Foot & Hoof Flashcards
What is the hoof a derivative of?
skin
What part of the hoof is epidermal and which is dermal?
Hoof capsule = epidermal; Corium = dermal
In the horse, what is the function of the digital cushion?
shock absorption
In the horse, what is the digital cushion made up of?
Collagen, fat, elastin fibers, cartilage
In the horse, where is the navicular bursa located?
Bt DDF tendon and the navicular bone
Why is the navicular bursa clinically relevant?
It is a high pressure area; anything causing inflammation here will cause great pain and can lead to lameness
What is the function of the impar and collateral ligaments?
Maintain positioning of the navicular bone
What does the navicular bone articulate with?
P2 and P3
In the horse, when viewing P3 from a proximal to distal view, what does it look like?
crescent-shaped
In the horse, when viewing P3 from a dorsal to palmar/plantar view, what does it look like?
triangle-shaped
What is at the apex of P3?
extensor process
What type of cartilage is the collateral cartilage of the foot?
hyaline-type
What happens to the collateral cartilage of the foot as the horse ages?
Becomes fibrous and can become ossified
What is the collateral cartilage called once it becomes ossified, and what is the clinical relevance of this?
side bone; pathologic, can cause a lot of pain and is palpable in a standing horse
Where is the collateral cartilage located in relation to the hoof capsule?
It extends proximal to the hoof capsule
What are the 2 venous plexi associated with the foot of the horse?
coronary plexus (smaller and more lateral) and palmar/plantar plexus (laager and more medial)
What connects the venous plexi in the horse foot together?
veins that pass through the collateral cartilage
What is special about the veins of the distal limb of the horse?
They lack valves, allowing blood to go whatever way it needs to
What is the primary hoof function (both epidermal and dermal parts)?
To transfer ground-reaction loads to the bony skeleton
What is the required criteria for the epidermal part of the hoof in order to properly perform its function?
- Has to be able to wear
- Has to resist cracks
- Has to be compliant
Why does the epidermal part of the hoof have to be compliant?
It helps the hoof capsule to exapand and contract with each limb cycle
What is the moisture content of the caudal part of the horse hoof and what does it allow for?
high moisture; allows for compliance
What are the main epidermal components of the hoof?
- Perioplic sulcus
- Coronary sulcus
- Stratum medium
- Stratum internum
- White line
- Sole
- Frog stay
What are the main dermal components of the hoof?
- Perioplic corium
- Coronary corium
- Laminar corium
- Solar corium
- Corium of the frog
What is another name for the dermal part of the hoof?
corium
What does the perioplic corium correspond to?
perioplic sulcus
What does the coronary corium correspond to?
coronary sulcus
What does the laminar corium correspond to?
stratum internum
What does the solar corium correspond to?
sole
What does the frog corium correspond to?
frog stay
What characteristic of the coffin bone allows it to carry many blood vessels?
It is very porous with many foramina
How many foramina do most coffin bones have?
> 200
What type of fibers pass from the dermal part to P3?
collagen
What is poorly developed in P3?
periosteum
Where does the dermal hoof lie?
Over the collateral cartilage
What is the hoof wall?
The part of the hoof you see when you are looking at it
How many layers does the hoof wall have and what are they called?
3; external layer, middle layer, internal layer/stratum internum
What is another name for the external layer of the hoof wall?
periople
What is another name for the middle layer of the hoof wall?
coronary horn
What is another name for the internal layer of the hoof wall?
stratum internum or parietal horn
What layer of the hoof wall is incomplete?
external
How far down the hoof wall does the external layer extend?
proximal 1/3
What is the external layer of the hoof wall high in?
high lipid content - helps slow the drying process of the remaining parts of the wall
What is the thickest layer of the hoof wall?
middle (coronary horn)
What is the external layer of the hoof wall derived from?
perioplic corium
What is the middle layer of the hoof wall derived from?
coronary corium
What is the internal layer of the hoof wall derived from?
laminar corium
What are the 4 main parts of the hoof capsule?
wall, sole, frog, bulb
What is the white line?
Non-pigmented area of the hoof that marks the junction bt the hoof wall and the sole
(it is a weak spot, seen when cutting hoof down)
What is the bar?
Where the hoof wall reflects on itself
Which way does the frog project?
cranially
What are the grooves of the frog?
2 paracuneal grooves, 1 central groove
What is the sole?
Everything bt the frog and the wall
What part of the hoof carries the majority of the horse’s body weight?
the wall (stratum internum)
What major thing happens at the coronary region?
Wall of the hoof is being formed
In what direction does the hoof wall grow?
From the coronary region down to the ground where it gets worn
How much new hoof is produced each month on average?
~6mm
What is the most substantial part of the hoof wall?
stratum medium
What projects from the coronary corium?
coronary papillae
What are coronary papillae?
Tiny hair-like structures that fit into sockets within the epidermis
How often does the germative cell of the stratum medium divide?
Every 8 hours
What is the tubular hoof?
Part of the stratum medium that corresponds to papillae fitting into sockets
What is the intertubular hoof?
Part of the stratum medium that isn’t associated with papillae
Which surface of the hoof wall has horn tubules that are more closely packed?
external surface
What are the lines that can be seen on the external hoof wall?
horn tubules
In the horse, how is P3 related to the inner surface of the hoof wall and what is the clinical relevance?
It is suspended from the hoof wall; reason that the coffin bone moves in a ventral direction during laminitis
What side of the hoof wall are blood vessels located?
dermal side
Where can you find primary dermal laminae?
Inner hoof wall extending from the dermal side, interdigitating with primary epidermal laminae
Where can you find primary epidermal laminae?
Inner hoof wall extending from the epidermal side, interdigitating with primary dermal laminae
Where can you find secondary epidermal and dermal laminae?
Interdigitating bt primary dermal and primary epidermal laminae
What type of cells can be found in the secondary laminae and what happens during laminitis?
Basal cells that maintain contact with the basement membrane; during laminitis the cells lose contact with the basement membrane and P3 is no longer suspended from the hoof capsule
How many primary laminae does the horse have?
550-600
How many secondary laminae does each primary laminae have?
150-200
Why does the horse have so many (secondary) laminae?
Increased surface area to assist with shock absorption; especially helpful when horse is at a gallop and only one foot is touching the ground
How much surface area does the horse end up with within the hoof capsule as a result of having a lot of laminae?
1 square meter
What is the purpose of the arteriovenous shunt in the laminar microcirculation?
Allows animal to warm the distal limb in the winter time by shunting blood directly from venous to arterial side
What species other than large animals takes advantage of the AV shunt in their legs?
birds
What is the perinychium?
Soft covering over hoof of newborn foal, present to help buffer blows that the fetus can deliver to the mother
How do you know when a newborn foal has walked?
The perinychium has worn away
At what age should the foal be able to fill the mother’s shoe?
18 months
What does the rmt lack in its hoof that the horse has?
frog and bar
Where is the sole of the rmt hoof?
Confined in bt the axial and abaxial parts of the wall
What are characteristics of the bulbar epidermis of the rmt?
Very loosely organized, easy to dig out (flaky), and is susceptible to infection
What is the thickest part of the rmt hoof?
Stratum medium from the coronary cornium
Which type of laminae does the rmt have?
Only primary
How many primary laminae does the rmt have within the hoof capsule and how does it overcome this?
Up to 1300; does not get enough surface area but overcomes this because rmt carries its weight differently than the horse
What is the weight bearing surface of the rmt digits?
More lateral = more weight-bearing (@ sole and bulb)
