The Equine Distal Limb Flashcards
canon bone aka?
metacarpal/metatarsal bone III
long pastern aka?
proximal phalanx
short pastern aka?
middle phalanx
navicular aka?
distal sesamoid bone
pedal bone aka?
coffin or distal phalanx
there are distal sesamoid bones and?
proximal sesamoid bones
what joints are found in the distal limb of horse?
MCP/MTP
PIP
DIP
MCP/MTP/fetlock joint?
metacarpophalangeal/metatarsaophalangeal joint
PIP joint?
Proximal interphalangeal joint aka
pastern joint
DIP joint?
distal interphalangeal joint; coffin joint
five parts of the hoof dermis?
perioplic
coronary
lamellar
solar
frog
dermis =
corium
subcutis =
coronary cushion and digital cushion
what is the breakdown of the ligaments in horse distal limb?
collateral ligaments
palmar ligaments
sesamoidean ligaments
how can diagnosis be narrowed down to individual ligaments?
diagnostic perineural anaesthesia, ‘nerve blocking’
what are the two palmar ligaments?
palmar axial and abaxial ligaments (PIP)
what are the annular ligaments?
palmar (PAL) over MCP
proximal digital over prox P1
distal digital over distal P1
what do the palmar and annular ligaments do?
keep flexor tendons in place (retinaculum)
tendon sheaths pass deep to the annular ligaments
what are the proximal sesamoidean ligaments?
short
collateral
oblique
cruciate
intersesamoidean
straight
AND distal (navicular) sesamoidean ligaments as well
flexor tendons?
suspensory ligament (aka interosseus muscle)
superficial digital flexor tendon (SDFT)
(and its associated proximal check ligament)
Deep digital flexor tendon (DDFT)
(and its associated distal check ligament)
extensor tendons?
common and lateral digital extensor tendons
common inserts on extensor process of distal phalanx
suspensory ligament?
tendinous remnants of the interosseus muscle
palmar aspect MC3
originates from distal row of carpal bones and proximal MC
inserts upon abaxial aspect proximal sesamoids
extensor branches connect with common digital extensor
deep digital flexor tendon (DDFT)?
inserts upon palmar distal phalanx
passes over palmar aspect navicular bone
distal ‘check’ ligament anchor tendon to proximal MC bone
distal check ligament?
AKA the accessory ligament of the DDFT
attaches the DDFT to the palmar carpal ligament
Stiffens the tendon
Less tension is placed on the DDF muscle
Hindlimb equivalent is less developed
deep digital flexor tendon (DDFT)?
inserts upon palmar distal phalanx
passes over palmar aspect navicular bone
distal ‘check’ ligament anchors tendon to proximal MC bone
superficial digital flexor tendon (SDFT)?
closely associated with DDFT
inserts either side of proximal interphalangeal joint
flattens and wraps around the DDFT at level of prox. sesamoid bones - the manica flexoria
Divides and allows emergence of DDFT at mid-level of proximal phalanx
bursae and sheaths: cushions and sleaves?
a cavity lined with synovial membrane
either forms a cushion (A) or sleave (B)
Bursae of the distal limb?
navicular bursa on palmar aspect of navicular bone
others too but less significance
tendon sheath of distal limb?
DDFT/SDFT share the digital tendon sheath
digital sheath starts proximal to MCP, terminates mid-level of middle phalanx
Lubricate passage of tendons as they slide against neighbouring structures and against each other
potential site of damage and infection
what does the navicular apparatus consist of?
navicular bone
collateral sesamoidean (navicular) ligaments
Distal sesamoidean impar (navicular)
Navicular bursa
Deep digital flexor tendon (DDFT)
Distal digital annular ligament
functions of navicular apparatus?
navicular bone displaces DDFT away from DIP - increases leverage
Bursa cushions both the DDFT and the navicular bone
sensory innervation of palmar aspect of distal limb?
medial and lateral palmar nerves
alongside SDFT
branch at MCP into dorsal branches and palmar digital nerves
palmar metacarpal nerves - from deep branch of lateral palmar nerve
Palmar digital nerves: innervate heel of foot
sensory innervation of dorsal aspect of distal limb?
dorsal branches of digital nerves: innervate toe of foot
additional dorsal foot innervation in hindlimb by dorsal metatarsal nerves
what is diagnostic anaesthesia - ‘nerve blocking’?
used to locate a source of pain/lameness
sensory nerves are blocked in a distal to proximal direction until lameness disappears
what happens during diagnostic anaesthesia?
local anaesthesia injected close to nerve locations (perineural anaesthesia)
skin and deep tissues distal to the site will be desensitised
give examples of diagnostic anaesthesia?
palmar/plantar digital nerve block
abaxial sesamoid nerve block
low 4 point nerve block
what nerves are blocked during a palmar/plantar digital nerve block?
medial and lateral palmar/plantar digital nerves
which region of the foot will be blocked if the medial and lateral palmar/plantar digital nerves are blocked?
heel
if the medial and lateral palmar/plantar digital nerves are blocked, what will they block pain from?
from sole, navicular bone, palmar fractures of distal phalanx and bulbs
what nerves are blocked for an abaxial sesamoid nerve block?
medial and lateral palmar/plantar digital nerves + dorsal branches
which region of the foot will be blocked if the medial and lateral palmar/plantar digital nerves + dorsal branches are blocked?
whole hoof (up to coronary band)
what will the nerve blockage of medial and lateral palmar/plantar digital nerves + dorsal branches block pain from?
PIP, distal sesamoidean ligaments, toe, heel structures
what nerves are blocked during a low 4 point nerve block?
medial and lateral palmar/plantar metacarpal/metatarsal nerves
medial and lateral palmar/plantar nerves
during a low 4 point nerve block - which region of the foot will be blocked?
entire foot up to MCP/MTP
the low 4 point will block pain from?
all structures of the foot
SDFT/DDFT up to MCP
insertions of suspensory ligament
how do you diagnose pain in the toe region?
start off w/ digital nerve block - block out heel
abaxial sesamoid nerve block - now it’s blocked out as toe is now included in nerve block
we can tell it was toe as toe wasn’t covered in first one
suspensory ligament and check distal ligament are actually…
tendons (I think)
