STUDY ON THE DEVELOPMENTAL-CHANGES IN ANGULATION OF SPINAL NERVES, THE LENGTH OF THE DORSAL ROOTS AND SPINAL NERVES IN SHEEP

This study reports the angulation of spinal nerves, the length of dors al roots, the length of spinal nerves and the transverse and vertical diameters of the spinal cord during pre-and postnatal life in sheep of the Mehraban breed in Iran. The spinal cord of these animals was divi ded into 4 regions with respect to the angulation of spinal nerves. Th e first region was from the first to fifth cervical and the second was from the sixth cervical to the eighth thoracic in fetuses and from th e six cervical to fourth thoracic in adults. The third region was from the ninth thoracic to second lumbar in fetuses and from the fifth tho racic to second lumbar in adults, and the fourth region was from third lumbar to fourth sacral in the animals of all age groups. The length of dorsal roots from their point of emergence from the spinal cord to the dorsal root ganglia showed a direct correlation with the length of the spinal nerves. While angulation of the spinal nerves showed a con verse correlation with the length of either spinal nerves or dorsal ro ots. The transverse diameters of the spinal cord were always longer th an the vertical diameters. The greatest diameters (vertical - 7.00 mm; transverse - 10.00 mm) are recorded at C-1, T-1 and L-6 in adult shee p.