The Equine Distal Limb Flashcards
distal limb
part of the limb distal to the carpus or tarsus
digit
region distal to the fetlock
pastern
region between fetlock and foot
foot
region distal to coronary band
hoof
epidermal structures only
bony structures of the distal limb
metacarpus/metatarsus, proximal phalanx, middle phalanx, distal phalanx, proximal sesamoid bones, distal sesamoid bone
metacarpus/ metatarsus
Metacarpal bone 2= medial splint
Metacarpal bone 3= cannon bone
Metacarpal bone 4= lateral splint
proximal phalanx
P1= long pastern
middle phalanx
P2
distal phalanx
P3= coffin bone
proximal sesamoid bones
2; on palmar surface behind ankle joint
distal sesamoid bone
1; navicular bone
soft tissue structures of distal limb
- Flexor tendons (SDFT,DDFT)
- Interosseous (suspensory ligament)
- Check ligament of DDFT
- Collateral ligaments
- Digital extensor tendon
- Impar ligament
- Collateral sesamoidean ligaments
- Distal sesamoidean ligaments
- Palmar ligament of fetlock joint (and others…)
- Annular ligament (multiple components)
Check ligament of the DDFT
comes off palmar aspect of cannon bone in middle of cannon bone?
collateral ligaments
on either side of joints; md and lateral; there will be one to stabilize each joint of the digit
digital extensor tendon
- forelimb has common (ends on P3, attaches to P1, P2, P3) and lateral (ends on P1)
- Pelvic limb has combined long / lateral which come together and attach to P1, P2, P3
impar ligament
runs between navicular bone and P3
collateral sesamoidean ligaments
blend with collateral ligaments of pastern
distal sesamoidean ligaments
x, y, zs; oblique sesamoidean ligaments (on sides), straight sesamoidean ligament (one in middle of obliques), cruciate sesamoidean ligaments (x, deep)
annular ligament
has multiple components,
- thickening of deep fascia
- palmar annular ligament
- proximal digital annular ligament
- distal digital annular ligament
palmar ligaments of fetlock
on back of and between proximal sesamoid bones
synovial structures of distal limb
- metacarpophalangeal joint
- proximal interphalangeal joint
- distal interphalangeal joint
- navicular bursa
- digital tendon sheath
metacarpophalangeal joint
ankel/ fetlock joint; has dorsal and palmar/ plantar pouches
proximal interphalangeal joint
pastern joint, has dorsal and palmar/ plantar pouches
distal interphalangeal joint
coffin joint; has dorsal and palmar/ plantar pouches
navicular bursa
formed between DDFT and navicular bone
digital tendon sheath
envelopes superficial and deep digital flexor tendons; deep to annular ligaments
palmar annular ligament
- annular ligament of the fetlock joint
- found on palmar aspect and attaches to proximal sesamoid bones
proximal digital annular ligament
- forms an x shape along the palmar aspect of the pastern and attaches to proximal and distal collateral tubercles of P1
- distal attachment is shared with SDFT
distal digital annular ligament
- runs over palmar surface of DDFT as tendon continues to attach to palmar aspect P3
- distal annular ligament attaches on distal aspect P1 medially and laterally
regions of equine foot
- wall (includes toe, quarters, heels)
- sole
- frog
- bulb
epidermal components of foot
- status externum
- stratum medium
- stratum internum
- Hoof is epidermal structures of foot only**
stratum externum
- periople proximally
- thin layer of glossy horn distally
- outermost layer
stratum medium
- thickest part of hoof wall (Bulk of wall)
- tends to be pigmented
- composed of horn tubules
stratum internum
- horny (epidermal or insensitive) laminae (non-pigmented)
- the horny laminae will interdigitate with dermal (sensitive) laminae
Dermal (Corium) components of foot
- perioploic dermis
- coronary dermis
- laminar dermis
- dermis of sole
- dermis of the frog
perioploic dermis
proximal
coronary dermis
bulges out
laminar dermis
longest; these get inflamed in laminitis
- this is also called dermal (sensitive laminae)
- the dermal laminae will interdigitate with horny laminae
horn tubules
- located in stratum medium layer of epidermis
- arise from region of coronary dermis and run parallel to hoof wall
- germinal layer of epidermis that overlies coronary dermis produces the horn tubules
intertubular horn
- produced by additional germinative epidermis proximally and contributes to filling the space around and between horn tunnels and interdigitation of dermal and epidermal laminae
proximally muscles of hindlimb innervated by
- obturator
- femoral nerve
- cr gluteal nerve
- cd gluteal nerve
- sciatic nerves
proximal to stifle sciatic nerve
splits into common peroneal (fibular) and tibial nerves
common peroneal (fibular) nerve continues down limb and _________ proximal to tarsus
divides into superficial an deep peroneal branches
deep peroneal branches
into medial and lateral dorsal metatarsal nerves
medial and lateral dorsal metatarsal nerves
provide innervation to dorsal aspect of limb to at least as far distal as the fetlock and potentially as far as the coronet
tibial nerve splits
to medial and lateral plantar nerve
lateral plantar nerve gives off
deep branch
deep branch of lateral plantar nerve gives off
medial and lateral plantar metatarsal nerves
medial and lateral plantar metatarsal nerve innervation continues
to level of fetlock
medial and lateral plantar nerves continue to digit as
medial and lateral plantar digital nerves
proximally muscles of forelimb are innervated by what nerves
- subscapluar
- suprascapular
- axillary
- musculocutaneous
- radial
- median
- ulnar
median nerve in distal limb
splits to form medial and lateral palmar nerves
palmar branch of ulnar nerve
blends with lateral palmer nerve
lateral palmar nerve gives off
deep branch
deep branch of lateral palmar nerve
divides into medial and lateral palmar metacarpal nerves
medial and lateral palmar nerves continue to digit as
medial and lateral palmar digital nerves
what is the reason for the ring block in the hind limb vs the high and low 4 point block in the forelimb
medial and lateral dorsal metatarsal nerves
Peri-neural anestesia
- Palmar Digital Nerve Block
- Abaxial Sesamoid Nerve Block
- Low 4 Point Nerve Block
- High 4 Point Nerve Block
For all 4 of these:
- clean preparation
- aim for superficial injections w/ in SQ tissue
- Aspirate to make sure you don’t get blood
- work distal to proximal
Palmar digital nerve block regions desensitized
- heel
- navicular bone and associated ligaments ie
2a. impair ligament
2b. sesamoid ligaments - coffin bone
3a. and collateral ligaments - Wings of coffin bone
- Portion of lamina
- Portion of coffin jt (potentially)
- Distal part of DDFT that attaches to P3
- Potentially could partially block pastern joint or totally block pastern jt (depending on amount of anesthetic injected)
Palmar digital nerve blocks what nerve
palmar digital nerve
Palmar digital nerve block needle location
needle inserted directly over the palpable neurovascular bundle located about 1cm proximal to cartilage of the foot; do this on medial and lateral side
Abaxial sesamoid nerve block regions desensitized
- distal sesamoidean ligaments
- distal DDFT
- distal SDFT
- Pastern Jt
- Pastern Bone
- Coffin Jt
- All lamina
- Collateral ligaments of pastern joint
- Annular ligament (proximal and distal)
* to test if this block has set in test D aspect of coronet
nerves blocked in abaxial sesamoid nerve block
palmar digital neve (at level of fetlock)
* this type of block may also be called basisesamoid block*
where is needle placed in abaxial sesamoid nerve block
base of proximal sesamoid bones over neurovascular bundle
Low 4 point nerve block regions desensitized
- Fetlock jt
- collateral ligaments
- distal suspensory ligament
- sesamoid bones
- intersesamoidean ligament
- DDFT
- SDFT
Low 4 point nerve block nerves blocked
palmar metacarpal nerves; * in hind limb do low 6 bc of medial and lateral dorsal metatarsal nerves*
Low 4 point nerve block needle location
between suspensory and flexor tendons at level of metacarpus
High 4 point nerve block regions desensitized
DDFT, SDFT, suspensory ligament, distal check ligament of DDFT, cannon bone
High 4 point nerve block nerves blocked
palmar metacarpal nerves
* in hind limb do low 6 bc of medial and lateral dorsal metatarsal nerves*
high 4 point nerve block needle location
between flexor tendons and suspensory just axial to splint (distal to level of carpometacarpal joint)
intra-articular anesthesia
can put anesthesia in limb joints
why go IA
- medicate
- establish communication with a wound
- obtain sample of fluid for analysis
- intra-articular antestesia to establish source of horse’s lameness
pouches of fetlock, pastern, and coffin joints
have dorsal and palmar (plantar) pouches both of which can be accessed clinically
when inject coffin joint will
- access dorsal pouch medial or lateral to tendon of common digital extensor
pastern jt access
- dorsal pouch is easiest point of access
- medial or lateral to tendon of common digital extensor
what is desensitized when injecting coffin joint with IA anestesia
will numb coffin joint and associated soft tissue structures +/- navicular bone and bursa and associated soft tissue structures
pastern joint palmar/ plantar pouch
- close to region of PD nerve block
structures desenstized by IA anesthesia into pastern joint
- pastern joint and associated soft tissue structures
equine metacarpo/metatarsophalangeal joint; dorsal pouch
medial or lateral to tendon of common digital extensor
equine metacarpo/metatarsophalangeal joint palmar pouch
cranial to dorsal edge of lateral suspensory branch, cd to distal cannon bone, distal to distal end of the lateral splint
structures desensitized by IA anesthesia in metacarpo/metatarsophalangeal joints
fetlock joint and associated soft tissue structures
joints of the pelvic limb
- hip
- stifle
a. femoropatellar
b. medial and lateral femorotibial - tarsal joints
a. tarsocrural
b. tarsocalcaneal
c. proximal and distal intertarsal
d. tarsometatarsal - fetlock
- pastern
- coffin
tendon sheaths of pelvic limb
- tarsal canal (branch of DDFT)
- Extensor tendon sheaths
- Digital tendon sheaths
Bursa of pelvic limb
- trochanteric bursa
- calcanean bursa
- navicular bursa
pelvic limb joints
- shoulder
- elbow
- carpal joints
a. radiocarpal
b. middle carpal
c. carpometacarpal - fetlock
- pastern
- coffin
pelvic limb tendon sheaths
- carpal canal
- extensor tendon sheaths
- digital tendon sheath
pelvic limb bursa
- infraspinatus bursa
- bicipital bursa
- bursa associated with corachobrachialis
- navicular bursa
