Abstract

SPINAL CORD- A CADAVERIC STUDY

Author(s): Vijayamma K. N, Ushavathy P, Margret William

BACKGROUND Spinal cord is situated within the vertebral canal extending from the lower end of the medulla oblongata at the upper border of first cervical vertebra. In early foetal life, it extends throughout the length of the vertebral canal, and at the time of birth, it reaches the level of third lumbar vertebra. In adult, it ends at the lower border of first lumbar vertebra and thereafter continued as filum terminale, which gets attached to tip of coccyx. Spinal cord is covered by three protective membranes called spinal meninges, diameter, arachnoid and pia mater. The diameter and arachnoid mater extent up to second sacral vertebra and the pia mater forms filum terminale and extend at the tip of coccyx. MATERIALS AND METHODS Forty spinal cord cadaveric specimen were studied by dissection method after exposing the vertebral canal. The roots of spinal nerve were sectioned on both sides and the cord is released along with its coverings. The dura and arachnoid mater were incised longitudinally and the subarachnoid space, blood vessels, nerve roots, ligament denticulata, cervical and lumbar enlargements were observed. The blood vessels including radicular arteries were also studied photographed. RESULTS The spinal cord is a highly vascular structure situated within the vertebral canal, covered by diameter, arachnoid mater and pia mater. Spinal dura is thicker anteriorly than posteriorly. The pia mater forms linea splendens, which extend along the whole length of the cord in front of the anterior median fissure. The average length of the cord is 38 cm. The length and breadth of cervical enlargement was more compared to lumbar enlargement. The number of rootlets in both dorsal and ventral roots accounts more in cervical compared to other regions of the cord. The ligament denticulata is a thin transparent bands of pia mater attached on either sides of the cord between the dorsal and ventral roots of spinal nerves. The tooth like extensions are well developed in cervical and upper thoracic region and become thin in the lower thoracic and lumbar regions. The last tooth of the ligament elongated and tendinous. The cord was surrounded by rich vascular plexus and seen more towards the lower and posterior aspect. CONCLUSION Spinal cord is a highly vascular neuronal structure situated within the vertebral canal covered with meninges and anchored by ligamentum denticulatum on either sides. It has a unique vascular anatomy. The anterior and posterior radicular arteries provide very crucial role in the vascular supply of the cord. Arteria radicular magna was observed in 70% of specimens, of which 50% at T11 segmental level. A profuse vascular anastomosis was observed around the cord between the branches of anterior and posterior spinal arteries supplemented by radicular arteries in the lumbar and sacral segments of the cord.