The sartorius muscle arises from the anterior superior iliac
spine (ASIS) of the pelvic bone. The sartorius muscle crosses the upper third
of the thigh obliquely, downwards medially and then descends vertically towards
its insertion. It is a superficial muscle, the longest muscle, and its fibers
are parallel. The sartorius muscle is inserted into the anteromedial surface of
the upper tibia. Other tendons are inserted into the same location. These
tendons are called the Pes Anserine tendons. Surgical approach to the Pes
Anserine insertion for harvesting of the semitendinosus and gracilis tendons
puts the terminal branch of the saphenous nerve at risk as it emerges between
the sartorius and the gracilis tendons. The sartorius muscle is innervated by
the femoral nerve. The sartorius muscle flexes, abducts, and rotates the hip
laterally as well as flexes the knee. It is sometimes referred to as the
“tailor’s muscle” in reference to the cross-legged position in which tailors
once sat. the “tailor” position helps to understand the function of the
sartorius muscle. The upper third of the sartorius muscle forms the lateral
border of the femoral triangle, and its middle third forms the roof of the
adductor (subsartorial) canal which contains the femoral vessels and the
saphenous nerve. The femoral triangle is a superficial triangular space located
on the anterior aspect of the thigh just inferior to the inguinal ligament. The
boundaries of the femoral triangle include the lateral border (formed by the
medial border of the sartorius muscle), the medial border (formed by the medial
border of the adductor longus muscle), and the base (formed by the inguinal
ligament). The femoral triangle contains three important structures: femoral
nerve, femoral artery, and femoral vein (from lateral to medial), and it also
contains the deep inguinal lymph nodes. The lateral cutaneous nerve of the
thigh crosses the lateral corner of the triangle and supplies the skin on the
lateral part of the thigh. It appears that the neurovascular bundle is medial
to the sartorius muscle. Therefore, in the anterior approach to the hip, it is
always safe to go lateral to the sartorius muscle in order to avoid the
important structures within the femoral triangle. It is important to remember
when performing this approach to avoid injury to the lateral cutaneous nerve of
the thigh. For the Hip Anterior Approach (Smith-Petersen) the internervous
plane superficially between the sartorius (supplied by the femoral nerve) and
the tensor fascia lata (supplied by the superior gluteal nerve). Bony avulsion
of the sartorius tendon occurs from a strong sudden pull of the sartorius with
the hip in extension and the knee in flexion. Avulsion of the sartorius from
its attachment site most commonly occurs in sprinters and other running
athletes. The avulsion can also occur after anterior iliac crest bone graft. It
is advisable to start harvesting the bone graft approximately 3 cm from the
anterior superior iliac spine to avoid weakening of the bone and avulsion
fracture. harvesting bone less than 3 cm of the ASIS may cause an avulsion
fracture of the sartorius muscle. If there is a persistent hip pain after
anterior iliac crest bone graft, get an x-ray of the pelvis to check for an
avulsion fracture. The adductor canal (subsartorial canal) is an aponeurotic
tunnel in the middle third of the thigh, extending from the apex of the femoral
triangle to the opening in the adductor magnus, which is called the adductor
hiatus. The canal contains the femoral artery, femoral vein, and the saphenous
nerve, which is a branch of the femoral nerve. It is important to recognize the
relationship of the saphenous nerve to the sartorius muscle and tendon. The
saphenous nerve is posterior to the sartorius tendon. The pes anserine bursa is
a small fluid filled sac located between the tibia and three tendons of the
sartorius, gracilis, and the semitendinosus. The pes anserine is the common
area of insertion for the three tendons along the proximal medial aspect of the
tibia. The sartorius is innervated by the femoral nerve. The gracilis is
innervated by the obturator nerve. The semitendinosus is innervated by the
tibial branch of the sciatic nerve. Pes anserine bursitis, or “breaststroke
knee”, is an inflammatory condition of the medial knee at the pes anserine
bursa that is common in swimmers. Pes anserine bursitis is usually seen as
causing pain, tenderness, and localized swelling after trauma or total knee
replacement. The pain is seen below the joint line on the medial part of the
proximal tibia with the bursa deep to the tendons. Pain at the joint line is
probably a meniscal tear. Pain below the joint line is probably bursitis.
