Thigh

Surgical surface anatomy

An imaginary line connecting the anterior superior iliac spine to the pubic tubercle marks the proximal border of the anterior thigh. The inguinal ligament travels between these two bony landmarks. The external iliac vessels become the femoral vessels deep to the ligament. Laterally, the lateral femoral cutaneous nerve enters the thigh, usually just medial to the anterior superior iliac spine. The pulse of the femoral artery can be palpated just distal to the inguinal ligament at roughly its midpoint. Distally, the epicondyles of the femur and the patella are easily palpable.

Clinical anatomy

The thigh provides several of the most commonly used workhorse flaps in the armamentarium of plastic surgeons, including the anterolateral thigh (ALT), gracilis, tensor fasciae latae, rectus femoris, antero­medial thigh (AMT) and sartorius flaps. These flaps offer low donor site morbidity, the versatility of both muscle and perforator flaps, and the ability to pursue a two-team approach to reconstruction. This chapter will cover the surgical anatomy of the thigh and the core procedures in reconstructive surgery used for this part of the body.

A thorough understanding of the musculature and of the blood vessels and nerves supplying each muscle is essential ( Chs 76 and 79 ). The thigh is divided into anterior, medial and posterior compartments ( Videos 81.1 and 81.2 ). The anterior compartment includes sartorius and quadriceps femoris, both innervated by the femoral nerve. Quadriceps femoris consists of four parts: rectus femoris, vastus lateralis, vastus medialis and vastus intermedius. Rectus femoris and sartorius can be used as pedicled flaps for coverage of the inguinal region. Vastus lateralis can be used as a pedicled or free flap with the ALT flap. Rectus femoris crosses the hip and knee, whereas the vasti originate from the femur and cross only the knee. The medial compartment contains gracilis, pectineus, adductor longus, adductor brevis, adductor magnus and obturator externus. These are all innervated by the obturator nerve, except for pectineus (femoral or accessory obturator nerve, when present) and part of adductor magnus (sciatic nerve). The gracilis flap will be discussed later. The posterior compartment contains the hamstrings (semi­tendinosus, semimembranosus and biceps femoris), all innervated by the sciatic nerve. Common flaps in this compartment include the posterior thigh flap, which incorporates biceps femoris for closure of pressure sores.

Cutaneous innervation of the lateral thigh is derived from the lateral femoral cutaneous nerve, which arises from L2–3 ventral rami and passes deep to the inguinal ligament; it is important to preserve this nerve when harvesting flaps in this area.

In the proximal thigh, the femoral artery lies within the femoral triangle, bounded by sartorius laterally, adductor longus medially and the inguinal ligament superiorly (see Fig. 79.2 ). Just distal to the inguinal ligament, the superficial circumflex iliac and superficial epigastric arteries branch from the lateral and medial surfaces of the femoral artery, respectively. The superficial circumflex iliac artery runs laterally, approximately two fingers’ breadths below and parallel to the inguinal ligament. It supplies the inguinal region and is used in groin flaps. The femoral artery gives rise to the deep femoral artery (profunda femoris artery), which typically arises 5 cm distal to the inguinal ligament. The deep femoral artery is the dominant blood supply of the thigh, and the majority of pedicles for reconstructive flap surgery arise from its branches. It courses deep to sartorius and rectus femoris, and divides into ascending, transverse and descending branches.

The ascending branch can be identified in the interval between tensor fasciae latae and rectus femoris, and supplies tensor fasciae latae and the gluteal muscles. The descending branch runs in the interval between rectus femoris and vastus lateralis, and is the blood supply to the anterolateral thigh flap. The branch to rectus femoris arises from the descending branch of the lateral circumflex femoral artery.

The medial circumflex femoral artery usually originates from the posteromedial aspect of the deep femoral artery at the same level as, or near the origin of, the lateral circumflex femoral artery; it arises directly from the femoral artery in approximately 25% of individuals. This branch passes between pectineus and psoas major to supply the medial compartment of the thigh. It divides into ascending and transverse branches. The ascending branch runs between adductors longus and magnus, and is the primary pedicle for a gracilis flap.