2 Anatomy: Equine Hl Joints, Reciprocal

Front 1

hip (coxal joint)

Back 1

hip (coxal joint):
- synovial
- composite: ilium, pubis, ischium, head of femur
- ball and socket (spheroidal), but functionally a hinge
- capacious joint capsule: holds articular surfaces together

Front 2

articular surfaces of coxal joint

Back 2

articular surfaces of coxal joint:
1. round head of femur
2. acetabulum:
- deepened by labrum acetabulare: fibrocartilage lip on rim of acetabulum
- transverse acetabular ligament: portion transversing or bridging the acetabular notch

Front 3

movements of coxal jt

Back 3

movements of coxal jt:
- functionally hinge: mainly extension and flexion in sagittal plane
- little abduction, adduction
- little rotation: due to antagonism between the biceps femoris and semitendinosus muscle at stifle jt

Front 4

angles of coxal jt

Back 4

angles of coxal jt:
- normally 110-155 deg: partially flexed, absorbs concussion
- shaft of ilium 30-50 deg inclined to the horizontal plane

Front 5

patellar ligaments

Back 5

patellar ligaments:
- medial, middle and lateral
- attach from sides of patella to tibial tuberosity
- tendons of insertion of quadriceps femoris m

Front 6

collateral ligaments of genual jt

Back 6

collateral ligaments of genual jt:
- medial and lateral
- from corresponding epicondyle of the femur to medial condyle of tibia and head of fibula, respectively

Front 7

cranial cruciate ligament of genual jt

Back 7

cranial cruciate ligament of genual jt :
- runs caudoproximally from fossa of the spine of the tibia to the lateral wall of the intercondyloid fossa of the femur

Front 8

caudal cruciate ligament of genual jt

Back 8

caudal cruciate ligament of genual jt:
- runs cranioproximally from popliteal notch of tibia to the cranial part of intercondyloid fossa of the femur
- intra-articular, covered by synovial membrane

Front 9

rupture of peroneus tertius m

Back 9

rupture of peroneus tertius m:
- abnormal, jerky flexing of the hock

Front 10

rupture of peroneus teritius and SDF tendons

Back 10

rupture of peroneus teritius and SDF tendons:
- hock drops to ground

Front 11

ligaments of coxal jt

Back 11

ligaments of coxal jt:
- no collateral ligaments
- adjacent mm help stabilize

Front 12

ligament of the head of the femur

Back 12

ligament of the head of the femur:
- very stout
- extends from acetabular fossa to the fovea capitis of femur
- intra-articular portion enclosed in synovial membrane
- previously thought to supply blood to head of femur although now it is believed to come from epiphyseal circulation through the joint capsule

Front 13

accessory ligament

Back 13

accessory ligament:
- only equids
- extends from prepubic tendon, through the acetabular notch to end in the fovea capitis
- close to ligament of the head of the femur
- limits inward rotation (pronation), abduction of thigh
- stabilizes coxal joint

Front 14

trochanter of femur

Back 14

trochanter of femur:
- protects coxal joint
- subject to extensive bruising or fracture

Front 15

movement of coxal joint

Back 15

movement of coxal joint:
- large muscle masses hamper movement, but initiate forward propulsion
- automatic movement of rest of limb after coxal movement with some regulation or moderation on a voluntary basis

Front 16

genual joint

Back 16

genual joint:
- largest single joint of body
- synovial, condylar
- bones: femur, tibia, patella
- compound:
1. femoropatellar: simple gliding
2. femorotibial: simple condylar

Front 17

genual joint capsules:

Back 17

genual joint capsules:
1. femoropatellar: trochlea of femur and patella
2. medial and lateral femorotibial:
condyles of femur and condyles of tibia

Front 18

genual joint communication

Back 18

genual joint communication:
1. femoropatellar and medial FT: 100% horses, at distal part of medial ridge of trochlea
2. femoropatellar and lateral FT:
communicates in only 25% horses
3. medial and lateral femorotibial:
no communication

Front 19

femoral surfaces of FP jt

Back 19

femoral surfaces of FP jt:
1. resting surface: proximal part of trochlea, faces craniodorsally
2. gliding surface: distal part of trochlea, faces cranioventrally

Front 20

medial ridge of trochlea of femur

Back 20

medial ridge of trochlea of femur:
- larger than lateral
- bears cartilage covered tubercle important in patellar lock

Front 21

patella

Back 21

patella:
- largest sesamoid of body
- provides quad femoris a large, gliding surface over the trochlea of the femur in flexion and extension
- part of tendon of insertion of quadriceps femoris m: protects from excessive friction
- parapatellar fibrocartilage: medial angle

Front 22

articular surfaces of patella

Back 22

articular surfaces of patella:
1. resting: short, distal
2. gliding surface: long, proximal

Front 23

medial and lateral menisci

Back 23

medial and lateral menisci:
- FT joint
- thick, semilunar fibrocartilage discs, avascular at center
- provide additional surface for lubricating action of synovial fluid
- minimize incongruence in space between condyles of femur and tibia which are not designed to form a jt

Front 24

femorotibial jt

Back 24

femorotibial jt:
- extensive, large capacity
- thin

Front 25

collateral ligaments of genual jt

Back 25

collateral ligaments of genual jt:
- from corresponding epicondyle of femur to:
1. medial: medial condyle of tibia
2. lateral: head of fibula

Front 26

meniscal ligaments of genual jt

Back 26

meniscal ligaments of genual jt:
- 4 attaching cr and ca horns of the menisci to the cr and ca intercondylar areas of the tibia

Front 27

femoropatellar ligaments

Back 27

femoropatellar ligaments:
- delicate bands of tissue
- medial: attaches to the parapatellar fibrocartilage
- both attach caudally to the femoral epicondyles from side of the patella
- fuse with fibrous layer of jt capsule

Front 28

movements of genual jt

Back 28

movements of genual jt:
- normally partially flexed: absorbs concussion
- flexion, extension, some rotation
- cruciates limit hyper- extension (esp cranial) and flexion
- FT and FP joints move in unison

Front 29

patellar lock mechanism

Back 29

patellar lock mechanism:
1. quadriceps femoris: patella glides proximally over medial ridge of trochlea on which the parapatellar ligament hooks and rests
2. medial trochlear ridge protrudes through loop formed by medial and middle patellar ligaments and patellar fibrocartilage
3. stifle locked in extension, muscular activity stopped

Front 30

patellar lock

Back 30

patellar lock:
- key to stay apparatus: reciprocal apparatus ensures hock extends with stifle
- when body weight on one limb: angle 145-150 vs 135 with both HL bearing wt

Front 31

patellar luxation

Back 31

patellar luxation:
- not uncommon in foals
- usually grow out of it, but may require attention

Front 32

arthrocentesis of genual jt

Back 32

arthrocentesis of genual jt:
1. lateral femorotibial cavity: between long digital extensor tendon and lateral collateral ligament
2. medial femorotibial cavity: between medial patellar ligament and medial collateral ligament
3. femoropatellar joint cavity:
caudal to lateral patellar ligament, close to patella

Front 33

tarsal (hock) jt

Back 33

tarsal (hock) jt:
- synovial, compound, ginglymus
- proximal bones:
1. calcaneus: fibular tarsal
2. talus: tibial tarsal
- distal bones:
1. central
2. T1 and 2: fused
3. T3, vascular canal for perforating tarsal a, T4

Front 34

angle of trochlea of talus

Back 34

angle of trochlea of talus:
- oblique and laterally directed vs straight and vertical in other spp
- outward movement of hock in motion while stifle and toe are turned inward, due to proximal gliding of tibia over trochlea
- flexion: obliquity of trochlea assists in turning stifle outward, avoiding caudal thoracic wall

Front 35

tarsocrural jt

Back 35

tarsocrural jt:
- cochlea of tibia and trochlea of talus (tibial tarsal bone)

Front 36

articulations of hock

Back 36

articulations of hock:
1. tarsocrural
2. intertarsal: prox and distal
3. tarsometatarsal

Front 37

proximal intertarsal jt

Back 37

proximal intertarsal jt between:
1. proximally: talus and calcaneus,
2. distally: central and fourth tarsals

Front 38

distal intertarsal jt

Back 38

distal intertarsal jt between:
1. prox/laterally: central and 4th tarsal
2. distally: 1, 2 (fused) and 3rd tarsals

Front 39

tarsometatarsal jt

Back 39

tarsometatarsal jt:
- between distal row of tarsals and metatarsal bones

Front 40

common joint capsule of hock

Back 40

common joint capsule of hock:
- distal end of tibia to periarticular surfaces of metatarsals
- deep surface attaches to component bones
- plantar and dorsal surfaces: thick, plantar may be partly cartilagenous
- proximal: thin, often bulges with synovial fluid accum (bog spavin)
- injections: dorsal pouch for tarsocrural and proximal intertarsal jts

Front 41

synovial sacs of hock

Back 41

synovial sacs of hock:
- one for each jt, named accordingly
- tibiotarsal/ tarsocrural: best formed, most important, communicates with proximal intertarsal
- other sacs rarely communicate

Front 42

medial collateral ligament of hock

Back 42

medial collateral ligament of hock:
- from med malleolus to talus and proximal ends of metatarsal II and II
- short, part enclosed by the long, inserts on the talus

Front 43

lateral collateral ligament of hock

Back 43

lateral collateral ligament of hock:
- from lat malleolus to calcaneus, tarsal IV, and metatarsals III and IV
- short part under the long
- inserts caudally on talus and calcaneus

Front 44

long plantar ligament

Back 44

long plantar ligament:
- lateroplantar aspect of hock
- from calcaneus to tarsal IV and metatarsals
- stabilizes calcaneus when under force of the common calcanean tendon
- curb: swelling due to strain causing convexity of plantar surface

Front 45

dorsal ligament of hock

Back 45

dorsal ligament of hock:
- triangular
- arises on distal tuberosity on medial part of talus to insert on metatarsal II and III, central and IIIrd tarsal

Front 46

accessory ligament of hock

Back 46

accessory ligament of hock:
- distal extension of the plantar part of the joint capsule
- joins the tendon of DDF in mid-metatarsus
- not always present

Front 47

cunean tendon

Back 47

cunean tendon:
- tendon of cr tibial m:
1. dorsal limb: inserts on MT 3
2. medial limb: cunean tendon, inserts on T1 and 2 (fused)
- subtendinous or cunean bursa lies under the cunean tendon over the medial collateral ligament

Front 48

tendon sheaths of hock

Back 48

tendon sheaths of hock:
- all except SDF
-tarsal synovial sheath: lateral digital flexor m and cranial tibial m (2/3 heads of the DDF m)
- generally extend from proximal to the malleoli to the proximal quarter of the metatarsus

Front 49

movements of hock

Back 49

movements of hock:
- flexion, extension, some gliding
- most in tarsocrural jt (no gliding)
- normally partially flexed: concussion-absorption
- hardest-worked jt: strains and stress cause spavin
- part of reciprocal apparatus

Front 50

reciprocal apparatus

Back 50

reciprocal apparatus:
- unsures that stifle and hock flex or extend simultaneously
- portion of stay apparatus in HL
- action mechanical: prevents m fatigue in prolonged standing and jerky, uncoordinated movements at affected jts

Front 51

reciprocal apparatus: cranial

Back 51

reciprocal apparatus cranial:
- peroneus (fibularis) tertius m entirely tendinous
- origin: extensor fossa of femur
- insertion: cr surface of proximal end of MT2, T3, talus and T4

Front 52

reciprocal apparatus: caudal

Back 52

reciprocal apparatus caudal:
- SDF tendon between 2 heads of gastrocnemius (some consider gastroc as well due to association)
- almost entirely tendinous
- origin: supracondylar fossa of femur
- insertion: tuber calcaneum, phalanges 1 and 2

Front 53

stay apparatus

Back 53

stay apparatus:
- structures similar to FL
- accessory ll may be weak
- SDF attachment at hock may make up for weak accessory ll

Front 54

components of stay apparatus

Back 54

components of stay appartus:
1. patellar lock
2. reciprocal apparatus
3. LDE m tendon
4. extensor slips of interosseus m
5. interosseus m
6. DDF tendon
7. accessory ligament of DDF
8. SDF tendon
9. straight and oblique _

Front 55

stay apparatus

Back 55

stay apparatus:
- structures similar to FL
- accessory ll may be weak
- SDF attachment at hock may make up for weak accessory ll

Front 56

components of stay apparatus

Back 56

components of stay appartus:
1. patellar lock
2. reciprocal apparatus
3. LDE m tendon
4. extensor slips of interosseus m
5. interosseus m
6. DDF tendon
7. accessory ligament of DDF
8. SDF tendon
9. straight and oblique _