The Knee Muscles

Muscles Around the Knee

  • Quadriceps Femoris (quads)—Large group of four muscles on the front of the thigh that helps to extend (straighten) the leg. All four muscles converge to form the quadriceps tendon, which attaches to the tibia, via the patella and patellar ligament (or tendon). Includes the:
    • Vastus lateralis—Exists on the lateral (outer) side of the anterior (front) thigh.
    • Vastus intermedius—Exist on the anterior and central part of the thigh. It lies underneath the rectus femoris (see below).
    • Vastus medialis—Exists on the medial (inner) side of the anterior (front) thigh.  Helps to stabilize the patella (knee cap).
    • Rectus femoris—On the anterior (front) thigh. It is also a weak flexor of the hip (bends the hip).
  • Sartorius – A slender and long muscle that comes from the anterior pelvis and attaches to the medial tibia to help form the pes anserinus (see below). Not a very strong muscle itself, it helps with multiple motions of the hip and knee.
  • Gracilis – Another slender and long muscle that comes from the pelvis and attaches to the medial tibia to help form the pes anserinus. Also a relatively weak muscle that helps with multiple motions of the hip and knee.
  • Hamstrings – Located on the posterior (back side) thigh. Bends the knee. Includes the following 3 muscles:
    • Semimembranosus – Attaches to the medial tibia
    • Semitendinosus – Attaches to the medial tibia. It is the 3rd muscle of three (in addition to gracilis and sartorious) that contributes to the pes anserinus.
    • Biceps femoris – Attaches to the head of the fibula
  • Gastrocnemius—The main bulk of your calf muscles. There are two heads, one along the posterior (backside) lateral (outer) leg and one along the medial (inside) leg. They attach to the heel bone (calcaneus) via the achilles tendon. This muscle plantarflexes the ankle (toes towards the ground) allowing you to stand on your tip toes. It also helps to bend the knee.
  • Pes Anserinus (the goose’s foot)- the tendinous attachment of the sartorious, gracilis, and semitendinosus on the medial tibia. It is covered by the pes bursa which can sometimes become irritated leading to pes bursitis.

Images of Muscles Around the Knee

Muscles Around the Knee Front (anterior) View

Muscles of the knee

Muscles Around the Knee

Muscles Around the Knee Inside (medial) View

Muscles Around the Knee Medial View

Muscles Around the Knee Medial (Inside) View

Normal Knee Anatomy


  1. Jo says
    I’m 55 yrs old & over weight !
    I started walking! 10kms 5 in morning 5 in arvo
    All good ! But I did a small jog !
    But now aspecially my right knee very pain full!
    under the front of knee cap ! Inner side of cap ! * little soft area ! Very sore when I walk ! Or try to walk now !
    Can you tell me wat it is !
    & how to fix or prevent it happening ?

  2. Hi I have been doing some hiit training which involves a lot of squats. But I have woken up with pain in my left knee on the top left corner of my knee cap, do u have any ideas what this could be ?

  3. Avatar Nadine Briscoll says

    I don’t understand why none of you are asking these questions of your PHYSCIAN!

  4. Avatar Abril Young says

    I have small pain right leg below the knee…the muscles feels sore when um on my knees…or starting to take off and run…been this way for 3 months or so now…wht do u think it may be?

  5. Avatar Zion fluellen says

    Hello i fractured my knee cap during a basketball game, it had split in half one part was in my wuad and the other slid dow to my shin, its been almost a year since the injury but im still having pain in my patellar tendon… do you think its possible to get back to playing without any pain

  6. I injured my right knee 3 weeks ago.. Dr. said I pulled ligament behind knee. Also said I have arthritis in the knee. Not severe yet. After week of resting and feeling better I started doing things around house and even went shopping. SHOULD NOT HAVE DONE!!! Now my knee hurts below knee cap and on inside. Hurts to put too much weight on it. Now have rested another week. Still hurts a little. Walk with cane. 64 year old and slight over weight. Dr. gave me 15mg Meloxicam but had to stop taking 2 days ago. Was causing too much shakiness in my body. Did not feel it was beneficial to take. No pain in back of leg just front. Been icing and heat pad and resting. Take 2 extra strength Tylenol mid day and again around 11:00 pm.

  7. Avatar Max Fisher says

    Following a stroke, I find that when I take a step my right knee snaps into its straight position, causing inflamation and swelling in the joint. I suspect I have lost control of one or more muscles in my leg due to nerve damage, but can anyone tell me exactly which muscle/s?

  8. Avatar James Gardner says

    What would be wrong with my knee. Right above my knee it hurts. It hurts on all 4 sides of my knee. Top, right side of my knee, bottom center of my knee, and left sife of my knee.

  9. Hi i have a slight swelling just to the lower outside of the knee cap. Wondering what it might be, I did a strenuous yoga session today, and the area is throbbing,?

  10. Avatar David Cheang says

    I can’t bend my right knees.

  11. Avatar Frank Kwader says

    My knee is swollen and swelling on outside of lower leg. I laid my motorcycle down on it in gravel. When sitting I have extreme pain trying to lift my foot up. The pain runs along the shin bone halfway up my lower leg to base of knee. Caps ok , no pain, maybe a little click bottom of knee cap at base.
    Any ideas ? Thanks, Frank

  12. Avatar Cindy Schmidler says

    Hi, Dionnie! Thanks for reaching out to us with your question. Was the pain a result of physical injury or trauma? Your primary-care doctor should be the first specialist you visit to consult regarding your concern. If they find any potential issues, they will refer you to a partner consultant in the appropriate field of specialization. Hope this helps!

  13. My muscle below the side of my knee is very painful, where do i go for treatment. Pls. Help.

  14. Avatar Jackie Woochang says

    I think your knee is broke!

  15. Avatar Huma sheikh says

    This is Huma sheikh
    My knee is very stiff and very pain full
    My full leg is v painfull
    Vcoz wanes ,scatica pain,,knee pain
    Leg lower side pain
    I already treatment ,,
    Eccupresher treatment
    Plz reply ,

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