Chapter 6 - Pelvic Limb (14 & 15)

Question 1

Compare and contrast the horse and cow hip joint, with regard to structure, function, and luxation susceptibility.

Answer 1

Horse: the acetabulum is deep to help facilitate force transfer from hind limb to the pelvis. The cow hip joint is much more susceptible to luxation than the equine hip. The acetabulum is surrounded by a fibrocartilagenous ring (“embraces” fem. head
-Horse: There are two ligaments: the ligament of the femoral head (most species) and the accessory ligament (only in horse and donkeys). The ligaments severely reduce rotation and abduction and generally only allow extension and flexion in sag. plane

Question 2

Compare and contrast horse and cow hip joint…(cont).

Answer 2

• Cow: A more sloped pelvis makes a more upright pelvic inlet and a less sloped pelvis makes a flat rump. The less sloped pelvis makes the femurs vertical, which makes the cow more susceptible to hip joint injuries.
• Cow: hip can be dislocated in several directions (although dorsocranial is most common). This is thought to be attributed to the weak or non-existent intra-articular ligament (ligament capitis)
• Cow: flexion and extension is the primary movement, but outward rotation of the thigh is required to keep the stifle out of the abdomen.

Question 3

Compare and contrast horse and cow hip joint summary.

Answer 3

Characteristic/Horse/ Cow

• Structure/deep acet.; accessory ligt./weak, missing intra-articular ligament
• Function/exten. and flexion in saggital plane only/exten. and flexion primarily, but also rotation
• Luxation susceptibility/rare/more common

Question 4

What is the location of the lesser trochanter, 3rd trochanter, extensor fossa, & trochlea lip which serves as a hook for patellar ligament. loop?

Answer 4

• lesser trochanter: 1/3 of way down femur on medial side
• third trochanter: 1/3 of way down femur on lateral side
• extensor fossa: distal to lateral condyle
• trochlea lip: the craniometrical side of the distal femur

Question 5

What attaches to the lesser and third trochanter?

Answer 5

• lesser trochanter attaches to the iliopsoas

- third trochanter attaches to the superficial gluteal muscle

Question 6

Is the patellar tendon really a ligament?

Answer 6

-The patellar tendon/ligament is both a tendon and a ligament

Question 7

What do various authorities say about the patellar tendon and why?

Answer 7

• Phys/neurologists say it is a tendon and that patella is a sesamoid bone in qudriceps tendon, which inserts on the tibial
• Anat/surgeons say is a ligament b/c quad. tendon inserts on patella and patellar ligament connects the patells & tibia

Question 8

What forms the loop that fixes the stifle? What does this loop “hook” over?

Answer 8

• the loop is formed by the medial and middle patellar ligaments vertically and the patellar fibrocartilage dorsally
• the hook is the medial lip of the femoral trochlea

Question 9

What is a desmotomy and why would it be performed on a stifle?

Answer 9

• desmotomy means to cut a ligament
• this would be done to the patellar ligament if the “loop” was getting stuck on the “hook” and keeping the horse from flexing the stifle. This would prevent the horse from locking the stifle joint

Question 10

What are the individual synovial sacs of the stifle ?

Answer 10

-Three indiv. joints: femoropatellar, medial femoraltibial, and lateral femoalrtibia

Question 11

How are the following connected in the horse: the femoropatellar, medial femoraltibial, and lateral femoraltibial joints?

Answer 11

• the femoropatellar always communicates w/ the femorotibial and comm. with the lateral femorotibial in 25% of horses
• in ruminants, the femoropatellar and medial femorotibial cavities always communicate, but lateral femor. never comm. w/ other two

Question 12

What is the clinical significance of the information in the previous card (regarding the three joints)?

Answer 12

• sig. b/c if injection into one of joints, it is imp. to know which other joint capsule it will migrate to (antib.)
• most of the time, if there is an infection in one joint, it probably is in the others as well
• femorotibial joints have menisci

Question 13

What are the components of the reciprocal apparatus?

*note: hock movement reciprocates w/ stifle movement

Answer 13

1. superficial digital flexor (extends)
2. peroneus tertius (flexes) -the peroneus tertius will rupture if the stifle flexes and the leg is caught so the hock is not allowed to flex (diagnose by flexing the stifle while keeping hock extended)

Question 14

Compare the talus of the horse and ruminants (the camelid talus is similar to ruminants).

Answer 14

• Horses: have semicircular oblique trochlea of talus that articulates w/ tibia. Most movement of hock is w/ tibio/tala joint which has a wide range of mvmts. and slackened joint capsule
• Ruminants: have prox. and dist. trochlea of talus

Question 15

Compare the talus of horse and ruminants (cont.)

Answer 15

-Rumin: prox trochlea articulates w/ the tibial cochlea and malleolar bone (making tarsocrural joint). The dist trochlea articulates w/ calcaneus and fused central and 4th tarsal bones (making prox. intertarsal joint). Can flex and extend (both jts)

Question 16

Give a possible behavioral explation for the structural differences in the talus of horses vs. ruminants

Answer 16

-ruminants spend a lot of time in sternal recumbancy w/ hocks flexed (it is thought that two joints allows the hock to be flexed for an ext. period of time)

Question 17

Give a possible behavioral explanation for the structural differences in the talus of horses vs. ruminants (cont.)

Answer 17

• the talus has a trochlea that acts like a pulley whereas the calcaneus is lever arm that is respons. for movement, but is not weight bearing
• the sustentaculum tali is so named b/c in plantagrade walkers, weight of talus is “sustained” by sus. tali

Question 18

Compare and contrast the talus and cancaneous

Answer 18

• talus: semicircular trochlea (pulley), which rotates the tibia, virtually all hock movements occurs in tibio/talal joint, and is weight bearing
• calcaneous: is a lever arm which is not weight bearing

Question 19

Why is the sustentaculum tali so named?

Answer 19

Name comes from the fact that it supports (sustains) the talus in plantagrade human

Question 20

What forms the tarsal canal and what is its content?

Answer 20

• formed by a groove on the medial side of the calcaneus and the flexor retinaculum
• contains: the lateral tendon of the deep digital flexor m. and plantar nerves

Question 21

What is thoroughpin and how does it relate to carpal tunnel syndrome? What is the derivation of the name?

Answer 21

• a swelling of the sheath of the lateral tendon (like carpel tunnel syndrome) of the deep digital flexor m.
• the name comes from shuttle pin since fluid in the swelling can shuttle from proximal lateral to distal medial as the swelling is palpated

Question 22

What structure is torn in curb? Why does this occur?

Answer 22

• plantar ligament tearing causes a round swelling

- occurs as a result of great force applied to the calcaneus by tendons of the calcanean group

Question 23

Which joint surfaces are involved in bog spavin and bone spavin?

Answer 23

• bog spavin: is a swelling to the dorsal side medial to the peroneus tertius/cranial tibial tendons and medial collateral ligament
• bone spavin: is an arthritis in the region of tc/t3 and t3/mt3 in the horse

Question 24

What is the cuneal tendon and what is the surgical significance of it?

Answer 24

• cuneal tendon: medial tendon of the cranial tibial m.

- significance: it is often cut to release pressure it applies which exacerbates the pain caused by bone spavin

Question 25

What tendon is cut for stringhalt?

Answer 25

tendon of the lateral digital extensor m.

Question 26

What are antigravity muscles? What would be some exceptions to the extensor rule?

Answer 26

• they support the body weight and are usually extensors and stronger than their non-weight-bearing antagonists
• though flexors, the digital flexor muscles are also antigravity muscles (tetanus and strychnine poisoning cause a clinical presentation called “extensor rigidity”)