Sciatic Nerve – Nerve Lesions of the Lower Limb

00:01 gluteal nerve, tibial nerve, and the common fibular nerve. So if we start with the sciatic nerve, then remember the sciatic nerve, formed from L4, L5, S1, S2, and S3, passes out of the pelvis via the greater sciatic foramen, which we can see here. Remember, it has its two parts. It has the common fibular and tibial divisions. We can also see that as it passes out, it passes from below piriformis, the infrapiriform fossa. So if you were to have compression of the sciatic nerve, then you’d have pain radiating from the buttock as it supplies the skin of the buttock here. You’d feel that pain coming from the buttock region.

00:41 And this can be due to compression of the piriformis muscle onto the sciatic nerve.

00:47 So, as the sciatic nerve passes out from below piriformis, piriformis can compress this nerve leading to pain coming from the buttock, and this is known as piriformis syndrome. If we have damage to the medial aspect of the buttock, then this puts the sciatic nerve, the inferior gluteal, and posterior cutaneus nerve of the thigh at risk. So a medially directed stab wound or intragluteal injection can put these nerves at risk - the sciatic nerve, the inferior gluteal, and the posterior cutaneus nerve of the thigh. This can lead to obvious problems with sensation via the coverage of the posterior cutaneus nerve. And also, damage to the sciatic nerve here leads to paralysis of the hamstrings, and you’d have impairments of thigh extension and knee flexion. So you’d have paralysis of the hamstring muscles due to damage of the sciatic nerve. And this would lead to those impairments, the lack of thigh extension and knee flexion. Now let’s turn to the superior gluteal nerve. The superior gluteal nerve