Anatomy of the Groin and Femoral Triangle
Knowledge of inguinal anatomy is essential before vulvectomy is performed. The lymphatics of the vulva drain to the superficial inguinal lymph nodes and to the femoral and external iliac nodes. To expose the area, an incision is made on the thigh just below and parallel to the inguinal ligament (Fig. 70–1A). A second incision is made to intersect with the first at the anterior superior iliac spine and is continued caudally toward the apex of the femoral triangle. The flap created is dissected medially (Fig. 70–1B).
The triangular area is bordered laterally by the sartorius muscle and medially by the pectineus and adductor longus muscles (Fig. 70–2A). Traveling from below upward within the medial aspect of the fat above the aforementioned medial muscles is a large vessel, the saphenous vein (see Fig. 70–2A). The vein pierces the cribriform fascia overlying the fossa ovalis and the femoral vessels and joins the femoral vein below the fascia (Fig. 70–2B). The femoral vein lies in its own tough fascial compartment. Several small veins and arteries join to or branch from the femoral vein and artery: (1) the superficial circumflex iliac, (2) the superficial epigastric, and (3) the superficial external pudendal (Fig. 70–2D). Directly medial and slightly posterior is the femoral canal, which is a potential space juxtaposed medially to the pubic bone (Fig. 70–3A). This canal may contain the lowest node of the external iliac chain, Cloquet’s node (Fig. 70–3B, C). Just lateral to the femoral vein, again within its own fascial compartment, lies the femoral artery, which accompanies the vein in a caudal and deep descending course (Fig. 70–4A, B). Finally, most lateral and again with a tough fascial compartment is the femoral nerve, which descends into the thigh as a series of branching, diverging fibers (Fig. 70–5A, B). The femoral nerve is vulnerable to injury during positioning of the inferior extremities for perineal operations (Fig. 70–5C). The inguinal ligament crosses the nerve perpendicularly, where the nerve probably is most exposed. The tight inguinal ligament therefore can put sufficient pressure on the underlying nerve to result in palsy. The nerve also may be injured by a hyperextended lithotomy position (high lithotomy) coupled with abduction at the thigh (Fig. 70–5D). This type of stretch injury occurs in the vicinity of the lumbar plexus, where the obturator nerve joins the lumbar plexus between the femoral nerve and the lumbosacral trunk (Fig. 70–5E). The obturator nerve and the relatively superficial genital femoral nerve are more susceptible to retractor injuries than is the femoral nerve, which is buried in the substance of the psoas major muscle (see Fig. 70–5D).
Farther lateral is the sartorius muscle, which in concert with the inguinal ligament takes its origin from the anterior superior iliac spine (Fig. 70–6A, B). It is useful to transplant this muscle over the exposed femoral vessels after a radical vulvectomy and inguinal lymphadenectomy (Fig. 70–6C).
The gracilis muscle is located at the medial side of the femoral triangle (i.e., medial and deep to the saphenous vein). This structure is useful as a myocutaneous flap for transplant to the vulva or vagina (Fig. 70–7A through C).
