footpads, claws, hooves, horns and antlers Flashcards
week 2 lect 3 Basu
what anchors the subcutis to the skeleton?
ligaments
what sweat glands do the footpads have?
eccrine sweat glands
what do the sweat glands in the footpads do?
gives footpads increased grip - the moisture increases friction
link between nails, claws and hooves?
homologous structures –> keratin
what is horn?
highly keratinised epidermis
how does horn grow?
grows from the epidermis at their base and gradually slides distally
transverse ridges on hoof
parallel with the ground
epidermal structure?
nail, hoof, claw
ridges in nails?
interdigitations of laminae
quick (pink bit) of the claw
the dermis - do not cut here when trimming nails
what keeps the claws retracted in cats?
elastic dorsal elastic ligaments
which is the only weight-bearing digit in horses?
digit III
What are the five parts of the dermis of the hoof?
perioplic
coronary
lamellar
solar
frog
in a hoof - what is the subcutis confined to?
the coronary cushion
the digital cushion
dermal segment supports the…
epidermal segment
what are the three layers of the hoof wall?
external layer - stratum externum
middle layer - stratum medium
internal layer - stratum internum
which is the thickest layer of the hoof?
the middle layer - stratum medium
what are cervids?
deer
what are horns seen in?
BOVIDS - cattle, sheep, antelope
whereas antlers are seen in?
CERVIDS - deer
where do antlers grow from?
they grow out from an attachment on the skull - the pedicle
where do horns grown from?
horn bud starts out in the subcutis and LATER fuses to the skull
horn fracture complication?
infection in the sinuses as the horn has sinuses that goes directly into frontal bone of skull
what does the number of digital pads represent?
the number of digits
what are footpads named after?
the underlying region e.g. metatarsal pad, carpal pad
digital footpads in dogs, cats etc. is homologous with what in ruminants and pigs?
bulb
digital footpads in dogs, cats etc. is homologous with what in horses?
frog
what other pads do horses have?
metacarpal/metatarsal pads and carpal/tarsal pads
what are metacarpal/metatarsal footpads called?
ergots
what are carpal/tarsal footpads called?
chestnuts
what are foot pads? describe their structure:
thick epidermis
thick subcutis
describe the subcutis found in footpads:
adipose tissue partitioned by collagen and elastic fibres
what do footpads function as?
shock absorbers
what are footpads known as in hooved animals:
digital cushions
describe footpads in terms of hair:
hairless
what characteristic of a foot pad protects the sensitive dermis from damage?
the thickly cornified epidermis (think - corneocytes)
footpads have an additional epidermal layer - name? and describe visibility:
stratum lucidum
sometimes visible
nails in primates - what are the homologous structures in carnivores/birds and ungulates?
claws in carnivores/birds
hooves in ungulates
3 functions of nails, claws and hooves:
protects the distal digit, scratching/digging etc, defence/hunting
what are the 3 similar components of the distal joints of primates, ungulates, carnivores, birds?
wall, sole, footpad
Describe the whereabouts of the wall, sole, footpad on humans:
wall - outer of the nail, and tip of the nail
sole - under the nail, where the footpad and wall meet
footpad - spongy part of finger (fingertip)
what is the footpad of a horse also known as?
the frog
describe the wall, sole and footpad whereabouts on a horse:
wall is the outer part enclosing the rest of the hoof
sole is underneath and connects the footpad to the wall.
the footpad is the base of the hoof (descriptive wise)
describe the epidermis of the nails/claws/hooves:
highly keratinised epidermis
what is highly keratinised epidermis called?
horn
how do nails/claws/hooves grow?
from epidermis at their base and gradually slide distally (as an animal is standing, growing towards ground)
What causes the ridges to appear in nails/claws/hooves? (look at your fingernail, you can see lines)
periods of disturbed growth - resulting in transverse ridges (which are parallel with the base/ground
what kind of structure is a nail/claw/hoof?
an epidermal structure
what anchors the nail/claw/hoof to the underlying dermis?
interdigitations of laminae
what is not present at the epidermal-dermal junction of a nail/claw/hoof?
there is no subcutis
what is the distal phalanx?
the bone of the finger/toe
what is the dermis closely adhered to?
the periosteum of distal phalanx (go over, slider 18 01/10/24)
THERE IS NO SUBCUTIS HERE
what is the ‘quick’?
the dermis - the pink bit of the nail
when trimming nails, what would cutting the ‘quick’ cause?
pain, and it would bleed
where is the muscle mass concentrated in the hooves of a horse?
proximally
describe the motion of a horses hoof:
protraction and retraction, literally just forwards and backwards
what does cursorial mean?
one that is adapted specifically to run
describe the venous return of blood for the hoof:
it is poor
if a horse damages one of its hooves, what happens?
it will really struggle, as a quarter of its bodyweight is supposed to be distributed through that hoof
what does squashing of digital cushion aid?
aids the blood return with each step - to help with the poor venous return of blood
What is the dermis of the hoof called?
the corium
what does the epidermal segment correspond to?
the dermal segment
what part of the dermis corresponds to the external layer of the hoof wall?
perioplic (dermal segment)
what part of the dermis corresponds to the middle layer of the hoof wall?
coronary (dermal segment)
what part of the dermis corresponds to the internal layer of the hoof wall?
laminar
what part of the dermis corresponds to the sole (epidermal segment)?
sole (dermal segment)
what part of the dermis corresponds to the frog (epidermal segment)?
frog (dermal segment)
what is the laminar (segment of dermis of hoof wall) also known as?
dermal laminae
what is the internal layer of the hoof wall (the epidermal segment) also known as?
epidermal laminae
describe the external layer of the hoof wall:
thin, glossy, produced by perioplic dermis
describe the middle layer of the hoof wall:
thickest layer of hoof wall, partially pigmented, produced by coronary dermis
describe the internal layer of the hoof wall:
produced by the lamellar dermis
where are there no blood vessels or nerves in the hoof wall and what does this mean?
none in the epidermis, all blood and nerve impulses come via diffusion from the dermis
describe horns strength: (in terms of the hoof wall)
strong with some elasticity
what is the travel time for the horn to go from top to bottom of the hoof? AT THE TOE, IN ADULT
9-12 months
what is the travel time for the horn to go from top to bottom of the hoof? AT HEEL
4-6 months
what have antlers?
cervids (deer)
what are ossicones found in?
giraffids
what are giraffids? give 2 examples:
giraffes, okapis
what are pronghorns found in?
antilocaprids
what are antlers and horns initially formed from?
from bony core which is covered by integument
where are antlers and horns located?
on the frontal bone of the skull
when growing - antlers are covered in?
well-vascularised skin
(in velvet)
when the antlers have finished growing, what happens and what is this stage called?
the blood supply to the skin is cut off and the velvet is shed
(in tatters)
what is mature antler?
exposed living bone
describe the cycle of antlers:
they are usually shed (cast) and re-grown every year, sometimes antlers grow bigger and more branched every year
what is the cycle of antlers related to?
sex hormones
Describe the growth of horns:
horn bud (starts off as soft tissue) starts out in the subcutis and later fuses to the skull
briefly describe the structure of the horn:
horns have a scabbard-like keratin covering a bony core
describe branching of horns:
not branched
do horns shed?
no
why can horns show rings/ridges?
horns grow with age
why do people sometimes choose to dehorn cattle?
reduce injury to people/other livestock
reduce space required (housing/feeding)
why is it better to ‘disbud’ as a calf?
horn bud starts out ‘floating’ in integument and LATER attaches to frontal bone
(better to do younger to reduced risk of infection of sinus as after 6 months, the frontal sinus starts extending into the horn’s bony core)
what happens to calf at 6 months - to do with their horn growth?
frontal sinus starts extending into horn’s bony core
what does horn fracture and dehorning of older animals risk?
risks sinus infection
need to watch vid for slides 24,25,26,27,28
What is the central sulcus?
The deep groove at the centre of the frog on the horses hoof
There are also lateral and medial sulcus
What is the bar on a horses hoof?
Where the hoof wall folds in on itself
There is a lateral and medial bar
What is the white line?
The continuation of the epidermal laminae, filled in with interlamellar horn. The white line isn’t always the palest structure, have a look at the adjacent hoof wall
What is the hoof wall?
the middle layer of the hoof wall (the stratum medium) may contain pigment, which is why some horses’ hooves are dark
What is the function of the grip?
The frog contains eccrine sweat glands so helps with a bit of grip
Compression of the frog when a horse walks will squash the digital cushion, in turn squeezing blood vessels in the hoof cartilages
What is the periople?
The slightly softer band of horn near the coronet
How does the calf or lamb’s hoof not damage the cow’s internal soft tissues during pregnancy?
The hoof is covered by a deciduous hoof capsule
This soft rubbery layer can be seen on newborn animal’s hooves (calves, piglets, lambs and foals). It protect’s the mother’s soft tissues and will wear off as the animal walks.
How many digits do cattle have? Weight bearing and non weight bearing?
Cattle have 2 weightbearing digits, however also have 2 additional non-weightbearing digits either side.
From medial to lateral, they are numbered II - V.
II and V are called dewclaws, III is the medial claw, IV is the lateral claw.
7 differences between horns and antlers?
- Horns develop in subcutis,
- horns covered in keratin sheath,
- horns never shed,
- different species (horns bovids),
- horns can have ridges,
- horns have no branches,
- horn core contains frontal sinus (cows)
7 similarities between antlers and horns?
- Initially covered in epidermis,
- contain bone,
- located on frontal bone,
- paired,
- bigger/present more in males,
- similar functions (defence, display),
- get bigger with age
