Monday, 1 December 2014

IlioPsoas: Psoas Major & Iliacus (and what the heck : Psoas MINOR.)

Everyone's always talking about their hip flexors.
Hip Flexors are often kept in a shortened state due to sitting all day, desk jobs, and even sleeping in fetal position all night (ahem - me!)

But what makes up these popular "hip flexors"?
 Today let's talk about the mainers: Iliacus, Psoas Major and Psoas Minor

here they are individually!

 IlioPsoas = Iliacus and Psoas Major
Together these two muscles are the primary mover of hip flexion and help to stabilize your lower back.

 Let's break it down:

Psoas Major:
 aka filet mignon or tenderloin - yep!

Psoas Major muscle is long and slender, deep to abdominal contents (that's deep!)
Origin: bodies and TVPS of lower vertebrae > specifically T12-L5 
(see breaking down the spine for that to make sense!)

Insertion: lesser trochanter (the inside of the top of the thigh bone - next door to the hip joint!)
see the highlighted blue areas below!

lesser trochanters of the femur (thigh) bone

Origin: Iliac Fossa (inside of hip bone)
Insertion: Lesser trochanter (same as Psoas)

Muscle Action(s):
Both Iliacus and Psoas Major do the same:

Hip Flexion (main action)
Laterally rotates hip/thigh
Adduct the hip (thigh)

Psoas Minor:
tiny and actually absent in about 60% of people - but still worth mentioning!

Origin: same as Major (body and TVPS of Lumbar vertebrae)
Insertion: on the front of pelvis bone: 'superior ramus of pubis' (whereas Psoas Major crosses the hip joint causing the action of flexion - Minor does not.

Action:  helps to flex the lower vertebrae in a weak way (cause its so tiny!) and helps to create the natural curve of our low back. It's just there really...or not! (60% ;)

Hip flexion can be done laying on your back (image above) , is automatically done when sitting, and can also be done standing! (gif below) :

And here are the other two movements !

Lateral rotation of hip/thigh (aka external rotation)

Hip/thigh adduction (bring leg toward/across midline of body)

These last two assisting movements can also be done seated or laying down :)
Thanks for getting to know the Hip Flexor Group!

But guess what ? There are a few more muscles that help to flex the hip (these were just the mainers!) Oh! And this is what tight hip flexors look like (it's super duper common)

image via

Notice the anterior (forward) tilt of the pelvis, causing the low back to have an exaggerated curve - basically it's like sticking out your bum. This imbalance can cause all kinds of fun problems like LBP (low back pain) and disc herniation :O (L4/L5 anyone? ;)