Dr. Ebraheim’s educational animated video describes the lumbosacral plexus.
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Lumbosacral Plexus
The lumbosacral plexus is easier than the brachial plexus. The sciatic nerve is the key nerve of the lumbosacral plexus. The sciatic nerve has two branches: the common peroneal nerve and the tibial nerve. It arises from the spinal nerves of L4, L5, S1, S2, and S3. The sciatic nerve is the cornerstone of the lumbosacral plexus. Knowledge of the lumbosacral plexus starts with knowledge about the sciatic nerve and its branches because it is the most important nerve. The lumbosacral plexus is predominantly the sciatic nerve, in addition to a small nerve root called S4. The superior gluteal nerve is predominantly L5. The inferior gluteal nerve is predominantly S1. L5 radiculopathy can give you Trendelenburg Gait. The superior gluteal nerve innervates the gluteus medius, gluteus minimus, and the tensor fascia lata muscles. The inferior gluteal nerve innervates the gluteus maximus muscle. When you add S4 to the sciatic nerve, that becomes the lumbosacral plexus (six nerve roots). Each branch will come from three nerve roots, and if you put them in order, the branches from the lumbosacral plexus will have a unique arrangement where the following nerve root will start with the lower numbered nerve root than the previous one.