The anatomical displacement (indicated by *) of the distal phalanx. Right vs left: The largest organ (glandular structure) of the horse is the dermal tissue, a voracious consumer of nutrients which includes not only the hooves, but also the skin, hair follicles, sweat glands, oil glands and related structures. Dewclaws are present in most ruminants but do not make contact with the ground. The Nervous System. The BM is folded into ridges along the longitudinal axes of the primary lamellae, forming the secondary lamellae, and the coronary and terminal papillae, increasing the surface area for the attachment of proliferative epidermal basal cells [12]. When the limb is weight bearing, the increase in pressure and change in shape of the digital cushion and the frog compress the veins in the foot aiding venous return. The outer wall is the same as that of a cow or sheep; however, the sole is slightly different. The organic matrix, or osteoid [24], is formed principally of type-I collagen (around ~95% type-I [25]) which affords the bone its tensile strength, alongside trace amounts of other collagens, in addition to non-collagenous proteins whose predominant purpose is to permit the mineralisation of the matrix. The remaining 20% of the osseous tissue is in the form of trabeculae (from the Latin trabs, meaning “beam” [27]) which provide structural support, in a buttress-like manner, to the surrounding cortex. Today's Rank--0. The final two lectures will jump into the various coat colors and markings in horses. By James Nguhiu-Mwangi and Peter M.F. This mechanism is enabled by the osteoclast’s stimulation at low pH, a peculiarity from a general cellular point of view, and the osteoblast’s synergistic inhibition [33]. Haematoxylin and eosin stained lamellae within the horse hoof. It has connection with the digital annular ligament and, at the apex to the deep digital flexor tendon at its point of insertion on the distal phalanx. The cartilages are securely attached to the other internal structures of the foot by a series of ligaments that extend from the medial and lateral cartilages to the distal and middle phalanx, the distal sesamoid bone (navicular), and the digital cushion. The wall of the hoof is the element of the hoof that is visible. 5 The Anatomy and Physiology of Pregnancy in the Mare 47 6 Endocrine Control of Pregnancy in the Mare 68 ... Equine Reproductive Physiology, Breeding and Stud Management 2nd edn (M.C.G. An additional feature of the blood circulation of the equine foot is the anastomoses of arteries and veins, which are blood vessels forming shunts [21]. The work was funded by PetPlan, Waltham, The Ministry of Higher Education and Scientific Research of Iraq, Western Scholarship and The University of Nottingham School of veterinary Medicine and Science. It covers the front and sides of the third phalanx, or coffin bone. Understanding the basic anatomy of the horse hoof is essential in order to further investigate the structures’ involvement in the pathogenesis of lameness and in order to help understand disorders such as lameness and laminitis. The frog is a wedge-shaped structure which sits between the bars and has an apex facing distally, with 2 crura flanking a central sulcus. Clinical Anatomy and Physiology Vet Tech Ch. Clinical anatomy and physiology of the normal equine foot C. C. POLLITT Department of Companion Animal Medicine and Surgery, School of Veterinary Science, University of Queensland, Brisbane, Queensland 4072, Australia. Licensee IntechOpen. Indeed, the failure of the connection between the epidermal laminae and the underlying basement membrane of the dermal lamellae would weaken the suspensory apparatus of the distal phalanx [46]. To date our community has made over 100 million downloads. In order to develop a better understanding of foot lameness, we review both the healthy and lame foot anatomy, cell biology and vascularisation and using micro-computed tomography show new methods of visualising internal structures within the equine foot. Epidermal basal cells are attached to the basement membrane (BM) on its border with the hoof epidermis [8]. While under normal physiological circumstances the pH of blood and extracellular fluid is maintained within narrow parameters by the removal and excretion of protons by the kidneys and lungs, a multitude of physiologically adverse conditions (e.g. The terminal branches of the blood supply enter the distal phalanx from the medial and lateral aspects and then form several anastomoses within the bone to make the terminal arch. The wall of the hoof is created at the coronary dermis and grows in a distal direction from the coronary dermis. This is the first of many pages displaying horse hoof anatomy pictures. We will then advance into hoof anatomy and care. 4. The ruminant/pig 'bulb' provides the hoof with the caudal and mid-hoof contact area with the ground and is chiefly involved in weight bearing. The Circulatory System. Where horn overgrowth occurs, the coffin joint is gradually overextended and the deep flexor tendon tensed. The origin of the hoof is as a form of protection to the distal phalanx and stems from local modifications of the epidermis, dermis and subcutaneous layers. Demarcation line where the sensitive and insensitive laminae meet. Hind: The angle between the toe and the ground is 50-55 degrees. Horse Hoof Anatomy. Finally, there is an inner laminar layer where there are interdigitating laminae of horn and dermal laminae which ensure the hoof itself is firmly anchored to the distal phalanx. This could explain the relationship between laminitis and ischemia [3]. The Equine Skeleton. Venous drainage is similar with the most distal vessels being the medial and lateral palmar/plantar digital veins. Dorsal lamellar plexus Built by scientists, for scientists. Although the aetiology of equine foot lameness is still an active research area, recent efforts have also tried to determine whether the hoof shape is a disposing factor for foot lameness-causing lesions. In addition, new information from cellular and molecular studies is advancing not only the anatomical and histological sides but also the physiology and function of the equine limbs and the disorders they are prone to. Horse Hoof Anatomy and Physiology If you look at the foot externally from the side (laterally), the front portion is largely static, whereas the back part of the foot is dynamic or deformable. Total Points. The compressive action of the hoof on the soft tissues within during locomotion generates an important function promoting venous return. Each primary lamella bears a further 150–200 microscopic secondary lamellae and, collectively, the primary and secondary lamellae create a surface area for attachment of around 0.8 m2 (Figure 2) [9]. The methodologies which are used are also being developed over time and giving new insights into anatomy and physiology. Terminal arch The wall of the hoof is widest at the distal aspect of the hoof, i.e. Abstract The equine hoof capsule protects the softer, more sensitive, structures within. *Address all correspondence to: catrin.rutland@nottingham.ac.uk, Edited by Catrin Sian Rutland and Valentina Kubale. © 2019 The Author(s). See the bovine lower limb for further detail. The pelvic limb digit is innervated on the dorsal aspect by the common digital nn. Publishing on IntechOpen allows authors to earn citations and find new collaborators, meaning more people see your work not only from your own field of study, but from other related fields too. By Ramzi Al-Agele, Emily Paul, Valentina Kubale Dvojmoc, Craig J. Sturrock, Cyril Rauch and Catrin Sian Rutland, Submitted: June 5th 2018Reviewed: January 17th 2019Published: February 8th 2019, Home > Books > Veterinary Anatomy and Physiology. The sole is oval in shape. Contact our London head office or media team here. Inflammation in the region is involved in navicular disease which is a common cause of lameness. These variations in the shape of the capsule are triggered by biological sources causing autolysis of the collagen fibres connecting the epithelium to the bone [68]. The frog corium overlies the digital cushion and generates the specialised soft epidermal tissues of the frog. Responsible for the extension of the interphalangeal joints is the common digital extensor tendon (CDET also known as m. extensor digitorum communis in the fore limb and m. extensor digitorum longus on the rear limb) [11]. In chronic foot lameness, the hoof capsule of the lame foot can be more distorted than in the non-lame one [85], as a result of altered loading forces applied to the hoof, hence affecting the shape of the hoof and the internal structures of the foot [86, 87]. Today 's Points. One of us! This insensitive horny structure encloses the distal part of the second phalanx (also known as the middle phalanx or short pastern bone), the distal phalanx (also known as the coffin bone or the pedal bone) and the navicular bone, in addition to connective tissues including, for example, the distal interphalangeal joint, medial and lateral hoof cartilage, with the terminal end of the deep digital flexor tendon and navicular bursa [1, 3–5]. Dyson and colleagues [39] highlighted that, despite the differences in the shape of the distal phalanx between horses, lameness is mainly associated with changes in the direction of the dorsal hoof wall. Coupled with more traditional techniques recent research has used these techniques to show bone conformation and growth, vascularisation and a number of other factors which could help inform us about anatomy and limb disorders. The relatively high prevalence of forelimb foot lameness [81] which reaches to more than 75% of equine foot lameness being found in a forelimb particularly in breeds such as Thoroughbred horses and 40% in Standardbred racehorses [82]. Assessment of the external anatomy can be a used as an important part of a lameness examination. In some species the hoof may play an important role in non-locomotion roles such as digging or being used as a weapon. My goal is to begin with the basic external parts of the hoof and progress to the internal workings of the foot. Once inside the hoof the annular ligament merges with the fibrous attachments of the ungual cartilages and digital cushion, and continues with the digital flexor tendon down to its insertion onto the distal phalanx. Get started! Thus, haemorrhage from the sublamellar circulation can result in the rotation of P3, as is observed in the case of founder [16, 18, 19]. In addition to the bones, ligaments, tendons and other soft tissues of the foot, the vasculature is essential in the equine foot. This may be explained by that fact that the centre of gravity of the horse is closer to the front limbs than the rear limbs, as the loading ratio is spread approximately 60% forelimbs: 40% hind limbs [66]. This page was last edited on 24 November 2016, at 17:53. The lateral digit carries more weight than the medial digit, and is larger. Foot lameness is classified into acute and chronic types depending on the severity of lesions and the time requirement for healing, if healing is possible [71]. Ramzi Al-Agele, Emily Paul, Valentina Kubale Dvojmoc, Craig J. Sturrock, Cyril Rauch and Catrin Sian Rutland (February 8th 2019). The navicular, or distal sesamoid bone, is a small, smooth bone located caudal to the distal interphalangeal joint. Equine Dentition. The Hoof By making research easy to access, and puts the academic needs of the researchers before the business interests of publishers. A Variety of Topics. Since the sole is slightly concave, the majority of the horse's weight is transferred through the margin of the sole. The investigation of variations between foot lameness and non-foot lameness affected horses [51], demonstrated that the angle between the capsular wall and the ground is larger in the lame horse with an enlarged heel, curved or misshapen coronary band, that diverging growth lines can occur, and that the tubular horns differ from non-lame horses. Trabecular osteons, or packets, are similar in their lamellar architecture to those of the cortex, but are smaller in size and semi-lunar in shape [23]. 100+ Hours of Vet CE. kidney disease or severe exercise) can lead to acidosis [33]. A number of hoof shapes can arise from this chronic condition, including sheared heels, crushed heels, club foot, long-dished toe, and high-heel foot [49, 51]. It is the most superficial structure in the region, lying just beneath the skin and fusing with the digital flexor tendon where it enters the hoof capsule. White line. Other research [80] has shown that horses with severe foot lameness in the front limb display an untrue foot lameness in the contralateral rear limb, whereas horses with a real rear limb foot lameness exhibit an incorrect foot lameness in the ipsilateral front limb. In the UK, the maintenance of each horse is estimated to cost about £2660 annually and much of this in the treatment of foot lameness [74]. There are also soft tissue structures including ligaments, cartilage, the digital cushion and the insertions of the common digital extensor tendon and the digital flexor tendon. The dermal lamella is drained by: the coronary vein; the independent superficial vein; the proximal branch of the caudal hoof vein; and the circumflex vein. Help us write another book on this subject and reach those readers. Features. Christopher C. Pollitt, Anatomy and physiology of the inner hoof wall, Clinical Techniques in Equine Practice, 10.1053/j.ctep.2004.07.001, 3, 1, (3-21), (2004). Our team is growing all the time, so we’re always on the lookout for smart people who want to help us reshape the world of scientific publishing. Advances in technology such as magnetic resonance imaging, computed tomography and other imaging techniques also play a role in assisting both anatomical knowledge and understanding equine conditions [99]. The vascular arteries of the dermis are divided into three independent arterial blood supplies: the dorsal coronary corium; the palmar/plantar portion of the coronary corium and laminar corium; and the dorsal laminar corium and solar corium, as the blood flow is reversely directed from the distal part to the proximal part within the dermal lamina (also termed lamella/lamellae and lamellar in the literature) [4]. Parts of the Horse. The ungual cartilages can ossify resulting in ‘side bones’ which have the potential for fracturing. The role of these fibres is to support and suspend the weight of the horse via the distal phalanx, as well as to maintain the shape of the capsule constant [88, 89]. In a similar vein, bone acts as a reservoir for calcium and phosphorus, making them available for the maintenance of mineral homeostasis. They act as mechanoreceptors, communicating with the osteogenic/osteolytic cells via gap junctions at the extremities of their cytoplasmic processes, and play a regulatory role in the bone synthesis/resorption cycle [25]. Catrin Rutland Orcid: 0000-0002-2009-4898. Each dermal papilla in the periople, coronary band, frog, sole and terminal papillae contain a meshwork of anastomosing arteriovenous vessels located at the base of the papillae. Also known as the distal phalanx, third phalanx, or "P3".The coffin bone meets the short pastern bone or second phalanx at the coffin joint. This inter-tubular horn is created by the spaces between the papillae within the coronary dermis. Associated with it is a fluid-filled sac that reduces friction between the bone and the digital flexor tendon that lies over the top of it— the navicular bursa. The distal interphalangeal joint is enclosed within the hoof capsule. The corium are connected to the underlying structures by the subcutis. We are IntechOpen, the world's leading publisher of Open Access books. It lies between the ungual cartilages and is comprised of collagenous, elastic tissue infiltrated by adipose tissue. The sole represents the part of the foot in contact with the ground and its composition differs between species. The frog extends inwards to the digital cushion which, being composed of poorly vascularised adipose tissue embedded in a fibroelastic mesh, is involved in shock absorbance and possesses blood pumping properties [6, 10]. In the middle of a horse’s sole is a V-shaped cleft, called the frog. In the hind limb, the small plantar common digital arteries contribute to form the digital arteries. In chronically laminitic horses, the lamellar wedge appears as an abnormal horny mass, that is formed between the inner hoof wall and the epidermal lamellae, and is linked to the slight rotation of the distal phalanx [55]. Lameness can also manifest itself in pain and lesions that, in turn, lead to an abnormal gait [62, 63] with undesirable consequences on performance [64] and welfare [65]. The blood vessel system is a vital part of transport of dissolved gases, nutrients, waste, signalling chemicals such as hormones, and immune cells to and from other organs [13]. The epidermis covering these papillae produce horn tubules which are embedded into amorphous inter-tubular horn. This wall glides distally at a rate of 5-6mm a month and by forming epidermal laminae itself it interdigitates with the underlying dermal laminae. However, despite being a success in its natural environment, the equine foot becomes a common site of disease and injury when subjected to the demands of human domestication. Our readership spans scientists, professors, researchers, librarians, and students, as well as business professionals. It is the main load support system of the equine foot1 and serves to transfer ground reaction forces to the bony skeleton.2. The navicular bone is held in place by the navicular suspensory ligaments which anchor to the distal edge of P1, just dorsal to the collateral ligament attachments, and converge at the navicular bone, forming the distal navicular ligament which terminates at P3 [10]. Along with the DDFT, which descends from the deep digital flexor muscle in the forearm to the flexor surface of P3, the superficial digital flexor tendon (SDFT) forms part of the back tendon pair, thus enabling flexion of the interphalangeal joints [10, 11]. The best place to start is with a basic understanding of how the hoof fits into the anatomy and physiology of the horse. The coronary dermis is studded with many papillae which are directed towards the ground in the direction of growth. The combination of both of these horn types ensures the horn has sufficient strength. We will then advance into hoof anatomy and care. 30. Brief introduction to this section that descibes Open Access especially from an IntechOpen perspective, Want to get in touch? at the toe. Equine Surface Anatomy. The separation of the distal phalanx inside the capsular wall can change the sole shape to become convex rather than be concave, due to differential growth of the proximal hoof wall portion [55]. The Reproductive System. There is an intermediate layer which represents the main structure of the wall and is composed of amorphous horn reinforced with many tubular shaped horn rods. The keratin in the epidermis, when thickened and cornified, is referred to as horn. Horn is largely arranged into a series of parallel microscopic tubules, interconnected by intertubular horn [9]. The white line is used as important landmark in farriery as structures central to the line will be dermal and so vascular and sensitive. , mainly inter-tubular horn the lower Leg and hoof of the wall the. 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