Equine Limb Equine Limb AnatomyAnatomy

Tissues and Functional AnatomyTissues and Functional Anatomy

!! BonesBones!! Cornified tissues comprising the Hoof Cornified tissues comprising the Hoof

CapsuleCapsule!! Cornified Tissue Coria and Laminae Cornified Tissue Coria and Laminae !! Tendons, Ligaments and Elastic structuresTendons, Ligaments and Elastic structures!! Arteries, Veins and NervesArteries, Veins and Nerves

Upper Bones of Upper Bones of the Front Limbthe Front Limb

!!ScapulaScapula!!HumerusHumerus!!RadiusRadius!!UlnaUlna!!Carpal bonesCarpal bones

Upper Bones of Upper Bones of the Hind Limbthe Hind Limb!!PelvisPelvis!!FemurFemur!!TibiaTibia!!FibulaFibula!!Tarsal bonesTarsal bones

Lower Limb bonesLower Limb bones!! Front limbFront limb

"" Cannon BoneCannon Bone•• MClll MClll

"" Splint bonesSplint bones•• MCll & MClVMCll & MClV

"" PhalangesPhalanges•• PlPl•• PllPll•• PlllPlll

"" Sesamoid bonesSesamoid bones•• Proximal SesamoidsProximal Sesamoids•• Navicular BoneNavicular Bone

!! Hind limbHind limb"" Cannon boneCannon bone

•• MTlllMTlll"" Splint bonesSplint bones

•• MTll & MtlVMTll & MtlV"" PhalangesPhalanges

•• PlPl•• PllPll•• PlllPlll

"" Sesamoid bonesSesamoid bones•• Proximal SesamoidsProximal Sesamoids•• Navicular BoneNavicular Bone

Distal limb AnatomyDistal limb Anatomy

Plll or Coffin BonePlll or Coffin Bone

!! Is the foundation of the entire skeletonIs the foundation of the entire skeleton!! Periosteum is highly modified into the Periosteum is highly modified into the

Laminae which attach the hoof capsule to Laminae which attach the hoof capsule to the skeletonthe skeleton

!! Is the terminal attach point for the Is the terminal attach point for the locomotor systemlocomotor system

Plll with Ungual (Plll with Ungual (ColateralColateral) Cartilages) Cartilages

ColateralColateral CartilagesCartilages

!! Provide the Provide the flexible attach flexible attach point for the point for the caudal hoof wall caudal hoof wall for dissipation of for dissipation of concussionconcussion

!! Ossification of Ossification of the cartilages the cartilages compromises compromises functionfunction

Proximal Proximal SesamoidsSesamoids!! Part of the Suspensory ApparatusPart of the Suspensory Apparatus

Sesamoid BonesSesamoid Bones

!! Distal Sesamoid Distal Sesamoid akaakathe Navicular bonethe Navicular bone"" Pulley of the DFTPulley of the DFT"" Increases the articular Increases the articular

surface of the Coffin surface of the Coffin JointJoint

Hoof CapsuleHoof Capsule

!! Wall and BarsWall and Bars!! Primary Epidermal Primary Epidermal

LamellaeLamellae"" ““Insensitive laminaeInsensitive laminae””

!! SoleSole!! FrogFrog!! PerioplePeriople

Hoof CapsuleHoof Capsule

Hoof CapsuleHoof Capsule

Wall Wall Primary weight bearing structure of the hoofPrimary weight bearing structure of the hoof

"" Hornified Hornified cornified cornified epitheliumepithelium

"" Tubular and Tubular and Intertubular Intertubular hornhorn

"" Bars are Bars are part of the part of the wallwall

Wall tubule ArchitectureWall tubule Architecture

Two types of Lamellae from 2 OriginsTwo types of Lamellae from 2 OriginsDermal and EpidermalDermal and Epidermal

!! Primary (1Primary (1°°))"" Arise Arise

perpendicular perpendicular to the inner to the inner surface of the surface of the hoof wall and hoof wall and PlllPlll

!! Secondary (2Secondary (2°°))"" Perpendicular Perpendicular

to the 1to the 1°°lamellaelamellae

!! 11°° Epidermal Epidermal Laminae are the Laminae are the laminae that migrate laminae that migrate distally with the hoof distally with the hoof wallwall

!! 22°° Epidermal, 2Epidermal, 2°°Dermal and 1Dermal and 1°°Dermal remain Dermal remain attached to Plllattached to Plll

SoleSole

!! Covers the bottom of PlllCovers the bottom of Plll!! The White line, Frog and Bars are not part The White line, Frog and Bars are not part

of the Soleof the Sole!! The exfoliation properties of the Sole The exfoliation properties of the Sole

control the length the hoof can attaincontrol the length the hoof can attain!! The Sole follows the contour of the Solar The Sole follows the contour of the Solar

Surface of PlllSurface of Plll"" The sole is divided into exfoliating sole and The sole is divided into exfoliating sole and

newer intact sole at the newer intact sole at the ““moisture linemoisture line””

SoleSole

FrogFrog

!! Structure allows for expansion of the hoof Structure allows for expansion of the hoof capsule for dissipation of concussioncapsule for dissipation of concussion

!! Has similar exfoliation properties as the Has similar exfoliation properties as the SoleSole

!! Is a secondary weight bearing structureIs a secondary weight bearing structure!! Sweat glands in the Digital Cushion keep Sweat glands in the Digital Cushion keep

the moisture content of the Frog higher the moisture content of the Frog higher than the other tissues of the capsule to than the other tissues of the capsule to increase pliabilityincrease pliability

FrogFrog

PerioplePeriople!! Overlies the proximal Overlies the proximal

border of the wall and border of the wall and blends with the Frog blends with the Frog at the bulbs of the at the bulbs of the heelsheels

!! Has the same tissue Has the same tissue structure as the Frogstructure as the Frog

!! Function appears to Function appears to be protection for the be protection for the corium of the wall and corium of the wall and perhaps some perhaps some moisture regulationmoisture regulation

White LineWhite Line!! The inner border defines the extent of PlllThe inner border defines the extent of Plll

Elastic StructuresElastic Structures

!! Digital cushionDigital cushion!! Coronary CushionCoronary Cushion!! Collateral Cartilages of PlllCollateral Cartilages of Plll!! Suspensory ApparatusSuspensory Apparatus

"" Suspensory ligament, Extensor branchSuspensory ligament, Extensor branch"" Distal Sesmoidian ligamentsDistal Sesmoidian ligaments

Digital cushionDigital cushion

TendonsTendons

!! Deep Flexor Tendon Deep Flexor Tendon (DFT)(DFT)

!! Superficial Flexor Superficial Flexor Tendon (SFT)Tendon (SFT)

!! Common Digital Common Digital Extensor TendonExtensor Tendon

ArteriesArteries!! M & L Digital arteries M & L Digital arteries

anastomose in the anastomose in the Terminal Arch Terminal Arch

!! The terminal arch is The terminal arch is within Plll within Plll

!! A portion of blood A portion of blood flow in the hoof must flow in the hoof must flow distal to proximal flow distal to proximal to perfuse the to perfuse the LaminaeLaminae

Venous ReturnVenous Return

!! No muscles are present in the distal limb No muscles are present in the distal limb to return blood back up the leg. to return blood back up the leg.

!! Return circulation is entirely dependent on Return circulation is entirely dependent on compression of vascular plexi in the hoof compression of vascular plexi in the hoof by movement of the horse.by movement of the horse.

!! There are no valves in the veins below mid There are no valves in the veins below mid pastern.pastern.