SPINALIS 



1356 



SPINE 



side of the spinous processes of the vertebral column . 

 S. Incurvation. See Lordosis. S. Irritation. See 

 Neurasthenia, Spinal. S. Localization, the deter- 

 mination of the functions of the various portions of the 

 spinal cord. S. Marrow, the spinal cord itself within 

 the vertebral canal. S. Nerves, the 31 pairs of 

 nerves arising from the cord are grouped into pairs 

 each, Cervical 8, Dorsal 12, Lumbar 5, Sacral 5, Coc- 

 cygeal I. Each arises by two roots, a dorsal (gan- 



Superior or Cervical 

 Segment of Spinal 

 Cord. 



Middle or Dorsal 

 Portion of Cord. 



Inferior Portion of 

 Cord and Cauda 

 Equina. 



1. Floor of fourth ventricle. 2. Superior cerebellar peduncle. 3. Middle 

 cerebellar peduncle. 4. Inferior cerebellar peduncle. 5. Enlargement at 

 upper extremity of postero-median column. 6. Glosso-pharyngeal 

 nerve. 7. Vagus. 8. Spinal accessory. 9, 9, 9, 9. Ligamentum denticu- 

 latum. 10, 10, 10, 10. Posterior roots of spinal nerves. 11, n, 11, 11. 

 Postero-lateral fissure. 12, 12, 12, 12. Ganglia of posterior roots. 13, 13. 

 Anterior roots. 14. Division of united roots into anterior and posterior 

 nerves. 15. Terminal extremity of cord. 16, 16. Filum terminale. 17, 

 17. Cauda equina. I, VIII. Cervical nerves. I, XII. Dorsal nerves. 

 I, V. Lumbar nerves. I, V. Sacral nerves. 



gliated) root, and a ventral (anterior, non-gangliated) 

 root. On the dorsal root is the spinal ganglion. 

 Beyond the ganglion the two roots unite to form, in the 

 spinal canal, the mixed trunk of a spinal nerve. 

 The ventral roots supply efferent fibers to all the 

 voluntary muscles of the trunk and extremities, to 

 the smooth muscular fibers of the bladder, ureter, 

 uterus, etc., vasomotor, inhibitory, secretory, and 

 trophic fibers. The dorsal roots intermediate sen- 

 sory and tactile impulses. S. Point. See Point 

 apophvsaire and Craniometric Points. S. Reflexes. 

 See Reflexes, Table of. S. System, the spinal cord 

 and nerves considered as a whole. 



Spinalis {spi-na' -lis). See Muscles, Table of. 



Spinate (spi'-ndt) \spinatus , having spines]. Armed 

 with spines or thorn-shaped processes. 



Spindle (spin'-dl) [ME., spindle, spindle]. A taper- 

 ing rod or pin. A body having a fusiform shape. 



S., Achromatic, S., Cleavage, S., Karyokinetic, 

 S., Nuclear, S., Segmentation, the double, cone- 

 like appearance of the nucleus during certain stages 

 of karyokinesis. S. -cataract, a form of cataract 

 characterized by a spindle-shaped opacity extending 

 from the posterior surface of the anterior portion of 

 the capsule to the anterior surface of the posterior 

 portion of the capsule, with a central dilatation. S.- 

 cell, a fusiform cell. S. -celled, having fusiform 

 cells, a form of cell typical of certain mor- 

 bid growths, especially sarcoma ; fuso- 

 cellular. S. -legged, having long, thin 

 legs. S.-oils. See Lubricating Oils. S.- 

 shanked. Same as, S.- legged. S. -shaped, 

 shaped like a spindle. Fusiform. 

 Spine (spin) [spina, a thorn, a prickle]. In 

 biology, (a) a sharp-pointed dermal out- 

 growth; (b) a point or process of a bone; 

 a sharp, hard, stiff bone or ossicle ; (c) a 

 back -bone or spinal column, so called froir 

 its spinous processes. S.-ache, pain ir 

 or about the spine. S., Cauda equina 

 of. See Cauda equina. S., Cleft, 01 

 Cloven. See Spina bifida. S., Cruciate 

 See S. of Tibia. S., Ethmoid, the spin* 

 on top of the sphenoid bone. S., Filurri 

 terminale of. See Filum terminale. S. 

 Frontal. See Frontal Crest. S., Hemall 

 the part that closes in the hemal arch of i 

 typical vertebra. Ss., Iliac, there are foui 

 of these : the anterior inferior is the emi ! 

 nence immediately above the acetabulum I 

 the anterior superior is the anterior termi 

 nation of the crest; the posterior inferior x\ 

 a slight eminence upon the margin imme 

 diately above the great sciatic notch; tin I 

 posterior superior is the posterior extremity 

 of the crest. S., Irritable. See Spina 

 Irritation. S., Ischiatic. See S. of Isch\ 

 turn. S. of Ischium, a pointed emineno 

 on the posterior border of" the body of th 

 ischium. It is the lower border of ftnj 

 great sciatic notch. S., Mental. Se>! 

 Genial Tubercles. Ss., Nasal, there ar> 

 three of these : the anterior, or nasal spin 

 of the superior maxillary, is the inferio 

 sharp edge of the nasal crest of this bone 

 the posterior, or nasal spine of the 

 bone, is the prominence upon the posterio 

 margin of the palatal plate of the palat 

 bone ; the third, or common nasal 

 is the sharp process projecting from the 

 die of the inferior surface of the front! 

 bone. S., Neural, the part that closes i 

 the neural arch of the typical vertebra. S., Occipita' 

 External, the external occipital crest. S., Palatine' 

 See S., A T asal. S., Pharyngeal, the ridge on th 

 under surface of the basilar process of the occipitf 

 bone. S. of the Pubes, the prominent tubercle oi 

 the upper border of the body of the pubes. S 

 Pubic. See 5. of the Pubes. S., Railway, th' 

 designation given to a series of nervous symptom 

 developed from shock produced by a railway accidei 

 or from the concussion produced by constant travfc 

 S. of the Scapula, the plate of bone crossing th 

 dorsum of the scapula and dividing it into two ui 

 equal parts. S., Sciatic. See S. of Ischium. S 

 Sphenoid, the spinous process of the greater win 

 of the sphenoid bone. S. of the Sphenoid. Se 

 .V., Sphenoid, and .V.. Ethmoid. S. of the Tibif; 

 the elevation ujwn the upper surface of the t i 1 -> i = 

 between its two articulating surfaces. S., Typhoid 



