Monday, 16 March 2015

Hamstrings (1 of 3) : SemiTendinosis

And we're into the HAMSTRINGS! 
There are three hamstrings, located on the back of (posterior) thigh bone (thigh bone = femur).  
They are also are also tucked between Vastus Lateralis (quad group

Together the hamstrings aren't quite as powerful as the quads, but they are super important for two key leg movements!
Let's start with:


Semitendinosis is the most medial of the three hamstrings (closest to midline of the body)

SemiTendinosis muscle attachment points

 Origin: Ischial Tuberosity *
Insertion: Pes Anserine Tendon
 ((proximal medial shaft of tibia (leg bone just below knee))

*did you know that all three hamstrings share the same origin of ischial tuberosity? 
Ischial tuberosities aka "sits bones", you know those points of the pelvis, butt bones if you will? here's a visual:

  The hamstring muscle bellies turn into skinny tendons that cross the knee. 
Because they cross both joints, the muscle actions will happen at the hip AND the knee:

SemiTendinosis Muscle Actions:
When we're talkin' hamstrings, there are two main actions that come to mind:
- Extension of the thigh at the hip joint (aka coxal joint)
- Flexion of the leg at the knee joint (aka the tibio-femoral joint)

But wait there's more!

Apparently SemiTendinosis also assists in:

'posterior tilt' of the pelvis at the hip joints
(tucking your tailbone down)

medial rotation of leg at hip joint
(imagine standing on one leg and then turn the lifted ankle INwards)

But wait!

-WHEN the knee is flexed, it is said that medial rotation of the knee @ the t/b joint is possible 
(say whaaaat? sounds unfortable - I imagine it's just a micro movement -barely noticable)

Standing up and sitting down would be really difficult to do with our hamstrings!
Hamstrings can get tight from too much sitting :(

because Bill <3

onnnnne more thing:
I've also seen the spelling SemiTendinoSUS
but I'm sticking with SemiTendinoSIS :)