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Topic:Anatomy
Anatomy in horses encompasses the study of the structural organization of the equine body, including the bones, muscles, organs, and systems that function together to sustain life and enable movement. Understanding equine anatomy is important for veterinarians, equine scientists, and horse owners, as it provides insights into how horses move, how they respond to external stimuli, and how various conditions can affect their health and performance. Key anatomical features in horses include the musculoskeletal system, which provides support and locomotion; the cardiovascular system, which circulates blood and nutrients; and the respiratory system, which facilitates gas exchange. This page compiles peer-reviewed research studies and scholarly articles that explore the detailed anatomy of horses, focusing on the structure and function of different body systems, their interrelationships, and their relevance to equine health, performance, and veterinary care.
Diffusion of mepivacaine between adjacent synovial structures in the horse. Part 1: forelimb foot and carpus. This paper tests the hypothesis that the local analgesic agent mepivacaine diffuses between adjacent equine synovial structures in the forelimb and with greater frequency than latex, gelatine dye or contrast media. We report the incidence of diffusion of mepivacaine between the distal interphalangeal joint (DIPJ) and navicular bursa (NB) of the forelimbs and between the intercarpal (IC) and radiocarpal (RC) joints of 31 fresh equine cadavers. The DIPJ of one forelimb and the NB of the contra lateral forelimb and the RC joint of one forelimb and the IC joint of the contra lateral forelimb were ...
Diffusion of mepivacaine between adjacent synovial structures in the horse. Part 2: tarsus and stifle. This paper tests the hypothesis that the local analgesic agent mepivacaine diffuses between adjacent equine synovial structures in the hindlimb and with greater frequency than latex, gelatine dye or contrast media. We report the incidence of diffusion of mepivacaine between the tarsometatarsal, centrodistal and tarsocrural joints, and the 3 synovial compartments of the stifle in 33 fresh equine cadavers. The tarsometatarsal joint and one synovial compartment of the stifle in the left limb and the centrodistal joint and a different synovial compartment of the stifle in the right limbs were inje...
Structure of equine infectious anemia virus matrix protein. The Gag polyprotein is key to the budding of retroviruses from host cells and is cleaved upon virion maturation, the N-terminal membrane-binding domain forming the matrix protein (MA). The 2.8-A resolution crystal structure of MA of equine infectious anemia virus (EIAV), a lentivirus, reveals that, despite showing no sequence similarity, more than half of the molecule can be superimposed on the MAs of human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV). However, unlike the structures formed by HIV-1 and SIV MAs, the oligomerization state observed is not trimeric...
An ovarian interstitial cell hamartoma in a newborn foal. A case of congenital ovarian interstitial cell hamartoma in a thoroughbred foal that died of apparent nutritional myopathy (white-muscle disease) 14 h after birth is described. An incidental finding at necropsy was a pale brown, mushroom-shaped, pedunculated mass (6 x 4 x 3 cm) attached to the left ovary. On the cut surface, the mass had a peripheral rim of dense parenchyma (3-5 mm wide), surrounding a pale gelatinous core. Histologically, the mass consisted of a peripheral zone of densely packed large cells that were quite similar, morphologically, to fetal ovarian interstitial cells, and a c...
Unusual osteochondral lesions of the talus in a horse. A 2-year-old Thoroughbred gelding was evaluated for a grade 3 out of 5 unilateral hind limb lameness. Flexion of the right hock and stifle joints (spavin test) exacerbated the lameness. Response to intra-articular and perineural anaesthesia isolated the source of lameness to the tarsocrural area, despite an absence of tarsocrural joint effusion. Routine radiographic examination of the hock did not reveal any significant abnormalities. Skeletal nuclear scintigraphic evaluation revealed a focal region of increased bone activity in the proximal medial trochlear ridge of the talus. Flexed laterome...
Handling forensic necropsy cases. Immediately record the findings. A tape recorder would be excellent for this. If none is available, findings should be written down as soon as possible before memory of the examination fades. It is important to record comments on every organ that you examined. Three years from now in a court deposition, it may be difficult for the practitioner to remember if he looked at the adrenal glands or if there was no gross evidence of hyperplasia. When writing a report, it is a good idea to describe the tissue changes rather than just to give an interpretation. An example of the latter would be, "The h...
Subchondral bone thickness, hardness and remodelling are influenced by short-term exercise in a site-specific manner. It was hypothesised that subchondral bone thickness, hardness and remodelling are influenced by exercise intensity, and by location within a joint. Dorsal carpal osteochondral injury is a major cause of lameness in horses undergoing high intensity training. This project aimed to determine the subchondral bone thickness, formation, resorption and hardness at sites with high and low incidence of pathology in 2 year-old horses undergoing 19 weeks high intensity treadmill training or low intensity exercise, and to compare these factors between exercise groups. Dorsal and palmar test sites were ide...
Computed tomographic study of the effect of a tongue-tie on hyoid apparatus position and nasopharyngeal dimensions in anesthetized horses. To determine the effect of manual tongue protrusion on the dimensions of the hyoid apparatus, nasopharynx, and oropharynx in anesthetized horses. tongue protrusion on the dimensions of the hyoid. Methods: 5 adult horses. Methods: Horses were anesthetized and positioned in sternal recumbency for 2 sequential computed tomographic (CT) scans. Images were acquired with the tongue in a natural position inside the mouth. Then, the tongue was pulled rostrally and secured, and a second CT scan was performed. Dorsoventral length of the hyoid apparatus and angles of the basisphenoid, basihyoid, and cera...
A mathematical model of the ascending colon of the horse. In this study we present a geometric model of the ascending colon of the horse, especially the left ventral colon and the right ventral colon, the left dorsal colon and the right dorsal colon and the pelvic flexure. We also present a mathematical model of the cross sections of these ascending colon parts with the exceptions of the pelvic flexure. We show that these cross-sections correspond to the closed algebraic curves known as epitrochoid.
Cervical stenotic myelopathy in a horse. A 13-year-old, Thoroughbred gelding presented with a 3-year history of progressive ataxia of all 4 limbs. Physical and neurological examinations indicated a compressive lesion affecting the cervical spinal cord. Radiographs confirmed a lesion, and a myelogram a narrowing of the spinal canal at cervical vertebrae (6-7). Necropsy confirmed cervical stenotic myelopathy.
Ultrasonography of the podotrochlear apparatus in the horse using a transcuneal approach: technique and reference images. The purpose of this paper is to describe the technique for ultrasonographic examination of the podotrochlear apparatus in the horse using a transcuneal approach. In this study, ultrasound scans were performed in 3 normal cadaver limbs and 5 sound horses and images were compared to anatomic sections to establish the normal ultrasonographic anatomy of the podotrochlear apparatus. Detailed description of transverse and sagittal reference ultrasonographic images of this region is provided. This new imaging technique allows the assessment of the distal sesamoid bone flexor surface, the distal porti...
The equine larynx. Abstract Extract A series of landmark studies on the function of the equine larynx was conducted by a group of researchers at Massey University between 1970 and 1987. These studies commenced with investigations on the normal laryngeal anatomy and physiology (Goulden et al 1976a; Anderson et al 1980; Quinlan et al 1982), and progressed to a clinical appraisal of laryngeal hemiplegia, the most important clinical disease affecting the horse's larynx (Goulden and Anderson 198 lab, 1982). The studies concluded with a series of in-depth cytological and pathological studies of the intrinsic laryngeal...
Morphology, histochemistry, and function of epaxial cervical musculature in the horse (Equus caballus). The semispinalis capitis and splenius muscles of the horse were analyzed for gross morphology, microarchitecture, fiber length, and fiber type. Although these two muscles are similar in size and anatomical position, they are very different from one another in structural design and histochemistry, implying diverse functional roles in the animal's behavior. The histochemical staining profile was limited to two fiber types: slow oxidative and fast glycolytic. The splenius muscle has simple architecture, long fibers, and a 60/40 ratio of SO to FG cross-sectional area. The semispinalis capitis has ...
Three-dimensional kinematics of the proximal interphalangeal joint: effects of raising the heels or the toe. The proximal interphalangeal joint (PIPJ) has always been considered as a low-motion joint with an almost constant angle during loading of the limb. Until very recently, its motion was not taken into account in kinematic studies in vivo. Recent in vivo studies yielded surprisingly high ranges of motion in this joint. The aim of this study was to measure, in terms of the 3 possible rotations (flexion/extension, collateromotion and axial rotation), the movements of the PIPJ in vitro during limb loading in a neutral position (500-6000 N) and after the addition of heel and toe wedges (6 degrees an...
Normal three-dimensional behaviour of the metacarpophalangeal joint and the effect of uneven foot bearing. The purpose of this study was to quantify small amplitude rotational movements in the metacarpophalangeal joint (MPJ) of the horse and to measure the influence of asymmetric placement of the foot on these articular angles. Trihedrons, supporting kinematic markers defining a local frame, were screwed into the third metacarpal bone and the proximal phalanx of 4 isolated forelimbs. The limbs were loaded in a press, and the lateral or medial aspects of the foot were raised alternately by a 12 degrees wedge. The use of the joint coordinate system permitted the simultaneous and continuous computing ...
Analysis of a radiographic technique for measurement of equine metacarpal bone shape. Accuracy and limitations of a radiographic technique were established for measurement of metacarpal bone shape in horses. A radiographic index (RI) has been used to measure changes in third metacarpal (Mc3) bone shape in response to training in young racehorses. The aim of these experiments was to determine the effects of positioning of the radiographic equipment on RI measurements from lateromedial radiographs of a left ex vivo metacarpus. Repeatability of the RI measurement in left lateromedial and right mediolateral view Mc3s were evaluated. The width of the dorsal cortex (DC), palmar corte...
Determination of hoof mass and centre of mass from morphological measurements. Determination of net joint moments and powers requires accurate measurements of mass and centre of mass (COM) for the limb segments. The objective of this research was to develop regression equations for calculating mass and COM of the hoof segment that are applicable over a wide range of hoof morphologies. Ninety-one hooves (mean +/- s.d. 0.99 +/- 0.50 kg) were weighed and the 3-dimensional COM determined using a mass balance technique. Ten morphological variables were measured and used as independent variables in linear regressions with dependent variables of mass and centre of mass. The reg...
Description of ciliary body anatomy and identification of sites for transscleral cyclophotocoagulation in the equine eye. To determine the most appropriate anatomical location for diode laser probe placement to accurately photoablate the equine ciliary body using a contact, transscleral approach. Methods: Original research. Methods: Forty-two freshly enucleated adult equine eyes were evaluated. The horizontal, medial vertical, central vertical, and lateral vertical lengths of the cornea were measured from limbus to limbus. Needles were inserted perpendicular to the sclera at specific distances posterior to the external limbus at the 1, 2, 4, 5, 6, 7, 8, 10, 11 and 12 o'clock positions. The per cent frequency that...
Body centre of mass movement in the lame horse. The body centre of mass (BCM) is a key factor in the analysis of equine gait, as its position and movement determines the distribution and magnitude of loads on the limbs. Changes in the BCM movement are proposed to be important factors in the lameness management of horses. In this study, changes in the position and the 3-dimensional (3-D) movement of the BCM in horses with induced forelimb lameness were studied using a kinematic, segmental method. The kinematics of 30 markers representing 20 body segments were recorded in 12 horses while trotting (3.9 m/s) on a treadmill using a high speed vi...
Effects of heel and toe elevation upon the digital joint angles in the standing horse. Five sound mature horses, age 8-14 years, with toe angles 45.5-55.0 degrees were placed on a specially designed platform with only the left forelimb weightbearing, which allowed the successive production of 7 different conditions of foot orientation: neutral position (N), 5, 10, 15 degrees heel (H5, H10, H15) and toe (T5, T10, T15) elevation, performed according to 2 different sequences. For each condition, 2 lateromedial radiographs were taken to evaluate the metacarpophalangeal joint (MPJ) and both interphalangeal joint (PIPJ and DIPJ) angles, respectively. In addition, two-dimensional (2-D)...
Quantification of hoof deformation using optical motion capture. Deformation of the hoof capsule occurs during stance phase as a result of loading by the distal phalanx. The objective of this study was to evaluate optical motion capture as a technique for measuring hoof deformation during locomotion, and to quantify the deformation of the dorsal wall during stance phase. The front left feet of 3 clinically sound horses were used for this study. The hoof wall was cleaned and 9 retroreflective markers were glued to the lateral and dorsal hoof wall, and shoe. Each horse was trotted in a straight line at constant speed while marker positions during stance phase...
Relationships between third metacarpal bone parameters and surface strains. The relationships were explored between measurements of bone quality, size (quantity) and shape, and strain data collected during treadmill exercise at 4 and 12 m/s from the third metacarpal bones of 6 yearling and 6 mature Thoroughbred racehorses. Peak strains in yearling and mature Thoroughbred horses during exercise were related to the size and shape of the third metacarpal bone. The peak strains were significantly lower in horses with a greater cross-sectional area of bone and with a greater proportion of the bone in the dorsal cortex. There was no consistent relationship between peak stra...
Distribution of epidermal growth factor receptor (EGFr) in normal and acute peptic-injured equine gastric squamous epithelium. Growth factors are important in healing and restoration of injured gastrointestinal tissues and, therefore, we characterised temporally the distribution and density of epidermal growth factor receptor (EGFr) in normal and peptic-injured gastric squamous epithelium of horses. Lesions were induced in the equine gastric squamous epithelium using a feed deprivation protocol that results in prolonged increased gastric acidity. Fifteen mature horses, 9 geldings and 6 mares, age 3 to 20 years, were used and divided into 3 groups: Group 1 (n = 5) were subjected to euthanasia for problems unrelated to ...
Wedge-shaped conformation of the dorsolateral aspect of the third tarsal bone in the Thoroughbred racehorse is associated with development of slab fractures in this site. Anecdotal evidence suggested that many cases of third tarsal bone (T3) fracture encountered clinically were associated with an abnormal shape to this bone. The radiographs of 10 normal horses and 10 horses affected with slab fracture of T3 were therefore examined to ascertain if any pre-existent radiological abnormality was present in cases of fracture. Measurement of the maximum and minimum width between the proximal and distal articular surfaces of the dorsolateral aspect of this bone was carried out on a standardised dorso-50 degrees medial-palmarolateral radiographic projection of the tars...
Vestibular signs associated with suspected lightning strike in two horses. Two previously healthy 14-year-old horses developed right-sided unilateral vestibular signs after they had possibly been struck by lightning. Repeated radiographic and endoscopic evaluations did not reveal any significant changes. A brainstem auditory evoked response test indicated a subtle left to right interaural latency difference of waves I, III and V in the more severely affected pony, but its central conduction time remained normal.
Arthroscopic anatomy of the equine temporomandibular joint. To develop an arthroscopic approach to, and describe the arthroscopic anatomy of, the equine temporomandibular joint (TMJ). Methods: Cadaveric study, after which the technique was tested in horses. Methods: Ten cadaveric equine heads and 5 normal horses (age, 5-13 years; weight, 425-545 kg). Methods: Specimens or horses were positioned in right lateral recumbency. After fluid distention of the TMJ, arthroscopic portals were made in the dorsal compartment over the most prominent portion of the joint outpouching (caudodorsal approach) and in rostral and intermediate locations. The joint was expl...
Effects of superior check desmotomy on flexor tendon and suspensory ligament strain in equine cadaver limbs. To measure the effects of transection of the accessory ligament of the superficial digital flexor (SDF) muscle (superior check desmotomy) on flexor tendon and suspensory ligament (SL) strain in vitro. Methods: In vitro experimental biomechanical investigation. ANIMALS USED: Ten equine cadaver forelimbs. Methods: The effects of superior check desmotomy were determined using equine cadaver forelimbs secured in a servocontrolled hydraulic testing machine. Strain sensors were used to measure strain on the superficial and deep digital flexor tendons and SL, and a goniometer was used to measure join...
Detailed ultrasonographic mapping of the pelvis in clinically normal horses and ponies. To map the equine pelvis using ultrasonography, validated by use of computed tomography (CT), magnetic resonance imaging (MRI), and measurements of frozen cadaver slices. Methods: 6 ponies and 6 horses. Methods: Ultrasonographic examination of the pelvis was performed on 6 clinically normal ponies. Measurements were obtained for imaged structures. Computed tomography, MRI, and measurements of frozen sections were performed after death and used to verify measurements. Linear regression determined the degree of correlation between measurements obtained ultrasonographically and the other modaliti...
Podotrochlear bursa endoscopy in the horse: a cadaver study. To evaluate podotrochlear bursa (navicular bursa) endoscopy as a diagnostic technique in horses and to correlate observations to radiographic and pathologic findings. Methods: Descriptive study. Methods: Seventeen equine cadaver forelimbs. Methods: Five standard radiographic views of the navicular region and a bursographic study with lateromedial and caudal tangential radiographic views were taken of each forelimb. Radiographic scoring of the navicular bone (0, excellent; 1, good; 2, fair; 3, poor) was performed using a previously reported technique. Endoscopic examination was performed using ...
