 Good day everybody. My name is Dr. Sanjay Sanyal, Professor Department Chair. This dissection demonstration is going to be mostly on the distribution of the common fibular division of the sciatic nerve right from its origin to its domination of its branches. So if we go to start from the public ear foster, this is the common fibular nerve which runs under the cover of the biceps femoris. This was the tibial nerve. The common fibular nerve, it goes behind the head of the fibula and then it winds around the neck of the fibula which is located here and under the origin of the fibularis longus, it passes and it divides into two divisions. One is the superficial fibular division, the other is a deep fibular division. Let's trace them right from their beginning. This is the superficial fibular nerve and you can see when I exert traction here it pulls on this. So this is the superficial fibular nerve. It is running in the lateral compartment of the leg and the lateral compartment as we know consists of two muscles, the fibularis longus and under that the fibularis brevis. The superficial fibular supplies the fibularis longus and the fibularis brevis and immediately thereafter as we can see here it pierces through the deep fascia that is the cruel fascia and it becomes cutaneous and we can see several of these cutaneous branches which were running in the superficial fascia. These cutaneous branches they cross superficial to the extensor retiniculum which is located deep here and then the superficial fibular nerve supplies most skin of the dorsum of the foot. So therefore the superficial fibular nerve after supplying the muscles supplies the skin of the antrolateral aspect of the lower one-third of the leg and the skin of most of the dorsum of the foot except the portion which is supplied by the deep fibular nerve which I'm going to mention just after this. One important clinical correlation pertaining to the superficial fibular nerve is that if a person suffers repeated inversion injuries it can produce attraction neuropathy of the superficial fibular nerve. Now let's take the next division of the common fibular and that is this division here. This is the deep fibular nerve. All these divisions are taking place deep to the attachment of the fibularis longus muscle. The deep fibular nerve runs in the anterior compartment and we can see this is the deep fibular nerve and when we exert traction here we can see it is pulling here. This is the deep fibular nerve. So the deep fibular nerve runs in the anterior compartment it runs essentially between the tibialis anterior and the extensor halosus longus along with the anterior tibial artery and both of them we can see clearly here. The deep fibular nerve supplies the muscles of the anterior compartment and after it runs all the way down the deep fibular nerve then runs under the extensor retinoculum and we can see the extensor retinoculum which I have opened up here and we can see the deep fibular nerve is running under the extensor retinoculum and it comes on the dorsal aspect of the foot and when I exert traction here we can see it is pulling on the deep fibular nerve as well as the anterior tibial artery which now has become the dorsalis pgis artery. The deep fibular nerve once it has crossed under the extensor retinoculum it then continues and supplies intrinsic muscles in the dorsal of the foot namely the extensor halosus brevis and the extensor digitalum brevis and after it has supplied all these muscles the deep fibular nerve then continues and it becomes cutaneous and it supplies the skin of the first interdigital cleft on the dorsum of the foot namely the space between the great toe and the second toe. So this is the only portion of the skin which is supplied by the deep fibular nerve. If the deep fibular nerve is injured or even if the common fibular nerve is injured which is quite likely if there's a fracture of the fibular neck here then the muscles of the anterior compartment are paralyzed and the most notable deficit that can happen when there's an injury to the deep fibular branch or to the common fibular is paralysis of the tibialis anterior and paralysis of the tibialis anterior which is the most powerful dorsiflexor of the foot leads to a very severe disability known as foot drop. That is one important clinical correlation. The next important clinical correlation is when the deep fibular nerve is passing under the extensor retinoculum here. It can get entrapped in a condition known as ski boots syndrome. Those who put the boot laces tightly while skiing it compresses the deep fibular nerve and it can lead to entrapment neuropathy of the deep fibular nerve under the extensor retinoculum and ski boots syndrome. The point to be noted is that the muscles of the anterior compartment are spared because the anterior compartment muscles have all been supplied. The symptoms are perceived mostly on the foot. There'll be numbness, palesthesia and tingling of the first interdigital cleft and there will be weakness of the muscles on the dorsal compartment of the foot. So this is about the deep fibular nerve and the superficial fibular nerve. Now let's focus on one small nerve which I have preserved here. We can see that it is starting from the lateral side of the foot and it is this nerve here. This is the sural nerve. The sural nerve actually was formed by the union of two branches. One from the common fibular and one from the tibial and the two of them united and they formed the sural nerve which of course has been removed in the rest of the place. The sural nerve supplies the skin of the back of the leg, lower one-third of the leg and then it continues and supplies this little bit of the skin of the lateral side of the foot and we can see a little bit of the sural nerve and this notable point to be remembered is that the sural nerve is accompanied by this superficial vein that we can see here which is opening into the propitial vein and if we put them together we find that they are running parallel to each other. This is an important anatomical relationship. Surgical practice we use the sural nerve for nerve grafting. We use the short saphenous vein as our landmark. We can see the short saphenous vein and immediately adjacent to that we look for the sural nerve. We can use it for nerve grafting. Before I conclude there's one more thing I wanted to show you. This again is the common fibular nerve. It is giving a branch shift. This is the lateral sural cutaneous nerve which is a cutaneous branch from the common fibular which supplies the skin of the back of the leg. So these are the complete distribution of the common fibular and all its branches, its cutaneous supply, its muscular supply and its clinical correlations. Thank you very much for watching ladies and gentlemen. Dr. Sanjay Sanyal signing out. If you have any questions or comments put them in the comment section below. Have a nice day. Hey guys make sure you subscribe and like this video.