Equine Flashcards
What are the main components of the horse foot?
bones
distal interphalangeal joint
medial & lateral hoof cartilages
extensor & flexor tendons, BV, nerves
List the bones of the foot.
distal phalanx
distal part of middle phalanx
navicular bone
Draw & label a schematic of an equine hoof.
add photo
Describe the hoof wall.
highest @ toe
thickest @ toe
Describe the periople.
external layer of hoof
thin soft horn near coronet
joins skin @ coronary band
Describe the sole.
ventral - between wall & bars
concave
3-4mm @ circumference is weight bearing
slightly flexible
Describe the white line.
junction between wall & sole
thin, soft, light horn
Describe the frog.
limited weight bearing
heel expansion & shock absorption
has central groove & collateral sulci
Describe the distal phalanx.
P3/pedal bone
interior of hoof capsule, suspended by interlocking laminae
palmar is concave
Describe the middle phalanx.
P2
articulates with P3 = coffin joint
Describe the navicular bone.
sesamoid
attached to P1 w/ navicular suspensory ligament & collateral sesamoidean ligaments
Describe the coffin joint.
dorsal & palmar pouches
between P2, P3, navicular bone
Describe the tendons & ligaments of the hoof.
deep digital flexor tendon
inserts on palmar surface of distal phalanx
common digital extensor tendon
inserts on extensor process of P3
Describe the digital seasamoidean ligament.
connects navicular bone & P3
Describe the navicular suspensory ligament.
suspend navicular bone from P1
Describe the vascular supply to the hoof.
medial & lateral digital arteries (accompanied w/ viens) -> artery of distal cushion, coronal artery, artery of hoof wall, artery of coffin bone
Describe the nerve supply to the hoof.
all arise from lateral & medial digital nerves
Describe the histology of the hoof wall.
stratum externum: originates from periople, thin horn
stratum medium: supportive, rods of horn parallel to surface, produced by stratum basale & spinosum @ coronary groove
stratum internal: keratinized primary laminae & secondary laminae (interdigitate with laminae from corium)
Describe the corium.
dermis equivalent of hoof
collagen
vascularized & innervated
Describe the growth cycle of an equine hoof.
grows 6-7mm/month
full cycle = 6-12m
constant wear & exfoliation
What is the hoof growth cycle influenced by?
heredity
diet
environment (avoid extreme dry/damp & ammonia)
farriery
Describe a new born foal foot.
capped with soft unpigmented hoof
reduces damage to uterus
shed
What is the normal hoof conformation?
dorsal hoof wall parallel to pastern axis
(HPA - hoof/pastern axis)
low angle = broken back
high angle = broken forward
What is the main function of the forelimb?
weight bearing (60%) shock absorption
What is unique about the ulna in a horse?
fused to radius in adulthood
List extensor tendons of the metacarpus.
Extensor carpi radialis (ECR)
Common digital extensor tendon (CDE)
Lateral digital extensor tendon (LDE)
List the flexor tendons of the metacarpus.
Superficial digital flexor tendon (SDFT)
Accessory ligament of the SDFT (ALSDFT) “superior check ligament” proximal to the carpus
Deep digital flexor tendon (DDFT)
Accessory ligament of the DDFT (ALDDFT) “inferior check ligament”
Suspensory ligament (SL)
List the ligaments of the metacarpus.
collateral ligaments
ligaments of the proximal sesamoid bones
ligaments of the navicular bone and ungular cartilage
Describe the suspensory ligament (metacarpal).
2 lobes with central fat-muscle bundle
prevents overextension of fetlock
Describe the accessory ligament of the deep digital flexor tendon.
metacarpal
continuation of the palmar carpal ligament
fuses with DDFT
prevents overextension
Describe the deep digital flexor tendon.
metacarpal
passes over nivicular bone
inserts @ P3
Describe the superficial digital flexor tendon.
metacarpal
emerges from carpal canal, then sub-q
splits at P1 to medial & lateral
inserts @ middle sputum on P2
Describe the palmar annular ligament.
metacarpal
palmar @ fetlock
maintain SDFT & DDFT, resist abaxial movement of sesamoids
inserts on palmar aspects of proximal sesamoids
Describe the navicular bursa.
forelimb
between flexor surface of navicular bone & dorsal border of DDFT
List the nerves of the forelimb.
brachial plexus ulnar nerve median nerve musculocutaneus nerve radial nerve
Describe the innervation of the distal forelimb.
palmar metacarpal nerves
palmar nerves
palmar digital nerves
Describe the stay apparatus.
Medial patellar ligament locks over trochlear ridge of the femur = Fixation of the stifle
Reciprocal apparatus ensures hock and stifle locked in unison = fixation of hock
Suspensory and sesamoid ligaments, flexor tendons and accessory ligament = Fixation of the fetlock and phalanges
List the equine vertebral equation.
C7, T18, L6, S5, Cd15-21
List the flexor muscles of the neck. (superficial)
sternocephalic
brachiocephalic
List the extensor muscles of the neck. (superficial)
rhomboid
trapezious
Splenius
cervical serratus
What is the function of the nuchal ligament?
support weight of head & neck
conserve elastic energy when head lowered to assist raising head
List the deep muscles of the neck.
flexor: long muscle of head long muscle of neck scalenus extensor: semispinalis capitis longest muscle of head
Describe lordosis.
Downward deviation of lumbar & distal
thoracic spine giving horse a dipped
back appearance
Describe scoliosis.
Lateral deviation of parts
of the spinal column
Describe kyphosis.
Upward deviation of spine giving horse
a hunched, camel-like appearance
Describe the sacrum in a horse.
5 vertebra
fused by 5y old
soft tissue structures replace foraminae
What’s special about the synovial sacroiliac joint?
different cartilages for each surface of the synovial joint
sacral - hyaline
ilial - fibrocartilage
Describe the effects of raising the neck.
cervicothoracic extension
relaxes the ligaments, brings the spinous processes back together and extends the thoracic spine
Describe the effects of lowering the neck.
ligaments
under tension, separates the thoracic
spinous processes and flexes
the thoracic spine
How is the back extended?
T-L and L-S extension
achieved by longissimus
& spinalis & multifidus
L-S extension Middle gluteal
How is the back flexed?
T-L and L-S contraction of rectus & internal oblique
L-S flexion contraction
of psoas major & minor
How is the back flexed laterally?
unilateral contraction of:
iliocostal
longissimus
oblique abdominal
How do you know a horse has back pain?
resists flexion of back
pain on palpation
Where can you collect CSF?
atlantooccipital space
lumbosacral space
