The human body is a complex and wonderful thing. We tend to take it for granted when we're going about our daily lives. One facet of the human body that's particularly interesting are the nerves, such as the deep peroneal nerve.
The nerves are fibers, or bundles of fibers, that facilitate communication between the brain and other parts of the body. Basically, everything you can do, you can do because of your nerves. You're not putting any conscious effort into it, but these processes are going on in your body at all times.
The deep peroneal nerve is no exception. It performs very important functions, and injuries to this nerve can be very debilitating. It helps, then, to learn a little bit more about this nerve and the injuries associated with it.
What Is the Deep Peroneal Nerve?
There are certain nerves that people generally know better than others. For example, you've likely heard people talk about the sciatic nerve at least on one occasion. But the deep peroneal nerve, also known as the deep fibular nerve, is not one that people tend to talk about a whole lot.
However, it's an important nerve. In fact, it actually comes from the sciatic nerve.
Where to find it
Where is the deep peroneal nerve, exactly? It originates from the sciatic nerve, as we just said. The sciatic nerve splits into the common fibular nerve and the tibial nerve at the popliteal fossa. The popliteal fossa is located at the back of your knee.
The common fibular nerve will wrap around the neck of the fibula (your calf bone) and then split into two terminal branches. One of these is the superficial fibular nerve, and the other is the deep fibular nerve, or deep peroneal nerve.
The actual deep peroneal nerve starts in the upper part of the calf. The origin is between the fibularis longus muscle and the neck of your fibula. Then, it moves to the front part of your leg and then follows the anterior tibial artery down and towards the middle.
As the deep peroneal nerve is traveling down your leg, it's following the same direction as the anterior tibial artery. These two structures will both pass between different muscles in your calf before arriving at your foot.
And the end
Then, the deep peroneal nerve gets to your foot. It'll cross your ankle joint, and then go into your extensor retinaculum. The extensor retinaculum is the thick part of the antebrachial fascia that holds the tendons of the extensor muscles of your foot in place.
Finally, this nerve terminates in the dorsum of your foot; specifically, this is within the muscles in the top area of your foot. Here, it'll divide into two branches, the lateral branch and the medial branch. Both of these branches of the deep peroneal nerve have their own distinct purposes.
What's it for?
The deep peroneal nerve has a few different functions, both sensory and motor. However, it's more prominent in terms of motor functions.
These motor functions
As far as your motor functions go, it innervates the muscles in the anterior, or front, part of your leg and some of the intrinsic muscles within your foot. Because of the connection it provides between these muscles in your brain, it's basically what allows you to move these muscles in certain ways.
Specifically, it innervates the tibialis anterior, extensor hallucis longus, extensor digitorum longus, and fibularis tertius. You need these muscles for dorsiflexion of your foot at your ankle joint.
This is really important for walking. While you're walking, dorsiflexion is necessary when you strike your heel on the floor and when you're swinging your leg forward.
The deep peroneal nerve also innervates the extensor digitorum brevis and extensor hallucis brevis. These are intrinsic muscles of the foot. The nerve allows them to extend your toes at certain joints.
Don't forget the sensory functions
This nerve also has a sensory function, within the triangular region of skin between your first (big) and second toe. It's what allows you to feel any sensations from the surroundings in this little webbed patch of skin.
Injuries of the Deep Peroneal Nerve
When you have an injury of the deep peroneal nerve, it interferes with the functions of this nerve. This means that you'll have a loss of movement and/or sensation in that leg and foot. Dysfunction of the peroneal nerve is a type of peripheral neuropathy, which is just a general term for damage to nerves outside of the spinal cord and brain.
When a single nerve is not functioning properly, this is referred to as mononeuropathy. In these cases, the nerve damage took place in one area of the body. However, it's also possible for certain conditions that affect the entire body to injure only one nerve.
When the nerve is damaged, the myelin sheath that covers the nerve cell is also disrupted. This causes symptoms in itself, but the symptoms are even more severe when an injury to the axon has occurred. The axon is the branch of the nerve cell within the myelin.
Why, why, why?!
There are a few common causes of injury to the peroneal nerve. One of them is some sort of injury or trauma to the knee. Also, if you happen to fracture your fibula, that could lead to deep peroneal nerve damage.
Anything that constricts your lower leg on a long-term basis can also put you at risk for this sort of mononeuropathy. This can happen if you wear a tight plaster cast on your lower leg. Even crossing your legs or wearing high boots on a regular basis can cause this type of damage as well.
There are other types of knee injuries that can also lead to deep peroneal nerve damage. These include pressure that that's inadvertently put on your knee when you're sleeping, in a coma, in knee surgery, or in some sort of awkward position while under anesthesia.
Find out if you are at risk
There are a few risk factors for peroneal nerve injury as well. Typically, these involve other medical problems that could lead to additional complications.
People who are very thin, such as those who suffer from anorexia nervosa, are at a greater risk. Those who have certain autoimmune conditions, including polyarteritis nodosa, are also more susceptible.
If you have pre-existing nerve issues, this can be another major risk factor. Nerve damage from other medical problems, including alcohol use and diabetes, can make peroneal nerve injury more likely. Charcot-Marie-Tooth disease, an inherited disorder that has an impact on all of your nerves, is another risk factor.
How to identify the signs of a peroneal nerve injury
Damage to the deep peroneal nerve results in a condition called foot drop. That is a general term that describes difficulty lifting the front part of your foot. Basically, the front of your foot is likely to drag on the ground when you walk if you have foot drop.
When the front of your foot drags on the ground as you're walking, this can alter your general gait. In some cases, it causes the person to raise his or her thigh more when he or she is walking, so that foot has an easier time clearing the floor.
That can lead to the person having to slap his or her foot down onto the ground with each step. In some situations, the skin on the top of the person's foot and toes will feel numb.
Foot drop isn't a disease in itself. It's a sign of some sort of other problem, such as a problem with your deep peroneal nerve. It can be either temporary or permanent, depending on the situation.
Other than foot drop, there are few other common symptoms that come with damage to the deep peroneal nerve. These include decreased sensation, tingling or numbness in either the outer part of the leg or the foot, and weakness in the feet or ankles. Other walking abnormalities are also possible.
Treatments for Deep Peroneal Nerve Damage
There are different treatments available for deep peroneal nerve damage, depending on the specific type of damage.
A type of injection may help
If you want a more conservative option, you might want to look into steroid injections. Doctors often recommend these injections to reduce pressure on the nerve that results from swelling.
Typically, they'll combine a steroid with an anesthetic and inject this solution into the area around the affected nerve.
Steroids inhibit the production of proteins that cause inflammation. That decreases the amount of nerve irritation. The anesthetic blocks nerve conduction in the area where the doctor applies it, which numbs the patient to pain.
Decompressing isn't just something to do after a long day
If steroid injections don't work to reduce symptoms, you might want to consider surgery. Typically, the surgery that would be done here is peroneal nerve decompression.
The surgeon will make a small incision below your lateral knee that follows the direction of the common peroneal nerve. Then, he or she will follow the entire nerve, to the point where it branches off into the superficial and deep peroneal nerves.
The surgeon will basically separate and retract muscles in order to fully release the nerve. Any areas where the nerve is trapped or compressed will be released.
This is typically a good option in severe cases. If the nerve is structurally damaged or even severed, this surgery might be the only option.
At-home management options
Whether you're getting injections or surgery, your doctor will tell you how to manage the site of the procedure afterward. It's possible that you may wish to take painkillers or wear a leg brace, although of course, you should make sure any treatments are approved by your doctor.
There are also helpful books that can make your life easier. If you just want to learn about nerve surgery so you're fully informed, you can find such a book. There are also books that advise you as to how you can deal with chronic pain.
Wearing on Your Deepest Nerve...
As you can see, there's way more to the deep peroneal nerve than you would have guessed. You may not think about it or hear about it a lot, but it's actually quite important in your life. You probably wouldn't be able to walk without it, at least not in the same way.
You've probably heard people say that you don't know what you have until it's gone. This probably applies to this nerve. You don't know how important it is until it's injured, and you're unable to use it.
Injuries of the deep peroneal nerve can be quite debilitating. You should make sure that you take care of them properly if you encounter them. It always helps to know about the nerve and possible injuries; as they say, knowledge is power!
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