 A little bit about Osteoconcuse of T421 discs and vertebrae at L4-5 and L5-S1 levels. The discs are normally convex posteriorly, little bit, but they do not go too much beyond the upper or lower vertebrate bodies, little bit of disgeneration with loss of water in the vertebrate muscles. The angular fibers start getting degenerated, the inner fibers start getting torn and the disc then starts bulging. At L4-5 and L5-S1 levels, you have to be careful to look in both sagittal and axial planes to call it bulging. At L3-4 discs upwards, the osteomargin of the disc should always be concave posteriorly. The signature of degenerative disc disorders is what we will see in this three or four slides, but you must understand a little bit of applied anatomy with degenerative disc disorders. So as I said, as the inner annular fibers get torn, the sharpness fibers, the nucleus gets degenerated and the annular starts bulging out. It covers more than 25% of the whole disc. Without being focal, it is called as diffuse posterior or anterior bulge with the effect of a bulge because it is relevant in patients coming with backache. So as I said, as the disc start getting degenerated, they start bulging beyond the upper and lower vertebrate bodies and when it covers more than 25% of circumference, it is called as diffuse posterior bulge. When it is focal, it is called as herniation and that is probably divided into protrusion and sequestration. When the base of herniated disc is broad and apex is narrow, it is called as protrusion. When the base is narrow and apex is broad, it is called as extrusion and when the herniated neutral fragment separates out from the parent disc, it is called as sequestration. I am going to quickly show you the examples of the same. Here is a patient who has come with backache with radiating pain in the left lower limb. What we see here is degenerated posterior herniated disc which has broad base, narrow apex. So this is left aerosol tip protrusion of L5's front disc causing compression. Here is herniation of L3 for disc. Now if you look at the base of the herniated disc which is narrow, the apex is very, very broad. The nucleus has come out to be ruptured annular fibers. The base is narrow, apex is very broad. So this is extrusion of L3 for disc which is central and right paracentrum. The thicker surface is severely complex. Here is the patient who came with severe backache radiating to right lower limb following a fall by coming out of car on a wet, slippery day. What we see here is herniation of a degenerated, not so much degenerated L5's front disc. Beyond the herniated disc, you see the nuclear material which is separated out from the parent disc has herniated on the right side and has migrated infrasily. It is also causing severe compression of this right S1 now root compared that with this left S1 now root and has migrated infrasily. After giving contrast, this nuclear material is showing peripheral enhancement because the nuclear itself is a vascular. It is the reaction from the adhering tissues from body reaction which gives rise to this enhancement. So, how do you describe this herniated disc? There is enlarged posterior and right paracental herniation of L5's front disc with sequestration and inferior migration. It is causing severe compression of right S1 now root and thicker sac. This is normal left S1 now root here. So, repeating the whole thing again, degeneration and diffuse posterior bulge which covers within 25% of disc circumference. Broad base and narrow apex is protrusion. Narrow base and broad apex is extrusion and separation from parent disc is friction. Let's quickly understand disc abnormality description based on location. So, in addition to posterior herniation what you need to describe is simply paracental lateral and far lateral. Based on how they are located in relation to thicker sac and anxiety and traversing no root. So, here are real life examples. This patient has degenerated L5's front disc which shows posterior central herniation which is compressing the thicker sac. Here is the same patient which we saw before left paracental protrusion of L5's front disc causing compression of thicker sac and left S1. Here is the patient who has left L4 radicals. What is seen here is lateral or foraminal herniation of this L4 side disc which is compressing the existing no root. That is L4, left L4 no root. The keyhole here which we see in top two locations is partially obliterated by this herniated disc. This is extra foraminal or far lateral disc herniation. So, this particular patient has degenerated posterior bulging L5's front disc. But what is symptomatic is this left extra foraminal or far lateral component which causes left L5 radical apathy. See the normal right L5 no root here and here. Approach, surgical approach for this patient with the extra spinal and that's how it is important to report extra foraminal or herniation.