Anatomy 2 - Equine Foot

drraythe's version from 2015-06-05 22:54


Question Answer
what constitutes the equine "foot"? (3)(1) outer= epidermis= the hoof. insensitive stratum corneum (2) middle=dermis= soft, sensitive. stratum germinativum+dermis. (3) deep=SQ tissue. Digital and coronary cushions.
what is included in the SQ tissue of the foot? what are the similarities and differences between limbs? what are the cartilages?contains the ligs, bones of the coffin joint, BVs, NN, flexor/extensor tendons. Between limbs are same features (just palmar instead of plantar, common digital extensor to long digital extensor) and the Ungual cartilages (lateral cartilages)
what is pyramidal disease?a ringbone (bone growth in the pastern or coffin joint of a horse, can make a ring around the joint) condition of the extensor (pyramidal) process of the distal phalanx
what is sidebone?ossified and rigid ungual cartilages of the distal phalanx (attached to the palmar process of the phalanx) normally hyaline cartilage in young but fibrocartilaginous in adults.
what is quittor?a suppurative (puss) and degenerative condition of the cartilages
what is the wall of the foot? what are the parts of it?the wall is the part that is visible when the foot is on the ground. the junction between it and the skin is the CORONET and the part on the ground is the BASAL BORDER
what are the three main topographical regions of the wall?toe, quarters (sides) and the heel [see pic]
explain what the bars of the wall are, and the two other structures associated with them.wall reflected at heels to form bars (like the outer ridges of the frog), separated from the frog (wedge-shaped thing) by the paracuneal grooves
where is the wall of the hoof the thickest? thinnest?thickest at the toe, thins progressively heel-ward
which quarter (side part of the wall) (L or M) is thicker?lateral is thicker
the angle between the dorsal surface of the wall of the hoof and the ground is? (fore vs hind)45-50* forefoot and 50-55* hindfoot
describe how the substance of the wall is composedtubules extending proximo-distally and held together by amorphous intertubular horny material
what are the three main layers of the wall?(1) stratum externum (2) stratum medium (3) stratum internum
explain the parts and composition of the stratum externum.a very thin, tubular horny covering with two parts: (1) PERIOPLE, the proximal, soft, non-pigmented part which expands caudally over the bulbs of the heel. (2) distal to periople is the STRATUM TECTORIUM which is relatively impervious to H2O, smooth, glossy.
what do the parallel, proximo-distal lines of the stratum tectorium indicate? how about the horizontal, smooth ridges?prox-dist lines= evidence of direction of growth of horny tubules. Horiz= evidence of variations in growth of hoof
Stratum medium- how thick is it? where does it begin? what does it accommodate? structures in it? pigmentation?thick, begins at coronary groove, bears openings which accommodate papillae of underlying dermis. structures of tubules and intertubular horn. May be pigmented on outer layers, but not inner (no fxn)
stratum internum- pigmentation? begins where? accommodates what?non-pigmented, begins at medial part of coronary groove, and bears openings accommodating papillae of underlying dermis.
name/describe laminae of the stratum internuminner surface carries KERATINISED PRIMARY and NON-KERATINISED SECONDARY laminae these are collectively the EPIDERMAL LAMINAE. They also form the laminae of the bar caudally
what is sandcrack?condition of a crack in the wall of the hoof extending proximo-distally
what is grasscrack?less serious, split in wall extending proximally from basal border.
what is the sole? what are the angles of the sole? what is the composition of the sole?the sole is normally concave, flaky outer surface. Angles of the sole are between the walls and the bars. The sole is the same composition as the wall, it consists of vertical horn tubules and intertubular horn
look at the stupid pictures some morewish i had a thing for feet, maybe i'd care
what is the frog? what are the parts of it (externally) and how do they relate?the frog is wedge-shaped and on the bottom of the hoof. two crura (M+L) separated by a central groove (the SULCUS of the frog) meet cranially to form pointed APEX of frog. The frog expands palmarly to join bulbs (M/L) of the heels. I has softer horn.
what is thrush?degenerative condition of the frog, esp when the animal is kept in moist or watery floor/ground
What are the structures of the internal surface of the frog?there is the innermost bump which is the SPINE of the frog (the FROG STAY- it is embedded in the digital cushion) which is bordered by grooves which are themselves bounded by the RIDGE of the frog.
explain the keratinisation of the frogit is INCOMPLETELY keratinised, which means it is softer. (50% water content compared to the sole's 33% water content)
what structures are on the internal, deep surfaces of the frog?they have holes into which fit the papillae of the frog and sole dermis
what is the composition of the dermis? what does it attach/link? and produce?highly vascular and sensitive. it attaches the hoof wall to the internal foot structures, and (except for the laminar dermis) produces the various parts of the wall by means of papillae on their surfaces. It ALSO provides the WALL with NOURISHMENT.
what are the 5 areas of the dermis? (be able to label them)perioplic dermis (most prox), coronary dermis, laminar dermis, frog dermis, and sole dermis
perioplic dermis- composition, where it lies, what does it produce?narrow, pale and at the coronet below the periople. It broadens out and joins the bulbs of the heels, and blends with the frog dermis. There are papillae present and they PRODUCE the HORN of (stratum externum) periople and stratum tectorium
what produces most of the wall of the hoof?the coronary dermis.
where does the coronary dermis lie? pigmentation? covers what?it lies in the coronary groove, distal to the perioplic dermis. it is pigmented in DARK hoofs. It covers the extensor tendon, cartilages of distal phalanx via SQ tissue of the coronary cushion.
describe the papillae of the coronary dermis (where, does what, etc)on surface of coronary dermis, fit into holes in strata medium and internum of the coronary groove. it PRODUCES MOST OF THE WALL
what produces the stratum medium of the wall? the tubular horn? the intertubular horn?STRATUM GERMINATIVUM of coronary dermis produces stratum medium. The cells of the PAPILLAE produce the tubular horn,but the inter-papillar cells produce the intertubular horn.
where does the coronary venous plexus lie? anastomoses with what? via?lies deep in coronary cushion. anastomoses with the palmar/plantar venous plexus through foramina in the cartilages.
apprx how many 1* laminae (of the laminar dermis)? what does each bear? pigmentation?about 600 1* (dermal laminae). each bears several non-keratinized secondary laminae. Colorless.
what do the 1* laminae of the laminar dermis interdigitate with? what part blends with the periosteum?they interdigitate with laminae of walls and bars (epidermal laminae). The DEEP part of the dermal laminae blends with the periosteum of the distal phalanx (pressure from second phalanx directed away from sole to wall)
what comes off of the distal part of the dermal laminae? what is produced by this?numerous papillae (terminal papillae). These produce only a part ("cement" horn or pigmented horn) of the WHITE LINE (wall laminae are produced by the distal fringe of coronary papillae)
where does the dorsal venous plexus lie?deep in the laminar dermis
what can happen in laminitis?separation between the sensitive and insensitive laminae can occur, new non-tubular horn may be produced (due to stimulation of stratum germinativum)
what is "seedy toe"?laminar dermis of toe region may be separated from wall by space filled with amorphous crumbly material produced by the dermis
what is dropped sole?third phalanx may be rotated downwards, pushing sole down
sole and frog dermis- pigmentation? structures within it? what part of these produces what?usually pigmented, numerous papillae (fit into holes in sole and frog). the stratum germinativum of frog/sole dermis produces horn of sole and frog
where does the sole dermis attach? the sole dermis is attached to under surface of third phalanx.
where does the frog dermis attach?attached to the digital cushion above
What is the white line? what happens here? what is the horn like?its visible, white. at junction of wall and sole. The horn is thin, soft and pale.
What are the two parts of the White Line?(1) pigmented horn- produce by stratum germinativum overlying TERMNIAL PAPILLAE (on distal parts of laminar dermis) (2) the pig. horn fills the space between the NON-PIGMENTED HORN. deep layer of stratum medium AND distal parts of horny (dermal) laminae.
where does the palmar(plantar) venous plexus lie?deep in the sole dermis and on surfaces of cartilages of third phalanx.
what is a corn?bruised sole dermis at angle of sole (anywhere else is just bruised sole)
what is a canker?chronic hypertrophy of frog dermis- due to infection, usually
what kind of tissue is in the DIGITAL CUSHION? Where is it most dense?MOSTLY FIBROELASTIC TISSUE. may have scattered areas of cartilage tissue, fatty, some modified skin glands, pale yellow. It is DENSER towards TOE than at heels where it supports the bulbs.
what function does the digital cushion perform? where does it lie?Concussion-absorption function. Situated between the cartilages of the distal phalanx, overlies the frog and is distal to the second phalanx and deep digital flexor tendon.
what does the digital cushion form caudally?forms bulbs of the heels
what kind of tissue is the CORONARY CUSHION? what does it attach (what to what) and what does it eventually blend with?Elastic, SQ tissue part of the coronary dermis. it attaches the coronary dermis to the digital extensor tendon and cartilages of the distal phalanx. It blends with the digital cushion at the prox. aspect of the heel.
how does elasticity of the foot change?elasticity increases from toe to the heel
what strikes the ground first?the frog and basal border.
after the frog and the basal border hit the ground, how does the force travel?frog compressed and expanded, bars forced apart, force of impact redirected to digital cushion and the cartilage, which move outwards, the heels are spread apart.
how do the venous plexuses of the foot work when they have no valves?There is a simultaneous compression of the wall when its basal border hits the ground, transmits tension via the interlocked laminae to the distal phalanx, which sinks, and then that puts pressure on the plexuses which forces bood proximally into the digital veins (which do have valves). Then when the foot is lifted, the neg pressure bring in the arterial blood. (no exercise/inability to shift foot= stagnating blood)

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