Stifle Joint & Thigh Muscles

What type of bones are the tibia and fibula?

• Type = long bones

What are the main roles of the tibia and fibula?

Does rotation occur within these two bones?

• Tibia:

• main weight bearing

• Prioritize stabilizing

• Fibula:

• much reduced but present in dog

• Lateral aspect of limb, along length

• Absent in larger species

• No rotation

Describe key features of the distal end of the tibia/fibula.

• Distal end

• Medial malleolus, dorsal surface of tibia

• Attachment of medial collateral ligament of hock

• Lateral malleolus in fibula

• Attachment of lateral collateral ligament of hock (or tarsus)

• Both palpable

Describe key features of the proximal end of the tibia/fibula.

Proximal End

• Tibial plateau / plate

• Medial condyle (c)

• Lateral condyle (c)

• Covered by smooth bone surface - articular cartilage

• Articulate with medial & lateral condyles of femur

• Intercondylar ridge (r)

• Non-articular rough bone surface

• ligament attachment

• Tibial crest

• Tibial tuberosity

• insertion of patellar ligament (Which is a tendon = a fake ligament)

• Is palpable in life

Describe the centers of ossification in the tibia.

• Tibia:

• Proximal end (epiphisys)

• Tibial tuberosity

• Body (diaphysis)

• Distal end (epiphysis)

Total = 4

Describe the centers of ossification in the fibula.

• Fibula: maximum = 3 (carnivores)

Proximal and distal epiphysis + diaphysis

How does the tibia / fibula look in:

• Carnivores + Pig

• Ruminant + Horse

• Carnivores + pig: present as two separate long bones

• Ruminant & horse:

• Incomplete & fused

• Horse - present in proximal aspect, fused to body of tibia, lateral mallelolus incorporated into tibia

• Ruminants - tear shaped tuberosity fused to lat. condyle of tibia (proximal) + isolated maleollar bone (distal)

What comprises the stifle joint?

1/ Femorotibial joint

2/ Femoropatellar joint

3/ Proximal tibiofibular (where fibula present)

4/ Femur + paired sesamoids (carnivores)

What are the articular surfaces, meniscus/menisci of femorotibial joint.

1/ Femorotibial - incongruent surface

Articular surfaces :

• Lateral & medial femoral condyles

• Lateral & medial tibial condyles

Meniscus / Menisci: produce a congruent surface

• C shaped wedges of cartilage

• Attached to tibial condyles (medial and lateral)

• Thick to thin from outer to inner

• Movement occurs between femoral condyles & menisci

What gives the femorotibial joint stability?

Stability:

1. Medial & lateral collateral ligaments

• Prevent lateral and medial movement

2. Cranial & Caudal Cruciate ligaments:

• Intercondylar eminence - intercondylar fossa

• Named for attachment to tibia

• CRANIAL CRUCIATE - attaches to cranial intercondylar ridge of tibia and runs to caudal intercondylar fossa of femur

• CAUDAL - attaches to caudal intercondylar ridge of tibia and runs to cranial intercondylar fossa of femur

• Maintain femur on mensici

• Resist rotation, keeps bones firmly attached together, preventing excessive cranial and caudal movement

What is the clinical significance of a cranial cruciate rupture?

• Cranial cruciate * rupture:

• Joint instability

• 'Cranial draw' sign

• Tibia moves cranial relative to femur

What are the components of the femoropatellar joint?

• Components, articulation of the femur and patella

• Trochlear groove (femur)

• Patella

• Patella is embedded in patellar ligament (which is a TENDON!!)

• Parapatellar (fibro)cartilages -

What provides the femoropatellar joint with stability?

• Stability: No lateral movement:

• Medial and lateral trochlear ridges of the femur

• Lateral & medial (collateral) femoro-patellar ligaments

  • Insert onto the femur itself in large species

  • Insert onto famellae sesamoids in domestics

  • Tend to be mineralized in canine species

• Fascia / retinaculum

How does proximal and distal glide of the patella occur?

• What movements will this result in?

• Proximal & distal glide only:

• Patella pulled proximally by contraction of quadriceps

  • Produces stifle extension

• Patella pulled distally by the caudal muscles (biceps femoris)

  • Allows stifle flexion

Describe the different types of sesamoid bones found within the stifle joint.

• Note any species differences as well.

• Sesamoid bones:

• Patella (x1)

• Visible all species

• More pointed in cat than dog

• Fabellae (sesamoids) (x2):

• In Gastrocnemius muscle

• Not visible in larger species

• Medial often not mineralised in cat

• Popliteal sesamoid (x1):

• Usually visible dog & cat

  • Not found in large animal species

• Dog & cat: maximum total = 4

• Large species: total = 1

Describe the joint capsule of the stifle joint.

• How does communication between joint compartments vary between species.

• Typical synovial joint:

• Extensive joint capsule

• Forms 3 compartments:

• Femoro-patellar

• Lateral femoro-tibial

• Medial femoro-tibial

• Communication between compartments varies between species

• Dog - good

• Horse - poor / none

Describe radiographic appearance of the stifle joint. 

• Radiography:

• Soft tissue components not visible

• Retropatellar fat pad

Describe the key features of the equine stifle joint.

 • Medial trochlear ridge:

• larger than lateral

• tubercle at proximal end, allowing for ligaments to “hook”

• Trochlear groove

• 2 parts to articular surface

• Vertical = portion for gliding

• Horizontal = portion for resting

• Patella:

• Large medial cartilage projection

• 3 patellar ligaments:

• Medial / middle /lateral

• All insert - tibial tuberosity

• Patella & medial patellar ligament form hook

What is the patellar locking mechanism.

The patellar locking mechanism in horses, part of the stay apparatus, allows them to sleep standing by locking the patella (kneecap) over a ridge on the femur (thigh bone) using the medial patellar ligament.

1. Patella pulled proximally as stifle extended, by contracting quadriceps

2. Patella rotated medially due to contraction

3. Engages or hooks horizontal / resting surface

4. Tubercle of medial trochlear ridge now sits between middle & medial patellar ligaments

5. Locks joint in extension

Describe how the equine patellar locking mechanism contributes to the stay apparatus.

• How does it “unlock”?

• Patella pulled proximally then back to midline to unlock

• Contributes to stay apparatus:

• Locks leg in extension

• Can rest other hindlimb / sleep standing up

• Clinical significance:

• Upward fixation / 'locked' patella

Summarize the stifle joint components. 

• 1/ Femur - tibia components:

• Medial & lateral menisci

• Collateral ligaments

• Cranial & caudal cruciate ligaments

• 2/ Femur - patella components:

• Medial and lateral trochlear ridges

• Medial & lateral femoro-patellar ligaments

• Retinaculum

• Patella & patellar ligament - palpable

• Locate joint space

• Further proximal than you would think!

What are the nerves supplying the hindlimb?

• Spinal nerves

• L5, L6, L7, S1, S2.

• Dorsal branches - dorsal structures

• Ventral branches - lumbosacral plexus

• Emerging peripheral nerves from the lumbosacral plexus to hindlimb:

• Gluteal

• Obturator

• Femoral

• Sciatic - tibial

  • fibular / peroneal

Describe the differences in flexor angles in the hindlimb.

At hip - flexor angle is a cranial aspect

• Hip joint - first mobile joint

• Protraction = flexion

• Retraction = extension

What is the pivotal point for the hind limb?

What structures provide the following movement?

• Abduction

• Adduction

• Protraction

• Retraction

• Hip joint = Pivotal point

• Ball & socket joint

• Movement in all directions

1. Abduction (carnivores)

• Dorsal thigh muscles

2. Adduction

• Medial thigh muscles

3. Protraction

• Hip flexion

• Cranial thigh muscles

4. Retraction

• Hip extension

• Caudal thigh muscles

Describe the following for the gluteal muscles.

• Origin

• Insertion

• Function

• Nerve Supply

Gluteal muscles:

• 3 parts

• O - sacrum & pelvis

• I - greater trochanter of femur

• acts as lever

Function:

• Hindlimb abductors - dog

• Hindlimb retractor / hip extensors - horse

• Since mostly flexion and extension in these species, angle at which muscles inserts restricts movement to flexion and extension

Nerve Supply;

• Gluteal nerve

Describe the following for the medial/ventral thigh muscles. (The GAPE muscles)

• Origin

• Insertion

• Function

• Nerve Supply

Medial /ventral thigh muscles:

• O - Ventral surface pelvis

• I - medial aspect limb

• 'GAPE' muscles =

• Gracilis (+)

• I = tibia

• I = calcaneus (tarsus)

(via common calcanean tendon)

• Adductor (*)

• Pectineus (#)

• Both | = femur

• (External obturator)

• Function - Adductors

• Nerve Supply - Obturator Nerve

Describe the following for the Quadriceps muscle. (Cranial Muscle)

• Origin

• Insertion

• Function

• Nerve Supply

• Quadriceps muscle

• Rectus femoris: O-ilium

• Vastus lateralis: O - lateral femur

• Vastus medialis: O - medial femur

• Vastus intermedius: O - cranial femur

• I - tibial tuberosity

• (via patellar ligament)

• Function:

• Stifle extensor

• (Hip flexor / limb protractor)

• Nerve Supply:

• Femoral Nerve

Describe the following for sartorius. (Cranial Thigh muscle)

• Origin

• Insertion

• Function

• Nerve Supply

• Sartorius (blue)

• O - ilium

• | - femur

• I - tibial tuberosity

• (via patellar ligament) fusion

• Function:

• Stifle extensor

• Hip flexor / limb protractor

Nerve supply: Femoral nerve

Describe the following for iliopsoas. 

• Origin

• Insertion

• Function

• Nerve Supply

• Iliopsoas muscle

• O - lumbar vertebrae & ilium

• I - medial proximal femur

• Function:

• Hip flexor / limb protractor

Nerve supply: Femoral nerve

Describe the following for the biceps femoris. 

• Origin

• Insertion

• Function

• Nerve Supply

• O - tuber ishium

• | - fascia latae

• I - calcaneus (tarsus)

• (via common calcanean tendon)

• Functions:

• Hip extensor / hindlimb retractor

• Stifle flexor

• Hock extensor

• Nerve supply

• Sciatic nerve

Describe the following for the semitendinosus and semimembranosus. 

• Origin

• Insertion

• Function

• Nerve Supply

• Semitendinosus (blue)

• O - Tuber Ishium

• I - Tibia

• I - calcaneus (tarsus)

• (via common calcanean tendon)

• Semimembranosus (pink)

• O - Tuber ischium

• I - femur & tibia

• Function:

• Hip extensor / hindlimb retractor

• Stifle flexor

• (Hock extensor)

• Nerve supply:

• Sciatic Nerve

Summarize the muscles (and their functions), of those located in the hindlimb.

What are some notable comparative differences considering the thigh muscles in the ruminant and horse?

• Ruminants - angular

• Horse - rounded rump / croup

• Gluteal muscles:

• Very well developed

• Caudal thigh muscles:

• Biceps femoris

• Semitendinosus

• Semimembranosus

• O- tuber ischium (same as other species)

• Extra O- lumbosacral fascia

• Very powerful limb retraction / hip extension

• Allows horse to gallop, rear, buck / kick and jump better than cows!