 Good day everybody. Dr. Sanjay Sanyal, Professor Department Chair. This is going to be a demonstration of the TBL nerve and a branch of the common fibular nerve. So to start with, I have lifted up the two divisions of the sciatic nerve in the perpendicular fossa. This is the TBL nerve, this is the common fibular nerve. The cutaneous branches we have already described, so therefore we shall not bother about that. Let's focus on the first, the common fibular. The common fibular runs infralaterally under cover of the biceps femoris and then it goes behind the head of the fibula. We can see that here. And then it winds around the lateral aspect of the neck of the fibula and then it disappears under this muscle. This is the fibularis longus muscle. In this region, when it is in relation to the neck of the fibula, this is libel to injury in fracture of the neck of the fibula and can lead to paralysis of the extensors of the foot, dorsi collection of the foot. And that is called foot drop. This is an x-ray of the knee to show fracture of the head of the fibula. In such cases, CFN injury is a strong possibility. To continue, inside the fibularis longus muscle, this common fibular nerve divides into a superficial fibular and a deep fibular. In this particular dissection, because this is a prone cadaver and this is the right leg of the cadaver, we can see only the superficial division and that is the one which I have picked up here. And we can see when I exert traction here, it moves here. So this is the superficial division of the common fibular nerve. This supplies two muscles. It supplies the fibularis longus and it supplies this muscle, the fibularis brevis, both of which are inverters of the foot. And after it is supplied this, if you watch closely, we can see that it pierces through the muscle and comes under the fascia of the leg, the cruel fascia. So this is the continuation of the same nerve. And then it runs under the cruel fascia for a certain distance and then we can see it is piercing through the cruel fascia here. So we have seen the four segments of this nerve. We have seen one segment here. We have seen another segment here. We have seen the third segment here and we have seen the fourth segment here. And once it pierces the deep fascia, the cruel fascia of the leg, it becomes subcutaneous and by means of multiple branches and we can see two of those branches. It crosses superficial to the extensor adeniculum of the ankle and it supplies the skin of the lower one-third of the front of the leg as well as an extensive part of the dorsum of the foot, except the first inter-digital cleft that is between the great two and the second two. So this is the full distribution of the superficial fibular nerve. People who suffer from repeated inversion injury, they can get traction neuropathy of the superficial fibular nerve, in which case there will be numbness, tingling and palesthesia of the greater part of the skin of the dorsum of the foot. Additionally, in thin persons, if we stretch the foot tightly, we can sometimes see the fibres of these nerves standing up under the skin. And that can be used as a landmark to give nerve block and anesthetize a large part of the dorsum of the foot for any surgical procedure. So we cannot see the deep fibular nerve here because as I said, it supplies the anterior compartment and we cannot see it in this view. Now let's take the next branch. This is the tibial division and we can see the tibial division is disappearing under these muscles and it's giving multiple branches also. It gives branches to the muscles, gastroponamias, it gives branches to the soleus and then it goes under the tendinous arch of soleus and my finger is going to go under that. This is the tendinous arch of soleus. I'm going to lift up this. We have cut the tendocalcaneus and I have lifted it up here and we can see the continuation of the tibial nerve here. This is the neurovascular plane between the soleus muscle and the deep muscles of the calf, namely flexor, digitorum, longus. The tibial is posterior, the flexor helices longus. So it runs in this neurovascular plane accompanied by the posterior tibial artery. It supplies all the muscles of the deep compartment of the posterior aspect of the leg. Then it runs in a tunnel here. We have split open that tunnel and we can see one cut margin of the fascia here and the other cut margin is here. This tunnel is referred to as the tarsal tunnel. It's a tunnel between the medial malleolus and the calcaneus, preserved by the flexor neculum of the ankle. And running through the tunnel is the tibial nerve. So let's take a look at the relations inside the tunnel. We have an ammonic here. Tom, Dick, Bloody, Nervous, Harry. Anteriorly we have this tendon here. This is the tibialis posterior tendon. T. Then we have this tendon here. This is the flexor digitorum longus. T, Tom and Dick. Bloody refers to the posterior tibial artery in the vein, vinecomitantes. Nervous refers to the tibial nerve. And Harry refers to this tendon, the flexor helices longus. This tibial nerve can get entrapped in this tarsal tunnel because this is a tight osteofibrous compartment. And that will lead to a condition known as tarsal tunnel syndrome. The patient will have weakness of the muscles of the sole of the foot, numbness in tingling and palesthesia in the distribution of the medial and lateral plantar nerve. And additionally, the person will have severe heel pain. And why so? Let's take a look at the tibial nerve here. We can see the tibial nerve is giving three branches. This first one is supplying the calcaneus. This is called the calcaneal branch. This second one is the lateral plantar nerve. And the third one is the medial plantar nerve. So let's take a look at this. I'm going to exert traction on the medial plantar nerve and we shall see it is moving here. So this is the medial plantar nerve. This is one division. The medial plantar nerve goes under the abductor helices tendon. And it can get entrapped under the abductor helices tendon in the condition known as joggers neuropathy. But in joggers neuropathy, there will be weakness of the medial plantar nerve, but there will be no heel pain. Now I'm going to pull on the lateral plantar nerve and we can see it is moving here. This is the lateral plantar nerve. Both the medial and the lateral plantar nerve, in the initial part of their course, they run between layers one and two of the sole of the foot. Layer one being the abductor helices and the flexor helices brevis. And the layer number two being the flexor digidrome longus, the flexor accessorius and the flexor helices longus. So it is running between layers number one and two. And we can see that here and we can see that here also. The medial plantar nerve supplies less muscle, more of the skin. The medial plantar nerve supplies the abductor helices, the flexor helices brevis, the first lubricant and the flexor digidrome brevis. So the first toe, the first layer and the first lubricant. And supplies the skin of the sole and aligned through the fourth metrotarsal and the digit that much of the sole. Lateral plantar nerve supplies the rest of the muscles and we can see that giving numerous branches and it supplies only this one fourth of the sole of the foot. The medial plantar nerve, apart from being entrapped by the abductor helices, it can also undergo traction neuropathy in those who suffer from repeated eversion injury, like for example, gymnasts. If the lateral plantar nerve is injured, it can produce weakness of most of the intrinsic muscles of the sole of the foot and can lead to cloto or hammer toe. And finally, there can be neuroma of the digital nerves, especially between the heads of the third and fourth metrotarsal. And that can lead to very painful condition, which is referred to as modern's metrotarsalgia. So these are all the points which I want to mention about the full distribution of the tibial and the common fibular nerve that we can see in this dissection. Thank you very much for watching. Dr. Sanjay Sanyal, Sanyout. David, who is the camera person. If you have any questions or comments, please put them in the comment section below. Have a nice day.