 Good day everybody. This is Dr. Sanjay Sanyal, Professor, Department Chair. This is going to be a demonstration of the arches of the foot. So we have positioned the left foot skeleton here and this is the right foot skeleton. If you take a good look, you'll notice that there's a curvature on the medial side of the foot as seen in this foot here, which is a very deep curvature. Therefore, when we are standing, the medial side of the foot does not come in contact with the ground. And if you want to take a look on the right foot, you find that there is a curvature on the lateral side of the foot also. However, it is not as deep as the medial curvature. This is what is called the arch of the foot. And more specifically, this is the longitudinal arch of the foot. So what happens is when we are standing, the force is exerted from the tibia. It goes to the talus, to the body, the trochlear surface of the talus. From there, it is transmitted to the calcaneus. More specifically, the tuberosity, the medial tubercle of the calcaneus is in contact with the ground. One part of the force is transmitted to the calcaneus, that is the heel. And the other part of the force is transmitted to the heads of the medial tarsus. The first, second, third, fourth and fifth. And we can see the same thing here also. Here there is no tibia, but we can see the force is transmitted to the calcaneus and it goes and transmitted to the heads of the medial tarsus. So this is what is the principle of the longitudinal arch of the foot. We shall go into the details just a little later. At the same time, when we take a close look, we notice that not only is there a longitudinal arch, but there is also a curvature of the foot like this. It is convex here on the tarsus surface and it is concave on the under surface. So that is called the transverse arch of the foot. So therefore, the foot has got two sets of arches. A longitudinal set of arches and a transverse arch. Let's take a look at the longitudinal arch first. The longitudinal arch is divided into a medial component and a lateral component. The bones involved in the medial component are the calcaneus, head of the talus, the navicular bone, medial, intermediate, lateral cuneiform and the first three meditarsals, the heads of the first three meditarsals. These are the bones which are involved in the medial longitudinal arch. The lateral longitudinal arch includes again the calcaneus, the cuboid and the fourth and the fifth meditarsal heads. That brings me to the next concept. What are the dynamic structures which are maintaining the longitudinal arch and what are the passive structures? Dynamic structures refers to the tendons and the muscles. First of all, we have those intrinsic muscles of the foot. They all have to maintain the arches of the foot. So, we shall not mention the individual intrinsic muscles. The important dynamic structures which are concerned with maintaining the longitudinal arches of the foot are, one, we have the tibialis anterior which goes like this and gets attached to the medial cuneiform and to the base of the first meditarsal. This is one structure which helps to maintain the longitudinal arch of the foot, the tibialis anterior. The other muscle tendon is the flexor halusis long tendon. It grooves the posterior aspect of the talus and it gets inserted onto the tip of the distal phalanx of the great toe. That is the flexor halusis long tendon. These are the dynamic structures which maintain the longitudinal arch. What are the passive structures which maintain the longitudinal arch of the foot? Going from superficial to deep, we have the plantarapodurosis. The apex of the plantarapodurosis is attached to the calcaneus and the base has got five slips which merge with the flexor digital sheets of the digits. That is the superficial most structure. Just under that, we have something called the long plantar ligament. In order to show that, I am going to turn this... We have the long plantar ligament which is actually extending from the calcaneus and goes across like this and it gets attached to the cuboid and it extends further. That is called the long plantar ligament. Under that, we have the next layer that is the short plantar ligament actually also from the calcaneus to the cuboid. And finally, deep inside, most important structure is what is known as the plantar calcaneum navicular ligament. I have turned the skeleton to show you the plantar calcaneum navicular ligament or the spring ligament which is the deepest structure. It extends from the sustenticulant ally which is a shelf leg projection from the middle surface of the upper border of the calcaneus. And the ligament then goes and gets attached to the tuberosity of the navicular bone here. And as it goes, it supports the head of the talus here. This is called the spring ligament and this is a very important structure and this composite constitutes what is known as the T-C-N joint. If this spring ligament gets weak or is congenital weak or gets degenerated or it ruptures, then the head of the talus drops down and that is what is known as dropped arch or fallen arch. And that is one important pathogenesis, the causation of flat foot. So that's about the longitudinal arch. This is a lateral view of the X-ray of an angle to show the location of the spring ligament and the talocalcaneum navicular joint. I'll mention more about flat foot once I've finished describing the other arch of the foot. Now let's take a look at the transverse arch of the foot. In order to understand the transverse arch of the foot, again, let's take a look at the planter surface and then I'm going to turn to show you the dorsal surface. We can see that the dorsal surface of the bones here, they are more convex and the planter surface are more concave. So this is the transverse arch of the foot. The transverse arch of the foot is maintained by the following bones. Navicular, the cuboid and the three cuneiforms. That means the mid-tarsal bones are the ones which are responsible for maintaining the transverse arch of the foot. This is the next ray of the foot in the ankle. Dorsal planter view to show the transverse arch to the foot. These are called cuneiforms because they are wedge shaped. That means the dorsal surface is wider, the planter surface is narrow. So therefore the shape of the bone itself contributes to the formation of the transverse arch. Apart from the intrinsic muscles and the short small ligaments which connect all these bones, we also have some structures, important structures which help to maintain the transverse arch. More specifically, two long tendons. One of them is the tendon of the fibularis longus, which comes from the lateral aspect of the cuboid. It grooves the lateral aspect of the cuboid, runs in a groove on the under surface of the cuboid and it goes and it gets attached to the lateral surface of the medial cuneiform and the lateral surface of the base of the first meditarsal. So that is the fibularis longus tendon. This gives a strong pull from the lateral aspect. Concomitantly, there is an extensive insertion of the tibialis posterior. The tibialis posterior comes from the medial side and it has got an extensive insertion, direct, indirect and reflected insertion onto the calcaneus, navicular, cuneiform and the basis of the second third and fourth meditarsals and that exerts a strong pull from the medial side. Both these tendons are located in layer number 4 of the sole and they also are dynamic structures which help to maintain the transverse arch of the foot. That brings me to the next point. Why do we need these longitudinal arches and why do we need these transverse arches? They are responsible for giving us the springiness of our gait as well as stance and they enable us to run, jump, walk, do everything with our foot. If we did not have these arches, it would be very difficult for us to walk. When there is a flat foot, it is called pesclanus. It can be congenital, it can be acquired. If you notice a baby, first year of life has a natural flat foot because these tendons ligaments are not developed fully and they are weak and therefore the foot is flat. And if you were to take an imprint of a baby's foot, you will find that the full imprint of the foot comes on the ground. On the other hand, if you were to take your own foot on a sand or a wet foot on the ground, you will find that it's only the heads of the meditar cells which are touching the ground and a little bit of the lateral surface will touch the ground and the calcaneus will touch the ground, the rest will not touch the ground. So that is what is the arch. This is a diagrammatic representation to show the imprint of a normal foot with its arches. On the other hand, if you were to take the imprint of a person with a flat foot, a pesclanus, then you will see that the whole foot, just like a baby touches the ground. With a flat foot, the person will not be able to run. The person will have foot pain. So that is the importance of the arch of the foot. If the person gets a fracture of the calcaneus, after the fracture calcaneus heals, the person develops a slight flat foot because the angulation, the so called Bueller angle becomes less than, little less than 20 degrees. These are two x-rays of the fracture calcaneus to show how the Bueller angle has become less than 20 degrees and partial flat foot. This is the few points which I wanted to mention to you about the arches of the foot and flat foot. Thank you very much for watching. Dr. Sajja Sanyal signing out. Please like and subscribe. 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