B • ANATOMY, NEUROPATHOLOGY AND REGENERATION
69
FIG.
2jb.
Dorsal view of the sacral region of the spinal cord, (i) Dorsal rootlet.
(2) Posterior spinal vein. (3) Posterior spinal artery; particularly large on this side because
of a large feeding vessel entering cranial to this photograph. Note large communications
(4) with smaller left posterior spinal artery. (5) Cut dorsal rootlet. (6) Two small feeding
vessels to the posterior spinal artery dissected off the cut dorsal rootlets (from Romanes
(1965),
Paraplegia,
2, 199).
thoracic arteries. In certain cases, however, the whole cervical cord down to
Cj
segment
receives its supply from the vertebral arteries only. Figs. 28a and b show variations in
the descending branches of the vertebral arteries. While in Fig. 28a the descending
branch is well developed on the right side, the left branch is only rudimentary. Fig. 28b
shows both descending branches well developed and united at the level of Ci into one
single branch. On the other hand the anterior spinal arteries may descend separately
over several segments of the cervical cord as shown in Fig. 28c.
With regard to the anterior radicular arteries, 296 were accounted for, of these, 138
in the cervical, 118 in the thoracic, 31 in the lumbar and 9 in the sacral region, and a
distinction is made between large, medium, small and minute sizes. Fig. 28d shows a
synoptic segmental representation of these 4 arterial categories in the various regions of
the cord. In the cervical region there is a prevalence of a great number of vessels of all 4
categories between C4 and C8 segments in particular of medium, small and minute
sizes, while the thoraco-lumbar region, T9-Li is supplied mainly by large vessels.
In accordance with previous workers Piscol found the contrast filling of posterior
radicular arteries more difficult because of their smaller calibre. In 39 preparations he
found 431 posterior radicular arteries, of these, 94 in the cervical and 229 in the thoraco-
lumbar region. The largest supply of medium and small size vessels were found in the
cervical areas between 4 and
Cj
corresponding to the cervical intumescence, while the
supply with the largest size vessels was found between Tio and L2, in particular, in Ti2
and Li.
