Strong quad muscles are important for a host of daily activities, such as walking and climbing stairs. While quad muscles are responsible for lifting your hips up and straightening your knees, it's the quadriceps nerve supply that gives them power to move.
The quadriceps femoris, or quad muscle, runs from the front of the hip, down the thigh and over the front of the knee. As indicated by its name, it is actually composed of four muscles: the rectus femoris, vastus medialis, vastus lateralis and vastus intermedialis, as explained by ExRx.net.
These four muscles ultimately come together to form the patellar ligament and attach to an area of the shinbone called the tibial tuberosity.
The quadriceps innervation nerve root comes from the lower back. It then branches off into the femoral nerve before it attaches to the quad muscle.
Read more: The Quadriceps & Muscle Atrophy
Quadriceps Innervation: Nerve Root
Nerve roots that supply muscles in the leg branch off the spinal cord at the lower back, or lumbar spine. They exit the spine through holes between the vertebrae, or stacked bones that form your spine. As they leave the lower back, they branch off into structures called peripheral nerves.
A series of nerves that emerge between the vertebrae of the lumbar spine ultimately provide power to the quadriceps femoris. According to the Geisel School of Medicine at Dartmouth, nerve roots L2 through L4 supply the quadriceps muscle.
Compression of these nerve roots, as can occur with arthritis or disk herniation, can lead to nerve pain in the quadriceps.
Identify the Peripheral Nerve
The femoral nerve is a branch off the combined nerve fibers of the L2, L3 and L4 nerves, which converge after exiting the vertebral canal. This nerve passes down the front of the pelvis, under the inguinal ligament of the hip, and adjacent to the femoral artery.
In addition to supplying sensory nerve function to the inner surface of the leg, the femoral nerve branches off to supply motor impulses to the four heads of the quadriceps femoris.
In addition, the femoral nerve provides sensation to the from of your thigh and inner front part of the lower leg, according to the Geisel School of Medicine at Dartmouth.
Read more: Damaging Effects of Tight Quadriceps
Avoiding Quadriceps Nerve Dysfunction
When the femoral nerve is damaged, paralysis and sensory deficits can affect the leg. Damage to the femoral nerve — or any peripheral nerve — can result from direct injury, nerve compression, nerve entrapment, systemic disorders, tumors, infections or internal bleeding.
Compression of the femoral nerve can also occur as a complication of surgery that involves lying on the back with the hips and knees bent, as described in an article published in the June 2014 issue of the International Journal of Gynecological Cancer.
Because the femoral nerve passes through some relatively narrow anatomical structures, it is vulnerable to damage from compression or entrapment. Even something as seemingly benign as an overly tight belt can cause compression of the femoral nerve.
Prolonged periods of pressure placed upon the femoral nerve can restrict blood flow and prevent oxygen from reaching the nerve tissue, leading to nerve damage.