The remaining hind limb anatomy of the sea otter corresponds well with that of terrestrial mustelids ( Fig. This enlargement corresponds to the use of the lateral surface of the pes to lead during the power stroke of the limb. The flexor digit V muscle is very large in the sea otter (relative to other mustelids). The biceps femoris muscle inserts onto the middle of the tibia and maintains the leg in a posterior position. As with pinnipeds, the fovea capitis is absent from the femur, marking the absence of the teres ligament. Pads are present on the phalangeal portion of each toe and are variably found ventral to the metatarsals. The hair densities for the ankle and interdigital webbing have been estimated at 107,0 hairs/cm 2, respectively, compared to a density of 125,000 hairs/cm 2 for the back. While swimming, sea otters use the hind feet to generate thrust and sweep the leg through the water such that the fifth digit forms the leading edge of the pes. The sea otter is unusual in that in overall length the digits decrease in size from the fifth to the first: V > IV > III > II > I. The digits are bound together by interdigital webbing, although the fourth and fifth digits are bound more closely together than other adjacent digital pairs.
Human webbed feet skin#
Externally, the leg is enclosed within the loose body skin to the approximate level of the ankle. Departures of sea otter hind limb anatomy from that of other terrestrial mustelids ( Tarasoff 1972 Tarasoff et al., 1972 ), however, are seen more readily. Adam, in Encyclopedia of Marine Mammals (Second Edition), 2009 B Polar Bears and Sea OttersĪdequate descriptions of polar bear ( Ursus maratimus) pelvic and hind limb anatomy have not yet been made, but there is little indication that the morphology of this species has diverged appreciably from that of other species of Ursus. Abnormal apoptosis regulation during development can therefore lead to a variety of developmental defects, including structural abnormalities, changes in immune function, reproductive system disorders, and other potential diseases. In these conditions, cells are eliminated in response to viral infection, unrepaired DNA damage, cell cycle alterations, and cell fate and differentiation defects. An important function of apoptosis is to serve as a “guardian” regulating the quality of developing and differentiating cells and removing abnormal and potentially dangerous cells. Additionally, many developing organs, including those within the nervous, immune, and reproductive systems, exhibit an overproduction of cells which are eventually removed via apoptosis in order to achieve appropriate cell numbers. During development, apoptosis is also involved in the removal of structures that are sex-specific, evolutionary relics, and structures that are transiently required. It is well established that programmed cell death, primarily through apoptosis, removes the interdigital webbing between fingers/toes in higher vertebrates, and it also is required for the generation of the four chamber heart architecture, among many other developmental sculpting events. For instance, apoptosis dictates the elimination of cells required for proper organogenesis and tissue remodeling. Rager, in Systems Biology in Toxicology and Environmental Health, 2015 Developmental DisordersĪpoptosis is critically involved in various events carried out during animal development. Hyperextension of the elbow may produce pain in dogs with an ununited anconeal process, whereas internal and external rotation with digital pressure applied at the medial joint line may produce pain that accompanies conditions such as OCD or a fragmented coronoid process. The elbow is similarly placed through a range of motion. The radiocarpal joint space lies at the same level as the base of the accessory carpal bone. This helps to rule out joint problems from distal radial swelling seen with neoplasia or hypertrophic osteodystrophy. Swelling detected on the standing examination is better identified when the exact location of the joint space can be identified. Palmar stress to the carpus is applied to assess for hyperextension injury and, if present, determine the anatomic location. The carpus is flexed and extended, and a valgus/varus stress is applied. The proximal sesamoid bones are palpated for swelling on the palmar aspect of the paw at the metacarpophalangeal junction. The interdigital webbing and foot pads are examined for discoloration, abrasions, and other conditions. The digits are flexed, extended, and examined for swelling, crepitus, and pain. Schaefer MS, DVM, in Brinker, Piermattei and Flo's Handbook of Small Animal Orthopedics and Fracture Repair (Fifth Edition), 2016 Paw and elbow
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