Quain's elements of anatomy . heir blmitconical anterior ex-tremity, over which itexpands so as to formthe glans penis alreadydescribed. In thewhole of this extentit encloses the urethra. The posterior bulbous part, or lulb of the urethra, varies in size indifferent subjects. It receives an investment from the triangular liga-ment on which it rests, and is embraced by the accelerator uringe, orbulbo-cavernosus muscle. The posterior extremity of the bulb exhibits,more or less distinctly, a subdivision into two lateral portions or lobes,separated by a slight furrow on the lower surface, and by a
Quain's elements of anatomy . heir blmitconical anterior ex-tremity, over which itexpands so as to formthe glans penis alreadydescribed. In thewhole of this extentit encloses the urethra. The posterior bulbous part, or lulb of the urethra, varies in size indifferent subjects. It receives an investment from the triangular liga-ment on which it rests, and is embraced by the accelerator uringe, orbulbo-cavernosus muscle. The posterior extremity of the bulb exhibits,more or less distinctly, a subdivision into two lateral portions or lobes,separated by a slight furrow on the lower surface, and by a slenderfibrous partition within, which extends for a short distance forwards ; inearly infancy this is more marked. It is above this part that themethra, having pierced the triangular ligament, enters the bulb,sinrounded obliquely by a portion of the spongy tissue, named by Kobeltthe colliculus hulM, from which a layer of venous erectile tissue passesback upon the membranous and prostatic portions of the urethra to the X X 2. 676 THE PENIS. neck of the bladder, lying closely beneath the mucous membrane. Atfirst the urethra is nearer the upper than the lower part of the corpusspongiosum, but it soon gains and continues to occupy the middle ofthat body. Structure.—This is essentially the same as that of the corporacavernosa, but with a much less developed fibrous framework. Like thecorpora cavernosa, it is distended with blood during erection, but itnever acquires the same rigidity. The fibrous tunic (fig. 588, 1)is much thinner, is less white in colour, and contains more elastictissue ; the trabeculee are finer and more equal in size ; the areolaeare smaller, more uniform, and directed for the most part withtheir long diameter in the line of that of the penis ; in the glans,the meshes are smallest and most uniform. Plain muscular fibresimmediately surround the canal of the urethra, and also form part ofthe external coat of the spongy substance. A considerable arteryderived fr
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