Sciatic Nerve – Lumbosacral Plexus

00:00 of the buttock and the posterior thigh. It comes from S2 and S3. The sciatic nerve, as I’ve mentioned, is really important. So I just want to dwell on it for a second.

00:06 Anterior divisions of the anterior rami from these nerve roots form the tibial nerve. And the posterior divisions of these anterior nerve roots form the common fibular nerve. So here we’ve got L4, L5, S1, S2, S3. Anterior rami from these split into these anterior divisions, and it’s these anterior divisions that form the tibial nerve. So here we can see the tibial nerve. We can see coming out here, we got L4, L5, S1, S2, and S3. And coming from them, we can see they’re splitting into these anterior divisions, not these posterior divisions down here, these anterior divisions here, and you see another one here, see another one here. And it’s these anterior divisions of the anterior rami from L4, L5, S1, S2, and S3 that forms the tibial nerve. The posterior divisions of some of these nerve roots, L4, L5, S1, S2. The posterior divisions, if we go back to them, see L5 here, is giving rise to this anterior division and the posterior division. And this posterior division here, we see another posterior division here, see another posterior division here. These are giving rise to the common fibular nerve. So these are very similar spinal cord segments but they’re dividing into these anterior and posterior divisions. The anterior division is giving rise to the tibial nerve; the posterior division is giving rise to the common fibular nerve; a similar principle that we had for brachial plexus. The sciatic nerve is the largest nerve in the body. It’s about two centimetres wide. As I mentioned, it supplies the majority of the muscles in the lower limb, except the gluteal region, the anterior thigh, and the medial thigh. It’s so big that it actually has its own artery, and this is artery to the sciatic nerve. And this artery comes from the inferior gluteal artery. We’ll see this when we look at the gluteal region. So briefly then to finish just the coccygeal