January’s Muscle of the Month

Welcome to the first of many features about the human body.  In order to share some knowledge and totally nerd out, I would like to introduce a new muscle or muscle group with you every month.  There are over 600 muscles in the human body so you can expect this to continue for awhile.  Just think of all the wonderful information you will gain!

In the spirit of a new year, and getting up and moving, January’s muscle is actually a group of muscles: the Quadriceps Femoris Group.  These are your thigh muscles, opposite your Hamstrings, on the front of your leg bone above your knee.  These muscles are in charge of straightening your knee.  One of the four also brings your knee toward your chest.

The Quadriceps Femoris Group is made of 4 different muscles: Rectus Femoris, Vastus Intermedius, Vastus Lateralis, and Vatus Medialis.

Latin is a bit foreign to most of us, so let’s break down these names first.

  • Quadricep basically points to there being four muscles in the group.  Quad = 4
  • Femoris refers to the bone they are located on the Femur.
  • Rectus, in the case of most muscles, refers to a muscle helping maintain a straight or upright posture.  The Rectus Femoris straightens the knee.
  • Vastus refers to the large, vast, nature of these muscles.
  • Intermedius means middle (it lies underneath the Rectus Femoris)
  • Vastus Lateralis lays on the outer side of the femur, and…
  • Vastus Medialis lays on the inner side of the femur.  Just for a little background medical terminology: the words lateral and medial are used to denote the proximity to the midline (or spine) of the body.

That concludes the medical terminology portion of this feature!

So what do they do?!  The main action that all four Quadriceps perform is knee extension: they straighten your leg.  The Rectus Femoris also helps with hip flexion: bending forward at the hip or lifting the leg toward the chest.  The other three do not contribute to this action because they don’t attach on the hip, they attach on the femur, where the Rectus Femoris crosses two joints (hip and knee), the Vastus Intermedius, Lateralis, and Medialis only cross over the knee joint.

Common activities that employ the Quadriceps: Running, walking, cycling, climbing stairs, coming up from a squat, standing up from a chair.

What can go wrong?  Some of the more common ailments experienced in the knee have something to do with the Quadriceps Group.  Muscle imbalance between the Vastus Medialis and Vastus Lateralis can cause the Patella (kneecap) to track incorrectly.  All of the Quadriceps Group ends in the Patellar Tendon which wraps the Patella from all sides, and attach at the Tibial Tuberosity.  If one muscle is tight it can push the Patella to one side or impact ease of movement.  The Quadriceps Group are all very strong muscles, and when they are flexed the knee is straight.  That means that their counterpart, the Hamstrings, are lengthened when you are standing up.  While these are also strong muscles, they are often overpowered by the Quadriceps.  This can cause pain in the Hamstrings.  Many activities work to stretch the Hamstrings, but I caution against too much of this.  Make sure to stretch your Quadriceps as much, if not more, than your Hamstrings.  (See picture slide show)

That concludes this month’s Muscle of the Month!  Check back in next month to learn more about the Hamstrings!

Disclaimer: I am not a doctor, and this information is not to be used for the use of self diagnosing.  If you have pain or think something is wrong, please call your doctor, then make an appointment with me for some muscle maintenance.  Thank you!