DISSECTION OF THE HEAD AND NECK 



241 



closely does this membrane invest the 

 cordf Note its extreme vascularity. 

 What is meant by the term " lepto- 

 meninx ' ' ? 



Study the lig amentum denticu- 

 latum. Where is the medial border 

 of the ligament inserted? On the lat- 

 eral border note the teeth and the 

 free arcades intermediate between the 

 teeth. Into what are the summits of 

 the teeth inserted! What is the rela- 

 tion of the ligamentum denticulatum 

 to the anterior and posterior roots? 

 The number of teeth varies from eigh- 

 teen to twenty-three. How many are 

 there in your subject? What is the 

 function of the ligament? 



Study the relations of the spinal 

 nerve roots to the pia, the arachnoid, 

 and the dura. (Cf. Poirier et Charpy, 

 iii., Fig. 103.) 



The Spinal Nerves (Nervi spinales). 

 (Figs. 99 and 100.) 



Count these on each side. Distin- 

 guish the cervical nerves (Nn. cervi- 

 cales, I -VIII.}, the thoracic nerves 

 (Nn. thoracales, I.-XIL), the lumbar 

 nerves (Nn. lumbales, I.-V. ) , the sacral 



Spinal cord in connection above with the medulla 



oblongata and pons. 



V, nervus trigeminus ; XII, nervus hypoglossus; C\, first 

 cervical nerve ; C*2-8, second to eighth cervical nerve ; Tl-12, 

 first to twelfth thoracic nerve ; L 1-5, first to fifth lumbar 

 nerve ; S 1-5, first to fifth sacral nerve ; G, nervus coccygeus ; 

 x, x, filum terminale of the spinal cord. From the root 

 marked LI to x, cauda equina; Rr, plexus brachialis; CV, 

 nervus femoralis ; Sc, nervus ischiadicus ; 0, nervus obtura- 

 torius ; the enlargements opposite L 3, 4, and 5 represent 

 the spinal ganglia on the dorsal roots. On the left side of 

 the figure the sympathetic trunk is shown, a to as are 

 ganglia; a, ganglion cervicale superius; & and c, ganglion 

 cervicale medium et inferius; d, first thoracic ganglion; 

 d', last thoracic ganglion ; I, first lumbar ganglion ; ss, first 

 sacral ganglion. (After Allen Thompson, from A. Rauber, 

 Lehrbuch der Anatomie des Menschen, V. Aufl., Leipz., 1898, 

 Bd. ii. S. 504, Fig. 485. ) 



16 



FIG. 100. 



V 



2 Rr 



