The saphenous nerve (long or internal saphenous nerve) is the largest cutaneous branch of the

femoral nerve The femoral nerve is a nerve in the thigh that supplies skin on the upper thigh and inner leg, and the muscles that extend the knee. Structure The femoral nerve is the major nerve supplying the anterior compartment of the thigh. It is the largest ...

. It is a strictly sensory nerve, and has no motor function.

Structure

It is purely a

sensory nerve A sensory nerve, or afferent nerve, is a general anatomic term for a nerve which contains predominantly somatic afferent nerve fibers. Afferent nerve fibers in a sensory nerve carry sensory information toward the central nervous system (CNS) fro ...

. The saphenous nerve is the largest and terminal branch of the

. Shortly after the femoral nerve passes under the inguinal ligament, it splits into anterior and posterior divisions by the passage of the

lateral femoral circumflex artery The lateral circumflex femoral artery, also known as the lateral femoral circumflex artery, or the external circumflex artery, is an artery in the upper thigh. It is usually a branch of the profunda femoris artery, and produces three branches. It ...

(a branch of the

profunda femoris artery The deep artery of the thigh, (profunda femoris artery or deep femoral artery) is a large branch of the femoral artery. It travels more deeply (posteriorly) than the rest of the femoral artery. Structure The deep artery of the thigh branches of ...

). The posterior division then gives off the saphenous nerve as it converges with the

femoral artery The femoral artery is a large artery in the thigh and the main arterial supply to the thigh and leg. The femoral artery gives off the deep femoral artery or profunda femoris artery and descends along the anteromedial part of the thigh in the f ...

where it passes beneath the sartorius muscle. The saphenous nerve lies in front of the femoral artery, behind the aponeurotic covering of the

adductor canal The adductor canal, also known as the subsartorial canal or Hunter’s canal, is an aponeurotic tunnel in the middle third of the thigh. It extends from the apex of the femoral triangle to the adductor hiatus. Structure The adductor canal exte ...

, as far as the opening in the lower part of the

adductor magnus muscle Adductor may refer to: * One of the anatomical terms of motion * Adductor muscle (disambiguation) * Adductor canal The adductor canal, also known as the subsartorial canal or Hunter’s canal, is an aponeurotic tunnel in the middle third of the t ...

. There it diverges from the artery, and emerges from behind the lower edge of the

aponeurotic An aponeurosis (; plural: ''aponeuroses'') is a type or a variant of the deep fascia, in the form of a sheet of pearly-white fibrous tissue that attaches sheet-like muscles needing a wide area of attachment. Their primary function is to join muscl ...

covering of the canal. It descends vertically along the medial side of the knee behind the sartorius muscle, pierces the fascia lata, between the tendons of the sartorius muscle and gracilis muscle. It becomes subcutaneous around 10 cm above the medial epicondyle of the femur. The nerve then passes along the tibial side of the leg, accompanied by the great saphenous vein. It descends behind the medial border of the tibia, and, at the lower third of the leg, divides into two branches: * one continues its course along the margin of the tibia, and ends at the

ankle The ankle, or the talocrural region, or the jumping bone (informal) is the area where the foot and the leg meet. The ankle includes three joints: the ankle joint proper or talocrural joint, the subtalar joint, and the inferior tibiofibular joi ...

. * the other passes in front of the ankle, and is distributed to the skin on the medial side of the foot, as far as the ball of the

great toe Toes are the digits (fingers) of the foot of a tetrapod. Animal species such as cats that walk on their toes are described as being '' digitigrade''. Humans, and other animals that walk on the soles of their feet, are described as being '' ...

, communicating with the medial branch of the superficial peroneal nerve.

Function

The saphenous nerve, about the middle of the thigh, gives off a branch which joins the subsartorial plexus. At the medial side of the knee it gives off a large infrapatellar branch, which pierces the sartorius muscle and fascia lata. It is distributed to the skin in front of the patella. Below the knee, the branches of the saphenous nerve ( medial crural cutaneous branches) are distributed to the skin of the front and medial side of the leg, communicating with the cutaneous branches of the femoral, or with filaments from the obturator nerve.

Clinical significance

Procedures such as saphenous vein cutdown or

orthopedic surgery Orthopedic surgery or orthopedics ( alternatively spelt orthopaedics), is the branch of surgery concerned with conditions involving the musculoskeletal system. Orthopedic surgeons use both surgical and nonsurgical means to treat musculoskeletal ...

that includes incisions or dissection over the distal tibia or medial malleolus can result in damage to the saphenous nerve, resulting in loss of cutaneous sensation in the medial leg. This is due to the intimate path that the saphenous nerve and the great saphenous vein travel. The saphenous nerve is also often damaged during vein harvest for

bypass surgery Bypass surgery refers to a class of surgery involving rerouting a tubular body part. Types include: * Vascular bypass surgery such as coronary artery bypass surgery, a heart operation * Cardiopulmonary bypass, a technique used in coronary artery ...

and during trocar placement during knee

arthroscopy Arthroscopy (also called arthroscopic or keyhole surgery) is a minimally invasive surgical procedure on a joint in which an examination and sometimes treatment of damage is performed using an arthroscope, an endoscope that is inserted into the ...

. There appears to be occasional meaningful individual variation in the pathway of this nerve, such that the illustration of it done for Gray's Anatomy, for example, likely represents an unusual rather than usual course. The saphenous nerve can experience entrapment syndrome from exercises involving the

quadriceps The quadriceps femoris muscle (, also called the quadriceps extensor, quadriceps or quads) is a large muscle group that includes the four prevailing muscles on the front of the thigh. It is the sole extensor muscle of the knee, forming a large ...

or from prolonged walking or standing. It is characterized by a burning sensation in most patients. Pain often occurs at night, long after the physical exercise which induced it has stopped, and may be aggravated by climbing stairs. Usually, in this case, motor function of the lower leg will not be impaired. This is a key distinction between saphenous nerve neuropathy and lower back radiculopathy. Saphenous nerve neuropathy only demonstrates ''sensory alterations'', while lumbar radiculopathy will affect the motor, sensory, and deep tendon reflexes of the lower leg.

Additional images

File:Gray432 color.png, Cross-section through the middle of the thigh. File:Gray440_color.png, Cross-section through middle of leg. File:Gray550.png, The femoral artery. File:Gray825and830.PNG, Cutaneous nerves of the right lower extremity. Front and posterior views. File:Gray826and831.svg, Cutaneous nerves of the right lower extremity. Front and posterior views. File:Gray834.svg, Diagram of the segmental distribution of the cutaneous nerves of the sole of the foot. File:Gray835.png, Deep nerves of the front of the leg. File:Gray836.png, Nerves of the dorsum of the foot.

References

External links

* - "Structures of the Adductor Canal" {{Authority control Nerves of the lower limb and lower torso