This is a pretty obvious one. We've all seen it, especially on anyone on a bike or in a pair of high heels. It's the back of the lower leg and has that distinct double-headed, bicep like bulge.
So where exactly is it?
Although this is thought of a muscle of the lower leg (or otherwise known as just the 'leg' anatomically) it actually attaches above the knee on the base of the femur bone (technically on the medial and lateral femoral condyles) and then extends down and becomes the Achilles Tendon which then inserts on the back of the heel bone (Calcaneus). It has two heads, one on the lateral (or outside) of the leg and one on the medial (inside) of the leg.
What does it do?
This muscle has two main functions:
Bend the knee (flexion)
Flex the foot downwards (plantar flexion)
Of course it is involved in a lot more. It also helps with standing, walking, running, jumping and raising up onto the toes. This muscle becomes very obvious when cycling. Next time you see someone on a bike check out their calves (without looking like a stalker).
What can go wrong?
The most common complaint I've noted with the lower leg is a 'tight calf muscle'. This is usually due to:
Standing for long periods
Standing for long periods in high-heels
Not stretching after long runs or workouts
and even dehydration.
In more severe cases small or even complete tears can occur.
What can be done?
For common tightness and stiffness massage is of course hugely beneficial. Using specific deep tissue techniques and stretches can greatly help release the tension. Even self-massage can be beneficial. While sitting use your fingertips and, starting on the Achilles Tendon, glide your fingers along the back of the calf working up towards the back of the knee. (Note: stop before you get to the back of the knee, don't dig your fingertips into the back of the knee. As there are lots of Lymph nodes in the back of the knee you don't want to apply deep pressure directly on these.) Work both up the central line as well as on the main body of the muscle more towards the sides. Work in an upwards motion from heel towards knee. This will increase the circulation as well as help break down any adhesions and stiffness.
Stretching is also effective. Here's just one example:
Stand facing a wall and place your hands against it for balance. Extend one leg back and with a straight leg extend the heel down, ideally placing the foot flat on the floor. In order to get an effective stretch you may need to extend the leg further back, away from the wall. Keeping the knee straight ensures you stretch the Gastrocnemius. If you bend the knee you will be stretching a different muscle (Soleus). Hold the stretch for about 20 seconds.