334 



THE SPINAL CORD. 



receives the sensory fibers of the nerves which form the cervical 

 and brachial plexuses. 



The lumbar enlargement (intumescentia lumbalis] begins at 

 the tenth thoracic vertebra and increases to the twelfth (Figs. 

 100 and 101). Opposite the first lumbar vertebra, it tapers off 



: imtim*mr-^* /uiv 



Superior or Cervical Segment Middle or Dorsal Portion Inferior Portion of Cord and 

 of Spinal Cord. of Cord. Cauda Equina. 



Fig. 100. Posterior view of the spinal cord, the dura mater and the arachnoid 

 being laid open and turned aside. (Brubaker after Sappey.) 



i. Floor of fourth ventricle. 2. Brachium conjunctivum. 3. Brachium pontis. 4. Res- 

 tiform body. 5. Clava. 6. Glossopharyngeal nerve. 7. Vagus. 8. Accessory nerve. 9, 9, 9, 9. 

 Ligamentum denticulatum. 10, 10, 10, 10. Posterior roots of spinal nerves, n, n, II, n. 

 Posterior lateral sulcus. 12, 12, 12, 12. Spinal ganglia. 13, 13. Anterior roots of spinal 

 nerves. 14. Anterior and posterior divisions of spinal nerve. 15. Conus medullaris. 16, 16. 

 Filum terminales internum. 17, 17. Cauda equina. I-VHI. Cervical nerves. I-Xn. Tho- 

 racic nerves. I-V. Lumbar nerves. I-V. Sacral nerves. 



almost to a point, the conus medullaris; but a very small process 

 continues in the filum terminate internum. From the lumbar 

 enlargement rise the motor fibers of the nerves contained in the 

 lumbar and sacral plexuses, and into it enter the sensory fibers 

 of the same plexuses. 



