Bones and Joints of Equine Distal Limb Q's Flashcards
what are the components of the carpus
proximal row: radial carpal bone (RCB), intermediate carpal bone (ICB), ulnar carpal bone (UCB), accessory carpal bone (ACB) distal row: 1st, 2nd, 3rd, 4th carpal bone
what are the differences in the equine carpus
3rd CB largest 1st CB absent
what are the differences in the canine carpus
radial and intermediate CBs are fused
how many centres of ossification does the carpus develop from
one centre
which carpal bones develop from more than 1 centre of ossification
accessory carpal bone (2) and the fused radio-intermediate CB in dog and cat (2)
what are the intercarpal joint spaces (3)
- antebrachio-carpal joint 2. middle carpal joint 3. carpo-metacarpal joint
what is the antebrachio-carpal joint composed of
antebrachium + proximal row of carpal bones *most movement
what is the middle carpal joint composed of
proximal + distal rows of carpal bones
what is the carpo-metacarpal joint composed of
distal row + metacarpal bones *least movement
what type of joints are intracarpal joints
fibrous joints held tightly
how is the carpus joint stabilized (3)
- collateral ligaments 2. cartilage plate on palmar aspect of joint capsule 3. retinaculum
what is the function of the accessory carpal bone
- lever for distal limb 2. insertion of major carpal flexor muscles
what is the function of the palmar ligament
stabilizes ACB flexion
how many digits to dogs and cats have
shed 1st digit for speed
how many digits do unguligrades have
shed more for speed
how many digits do artyrodactyla
ruminants an even number –> 3rd and 4th digits remain
which digit remain in perissodactyla
equines have the 3rd digit
what are the 3 types of stances
- plantegrade (rabbits, bears, humans) –> bear weight on digits + metatarsals + tarsal bones 2. digitigrade (dogs, cats) –> bear weight on digits/phalanges protected by foot pads 3. unguligrade (ruminant, horses) –> bear weight on distal phalanx only, protected by hoof
how many centres of ossification are in the distal limb bones
2 centres except the distal phalanx has 1
what are the metacarpal bones in the horse
3rd metacarpal/metarsal bone = cannon bone 2nd
and 4th MC/MT = splint bones
what are the features of the 3rd metacarpal/metatarsal bone
weight bearing distal articular surface –> sagittal ridge
what are the features of the 2nd and 4th MC/MT bone
vestigial/non weight bearing button at distal end (palpable)
where are the proximal sesamoid bones in the horse
palmaro-distal to every MC3/MT3 paired
what is the function of the proximal sesamoid bones
protect the SDFT, DDFT embedded in suspensory ligament
where are the dorsal sesamoid bones in the dog
single dorsal aspect of MCP/MTP joint
what are the functions of dorsal sesamoid bones in the dog
embedded in and protect extensor tendons
where is the proximal phalanx
long pastern bone/P1
what are the features of the proximal phalanx
raised V on palmar surface
what is the ligament attached to the proximal phalanx
oblique distal sesamoidean ligament
how many grooves are on the proximal phalanx
2 sagittal grooves
what are the components of the metacarpo-phalangeal (MCP)/metatarsal-phalangeal (MTP) joint
- 3rd metacarpal/metatarsal bone 2. proximal phalanx 3. proximal sesamoid bones
what are the functions of the palmar and dorsal pouch in the MCP/MTP joint
palmar pouch incorporates proximal sesamoids dorsal pouch cushions extensor tendons
how is the MCP/MTP joint stabilized
- collateral ligaments 2. sagittal ride/groove
what is the movement of the MCP/MTP
limited to flexion and extension high motion joint **very large articular surface + joint capsule
where does the suspensory ligament originate
proximal palmar MC3/MT3
where does the suspensory ligament run
fills area between splint bones and divides into two –> attaches to abaxial aspect of proximal sesamoids passes to dorsal aspect limb
what does the suspensory ligament fuse to
fuses with common digital extensor tendon
what is the function of the suspensory ligament
acts like a sling returns joint to resting position relies on stability of proximal sesamoids
what is the function of the sesamoidean ligaments
stability of proximal sesamoids
what are the sesamoidean ligaments (3)
- inter-sesamoidean ligament
- collateral sesamoidean ligaments (medial and lateral)
- distal sesamoidean ligament –> 1. cruciate 2. short 3. oblique ligament 4. straight ligament
where is the inter-sesamoidean ligament
fibrocartilage plate between proximal sesamoid bones
what is the function of the inter-sesamoidean ligament
smooth passage of DDFT and SDFT
where is the collateral sesamoidean ligaments
proximal sesamoids to MC/MT 3 and PP
medial & lateral
what are the distal sesamoidean ligaments
- cruciate - PP
- short - PP
- oblique ligament - PP (v-shaped through on PP)
- straight ligament - MP
what is the suspensory apparatus composed of (4)
- suspensory ligament
- proximal sesamoids
- sesamoidean ligaments
- common digital extensor tendon
what is the middle phalanx (MP) bone
short pastern bone/P2
where is the sagittal ridge in the middle phalanx
proximal
where is the sagittal groove in the middle phalanx
distal
what are the components of the proximal interphalangeal joint (PIP)
proximal and middle phalanges
what are the features of the PIP joint
typical synovial joint extensive joint capsule
what does the PIP form
dorsal bursa to cushion the extensor tendon
what stabilizes the PIP joint
collateral ligaments
what is another name for the distal phalanx
DP pedal bone/P3
what is the function of the extensor process on the distal phalanx
attachment of the common digital extensor tendon (CDE)
what is the function of the palmar process
support lateral cartilages
what attaches onto the solar surface of the distal phalanx
attachment of deep digital flexor tendon (DDFT)
what are the features of the distal phalanx
striations for hoof attachment and vascular channels for blood vessels
where is the distal interphalangeal joint (DIP)
coffin joint is buried within the hoof
what are the components of the DIP joint
- middle and distal phalanges 2. distal sesamoid (navicular bone) and distal phalanx 3. distal sesamoid and middle phalanx
how is the DIP stabilized
collateral ligaments
what movement is in the DIP
flexion and extension some rotation to accommodate uneven ground
what is the distal sesamoid
navicular bone
how many articular surfaces are on the navicular bone
2 smooth articular surfaces with a cancellous centre with vascular channels
what is the function of the navicular/podotrochlear bursa
fluid filled pocket between distal sesamoid and DDFT acts to cushion DDFT
how is the navicular bursa separated from the joint space
separated by impar ligament
what are the functions of the ungual process, ungual crest, extensor process and palmar process in the distal phalanx of a carnivore
ungual process - supports claw
ungual crest - vascular root of claw
extensor process - extensor tendons
palmar process - flexor tendons
identify the structures of the equine distal limb
identify the structures of the equine distal limb
identify the distal structures of the canine paw
identify the distal limb structures
identify the sesamoidean ligaments
- intersesamoidean ligament
- collateral sesamoidean ligaments
- distal sesamoidean ligaments –> 1. cruciate 2. short 3. oblique ligament 4. straight ligament
identify the sesamoidean ligaments
A. intersesamoidean ligament
B. collateral sesamoidean ligaments (medial and lateral)
C. distal sesamoidean ligaments
C1. cruciate
C2. short
C3. oblique ligament
C4. straight ligament
identify the structures of the dorsopalmar radiographs of hoof and the palmar and dorsal surfaces of the distal phalanx
identify the structures of the navicular bone (distal sesamoid)
