The saphenous nerve (long or internal saphenous nerve) is the largest

cutaneous branch Cutaneous innervation refers to the area of the skin which is supplied by a specific cutaneous nerve. Dermatome (Anatomy), Dermatomes are similar; however, a dermatome only specifies the area served by a spinal nerve. In some cases, the dermatome i ...

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) fr ...

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

. Shortly after the femoral nerve passes under the

inguinal ligament The inguinal ligament (), also known as Poupart's ligament or groin ligament, is a band running from the pubic tubercle to the anterior superior iliac spine. It forms the base of the inguinal canal through which an indirect inguinal hernia may dev ...

, 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 i ...

(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 fem ...

where it passes beneath the

sartorius muscle The sartorius muscle () is the longest muscle in the human body. It is a long, thin, superficial muscle that runs down the length of the thigh in the Anterior compartment of thigh, anterior compartment. Structure The sartorius muscle originates f ...

. 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 extends ...

, 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 th ...

. 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 musc ...

covering of the canal. It descends vertically along the medial side of the

knee In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the hu ...

behind the sartorius muscle, pierces the

fascia lata The fascia lata is the deep fascia of the thigh. It encloses the thigh muscles and forms the outer limit of the fascial compartments of thigh, which are internally separated by the medial intermuscular septum and the lateral intermuscular septu ...

, between the tendons of the sartorius muscle and

gracilis muscle The gracilis muscle (; Latin for "slender") is the most superficial muscle on the medial side of the thigh. It is thin and flattened, broad above, narrow and tapering below. Structure It arises by a thin aponeurosis from the anterior margins o ...

. It becomes subcutaneous around 10 cm above the

medial epicondyle of the femur The medial epicondyle of the femur is an epicondyle, a bony protrusion, located on the medial side of the femur at its distal end. Located above the medial condyle, it bears an elevation, the adductor tubercle,Platzer (2004), p 192 which serves ...

. The nerve then passes along the tibial side of the leg, accompanied by the

great saphenous vein The great saphenous vein (GSV, alternately "long saphenous vein"; ) is a large, subcutaneous, superficial vein of the leg. It is the longest vein in the body, running along the length of the lower limb, returning blood from the foot, leg and thig ...

. It descends behind the medial border of the

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

, and, at the lower third of the leg, divides into two branches: * one continues its course along the margin of the

, 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 join ...

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

foot The foot ( : feet) is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made ...

, 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 '' pl ...

, 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 The subsartorial plexus is a plexus of nerves that is located under the sartorius muscle. Structure The subsartorial plexus is formed by: # the medial cutaneous nerve of the thigh (a branch of the femoral nerve).{{Citation, last=Gardner, first= ...

. At the medial side of the knee it gives off a large

infrapatellar branch The infrapatellar branch of saphenous nerve is a nerve of the lower limb. The saphenous nerve, located about the middle of the thigh, gives off a branch which joins the subsartorial plexus. It pierces the Sartorius muscle, sartorius and fascia la ...

, which pierces the

and

. It is distributed to the skin in front of the

patella The patella, also known as the kneecap, is a flat, rounded triangular bone which articulates with the femur (thigh bone) and covers and protects the anterior articular surface of the knee joint. The patella is found in many tetrapods, such as m ...

. 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 The obturator nerve in human anatomy arises from the ventral divisions of the second, third, and fourth lumbar nerves in the lumbar plexus; the branch from the third is the largest, while that from the second is often very small. Structure The ob ...

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 A trocar (or trochar) is a medical or veterinary device that is made up of an awl (which may be a metal or plastic sharpened or non-bladed tip), a cannula (essentially a hollow tube), and a seal. Trocars are placed through the abdomen during lap ...

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 jo ...

. 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 ''Gray's Anatomy'' is a reference book of human anatomy written by Henry Gray, illustrated by Henry Vandyke Carter, and first published in London in 1858. It has gone through multiple revised editions and the current edition, the 42nd (Octob ...

, 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 Radiculopathy, also commonly referred to as pinched nerve, refers to a set of conditions in which one or more nerves are affected and do not work properly (a neuropathy). Radiculopathy can result in pain (radicular pain), weakness, altered sensati ...

. 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