Anatomy of the spinal cord of Alouatta belzebul

Abstract

The genus Alouatta hosts species popularly known as red-handed howler, presenting wide geographic distribution and being found in several biomes. The objective was describe the anatomy of spinal cord of Alouatta belzebul specimens, focusing on the topography of medullary cone, stressing the cervical and lumbar intumescences and cauda equina, to provide anatomical data and compare it with other species to assist in anesthetic and surgical procedures. Four animals were received for scientific research, post mortem, from the fauna rescue program of Hydroelectric Plant of Belo Monte, Pará, and they were fixed in 10% formaldehyde solution. Structures such as the medullary cone, cervical and lumbar intumescence, and cauda equina were photographed (Sony α200-10.2 mpx). After thawing, we measured the specimens and observed a size of 80 to 82 cm from head to toe. After the skin and musculature were removed, it was observed that the spine of all specimens presented 7 cervical, 13 thoracic, 5 lumbar and 3 fused sacral vertebrae. The spinal cord was exposed after the removal of vertebral arches, it has 22 cm length in all animals, presenting the cervical intumescence between C3 and C6 vertebrae, with average of 2.2 cm and lumbar intumescence between T11 and T12 vertebrae, with average of 1.65 cm. The medullary cone is located between T12 and L1 vertebrae, with average of 1.5 cm, and the cauda equina between L1 and S3, with an average of 15 cm. This study has an important role as the basis for epidural anesthesia in the species.