal row of tarsal bones (tarsus and calcaneus)
• proximal intertarsal (centroproximal): articulation between proximal row of tarsal bones and second row of tarsal bones (central and 4th tarsal bones)
• distal intertarsal (centrodistal): articulation between central tarsal bone and distal row of tarsal bones ( fused 1st and 2nd tarsal bones and 3rd and 4th tarsal bones)
• tarsometatarsal: articulation between distal row of tarsal bones and the medial splint, lateral splint, and canon bones ( 2nd, 4th, and 3rd metatarsal bones)

Question 6

Fetlock joint

Answer 6

• articulation between distal end of 3rd metatarsal (canon), proximal sesamoid bones, and 1st phalanx

Question 7

Pastern joint

Answer 7

• articulation between 1st and 2nd phalanges

Question 8

Coffin joint

Answer 8

• articulation between 2nd and 3rd phalanges
  (Coffin bone and navicular bone)

Question 9

Semimembranosus and semitendinosus m.

Answer 9

Site for IM injections

Question 10

Trochanteric bursa

Answer 10

• formed by tendon of insertion of gluteal muscle and lower cranial portion of greater trochanter of femur
• trochanteric bursitis: causes severe lameness

Question 11

Sciatic n.

Answer 11

• lateral surface of thigh
• motor n.
• supplies semimembranosus, semitendinosus and biceps femoris muscles
• paralysis: atrophy of previous muscles, hip drop, asymmetry, toe-touch lameness

Question 12

Femoral n.

Answer 12

• medial surface of thigh

Question 13

Sacroiliac ligament

Answer 13

• attaches ilium of pelvis and vertebral column
• hunter’s pump/sacroiliac subluxation: sacroiliac ligament ruptures; asymmetry between both sides at hip level. Elevated hip is affected side.

Question 14

Ligaments that strengthen the hip joint (3)

Answer 14

• transverse ligament of acetabulum
• ligament of the head of femur
• accessory ligament (from prepubic tendon)

Question 15

Femoropatellar joint

Answer 15

• one joint capsule
• one compartment
• easier to puncture

-puncture landmark: either side of middle patellar ligament

Question 16

Femorotibial joint

Answer 16

• medial & lateral compartment
• one capsule
• larger than femoropatellar
• medial compartment communicates w/ femoropatellar jt in 80% horses
• lateral compartment communicates w/ femoropatellar jt in 25% horses
• lateral compartment is directly behind lateral patellar ligament

Question 17

Patella

Answer 17

• articulated to tibia and femur via: lateral patellary lig, middle patellary lig, medial patellary lig, and patellary fibrocartilage
• all previous structures except middle patellary ligament are part of patellar locking mech (1st part of passive stay mech)
• upward fixation of patella

Question 18

Upward fixation of patella

Answer 18

• when patella stays on femur due to poor conformation and joint locks; stifle and hock joint are overextended
• treatment: severing medial patellary ligament

Question 19

Long digital extensor m.

Answer 19

• only muscle to reach P3
• inserts on extensor process of P3
• pyramid disease
• landmark for injections in coffin joint

Question 20

Lateral digital extensor m.

Answer 20

• tendon joins long digital extensor tendon on dorsal aspect of cannon bone
• stringhalt

Question 21

Stringhalt

Answer 21

• involuntary flexion of hock joint
• treatment: severing of tendon shared by lateral digital extensor m. and long digital extensor m. at musculotendinous junction and before it joins tendon of long digital extensor m.
• treatment is called tenotomy

Question 22

Tendinous peroneus tertius

Answer 22

• ventral to long digital extensor m.
• forms cranial part of reciprocal apparatus (passive stay apparatus)
• rupture of peroneus tertius causes loss in synchronization of hock and stifle
• tendon has superficial lateral branch and dorsal branch

Question 23

Reciprocal apparatus

Answer 23

• cranial: tendinous peroneus tertius
• caudal: tendon of SDF

Question 24

Tibialis cranialis m.

Answer 24

• dorsal br: inserts on 3rd tarsal bone
• medial br: cunean tendon

Question 25

Cunean tendon

Answer 25

• medial tendon of insertion for tibialis cranialis
• cunean bursa under tendon
• severed to treat cunean bursitis, bone spavin, osteoarthritis of tarsocrural/ tibio-tarsal joint (relieves pressure off joint)

Question 26

Medial saphenous v.

Answer 26

• avoid when doing hock arthroscopy or injections
• blood spavin (engorgement of vessel w/ blood)

Question 27

Calcanean bursa

Answer 27

• under skin of calcaneus
• capped hock
• another bursa under SDF tendon called “sub-tendinous calcanean bursa”

Question 28

Capped hock

Answer 28

• calcification of bursa contents

Question 29

Fibular (peroneal) n.

Answer 29

Flex hock

Question 30

Femoral n.

Answer 30

Extend stifle

Question 31

Obturator n.

Answer 31

Adductor/gracilis