1 of 3 Hamstrings: Biceps Femoris

We've covered SemiTendinosus & SemiMembranosus, so

Today we're talking about the 3rd and most lateral hamstring, 

Biceps Femoris.

Biceps: referring to the fact that this muscle has "two heads" or 'origins' - not to be confused with

biceps brachii (which is your ARM flexor!)

Femoris: referring to the femur (aka thigh bone)

Biceps Femoris muscle attachment points:

This muscle has two points of origin or "heads". The long head refers the origin that is furthest away from the insertion point. The long head is also more superficial & the short head origin is deeper.  And of course the short head would be closest the the insertion point.

Origin:  

Long Head: Ischial Tuberosity * & the sacrotuberous ligament
Short Head:  linea aspera and lateral supracondylar line of the femur.

Insertion: head of the fibula and the lateral tibial condyle

 

 The other two hamstrings attach on the inside (medial side) of the knee, whereas Biceps Femoris attaches to the lateral (outside) edge of the 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:

Biceps Femoris Muscle Actions:

same actions as the other two hamstrings:

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 Biceps Femoris also assists in:

'posterior tilt' of the pelvis at the hip joints

(tucking your tailbone down)

 And!

Biceps femoris is the only hamstring muscle that can laterally rotate the thigh @ the hip joint
AND the leg @ the knee joint - when the knee is flexed (!)

There are three hamstrings, located on the back of (posterior) thigh bone (thigh bone = femur).  

More specifically, they are tucked between Vastus Lateralis (quad group)

and Adductor Magnus (adductor group)

The term 'Hamstring' apparently comes from 18th century England. Butchers would display pig carcasses in their shop window by hanging them from the long tendons at the back of the knee. 
((I tried to find an image of this with no luck but I also didn't search too hard 
- maybe it's better that way ;))

 

1 of 3 Hamstrings: SemiMembranosus

Last week we got into the Hamstrings! 

We started with SemiTendinosus and Today we're talking SemiMembranosus

(see how I've capitalized the T in SemiTendinosus -and the M in SemiMembranosus? I just wanted to note that that is something that I do to help me distinguish between the two ;)

  SemiMembranosus  also lives deeper than - and larger than - SemiTendinosus.

okay, now forget T  :

SemiMembranosus

SemiMembranosis muscle attachment points:

Origin: Ischial Tuberosity *

Insertion: Posterior surface of the medial condyle of the tibia

((approx behind and just below the knee joint))

 *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 tibia is a lower leg bone, the larger one that mid way down we refer to as our shin (bone)

This muscle also attaches to the medial meniscus of the knee ( a pad of cartilage wedge between your femur (thigh) bone and your tibia.  Medial Meniscus helps to reduce friction in the knee joint.

Here is a view of the back of the knee (aka Posterior view)

Posterior View of knee joint. 

not shown: Lateral menisus (also wedged between just on the outside (lateral) side of the knee joint.

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:

SemiMembranosus Muscle Actions:

same actions as last week's SemiT

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 SemiMembranosus 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)

Alsoooo...

Standing up and sitting down would be really difficult to do with our hamstrings!

Hamstrings can get tight from too much sitting :(

There are three hamstrings, located on the back of (posterior) thigh bone (thigh bone = femur).  

More specifically, they are tucked between Vastus Lateralis (quad group)

and Adductor Magnus (adductor group)

One more Ham to go!

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) 

and Adductor Magnus (adductor 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

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)

Alsoooo...

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 :)