F- CLINICAL ASPECTS OF SPINAL CORD INJURIES
315
1954; Mullner, 1958; Murphy & Schoenberg, 1960; Petersen
et
a/., 1962; Abramson
et at.,
1962).
Abramson and his associates combining electromyography of the pelvic floor muscles
with suprapubic cystometry, found a variable delay of detrusor contraction following
relaxation of the pelvic floor. The electrical silence of the striated muscles of the pelvic
floor preceded the detrusor contraction by 2-20 seconds. Bors (1963) came to the con
clusion that 'pelvic floor relaxation seems to precede or coincide with the detrusor
action more often than following it, depending on individual variations'. Hinman
et al.
(1954) found during cineradiography the following sequence of events in nulliparous
women:
1
Isometric detrusor contractions and opening of the internal sphincter.
2 Relaxation of the perineal muscles.
3
Emptying contractions of the detrusor.
4 Closure of the external sphincter.
5
Contraction of the perineal muscles and elevation of the bladder base.
6 Closure of the internal sphincter with relaxation of the detrusor.
HIGHER CONTROL OF MICTURITION BY
CORTICAL AND SUBCORTICAL STATIONS
From all that has been said, it is obvious that supraspinal stations—i.e. cortical and
subcortical structures—exert, under normal and pathological conditions, a considerable
influence on the complex act of micturition as they do on other autonomic mechanisms
such as gastro-intestinal function, vasomotor control, temperature regulation, sweating,
etc.
Cortical influences
Cortical centres situated in areas 4 and 6 are supposed to exert some degree of inhibitory
control of the reflex function of the bladder (Lewis, Langworthy & Dees, 1935). Kleist
(1934) and Foerster (1936) localized the cortical representation of bladder and rectum
in the lobulus paracentralis just above the fissura calloso-marginalis. Adler's hypothesis
(1920) of two cortical vesical centres, one for the detrusor, situated in the lobulus para
centralis, and the other for the vesical sphincter mechanism situated in the convexity
of the brain between the cortical representation of leg and arm, was not substantiated
by other authors (Kleist, 1934; Foerster, 1936). However, recently Gjone
et al.
(1963)
found in the chloralized cat that stimulation of the sensori-motor cortex elicited inter
mixed facilitatory and inhibitory responses on the micturition reflex. Actually, the absence
of inhibitory cortical control in the young infant is correlated to the late development of
cortical centres.
The representation of vesical function in the cortex is bilateral, and it is well known
that unilateral cortical and subcortical lesions have no or only very transient effect on
sphincter control, as has been confirmed in recent years by Rothfield & Rabiner (1954).
