Video: Bones of the foot
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Did you know there are a grand total of twenty six bones in each of your feet? This means that about one quarter of all the bones in your body are found just in your own two feet. I know this seems... Read more
Did you know there are a grand total of twenty six bones in each of your feet? This means that about one quarter of all the bones in your body are found just in your own two feet. I know this seems like a lot, but don't let this overwhelm you. We'll work through it together as we learn all about the bones of the foot.
Before we embark on this journey, let's take a second to go over what we'll learn today. First, we'll look at all twenty six of those bones that give structure to your foot – don't panic. A lot of these bones are grouped together so it won't be as bad as it seems. To learn the bones, we’ll section them off into bones of the hindfoot, midfoot, and forefoot. The bones of the hindfoot and the midfoot make up a group of bones called the tarsal bones while the forefoot is comprised of metatarsals and phalanges. Finally, we'll wrap things up by looking at an important clinical scenario that relates to this anatomy. So let's get started with our first and most proximal group of bones – the bones of the hindfoot.
The hindfoot includes only two bones – the talus and the calcaneus. In this video, we'll just do a quick and dirty overview of these two bones, and if you want to dive into more detail, check out our talus and calcaneus videos that take a much deeper look at each bone.
In this image, we're looking at the foot and ankle from a lateral view with the talus highlighted. In situ, we can see its relationship with neighboring bones and identify the joints that it contributes to. Medially and superiorly, it articulates with the tibia and, laterally, with the fibula to form the talocrural joint. Inferiorly, it articulates with the calcaneus to form the subtalar joint. Last but not least, the distal part of the talus articulates with the navicular to form the talonavicular joint. Interestingly enough, although it has several bony articulations, the talus is unique in that it has no muscular or tendinous attachments. Keep all of these articulations in mind for now, we'll be revisiting them later.
In isolation, we can study the talus from numerous perspectives and now we can appreciate why this snail-like bone is classified as being a short bone. Spoiler alert! It’s because it's about as wide as it is long. The three main parts of the talus can be seen here too. These include the body which is the posterior most part of the bone, the neck which is a thin narrowing anterior to the body, and finally, we have the distal expanded part of the talus which is the head. You can see that each of these parts have several bony features and landmarks that are important to know, but won't be covered in this overview video today. If you're curious though, you can learn about each and every nook and cranny of the talus bone in our dedicated video tutorial on this bone.
So, although we won't get into the nitty-gritty of each part of the talus in this video, let's take a minute to look at the talar articular surfaces that form the joints we mentioned earlier. First, we have the trochlea which is this large triarticular structure here on the superior aspect of the bone, and I say triarticular as it has three articular surfaces – a superior malleolar articular surface and a medial malleolar articular surface which articulate with the distal end of the tibia. There’s also a lateral malleolar articular surface which, true to its name, articulates with the lateral malleolus of the fibula. Collectively, these articulations form the talocrural joint.
On the inferior aspect of the bone, we have three articular surfaces – all of which articulate with the calcaneus forming the subtalar joint. The first is the anterior calcaneal articular surface, which is seen here on the head of the talus. Next is the middle calcaneal articular surface. This feature is found on the neck of the talus. And the third and final point of articulation between the talus and the calcaneus is located at the posterior calcaneal articular surface, seen here on the body of the talus.
Finally, on the anterior or distal surface of the head of the talus, we have the navicular articular surface, which is the point of articulation with the navicular bone. We’ll learn more about the navicular bone when we go over the bones of the midfoot. But before we do that, let's briefly go over the second and final bone of the hindfoot – the calcaneus, which is situated immediately inferior to the talus.
Like the talus, the calcaneus has plenty of bumps, grooves, and surfaces, but for the purpose of this video, we’ll only be learning about a few of them. To dive into more detail, you're encouraged to check out our tutorial that takes a more comprehensive look at the calcaneus.
In situ, we can see that the calcaneus articulates with the two bones. Fortunately, we just went over one of them so you're already halfway there. We know from earlier that there are three separate points between the talus and the calcaneus, which collectively form the subtalar joint, seen here. We’ll look at the three calcaneal contributions to this joint in just a second.
The second bone that articulates with the calcaneus is the cuboid, which forms the calcaneocuboid joint. Like the talus, studying the calcaneus in isolation allows you to view the bone from multiple perspectives. And now we can see those articular surfaces that we mentioned previously.
First, we'll go over the calcaneus’s three contributions to the subtalar joint, each of which corresponds with the three calcaneal articular surfaces that we saw on the talus. Here we have the most anterior of the three which is cleverly named the anterior talar articular surface. If we move a little more posterior, we find the middle talar articular surface. You can just barely see a sliver of it from the posterior view. Finally and the most posteriorly is the posterior calcaneal articular surface.
Although there are many bony projections on the calcaneus, we're only going to look at one for now which is the calcaneal tuberosity. As you can see, it's pretty big, so big in fact that you can see it from the superior, posterior, and medial perspectives. This large bony mass is at the most posterior part of the foot and forms the bulk of your heel. And that's it! The bones of the hindfoot are finished and we can now move on to the bones of the midfoot.
These are bones found anterior to the talus and calcaneus and include the navicular bone, the cuboid bone, in addition to the lateral, intermediate, and medial cuneiform bones. Let’s take a closer look at each of these bones and their bony features.
Here we see the navicular bone from superior and inferior views, and from this we can see that it is found along the medial aspect of the foot. We know from what we learned about the talus that this bone is just anterior to and articulates with the talus forming the talonavicular joint. It also articulates with other bones of the midfoot including the lateral, intermediate, and medial cuneiforms at the cuneonavicular joint.
On the inferior side at the navicular bone, it has a small bump which is called the tuberosity of the navicular bone. This bony feature serves as one of the insertion points for the tibialis posterior muscle.
The next bone of the midfoot that we'll look at is the cuboid bone, which is located on the lateral side of the foot. We learned earlier that the cuboid bone articulates with the calcaneus posteriorly and now we can also see that it articulates with the lateral cuneiform of the midfoot as well as two bones of the forefoot called the fourth and fifth metatarsals which we'll get to later. On the inferior side of the cuboid bone, there's a shallow groove called the fibular sulcus, also sometimes referred to as the peroneal sulcus. Passing through this sulcus is the tendon of the fibularis longus muscle.
Next up for the midfoot is the lateral cuneiform bone. As the name suggests, it is the most lateral of the three cuneiforms. It articulates with the intermediate cuneiform medially, the cuboid bone laterally, the navicular bone posteriorly, and the third metatarsal anteriorly. This bone also serves as one of the insertion points for the tibialis posterior muscle.
Situated medially to the lateral cuneiform is the intermediate cuneiform. This is the smallest of the three cuneiforms. The intermediate cuneiform articulates with the navicular bone posteriorly, the medial cuneiform medially, the lateral cuneiform laterally, and the second metatarsal anteriorly.
The final bone of the midfoot is the medial cuneiform. This is the largest of the three cuneiforms and it articulates with the navicular bone posteriorly, the intermediate cuneiform laterally, and the first and second metatarsal bones anteriorly. The medial cuneiform serves as an attachment point for the tibialis anterior and fibularis longus muscles.
And with that, we've finished the midfoot. We’re now ready to move on to the bones of the forefoot.
This last group of bones that we'll talk about is what makes up your pedal digits – better known as toes. These include the metatarsal bones, the proximal phalanges, the middle phalanges, and the distal phalanges. Let’s start proximally with the metatarsals.
These typical long bones are numbered one to five with one being the most medial and five being the most lateral. Proximally, each of the five metatarsals articulate with its neighboring bone of the midfoot to collectively form the tarsometatarsal joints. This joint will be of particular importance later on when we investigate a clinical scenario associated with it. The proximal ends of the metatarsal bones also articulate with each other forming intermetatarsal joints. Proximally, the metatarsals have enlargements called bases which extend distally as long slender bodies, also known as shafts. At the distal end of each body, there's a further expansion of bone known as the metatarsal head.
The metatarsals are structurally important since they contribute to two important arches of the foot. The first, seen here, is the longitudinal arch. Specifically, the metatarsals form the distal half of this arch. The second arch that these bones help to form is the transverse arch. Specifically, it's the bases of the metatarsals that form this arch.
We’ll now look at the bases of two specific metatarsals since they have bony features of particular importance. We’ll first look at the base of the first metatarsal bone seen highlighted here. Located on the medial side of the base of the first metatarsal bone is a small bump or eminence which is simply known as the tuberosity of the base of the first metatarsal – sometimes, anatomists do make things easy for us. This small bony bump is important to note since it is where the fibularis longus muscle attaches.
If we now jump to the other side of the foot, we can see the base of the fifth metatarsal bone. This bony feature is noteworthy because if you look really closely on its lateral side, you can see the tuberosity of the base of the fifth metatarsal. Attaching to this bony feature is the fibularis brevis muscle. If we now move our attention to the distal end of the metatarsal bones, we can see where the head meets up with the proximal phalanges. This point of articulation is called the metatarsophalangeal joint.
Speaking of the proximal phalanges, we can see them here. This group of five bones make up the base of each of your toes. Just distal to the proximal phalanges are the middle phalanges. Note that there are only four of these bones since the first digit or the big toe doesn't have a middle phalanx. The middle phalanges serve as the point of attachment for the extensor digitorum brevis on their dorsal aspect and the flexor digitorum brevis on their plantar or bottom side.
And last but not least at the very end of the toes are the distal phalanges. You can see from the illustration that each digit has a distal phalanx, therefore, this is another group of five bones like the proximal phalanges. On the back or the dorsal side of these bones on digits two to five is where the extensor digitorum longus attaches and the first digit or the big toe is where the extensor hallucis longus attaches.
Similarly, the plantar side of the distal phalanges also have muscular attachments. On digits two to five, the distal phalanges serve as an attachment for the flexor digitorum longus and the first digit is the attachment site for the flexor hallucis longus. Between each of the phalanges are small joints called the interphalangeal joints. These are simply the articulations between the proximal, middle, and distal phalanges. And that's it for the bones of the foot – all twenty-six of them!
For the next part of the video, we're going to use what we've learned about these bones to investigate a clinical scenario. With all the activities that we do with our feet, the twenty six bones that comprise it are sometimes left vulnerable to injury. One such injury that can occur is called a Lisfranc fracture. This occurs when the tarsometatarsal joint is disrupted. You may also hear this joint referred to as the Lisfranc joint which makes sense when you consider the name of the fracture. Remember, this joint is what connects the midfoot with the forefoot.
The Lisfranc fracture varies greatly in severity and complexity possibly involving just minor ligamentous tears or it could involve major dislocation of the metatarsal heads. It is often caused by twisting or falling, so soccer and football players are particularly susceptible.
This player twisted his foot awkwardly during a game. Afterwards, he experienced pain, bruising on the bottom of his foot in addition to swelling, so he decided to have it checked out. The physician, after suspecting a Lisfranc fracture based on the symptoms, ordered an x-ray to confirm her diagnosis, which we can see here. Can you spot the Lisfranc fracture? Since you're now a master of the bones at the foot, I'm sure you had no issue identifying the fracture, which is just here.
For treatment, the physician may prescribe rest, ice, and elevation for swelling; a cast for immobilization, or surgery depending on the severity of the injury.
Okay, so before we call it a day, let's take a minute and quickly recap what we went over today.
We started with the bones of the foot which we grouped into the hindfoot, the midfoot, and the forefoot. Of the two bones of the hindfoot, the talus is found more superiorly. We divided this bone into the body, the neck, and the head and we went on to identify its different articular surfaces. We wrapped up the hindfoot by looking at the calcaneus including its articular surfaces as well as the calcaneal tuberosity.
Next, the bones of the midfoot were discussed which included the navicular, the cuboid, and the lateral, intermediate and medial cuneiforms. Anteriorly, the bones at the midfoot articulated with the bones of the forefoot forming the tarsometatarsal joint.
The last group of bones that we looked at was the bones of the forefoot. Included in this group were the metatarsals and the proximal, middle, and distal phalanges. On the metatarsal bones, we looked at the base, the body, and the head. Remember that the bases of the first and fifth metatarsals were particularly important as they served as important muscular attachments. Also the metatarsals helped contribute to the longitudinal and transverse arches of the foot.
The proximal phalanges, the middle phalanges, and the distal phalanges were also discussed and we talked about the muscles that attach to each. We then wrap things up by looking at one clinical correlate related to this anatomy – the Lisfranc fracture, which remember, is a fracture that occurs along the tarsometatarsal joint. We learned about the mechanism of injury, diagnostic measures, and treatment options associated with this injury.
And that's it! Thanks very much for joining us today. Happy studying!