![]() The veterinarian contacts the horse at the ventral aspect of the transverse process, ipsilateral to the affected cervical motion segment with the caudal hand, with thenar contact. The veterinarian's position is standing directly in front of the patient, ipsilateral to the side of restriction, facing caudally. Upon motion palpation, the veterinarian finds restriction in flexion of the C2 to C5 vertebrae. It eats or drinks from ground with a scissor stance (foal posture). The horse is not able to lower head and neck. ![]() The C2-T2 articular facet orientations support relatively large ranges of flexion extension and coupled motion of combined rotation and lateral bending. The articular facet orientation of the caudal C2 to T2 vertebrae, relative to the lateral aspect of the neck, lie at about 45 degrees to the long axis of the neck. The cervical vertebrae have relatively large articular facets compared to the vertebrae in other vertebral regions. McCormick, in Equine Geriatric Medicine and Surgery, 2006 Middle and Lower CervicalRegion (C2 to C7) Normal Joint BiomechanicsĪrticular processes support both vertebral stability and mobility due to the interlocking articular surfaces. Comparison of the left and right synovial intervertebral articulations of the same intervertebral joint is helpful to assess size and shape. 19 This joint space is limited dorsally by a thin articular capsule. On each side the joint space separating the cranial (lateral) and caudal (medial) articular process can be identified. On transverse ultrasonographic images obtained using 2.5- to 5-MHz probes, the synovial intervertebral articulations can be imaged ( Figure 52-15). The cranial articular process is extended dorsocranially by a mammillary process, which is larger in the thoracic area than in the lumbar area. The thickness of the dense subchondral bone of the cranial articular process increases caudally. The caudal articular process is dorsal to the corresponding intervertebral foramen and is triangular with a caudal apex in the lumbar region. Usually, the joint space is linear and makes a 40-degree angle with the horizontal (see Figure 52-14). At the thoracolumbar junction and in the lumbar region the joint space is less well defined. Between T12 and T16 the joint space is a wide V shape, with a cranial oblique branch and a shorter vertical caudal branch (see Figure 52-13). 6 The radiolucent cartilaginous joint space is thin and more clearly defined in the thoracic areas, where the articular facets are flat (see Figure 52-12), than in the lumbar area because of the condylar shape. Oblique radiographic images from left to right and right to left permit evaluation of the left and right synovial intervertebral articulations independently. In some horses the ribs are extremely convex dorsally and are superimposed over the thoracic and the first lumbar synovial intervertebral articulations, prohibiting assessment. On the extremities of the film, the images of the left and right synovial intervertebral articulations are progressively dissociated because of the divergent x-ray beam. ![]() On lateral radiographic images, in the middle of the film, the left and right synovial intervertebral articulations are superimposed. The articular processes' synovial intervertebral articulation complex is located dorsal to the vertebral canal and is composed of the caudal articular process of one vertebra, the joint space, and the cranial articular process of the following vertebra ( Figures 52-12 through 52-14). Dyson, in Diagnosis and Management of Lameness in the Horse (Second Edition), 2011 Normal Anatomy
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