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CHAPTER 26
thalamic tract results in immediate disorganization of the micturition reflex. However,
as to whether the fibres descending from the facilitatory cerebral centres transverse into
lateral columns and those of the inhibitory areas run into the ventral columns still needs
clarification. Kuru
et al.
(1960) studying the connections of the pontine area with the
Marchi degeneration technique found descending fibres running down into the lateral
reticulo-spinal tract decussating at the midlumbar level of the spinal cord and terminating
in the intermedio-lateral cell column of the sacral cord. They also found afferent con
nections to the thalamus. Nathan & Smith (1958) concluded from their studies following
cordotomy in man that the pathways for voluntary control of micturition lay in a trans
verse equatorial plane passing through the ependymal canal. Efferent and afferent fibres
running more medially. However, their evidence given by their anatomical sections of the
cord following cordotomy does not appear to be conclusive.
Spinal segmental and peripheral control of micturition
The synaptic connections of ascending and descending nervous pathways subserving
micturition take place in the lumbo-sacral segments of the spinal cord which represent
the spinal micturition reflex centre. Destruction of this centre, in particular of its sacral
part, results in depriving the bladder of its reflex function and it has to rely on its intra
mural autonomous nerve supply only. From the spinal vesical centre originates the
peripheral control and integration of vesical reflex function. The efferent and afferent
components involved in the peripheral innervation of the forces of expulsion and
retention are:
A. EFFERENT INNERVATION
i.
The sympathetic innervation
derives from L2, L3 and L4 segments. Their pre-gang-
lionic fibres pass to the inferior mesenteric ganglion and their post-ganglionic fibres
traverse through the hypo-gastric nerves to the bladder wall and urethra. The participa
tion of the sympathetic innervation in the act of micturition has been the subject of
controversies for some time. In particular, the effects of stimulation of the sympathetic
nerves on micturition are not unequivocal. The old concept (Elliott, 1907) that the
hypo-gastric nerves constrict the sphincter and inhibit the tone of the detrusor muscle
has been rejected by Van Duzen (1932) and Evans (1936), who found no convincing
evidence that the sympathetic system plays any part in the act of micturition, especially
with regard to the internal sphincter complex. Other investigators supported the view that
sympathetic stimulation results in contraction of the internal sphincter orifice and the
detrusor, followed immediately by the latter's relaxation (Learmonth, 1931; Langworthy,
Kolb & Lewis, 1950; Kuntz & Saccomano, 1944; Ingersoll, Jones & Hegre, 1954). See
also Burgheli's and Ichim's observations reported above. Langworthy and his colleagues
held the view that sympathetic stimulation is mainly concerned with the mechanism of
ejaculation, and Learmonth found discharge of seminal fluid in man following stimulation
