נד בעי רבי ירמיה
54 - Rab Judah said in the name of Samuel: Up to the interval between the branch nerves.<span class="x" onmousemove="('comment',' Heb. , 'between the partings', i.e., that part of the cord between the pairs of nerves that branch off from the cord (Rashi, first interpretation) . It must be observed that the spinal cord is a long, almost cylindrical rod of nerve tissue accommodated in the vertebral canal, and it extends from the skull to about the middle of the sacrum (the bone at the lower end of the spine and is wedged in between the hip bones) . At intervals along the entire length of the cord are given off pairs of spinal nerves (thirty-seven in number, classified as eight cervical, thirteen thoracic, six lumbar, five sacral, and five coccygeal) which break up into branches, and these again into smaller ones until almost every tissue in ,uarp the body is reached. These spinal nerves (called in the text 'branch nerves': Heb.) as they emerge from the vertebral canal are at once concealed in muscles and are not visible, with the exception of the first three sacral nerves which are visible and soon unite to form the sacral plexus from which proceeds the sciatic nerve, the largest nerve in the body. Accordingly the intervals between the branch nerves spoken of in the text will refer to the length of spinal cord between the first pair of sacral nerves and the second, and between the second pair and the third. The significance of Samuel's statement is that any severance of the cord below the interval is of no consequence and the animal is valid.');"><sup>22</sup></span>