374 THE GENITO-URINARY SYSTEM 



a focus is usually set up by pathological conditions of the 

 bladder, it may also arise as the result of abnormal afferent 

 impulses from the large intestine. Frequency of micturition 

 is a frequent accompaniment of irritative conditions of the 

 rectum, and it is not uncommon in connexion with appendicitis 

 (p. 277). 



It is interesting to observe that cases of retention of urine 

 are occasionally mistaken for appendicitis, and that the passage 

 of a catheter is sufficient to remove the symptoms. 



The Prostate lies between the neck of the bladder and 

 the pelvic surface of the urogenital diaphragm (p. 379) and is 

 traversed by the first part of the urethra. It consists of 

 non-striped muscle fibres, which are continuous with the 

 corresponding coat of the bladder, fibrous tissue and glandular 

 tissue. On each side the prostate is related to the levator 

 prostatae (the anterior portion of the levator ani, p. 184), and, 

 posteriorly, it is only separated from the anterior aspect of the 

 rectal ampulla by some loose connective tissue. The posterior 

 aspect and the adjoining parts of the lateral surfaces of the 

 prostate can be palpated on rectal examination. 



Prostatic hypertrophy may be due to overgrowth of all or 

 any of its constituent tissues. When non-malignant, the 

 condition is only important in so far as it obstructs the outflow 

 of urine from the bladder. In this respect, enlargement of 

 the, so-called, middle lobe of the prostate is of great importance. 

 The portion of the organ which gets this name is situated 

 between the ejaculatory ducts and the urethra, i.e., in the 

 upper and posterior part of the prostate (Fig. 127). In some 

 subjects, it projects upwards and forms a small elevation in 

 the internal trigone of the bladder, immediately behind the 

 internal orifice of the urethra. When the middle lobe becomes 

 hypertrophied, the normal elevation becomes larger and is 

 crushed forwards over the internal orifice when the bladder 

 contracts. In these cases, therefore, the patient fails to 

 empty his bladder completely at each micturition. The 

 urine which is left behind is termed the " residual urine," and 



