Victor: As you know, the the CNS is made of the brain and spinal cord. The cauda equina is formed because, after age 4, the spinal cord stops growing but the vertebral column continues to grow. This vertebral growth carries with it the spinal nerves and the dorsal root ganglia farther from their original position relative to the adult spinal cord. As a result of this, the dorsal and ventral roots gradually elongate. The long ventral and dorsal roots that extend caudal to the conus medullaris form the cauda equina. (Human Anatomy, 5th ed., Martini, Timmons and Tallitsch). Now, the question is this: Is the CNS composed of the brain, spinal cord and the ventral roots and dorsal root ganglia of the spinal nerves, or just the brain and spinal cord. That the cauda equina is surrounded by the meninges does not mean it is part of the CNS. The blood vessels that supply the brain and spinal cord are (at least in part) covered by the meninges, but they are not part of the CNS--they are part of the cardiovascular system. Spinal nerves, as well as the dorsal and ventral roots of the spinal nerves, are not typically considered to be part of the CNS, even though the proximal portions of the ventral and dorsal roots are covered by meninges. So, even through there is no clear cut definition in the sources I can find, my vote would be that the cauda equina is NOT part of the CNS Bob Tallitsch -----Original Message----- From: valvarez@xxxxxxxx [mailto:valvarez@xxxxxxxx] Sent: Wed 21-Mar-07 3:20 PM To: HAPS-L@xxxxxxxxxxx Subject: Re: [HAPS-L] Cauda Equina Is the cauda equina part of the CNS or PNS? (It is still surrounded by the meninges...) Thanks in advance, Victor -- Victor Alvarez, D.C., M.A. Delaware Technical and Community College Stanton Campus 400 Stanton-Christiana Rd. Newark, DE 19713-2111 (302) 454-3951 ************************************************************ Robert B. Tallitsch, Ph.D. Professor of Biology Augustana College 639 38'th Street Rock Island, IL. 61201-2296 Internet: RobertTallitsch@xxxxxxxxxxxxx Web Page: http://www.augustana.edu/users/bitallitsch Office telephone: (309)794-3441 FAX: (309)794-7722 (please mark to my attention) ALTERNATE FAX: (309)794-8399 (please mark to my attention) ************************************************************ I am a teacher. A teacher is someone who leads. There is no magic here. I do not walk on water, I do not part the sea. I just love my students. (adapted from Marva Collins) ************************************************************ Teaching is the playful search and discovery with others for the potential in each of them?and in me. (Louis Schmier) ************************************************************ Confidentiality Notice: This email and its attachments may contain confidential and/or copyrighted material. If you were not an intended recipient, please do not read, copy, use or disclose this communication to others; also please notify the sender by replying to this message, and then delete it from your system. Thank you. We may monitor email to and from our network.
<<winmail.dat>>