Articulations

Question & Answer

Hip Internal vs External Rotation

On the hip articulation page, I think internal and external rotation ‘exercise/concentric’ movements are reversed. I find your site very helpful and I really enjoy it, thanks.

Thanks for pointing this sort of possible errors. However, this is a common illusion in movement analysis with hip rotation exercises involving a bent knee: Articulations/Hip

Take another look at these movements but imagine the knee straight. You need to be looking at the direction of the front of the thigh, not the bent lower leg. I’ve made note of this illusion on their respective exercises:

Cable Seated Hip Internal Rotation

Oh wow, I absolutely see it now! Now that I’ve embarrassed myself slightly by being fooled I will always remember this! Thank you so much for responding!

I guess I made a “less than thoughtful” comparison to the shoulder. While focusing on the direction of the forearm (flexed elbow) may work as a “cheat” for direction of shoulder rotation, it is inaccurate by definition. Since knee flexion has the calf move posteriorly that same “cheat” doesn’t apply.  By “cheat” I really just mean something easier to visualize. I now know this cannot be applied to the hip and that is just as well. It’s much better to focus on the true meaning of the term.  I’ve learned something!

Thanks again!


Ankle Plantar Flexion

Love the website, however ankle plantarflexion is 'flexion' of the ankle not 'extension.

thanks, Mark Conley

Hi Mark,

Thanks for kudos and constructive feedback. This movement is obviously called plantar flexion, but from a functional standpoint it ‘extends’ the ankle thereby prolonging the lower leg, or foot. For example, ‘triple extension’ refers to movement pattern of the hip, knee, and ankle during jumping and running activities.

In attempt to rectify future confusion, I have added quote marks around the word ‘extension’ depicting a variation of the term from the standardized nomenclature. Although plantar flexion is technically not an extension, it's been included to describe its movement pattern relative to other joint movements, so it can be better understood. I believe the included animation can clear up any confusion.

Good aye James, it is very confusing. When I did anatomy 45'ish years ago we were told that the lower limb 'rotates' the opposite way (in the femoral shaft?) to the upper limb during foetal development, thus in the anatomical position the joints distal to the hip are 'at 180º' relative to those of the upper limb.

Quote from, yes, Wikipedia, sorry, " Dorsiflexion and plantar flexion refers to extension or flexion of the foot at the ankle. These terms refer to flexion between the foot and the body's dorsal surface, considered the front of the leg, and flexion between the foot and the body's plantar surface, considered the back of the leg. These terms are used to resolve confusion, as technically extension of the joint refers to dorsiflexion, which could be considered counter-intuitive as the motion reduces the angle between the foot and the leg.


Pectoralis Major Adducts and Abducts

In shoulder articulations, pectoralis major (clavicular part) appears as a weak adductor as well as a weak abductor. How is this possible - that a muscle behaves in the same way in contrasting activities?

When the shoulder is externally rotated, the clavicular pectoralis assists in abduction; particularly beyond where the arm is already abducted 90º. (Thompson & Floyd 1994) This muscle is even more involved in abduction or pushing an object overhead in an individual with a deep rib cage (barrel chest) and/or with their chest held high, as in the military press.

The clavicular pectoralis assists the sternal pectoralis in adduction, particularly when the shoulder is internally rotated (Moore 1985; Thompson & Floyd 1994) where the arm is already adducted 90º. It is even more involved when the adduction is accompanied by slight horizontal flexion as with bending over slightly when performing the chest dip or standing cable fly.

Moore KL (1985). Clinically Oriented Anatomy, Williams & Wilkins, 2.

Thompson CW, Floyd RT, (1994). Manual of Structural Kinesiology, Mosby-Year Book, Inc., 12.


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