When it comes to the nerves affected by L5 and S1, it’s important to understand the anatomy of the lumbar and sacral spine. The L5 nerve root originates from the fifth lumbar vertebra, while the S1 nerve root originates from the first sacral vertebra. These nerve roots are a part of the lumbosacral plexus, a network of nerves that innervate the lower extremities and pelvic region.
The L5 nerve root primarily supplies sensation and motor control to the muscles of the lower leg and foot. It travels through the pelvis and down the back of the thigh, eventually branching off into smaller nerves that innervate specific muscles and provide sensation to specific areas of the leg and foot. The L5 nerve root is responsible for dorsiflexion of the foot (lifting the foot upwards), as well as controlling the muscles that allow for extension of the big toe.
The S1 nerve root, on the other hand, innervates the muscles of the calf, as well as the back of the thigh and the sole of the foot. It is responsible for plantar flexion of the foot (pointing the foot downwards) and controls the muscles that allow for flexion of the toes. Additionally, the S1 nerve root provides sensation to the back of the leg and the outer edge of the foot.
When there is compression or irritation of the L5 or S1 nerve roots, it can result in a variety of symptoms. Common symptoms include pain, numbness, tingling, or weakness in the lower back, buttocks, thigh, leg, or foot. The exact symptoms experienced will depend on the specific nerve root affected and the severity of the compression or irritation.
In the case of a large, extruded disc herniation at the L5-S1 level, there is a possibility that it may impinge on not only the L5 and S1 nerve roots but also the superior hypogastric plexus or pre-sacral nerve. The superior hypogastric plexus is a collection of nerves located in the pelvis anterior to the last lumbar vertebra, the middle sacral artery, and the lumbosacral intervertebral disc.
Compression or irritation of the superior hypogastric plexus or pre-sacral nerve can potentially lead to symptoms such as pelvic pain, lower abdominal pain, and dysfunction of the pelvic organs. However, it’s important to note that this is a rare occurrence and would typically require a significant disc herniation or other pathology to affect these nerves.
The L5 and S1 nerve roots are primarily affected by a large disc herniation at the L5-S1 level. However, in rare cases, the superior hypogastric plexus or pre-sacral nerve anterior to the last lumbar vertebra, the middle sacral artery, and the lumbosacral intervertebral disc may also be affected. It is always best to consult with a healthcare professional for an accurate diagnosis and appropriate treatment.