Fig. 10.10 An illustration of the complexity of the innervation of the trigone. Responses are shown of strips of human superficial trigone to transmural nerve stimulation. In (a) parameters were chosen which produced contractile responses only, whereas in (b) both contractile and relaxant responses are apparent. In (a) the filled circles show the control responses. The open circles show responses in the presence of atropine (10~6M) to block the cholinergic response, the filled squares in the presence of phentolamine (10-6 M) to block the adrenergic response, and the open squares in the presence of both drugs. Note there is still a non-adrenergic, non-cholinergic response left. These results suggest that the trigone is innervated by at least three types of excitatory nerve and an inhibitory one.

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Bladder neck chapter 10

The bladder neck smooth muscle is histologically and pharmacologically distinct from the detrusor proper. Muscle bundles are much smaller, and in the male these are mainly circularly oriented, so that there is a collar of smooth muscle round the bladder neck (the internal sphincter), contraction of which probably prevents retrograde ejaculation. Cholinergic and noradrenergic nerve fibres supply this muscle and the smooth muscle of the proximal urethra. In the female, the muscle bundles extend obliquely and longitudinally from the bladder neck into the urethral wall, and there is no true internal sphincter, although the bladder neck is normally closed during filling. The innervation of the female bladder neck is largely cholinergic, with only a sparse sympathetic supply.

Renal, Urinary and Reproductive Tract Systems

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