Week 2 Lesson 13: Structure and function of hind limb joints and ligaments

What are the four major joints associated with the hindlimb?

Sacroiliac, hip, stifle, and tarsal joints.

What are the two primary classifications of synovial joints based on complexity?

Simple and compound.

What is a "ginglymus" joint?

A functional type of joint also known as a hinge joint.

What functional type of joint is the coxofemoral joint?

Spheroidal or ball and socket.

What functional joint type is the pastern joint?

Saddle joint.

What is the functional classification of the fetlock joint?

Hinge joint.

What type of joint is the tarsocrural joint in horses?

Cochlear joint.

What is the synovial classification of the stifle joint?

Composite, condylar joint.

How is a "simple" joint defined?

It involves only two articulating bones.

How is a "compound" joint defined?

It involves more than two articulating bones.

What bones form the articular surface of the SI joint?

The wing of the ilium and the wing of the sacrum.

What is the dual nature of the SI joint's composition?

It has both synovial and fibrocartilaginous components.

Which ligaments reinforce the SI joint capsule?

The dorsal, ventral, and interosseous sacroiliac ligaments.

What is the broad sacrotuberous ligament's function in ungulates?

It forms the lateral wall of the pelvis.

What is the primary role of the SI joint regarding weight?

It transmits the weight of the trunk to the hindlimbs.

Does the SI joint prioritize mobility or stability?

Stability.

How does the pelvis appear in a horse with a weak SI connection?

The pelvis tilts forward.

What can SI damage cause in a horse's pelvic symmetry?

A distorted pelvis.

What is a clinical sign of SI joint issues in canines on a radiograph?

The wings of the ilium appearing out of place.

What is the primary function of the sacrotuberous ligament's support mechanism?

It acts as a support for the pelvic floor.

What bones articulate to form the hip joint?

The head of the femur and the acetabulum.

What structure deepens the acetabulum in ungulates?

The labrum acetabulare (fibrocartilage lip).

What ligament bridges the acetabular notch?

The transverse acetabular ligament.

What are the two names for the ligament attaching the femoral head to the acetabular fossa?

Ligament of the head of the femur or round ligament.

Where does the ligament of the head of the femur insert on the femur?

The fovea capitis.

Does the hip joint have collateral ligaments?

No, it has no collateral ligaments.

Which ligament is unique to equids?

The accessory ligament.

From what structure does the equine accessory ligament originate?

The prepubic tendon.

What is the functional purpose of the accessory ligament in horses?

It limits inward rotation (pronation) and abduction of the thigh.

Why is hip luxation uncommon in horses?

Because the joint is highly stable.

In which horses is hip luxation most frequently seen?

Ponies and miniature horses.

What movements are permitted by the hip joint in small animals?

Flexion, extension, abduction, adduction, circumduction, and rotation.

What movements are the hip joint restricted to in large animals?

Flexion and extension.

What is canine hip dysplasia?

An inherited disease causing hip joint laxity, subluxation, and osteoarthritis.

Name three factors contributing to canine hip laxity.

Weak joint capsule, lack of muscle development, and increased joint fluid volume.

What is the "Ortolani sign"?

A palpable or audible "clunk" felt during a clinical test for hip laxity in young dogs.

What is a "steep dorsal acetabular slope" associated with?

Canine hip dysplasia.

What structure primarily stabilizes the canine hip joint?

Ligament of the head of the femur.

What is the "acetabular fossa"?

The area where the ligament of the head of the femur attaches within the acetabulum.

What is the "fovea"?

The specific depression on the femoral head for ligament attachment.

What are the three bones involved in the stifle joint?

Femur, patella, and tibia.

What are the two component joints of the stifle?

Femoropatellar and femorotibial joints.

What is the largest synovial joint in the body?

The stifle joint.

How many patellar ligaments do dogs have?

One.

How many patellar ligaments do horses and cattle have?

Three (medial, intermediate, lateral).

What is the function of the parapatellar fibrocartilage in the horse?

It extends the joint and helps in the locking mechanism.

Which animal has a very well-developed medial parapatellar fibrocartilage?

Large animals (horses/cattle).

What is the "passive stay-apparatus" locking mechanism?

A system allowing one pelvic limb to support weight while the other rests, allowing the horse to remain standing.

What are the "menisci"?

Two semilunar fibrocartilage discs over the tibial condyles.

What is the main function of the menisci?

To distribute load and reduce contact stresses in the joint.

To which ligament does the medial meniscus attach?

The medial collateral ligament.

Where do the cruciate ligaments cross?

At the center of the stifle joint.

What is the primary stability provided by the cruciate ligaments?

Cranio-caudal stability.

From where does the cranial cruciate ligament arise?

The lateral condyle of the femur.

From where does the caudal cruciate ligament arise?

The lateral surface of the medial femoral condyle.

Which stifle ligament is at the greatest risk of rupture during overextension?

The cranial cruciate ligament.

What is the "cranial drawer sign"?

Abnormally free forward displacement of the tibia indicating a cranial cruciate rupture.

When is the caudal cruciate ligament at the greatest risk of injury?

In the flexed position of the joint.

What are the sesamoid bones in the gastrocnemius muscle called?

Fabellae.

Which species lack the gastrocnemius sesamoids?

Equine and bovine.

What is the "popliteal sesamoid"?

A small sesamoid bone related to the margin of the tibia in dogs.

What is the largest sesamoid bone in the body?

The patella.

In which tendon does the patella ossify?

The tendon of insertion of the quadriceps muscle.

Where does the patellar ligament attach on the tibia?

The tibial tuberosity.

What is "patellar luxation"?

A condition where the patella slips out of the trochlear groove, most common in small breed dogs.

What is the ratio of medial to lateral patellar luxation in large dog breeds?

4:1.

What is the ratio of medial to lateral patellar luxation across all dog breeds?

7:1.

What are TPLO and TTA?

Surgical corrective principles for cranial cruciate ligament (CCL) repair.

What is the "medial and lateral femoropatellar ligaments"?

Thin fascial bands extending from the patella to the gastrocnemial sesamoids.

Which stifle joint sacs communicate 100% of the time in all joints?

The medial femorotibial sac and femoropatellar sac.

What are the four levels of articulation in the hock?

Tarsocrural, proximal intertarsal, distal intertarsal, and tarsometatarsal.

Which hock articulation is the most moveable?

The tarsocrural joint.

What is "bog spavin"?

Synovial effusion of the tarsocrural (tibiotarsal) joint in horses.

Which two hock joints communicate directly in horses?

Tarsocrural and proximal intertarsal.

Which bones form the tarsocrural joint in the horse?

The tibia and the talus.

Why is the fibula not mentioned in the equine tarsocrural joint articulation?

The distal aspect of the fibula is incorporated into the tibia.

What movement is possible in the carnivore proximal intertarsal joint?

Lateral movement, rotation, flexion, and extension.

What movement is possible in the equine proximal intertarsal joint?

Almost no movement.

What is "bone spavin"?

Osteoarthritis or arthritis of the distal intertarsal and tarsometatarsal joints.

What is a "low motion joint" in the equine hock?

The distal intertarsal and tarsometatarsal joints.

What is the "trochlea" of the talus like in horses?

Quite oblique and laterally directed.

What does the obliquity of the equine hock help avoid during flexion?

Caudal interference with the stifle.

What is "Osteochondrosis (OCD)" in horses?

A developmental disorder where pieces of cartilage or bone break off.

Name a common site for OCD in the equine tarsus.

The intermediate ridge of the distal tibia.

Which hock ligaments are divided into long and short branches?

The medial and lateral collateral ligaments.

What is the "long plantar ligament"?

A strong band on the plantar aspect that stabilizes the calcaneus.

What is "Curb"?

Desmitis (inflammation) and thickening of the long plantar ligament.

Where does the long plantar ligament insert?

The 4th metatarsal bone.

What is the "accessory (check) ligament" of the DDF in horses?

A tendinous slip connecting the deep digital flexor tendon to MT III.

Does the horse have a check ligament for the superficial digital flexor (SDF)?

No.

What is the "cunean tendon"?

The medial tendon of the tibialis cranialis muscle.

Where is the cunean bursa located?

Between the cunean tendon and the medial collateral ligament.

Why might a portion of the cunean tendon be resected?

To reduce pressure over a lesion and eliminate movement.

What is the "reciprocal apparatus"?

A system where the hock is forced to flex or extend in unison with the stifle and hip.

What is the hardest-worked joint in the equine body?

The tarsal (hock) joint.

In which hock joint is synovial fluid typically harvested?

The tarsocrural joint.

What defines "High Spavin"?

Osteoarthritis occurring at the tarsocrural joint.

What hock joints communicate 25–38% of the time?

The distal intertarsal and tarsometatarsal joints.

What are the clinical signs of hock OCD?

Joint effusion with minimal lameness.

What is the primary motion allowed by the stifle?

Flexion and extension.