The vagina has an abundant vascular supply. The proximal portion is supplied by the cervical branch of the uterine artery and by the vaginal artery. he latter may variably arise from the
Vesicovaginal space (filled with loose connective tissue) uterine or inferior vesical artery or directly from the internal iliac artery. The middle rectal artery contributes supply to the posterior vaginal wall, whereas the distal walls receive contributions from the internal pudendal artery. At each level, vessels supplying each side of the vagina course medially across the anterior or posterior vaginal wall and form midline anastomoses.
An extensive venous plexus also surrounds the vagina and follows the course of the arteries. Lymphatics from the lower third, along with those of the vulva, drain primarily into the inguinal lymph nodes. Those from the middle third drain into the internal iliac nodes, and those from the upper third drain into the external, internal, and common iliac nodes.
his diamond-shaped area between the thighs has boundaries that mirror those of the bony pelvic outlet: the pubic symphysis anteriorly, ischiopubic rami and ischial tuberosities anterolaterally, sacrotuberous ligaments posterolaterally, and coccyx posteriorly. An arbitrary line joining the ischial tuberosities divides the perineum into an anterior triangle, also called the urogenital triangle, and a posterior triangle, termed the anal triangle.
he perineal body is a fibromuscular pyramidal mass found in the midline at the junction between these anterior and posterior triangles (Fig. 2-5). Also called the central tendon of the perineum, the perineal body sonographically measures 8 mm tall and 14 mm wide and thick (Santoro, 2016). It serves as the junction for several structures and provides significant perineal support (Shafik, 2007). Superficially, the bulbospongiosus, superficial transverse perineal, and external anal sphincter muscles converge on the perineal body. More deeply, the perineal membrane, portions of the pubococcygeus muscle, and internal anal sphincter contribute (Larson, 2010). The perineal body
Ischiocavernosus m.
Cut edge of Colles fascia
Bulbospongiosus m.
Superficial transverse perineal m.
External anal sphincter m.
is incised by an episiotomy incision and is torn with second-, third-, and fourth-degree lacerations.
Superficial Space of the Anterior Triangle
This triangle is bounded by the pubic rami superiorly, the ischial tuberosities laterally, and the supericial transverse perineal muscles posteriorly. It is divided into supericial and deep spaces by the perineal membrane. This membranous partition is a dense ibrous sheet that was previously known as the inferior fascia of the urogenital diaphragm. The perineal membrane attaches laterally to the ischiopubic rami, medially to the distal third of the urethra and vagina, posteriorly to the perineal body, and anteriorly to the arcuate ligament of the pubis (see Fig. 2-5) .
The supericial space of the anterior triangle is bounded deeply by the perineal membrane and supericially by Co lIes fascia. As noted earlier, Colles fascia is the continuation of Scarpa fascia onto the perineum. On the perineum, Co lIes fascia securely attaches laterally to the pubic rami and fascia lata of the thigh, inferiorly to the supericial transverse perineal muscle and inferior border of the perineal membrane, and medially to the urethra, clitoris, and vagina. As such, the superficial space of the anterior triangle is a relatively closed compartment.