Pelvis and Perineum

Pelvis and Perineum

Pelvis

Clinical Note

The crest of the ilium is the most common site for the harvesting of red bone marrow for allogenic or autologous transplantation after loss of marrow due to disease, or chemotherapeutic or radiation treatments for cancer. It is also the site for obtaining small samples of marrow for diagnostic purposes.

• The external surface of the iliac blade is the attachment site for the gluteus medius and minimus muscles. These two muscles are primarily responsible for maintaining pelvic stability when one foot is lifted off the ground (e.g., during the swing phase of walking). They both insert into the greater trochanter of the femur.

• The lunate surface is the articular part of the acetabulum.

• The symphyseal surface of the pubis undergoes predictable changes with aging so that the surface can be used to estimate the age of skeletal material collected forensically or archeologically.

Female Pelvis, Round Ligament, and Ovary

Clinical Note

Lipomas of the round ligament can mimic signs of hernia. They should be suspected in a woman with groin pain whose physical examination is normal.

• The round ligament passes through the inguinal canal to reach the labia majus. Lymph vessels travel with the ligament so that some lymph from the uterus drains to the inguinal nodes.

• The position of the ovary can vary within a patient with the amount of bladder and bowel distention and the patient’s position.

Female Pelvic Viscera, Sagittal View

Clinical Note

A rectocele occurs when the anterior wall of the rectum bulges into the vagina; this occurs because of weaknesses in pelvic support mechanisms (i.e., pelvic ligaments) that sometimes are associated with repeated stretching due to multiple pregnancies.

• The anal sphincter has both internal (innervated by pelvic splanchnic [parasympathetic] nerves) and external (innervated by the inferior rectal [somatic] nerves) divisions.

• The uterus is not well seen in this patient because much of it extends to one side, out of the plane of this midline sagittal image. Such “tilting” and other variations of the uterus are common and must be kept in mind when viewing cross-sectional images so that erroneous conclusions pertaining to uterine conditions are not made.

Uterine (Fallopian) Tubes

Clinical Note

Ligation of the uterine (fallopian) tubes (tubal ligation), once a common surgical procedure for elective sterilization, now is often done with devices inserted into the uterine tubes during hysteroscopy. Hysterosalpingography (HSG) is used to identify tubal occlusion as a cause of infertility and to document tubal occlusion after elective sterilization.

• The cornua of the uterine cavity lead to the fallopian tubes.

• The uterine tubes can be very mobile.

• The fimbriated ends of the uterine tubes open to the peritoneal cavity.

Bulb of Penis, Coronal Section

Clinical Note

A Cowper’s cyst or syringocele is a cyst-like swelling of a bulbourethral gland or one of its ducts. This condition is typically found in infant boys or occasionally in older men.

• The levator ani muscle comprises most of the pelvic diaphragm and is critical to the maintenance of urinary and fecal continence.

• The bulbospongiosus muscle is a sphincter of the urethra and may play a role in maintaining an erection by forcing blood into the distal penis.

• The ischiocavernous muscles also function in that manner to maintain an erection.

Uterus and Uterine Tube

Clinical Note

As shown in the upper image on the opposite page, the intrinsic soft tissue contrast in MRI is clinically useful in examining the uterus. Note the central hyperintense (bright) endometrium surrounded by the hypointense (darker) transitional zone, as well as the intermediate to high signal of the myometrium. Uterine fibroids, adenomyosis, and endometrial hyperplasia and carcinoma are clearly shown in pelvic MRI.

• Image is a cross section along short axis of the uterus, which is in its common anteverted position.

• Notice the small, rounded foci of high T2 signal in the periphery of both ovaries, representing small, fluid-filled follicles.

Uterus and Adnexa

Clinical Note

Pelvic pain in female patients can have many causes—for example, ovarian cysts, ectopic pregnancy, endometriosis, and pelvic inflammatory disease (PID). Ultrasound offers a relatively easy (and non-ionizing) procedure that can confirm or rule out many of these conditions.

• The ultrasound transducer used to generate this image was placed on the anterior abdominal wall and the fluid-filled bladder provided a “window” through which the more posterior structures were imaged.

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Tags: Netters Concise Radiologic Anatomy

Jan 10, 2016 | Posted by admin in RADIOGRAPHIC ANATOMY | Comments Off

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