[Music] when we talk about exam findings you know l3 nerve uh compression leads to hip abduction weakness l4 knee extension weakness with a decreased patellar reflex l5 ankle dorsiflexion and inversion weakness with also ehl weakness you can also get some hip abduction weakness and then s1 uh and ankle plantar flexions with a decreased achilles tendon so big things here to remember our l5 will give you a foot drop s1 will classically give you plantar flexion weakness again not written in stone but you know things to really think about when you see that person with the foot drop you really need to think about l5 nerve root compression whether that's an alpha s1 far lateral disc hitting the l5 nerve root or a l45 paracentral disk hitting the traversing l5 nerve root this is i'm going to skip over this because this is just sort of summarizing everything we just talked about so here we are back to our picture l5 s1 disc herniation you can see where why i say this leads to compression of the traversing nerve root if you look at in the axial here the left side this is the traversing nerve right here you can see that's sort of obliterated on the right side so ultimately leading to compression of that traversing nerve root and when we look at this so this picture i'm showing you an axial through the disc at l45 and this looks relatively normal maybe a little bit of foraminal stenosis on the left here is the classic far lateral disc herniation you can see the positive arrow sign there on the right these are really easy to miss miss because we look at the mri and we want to look at that central canal and we say oh looks perfect no nerve root compression everything looks great a person has a really acute radiculopathy you can see here this is a relatively large disc herniation and it's pushing on that nerve kind of right in the reason of the drg the dorsal root gangrene which is a very painful spot to have compression so really important to look at the whole picture and not miss these far lateral disc herniations another example here of the 4-5 disc herniation this is a massive disc herniation you can see in the axial it just completely obliterates the central canal this would be a disc herniation that i would you know consider caught equine as a real possibility because this has really completely obliterated the central canal and this is certainly one that you know when we talk about conservative management this is probably not one you're managing conservatively because this person's probably got some pretty significant symptoms and weakness that being said if they fall into that 20 of people that don't have that maybe this is something that you can manage more conservative hey everyone ryan rad here from neurosurgery training.org if you like that video subscribe and donate to keep our content available for medical students across the world