Rectum, anatomy

FIGURE 88-1. Colon and rectum anatomy. (From DiPiroJT, Talbert... 

Anatomy and Physiology of the Rectum and Its Role in Drug Absorption... 

Gross and microscopic anatomy. Nematodes are bounded externally by a complex, multilayered cuticle that extends into and lines the pharynx, rectum, cloaca and other orifices. The cuticle represents an extracellular secretion of the hypodermis, an anatomical syncytium that forms a continuous cellular layer immediately beneath the cuticle and is specialized for transport and secretion. Though the cuticle and hypodermis are morphologically distinct, they represent a functional unit (Fig. 12.3). 

Fig. 12.1a-c. CT anatomy of the normal vagina. a,b CT. c Sagittal CT reconstruction. CT anatomy of the vagina - middle third at the level of the urinary bladder (a) and distal third at the level of the urethra (b). The vagina has the same density as the walls of the bladder, urethra, and rectum and can be distinguished from these structures on CT by the presence of a small fat layer. For differentiation of the vagina, it is also helpful if the bladder is filled with urine and the rectum is filled with air... 

FIGURE 6 Planning and execution of MRI-guided prostate brachytherapy. Left three-dimensional model of the prostate, tumor, rectum, bladder, and seminal vesicles. The pelvic anatomy was segmented based on MR images. Middle the planning of the procedure. The peripheral zone and central zone of the prostate are depicted on a cross-sectional MRI slice acquired with an endorectal coil. The dashed lines represent individual needle trajectories. Right display of dose distribution on two-dimensional MRI of the prostate. 

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