Did you know that most of the muscles that control the movement of your foot are actually located in your lower leg? Learn about the muscles below the knee that control the feet and toes in this lesson.
Movement, we all depend on it to survive. We depend on our skeletal or voluntary muscles to get us from one spot to another, and we depend on our involuntary or smooth muscles to breath and digest - and even our heart is a muscle, without which, we wouldn't be alive! And, while we have tons of muscles in our bodies, the ones most responsible for getting us from one place or position to another are those found in our legs.
If you've been following some of our other lessons on anatomy, you have probably already learned about the leg muscles located above the knee. So, for this lesson, we are going to go through some of the main muscles located below the knee. These muscles are used in the movement of the ankle, feet and toes.
The Knee Muscle
The patella is your knee cap.
So, let's get started at the patella (that's your knee cap).
The popliteus muscle kind of has its own category; it's neither below nor above, but is located at the knee. This muscle allows you to unlock your knee during flexion of the leg.
Flexion of a body part - in this case your lower leg - is a bending motion at a joint that decreases the angle between the two bones on either side of the joint. The opposite of flexion is extension, which usually involves the straightening of a bent joint, increasing the distance between the bones on either side of the joint. So, flexion of the knee brings the lower leg closer to the upper leg. This movement is aided by the popliteal muscle of the knee. It wraps around the back of the knee, helping to stabilize your knee joint. When your legs are moving, like running or walking, the popliteus rotates the tibia bone inward, helping to initiate flexion at the knee.
The popliteus muscle is at the knee.
Other than the popliteus, all other muscles below the knee are connected to the foot. They can be divided into three general groups:
- Muscles that flex or extend the foot
- Muscles that flex and extend the toes
- Muscles that support the structure of the foot
The muscles that flex and extend the foot are located along the tibia and fibula.
Let's start with those that flex and extend the foot. These muscles are located above, along the tibia and fibula of the lower leg. The movement and structure of your foot is probably more complex than you may have thought. While they don't have all the dexterity that your hands do, they can still move and rotate in multiple directions requiring the use of many muscles. The coordination of all the muscles in your feet and toes is essential to keep you walking upright, to allow you to dance or to dribble a soccer ball.
We won't get into all those muscles here, but we will cover the general function of the muscles that move the foot. So, let's start with an exercise. Put your right leg out in front of you so your foot isn't touching the floor. Now, pull the toes of your right foot toward the front of your body. This movement is called dorsal flexion. Now, point your foot and toes back, as far you can towards the floor. This movement is called plantar flexion.
Most of the muscles that move your ankle and foot are extensors and produce plantar flexion. I know, the terms sound confusing, I mean, 'an extensor produces flexion?' But, if you think about the movement itself and not the name, you will see you are actually extending your foot and ankle away from your body.
These muscles are also involved in other movements of your foot called eversion and inversion. So, let's go back to our exercise. Are your feet out in front of you? Now, twist your right foot so that the underside is facing the left foot. This action is called foot inversion. So, inversion turns your foot inward. Now, rotate your foot in the other direction, like you are trying to face the bottom of your foot outward towards your right side. This movement is called foot eversion and is the opposite movement of foot inversion. These movement help you make adjustments in your posture so that you don't fall over.
The tibia and fibula
These movements are performed by the same sets of muscles that allow dorsal and plantar flexion. Most of these muscles originate on the shaft of the tibia or fibula of the lower leg, those bones below. They travel down to your leg and insert into the tendons or bones in your ankle and foot.
The most well-known and strongest of these tendons is commonly called the Achilles tendon - for the Greek hero Achilles - but its actual name is the calcaneal tendon. This tendon is the insertion point for two of the largest muscles of the calf. The first is the gastrocnemius muscle. This muscle is important in plantar flexion, allowing you to lift your heel when walking, running and jumping. Underneath it lies the soleus muscle, which, in addition to plantar flexion, continually adjusts your posture when standing and moving.
These two are helped out by other, smaller muscles, called deep extensors, which are located underneath and to the side of the soleus and gastrocnemius muscles. On the front of your lower leg is another large muscle called the tibialis anterior (anterior because of its location at the front). This is the opposite of the gastrocnemius muscle and, therefore, is the main muscle responsible for dorsal flexion of the foot.
The tibialis anterior controls dorsal flexion.
Muscles That Move the Toes
Underneath the soleus muscle, you also have muscles that are responsible for the movement of the toes. I know, toe muscles in the leg? But, just like in your hands (where the muscles that control your fingers are actually located in your arm), some of the muscles that control your toes are located in the leg! These muscles are closer to the surface of the tibia and fibula than the larger calf muscles.
They include the digital flexors, which, as the name suggests, cause flexion at the toes, while the digital extensors extend the toes (also referred to in science as 'digits,' and no, not the type you ask a girl for when you want her number). The muscle part actually ends around the ankle, where it transitions into a long tendon. The tendons of the extensors extend across the top part of your foot and down to the toes, while the tendons of the flexors cross around the sides of your ankle and extend along the bottom of the foot.
They are also aided by muscles within the foot itself. The intrinsic muscles of the foot are involved in flexion, extension and movement of the toes toward and away from the body.
In addition to aiding in toe movement, the intrinsic muscles are important for supporting all the bones and tendons and the overall structure of the foot. They are especially important in supporting and maintaining the arch of your foot.
Most of the intrinsic muscles have origins on the tarsal and metatarsal bones of the foot. Their insertion points vary, with some inserting onto the bones of the toes, while others insert onto tendons of the digital flexors and extensors.
And that's it, the major muscles of the lower leg and foot. But, let's not forget about the knee; the popliteus muscle allows you to unlock your knee when you flex your leg. Underneath that are the muscles that control your foot; most of these are located at the back of your leg - the calf muscles. These are extensor muscles involved in plantar flexion, eversion and inversion of the foot.
The largest extensor muscles of the calf are the gastrocnemius and soleus muscles. The opposing muscle, the one that controls dorsal flexion of the foot, is called the tibialis anterior and is located below, at the front of the leg.
Moving down towards the ankle - well, right above the ankle - we have the digital extensors and flexors, muscles that control the extension and flexion of the toes. These muscles are connected to tendons that extend along the top and bottom of your foot, down to your toes.
Within the foot you have the intrinsic muscles of the foot. These muscles have multiple roles. Some aid in the extension and flexion of the toes, while others support the structure and arch of the foot, and some even do both! All in all, the feet are very complex appendages, and even though they aren't as versatile as your hand, they are just as important - especially for getting around easily, playing sports and keeping your balance!
Once you've finished with this lesson, you will have the ability to:
- Identify the patella and the popliteus muscles and their functions
- Describe the muscles that extend and flex the foot
- Explain the functions of the digital extensors and flexors as well as the intrinsic muscles of the foot