Knee pain: Understanding the popliteus and plantaris muscles

Knee pain, Lower leg pain, Muscle information / Monday, June 29th, 2009

popplantthmPain behind the knee when crouching or going downstairs could be from the little popliteus or plantaris muscles. More likely the pop. I had a personal experience with this muscle backpacking in New Hampshire. My son and I hiked down the mountain after being in the sky for a few days and when reaching flat ground I couldn’t walk to my car! The back of my knee was in a painful spasm.

The major complaint of patients with knee pain caused by Trigger Points in the popliteus is pain when crouching or walking, especially downstairs or downhill. Often overlooked in knee pain complaints, I pay attention to these deep little muscles in my Neuromuscular Therapy center near Boston.

The popliteus is a triangular flat thin muscle behind and below your knee. It’s tendon attaches at the outside of your knee on the thigh bone (femur) and spreads across the space between the two bones of the lower leg to the bigger of the two (tibia) in a wide attachment along the ridge of bone below the inner crease in your knee.

The popliteus has an important function of preventing your thigh bone from sliding off the lower leg bones when your knees are bent, like when you’re going downstairs, crouching, skiing or hiking downhill, or walking in high heels!

The action of the popliteus when it contracts is twofold. 1) It rotates your lower leg at the knee like when you do a twisting turn to change direction in sports. Any action that can tear the cruciate ligament can also injure the popliteus. 2) The second action is to unlock your knee. It stays active through any weight-bearing bent-knee activity.

The plantaris is a delicate little muscle that crosses the space behind your knee. It doesn’t do much by itself, but it helps invert your foot and point your toe. It’s Trigger Point is behind the knee and down into the calf.

Both pop and plant muscles can be aggravated by flat feet or from walking on a slanted surface. So wearing an arch support and walking the beach in both directions are good ideas! Remember not to overload them during a flare-up.

34 Replies to “Knee pain: Understanding the popliteus and plantaris muscles”

  1. Hi – I have been having an issue for about a year that prevents me from doing the elliptical machine. After about 10 minutes, the back of my knee contracts and i cannot straighten my leg. It is painful and feels like a tendon is about to tear. The only way I can get it to release is to use a ball on the back of my hamstring and foam roll from mid thigh down to mid calf. Until today, i thought it was my hamstring cramping, but now i think it is this muscle freaking out.

    It also happens when i use machines like the step mill (an escalator-type step machine) and when i walk on the treadmill uphill. I’m having a lot of trouble getting a cardio routine going because of this… I used to do 45-60 minutes cardio 4-5 days a week, and now i’m lucky if I can get 25-30 in on a treadmill. It is driving me crazy.

    I have tried a lot of different kinds of stretches, but nothing seems to work. Do you have suggestions for how I can treat this? I’m in Michigan, so Boston is a bit far for me to come for an office visit… 🙂

    Thanks so much… I really need some suggestions!

    1. Hi Holly, Thanks for your question! Could be the popliteus, but sounds more like gastroc to me because of your comment that it reacted going uphill. Popliteus doesn’t like going downhill. Just treated an athlete yesterday with the same complaint. You can test it by pressing with a ball just below the crease of your knee, squeezing it with your thigh. Don’t hold for longer than 20 seconds because there are nerves and blood vessels there. The popliteus hurts when you crouch. In addition to the several entries on the muscles that can cause knee pain, I posted one yesterday on other sources and one today on stretches for all of the muscles. The stretch for the popliteus should hurt when you do it. If it doesn’t, try the other stretches and feel for tension and pain and check for range of motion. Let me know what you find. Christina

  2. Hi,
    I’ve had a similar knee problem for about one year. Except with one or two variations. When I sit in a chair and try to scoot forward with my feet planted on the ground my knee gives me some pain, about a 4 on a scale of 10. I went to the doc today and she said it was a joint problem, but I really think its muscular. I am in the military and really have no choice of doctor. I really do not want to take the anti inflamitory I was prescribed unless that is what I really need. I did not get any advice on prevention or any alternative to the med. Do you have any advice?

    1. Hi Sergio, If I understand you correctly, I would suspect the quadriceps as the problem. They cross the knee joint and when they tighten up (as they do when you start to stand up which is the muscle action when you scoot forward) they can compress the joint and cause pain. The quads also have Trigger Points that refer into the knee. If the pain is behind your knee, it could be the hamstrings or the popliteus/plantaris. Pain in the sides of the knee are from the quads or the inner thigh muscles (adductor magnus, sartorius, gracilis).The outside of the knee can also be from the popliteus tendon or colateral ligaments. The treatment would be pressure on the muscles using NMT protocol and stretching to reduce tension and release Trigger Points. The way to know if the muscles are involved is to be very specific in your self-applied pressure. The places that hurt indicate muscle dysfunction. Let me know if that helps.

  3. Thanks for the great article on the popliteus. I am not a bowler, but went to a bowling party and played 3 games without problems, then, when changing into my street shoes the spasm occurred. I could not believe the pain. No popping, swelling, or point tenderness. The pain persisted, even with anti-inflammatory meds. I now have a neoprene sleeve which helps, and I am able to walk without pain 2 days later. I now know I need to strengthen the whole knee joint, and will do so in the coming months. I am a regular biker and hiker, yogi, and gym person, and am so surprised that this occurred. But it is my “Achilles”!! Is there a special move to strengthen the pop?

    1. Hi Lake, The popliteus is a hard one to strengthen and to treat because it functions in subtle ways and is deep in the leg. Downhill walking and hiking are when it gets used a lot, so that would be the best strengthener. Be careful about going beyond 90 degree flexion. Stretching all the muscles that cross the knee would be a good course of therapy. In yoga you have stretches you can use, but in your case, hold the stretches for only two seconds and repeat 10 times instead of holding the stretch. If there are Trigger Points, holding a stretch can irritate them because of the activity of the stretch reflex which under these conditions can activate the response and contract the muscle you are trying to stretch. It sounds as if your muscles are getting a little tight with all your activity and addition of a regular Active Isolated Stretching routine would take care of your problem. Look in the sidebar to the right for Specific Stretching for Everyone by Aaron Mattes. You’ll find great stretches in this book for every muscle in your body. It’s a good investment.

  4. I’ve never had problems before, but a week ago I was playing paintball on a rather steep hill. Out of the blue, while I was crouched, I felt a pop behind my left knee that felt like a charly hourse and I had to straighten my leg out. I walked it off, but it happened two more times that day. I was left with a soreness behind my knee. Today, while I was crouched down painting a doorway it happened again. Do you think this is my issue and if so, what are my options? I’d prefer not to go to a docter, but if it’s something major, i’d rather not wait.


    1. Hi James, Yes, definately this is a problem with your popliteus muscle! Your symptoms are classic, but your doctor may not know about it because it is deep between the bones of your lower leg and is rarely treated. The medical text on Trigger Points in the lower body, Myofascial Pain and Dysfunction by Travell and Simons Vol II wasn’t published until 1991, so many doctors are not educated about these muscle pain symptoms. What they know is mostly about joints and nerves. Stretching this muscle is a bit awkward and is best done with the help of a friend. Sit down with your heel propped up on the floor in front of you. Hold your thigh steady with your hands and rotate your foot outwards. Hold the stretch for two seconds and repeat it 10 times. If you have a helper, sit back in the chair with your leg straightened out in front of you. Have your friend hold your foot at the heel and forefoot. You hold your thigh steady at your knee. Start by rotating your foot outwards as far as you can. At the end range, have your helper continue the rotation past where you can go yourself. Hold the stretch for 2 seconds and repeat 10 times.
      If you have another spasm, use an icepack at the back of your knee for up to 5 minutes to calm the spasm and increase blood flow. Blood is essential for healing, stops muscle spasms, takes away the heat of inflammation and removes waste products that cause pain. Ice can be reapplied when your skin is warm again and can be used several times a day when you’re in trouble. 1000mg of vitamin C right after vigorous exercise will help as well as a big glass of water.

  5. I injured my leg at work struggling with an aggressive patient I had a severe pain in my calf and inside of my knee. I went to the doctor and was told I had a calf strain. I was given physio and told to ice the injury. It has been 2 months and my leg is still very painful but mostly when I weight bear and do to much walking or stairs. The most severe pain is inside the knee at the top and on the inside of the knee more towards the upper part of my leg. My knee has periodically given out and not supported my weight but only when doing stairs. Recently I went to a knee specialist and was told I have a plantaris tear? I am in an extreme amount of pain after walking and can not run. I had an MRI which suggested a osteochondrial injury and a bakers cist. Both of which the specialist disregarded because when he manipulated my knee I did not seem to be in pain. If you have any thoughts it would be much appreciated. Thanks. Merry

    1. Hi Merry, It sounds like the popliteus to me in your description of the pain. The plantaris could easily be injured, but it is a tiny muscle and works to invert the foot. It isn’t in your calf and doesn’t attach to the inside of your knee. The popliteus matches in both instances. The medial gastroc could be injured. Both muscles are used in a bent-knee position, the popliteus to hold back the femur on the tibia, and the gastroc to actually bend the knee and stabilize it in that position. The other possibility is the medial hamstrings which cross the joint and would be felt both above and below the inside of the knee.
      A Bakers Cyst wouldn’t necessarily hurt with manipulation, but a tear in the joint tissue would. So I would recommend finding a good therapist who knows the deeper muscles really well and can be effective treating them. You can stretch the gastroc and hams, but the popliteus is hard to work effectively. Try the manual work and do some icing regularly and often for 2-5 minutes. Look in the search box in the side bar for the post on the ice and heat controversy. Let me know if this helps.

  6. Hi! I am so glad to find your blog…..My 10 year old said that when he was running home from school yesterday when he suddenly felt a pop behind his knee cap. His leg cramped up and it was painful to straighten it out…. He walked with his leg bent all last evening, went to bed and when he woke up it didn’t hurt anymore and he could walk normally. But then at school today, the “pop” happened again and he is walking with his leg bent again. I am wondering if this sounds like the popliteus muscle problem…This is of course Friday and we thought we would take him into the doctor on Monday. What do you think is the problem here? I would so appreciate hearing your thoughts and what can be done? It is sad to see an active 10 year old boy sit in class during recess because he can’t run with his buddies. 🙁 Thanks for your help!

    1. Hi Anne, Hopefully this helps a little before you go to the doctor. When I think of a pop behind the kneecap I think of a ruptured ligament, but I don’t think that’s it because there was no event or trauma and the pain stopped with rest. The popliteus is at the back of the knee and below it, not behind the kneecap. The test there is whether he can’t crouch because of pain behind the knee or a sensation of swelling there, like there’s a ball where the knee bends. My suspicion is that his quadriceps are cramping and pulling the kneecap (patella) back against the bony joint of the knee. The patella is a sesamoid bone, meaning that it floats within a tendon rather than attaching to a bone, in this case the quadriceps. When the quads are tight it could mean the patella is rubbing on the bones beneath it causing a sound that he could be describing as popping. The quads straighten the knee, so that makes sense that if they are cramping he would limp, being unable to straighten the leg to walk. Resting a muscle allows it to recruit what it needs to do work. As soon as he starts using it again, the muscle runs out of fuel. When a muscle is tight, it doesn’t get enough blood and blood carries the fuels and takes away the wastes that cause pain. Try massaging his thighs and using alternating ice and heat for up to 5 minutes each.
      The other logical reason would be the hamstrings in the back of the thigh. They attach at the sides of the knee joint and bend the knee. Cramping there would prevent straightening the leg because the muscles are shortened. Treatment would be the same, massage and ice or alternating ice and heat.
      Lastly, If he’s growing fast, his bones might be growing faster than his muscles. The same treatment would apply. Massage brings blood to help the muscles grow and keeps them from cramping. If when massaging you find knots in the muscles, hold pressure on them for 10-20 seconds to stop the muscle from firing, then do long strokes toward the heart to flush out the wastes. Good luck.

  7. I have been experiencing a more annoying than painful popping/snapping feeling when I run. It is behind my knee back of leg. Mainly my right leg. Just a jolt then it is gone. Suggestions?

    1. April, You can stretch the plantaris when you stretch the calf muscles, but the popliteus needs a specific stretch, rotating the lower leg at the knee without moving the thigh. For the plantaris and gastrocnemius, stretch sitting down with your knee straight, dorsiflex actively (toes toward shin) then pull on the ball of our foot (with a rope, strap, belt, towel) for two seconds to stretch it farther. Release and repeat 10 times. For the popliteus, fix your thigh in place and turn your foot/lower leg inward. On this one, the knee should not be locked or it prevents movement of the joint. Christina

  8. I had a torn calf muscle 2-3 years ago. Last year I had symptoms similar to plantar fasciatis but was told it was a spur even though no spurs showed on xray. Major pain went away after rehab. I still have a flair up once in awhile but stretching usually takes pain away. Recently I noticed that I can not use the same leg to climb a ladder, it is painful behind knee and radiates to outside of knee when climbing steps and is very weak. My RN wife noticed the leg has atrophied compared to the other. Could this all be connected?

    1. Hi Mark, Symptoms of plantar fasciitis can come from Trigger Points in the gastroc and soleus muscles. If you had a partial tear of the calf muscle, sounds like it was the lateral gastroc head, judging by your knee pain. Stretching is most important, two-second assisted holds with 10 reps with no weight-bearing. Stretch sitting down with your knee straight using a strap, rope, towel or something to assist dorsiflexing your ankle (flexing toward your shin). The popliteus also attaches to the lateral knee, but you would feel that going downhill or crouching. The atrophy would be due to the gastroc, not the popliteus, but you may have injured both. Weakness can be from tension in the muscle. If it’s tight it will be weak because it can’t work efficiently from a shortened (tense/contracted) position. Hope that helps, Christina

  9. hi.sir…i m from pakistan i was studying your this page .my mom has that problem with back of her leg.she feel pain every time.pain goes like spark from the knee to down feet.she can not sleep from it.she feel pain while resting or walking both time.can u recommend me some tablet for that.

  10. Hi there I wonder of you can help!
    I have just started my pre season for my upcoming football season, and Im getting a uncomfortable pain jut below my left knee on the back.
    The pain does occurr when going down stairs and also when I try and raise my knee to waist level to create a right angle with my leg when standing up.
    The pain is also there when I kick a ball!
    I just wondered what you think this could be and any tips to aid getting rid of this?
    I originally thought the pain was due to tight hamstrings which I have suffered with for years however as I say the pain does now seem to
    Be coming from below the crease of my knee!
    Any help would be great!

    1. Hi Tom, Sounds like the popliteus to me. It could also be related to your gastrocnemius muscle in your calf. The tendons attach just above the knee on the back sides, but the belly of the muscle is below the crease of the knee. Stretch your calf seated with your leg straight using a rope or towel to pull the ball of your foot toward your face, holding the stretch for two seconds, then release and repeat 10x. To stretch the popliteus you hold the thigh bone in a fixed position and have someone assist by twisting your lower leg inward. Hold for two seconds, release and repeat. You can also put pressure along the muscle at the attachment to the bone inside and behind the shin, working your way toward the middle of your calf. Be careful of the neuromuscular structures in the hollow of your knee.
      Look at my information on the popliteus and plantaris for more information.
      Good luck! Christina

  11. Hi i was wondering if you could let me know what might i have i get pains on the muscle behind my knees doing nothing but standing what can it be ive had this ache before many times and never treated it all i do is put icy hot and k relieves the pain sometimes or sometimes it worsens any ideas?

    1. Hi, If it hurts when you’re just standing, then it probably isn’t the popliteus. More likely it’s the gastrocnemius muscle in the calf which would be working to stabilize your leg at the knee. The gastroc tendons attach above the knee on both sides in back and trigger point referrals go upward into the back of the knee. Try icing and stretching the calf with a straight leg, seated with something around the ball of your foot to pull on. Dorsiflex your foot toward your nose, pull on the foot for 2 seconds to stretch the calf, relax and repeat 10 times. The plantaris may be involved, but less likely because it inverts the foot at the inner heel and would work more when you’re moving not standing unless you have fallen arches. The same stretch would help, but try everting the foot as you stretch the calf. You could also learn to compress the muscles to get relief using a tool like the Theracane. Good luck.

  12. I’m glad I found your article while searching for the cause behind my back of knee pain. It started with me not being able to really put weight on it, as in going up the stairs. Then it got really bad where I couldn’t put weight in it to walk. After the 2nd day it got better on it’s own (plus 2 ibuprofen). But it never quite healed. Sometimes I can stand on it, lean on it. Walk with it if I make sure my leg straightens out all the way before I take the step. But I cannot crouch nor sit on it. Today has been the worse, I was sitting on a low seat, as I leaned forward to stand my knee felt like it had that ball (you mentioned) behind it. I had to straighten in a bit before trying it again all while putting most of the weight on the good knee. I can actually feel the pain on the “tendon” (as I call it because I think that’s what it is that’s causing said pain). I have, at times, felt as if said tendon popped out of the bone and then went back in (this has been the most painful yet). I also stumbled across something else, by chance. I was sitting on a stool/foot rest, leaned forward and rested my arms on the top of my knees (I was doing a search on my phone for some technical help with my tv) and that’s when I felt it. The pressure. If I press on the right spot on the top of my knee (while sitting down and my knee bent) I can feel the pressure bother me at the back of my knee. Hmmm… I have also noticed that if I stand for a long period of time, with straight legs, it feels as if my knee is on a rubber band and when I bend it, it sort of wants to pull all the way back as if in relief from the stretch. Of course after I’m done teaching my class (1.5hrs) I can hardly walk up the stairs! And forget down the stairs, I need to walk like the older folks do, one step at a time- and with the good leg taking the step! What do you think?

    1. Hi, So it sounds like a popliteus problem to me. The only other thing I can think of is that you might have a Baker’s Cyst, but with all the other muscle symptoms I think it’s the popliteus. To stretch it you’ll probably need someone to assist. Lie face down with your knee straight. Have your helper hold your thigh just above the knee to keep it from moving, then have him/her turn your lower leg at the knee by holding the ankle/foot and twisting so that the whole lower leg rotates inward (heel comes closer to the other foot). Hold the stretch for only two seconds, release and repeat 10 times. Icing is important to calm the muscle down, but only for 5 minutes at at time to get the blood flushing through the capillary beds. Hope that helps.

  13. Hi! I am preparing for a marathon and since some weeks i suffer from pain in theback of the knee. It started with a severe cramp on training after 25k, probably, due to overuse?. But the pain comes back everytime i train, each time at the moment i bring my lower leg back in flexion. During training, running uphill hurts more. At home going down the stairs with some weight is more painful. I rested 1 week but pain comes back after some kilometers in training, however i could run and stand the pain, it doesnt feel comfortable and i feel my leg position changing and compensating during training (which is dangerous for other injuries). Kinesiotaping seels to help a little, but what can i do to get rid of this ennoying pain? Should i fear for my marathon in 5 weeks? Should i persist training with pain? Thank you very much!

    1. Hi, While you’re training, use an elastic sleeve around your knee with a hole for your kneecap. To stretch it, you’ll need another person. Lie face down with your leg straight. Have your assistant hold your thigh in place securely above the knee. Turn the lower leg so the heel goes toward the midline, hold for 2 seconds, release and repeat 10 times. To treat a Trigger Point, press below the inside of the knee just inside the ridge of bone and toward the shin, there and also down a couple of thumb-widths along the muscle attachment. Hold the pressure for 8-12 seconds or until you feel a lessening of the tension and less tenderness. Check to be sure your arch is supported and take vitamin C before you run. Good luck!

      1. Dear Christina, many thanks! Do you think it’s the Plantaris or Popliteus or Gastrocnemius bothering me? Is there a chance to cause major damage in persisting through the pain?
        Thanks again for your advice and support!

  14. Good Morning Christina:
    Here’s my problem: After driving about 7 – 10 miles, I start feeling a pain behind my right knee , and then behind my left knee. The pain becomes worse if I continue driving, at which time I ask my wife to take over.
    Also, I can no longer crouch nor squat due to pain behind both knees.
    I do not have any pain walking, either on a flat surface nor an incline.
    Are there any medications I can take to relieve the pain?
    Thank you,

    1. Hi Richard,
      You’ll have to talk to a doctor about medications. My job is fixing muscle pain, so on that subject I would venture a guess that your problem is in your hamstring muscles. They have Trigger Points that refer into the back of the knee that can be activated by the pressure of a chair seat against the muscles.
      Do a search in my blog on “Knee pain: 5 effective stretches” All of them can help and one of them might do the trick.
      If you’re in pain, use ice for 5 minutes at a time. When driving, you could put an ice pack under your thighs to keep the muscles calmer. Another suggestion is to put a rolled towel or small round foam pillow under your thighs near your knees to keep your thighs raised and prevent them from pressing on your car seat.
      Hope this helps. ~ Christina

  15. Hi Christina,
    A bit long winded but here goes!….
    I developed pain posteriorly and laterally to my right knee some months ago ,there was no specific injury, but I do thai boxing and lots of weight/cardio work so may have done something. There was no “pop”

    What tends to happen is the pain develops behind and laterally stopping me from bending the knee due to pain – there is no meniscal or ligament damage at all on scanning. A few examples – squatting is no problem, however, after this if I go to do hamstring curls on very low resistance I can’t due to above pain. Also if I do hill sprints running uphill brings the pain on. Additionally when the pain is present if I try to bend my knee with my foot in dorsiflexion it is a lot easier and less painful than when I try in plantar flexion (bending with foot in plantar flexion is unbearable).

    Interestingly I recently noticed if I foam roll/stretch hams, calves before exercise and then again when the pain begins it helps and I can tolerate the exercise for a bit longer.

    Days when I do nothing in terms of exercise there is no pain.

    I am currently being told there is joint damage in my knee – which there is, but I feel this pain is more related to muscle/tendon.

    Any ideas?!

    1. From what I can understand from your description, I would guess it was one of two things. Most likely is tenison/spasm in the lateral head of the gastrocnemius. I say that because when you plantar flex your foot, you tighten the gastroc. The lateral tendon is above the knee and could hurt with the tight muscle pulling on it. Secondly, when you sprint uphill, you are pushing hard on the ball of your foot, and therefore your calf muscles, which are already “loaded” and stretched from being dorsiflexed from the forward-leaning position. Alternatively, it could be the lateral hamstrings, most likely the short head of the biceps femoris.
      Go to the following post to find stretches for both: Let me know if that helps.

  16. Please help. I am a trail runner. 3 weeks ago i ran a 7 mule trail in shoes I have never worn. Needless to say my feet hurt bad amd my hips got tight. I never felt a specific injury. But when i got home and walked the back of my knee was super tight. The two big tendons and right in the middle behind my knee. It is some better. But still tight and sore. Stretching my calf irritates it and calf raises hurt behind my knee. Thank you

    1. The muscle in the calf called the gastrocnemius attaches just above the joint. Since stretching and raises seem to irritate it, I would guess that’s the problem. Doing Active Isolated Stretching with a two-second hold and icing should help in the acute stage. Stop strengthening the calf until it resolves. Using the muscle while weight-bearing is straining it more.

  17. I’ve been diagnosed with osteochondral defect of the patellla on the right leg. I have severe pain walking up and down stairs, and that’s about all. Nothing else causes pain. Can anything be done to alleviate the pain. I’ve tried knee braces but none help at all. I’ve had cortisone shots but that only lasts a few weeks, so I don’t want to do that anymore. Thanks.

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