There are 26 bones and 33 joints within our foot and ankle. It is a complex structure. Many of you may think there is a few basic motions mainly dorsiflexion and plantarflexion or up-and-down. But is a more a joint complex. The ankle joint is made up of the fibula, tibia, and talus. The talus is an interesting bone in of itself, it has no muscular attachments and plays an important role in our flexor withdrawal reflex when we are in danger of being injured. This part of the ankle is the talocrural joint. Below it is the talocalcaneal joint or subtalar joint. The subtalar joint is made up of 3 facets; the posterior (back), middle, and anterior (front). This allows for triplanar motion.
The talocrural joint allows for the up-and-down motion while the subtalar joint helps us by providing mobility when walking over varied surfaces. Think of when hiking on a steep, rocky terrain. You need ankle mobility to accomplish this well. The rest of the bones and joints of the foot are important too each working together for that firm foundation we are seeking.
There are several muscles that act on the foot and ankle that are very important to highlight. Most of these originate in the leg. The intrinsic muscles of the foot itself are important too but I am going to focus on some of the big players.
Firstly, the tibialis posterior. This muscle originates from inner posterior portions of the fibula and tibia attaching to the interosseous membrane that lies between the two bones as well. The muscle tendon wraps behind the medial malleolus inserting itself to several bones on the plantar side of the foot, specifically the navicular, calcaneus, the cuneiforms, cuboid, and 2nd, 3rd, and 4th metatarsals. When speaking of origin and insertion, please understand that this a specific term for something that is more general. Because of ligaments, tendons, and fascia, the origins and insertions are broad points of contact that interact with the surround structures in a variety of ways. That being said there are a couple of main actions the tibialis posterior muscle performs. It is responsible for inversion and assisting in plantarflexion of the foot. It also plays a very important role in supporting the arch of the foot. This is where I see it commonly. Many who deal with fallen arches and overpronation have an issue with their tibialis posterior. Abductor hallucis, the muscle that holds our big toe out, is another common cause.
The soleus and gastrocnemius are the muscles that make up your calf. The gastrocnemius acts on both the knee and the ankle joints but the soleus only acts on the ankle. However, that being said remember what I said above. I am applying specific terms or simplifying complex anatomy. The soleus originates on the fibula and medial tibia. The gastroc, divided into two heads, originates just above the medial and lateral condyles of the femur. They share a common insertion via the achilles tendon onto the calcaneus. Together their action is to plantarflex the foot. The gastroc also assists in knee flexion. I am sure many of you have seen many athletes suffering from achilles tendon tears and ruptures.
Some other muscles that play an important role are tibialis anterior, which helps with inversion and dorsiflexion and the fibularis muscles which help eversion, dorsiflexion, and plantarflexion. I won’t go into detail with these, hoping that the above details illustrate the point that our feet are part of a complex system of muscles, joints, ligaments, etc., all providing us with the ability for mobility, support, and movement. It is very important to take care of our feet!