By Maggy Ashby, RMT

As we continue along the Foot-Pain trail expect sightings of the local fauna: the community of muscles that work and interact at the big toe (hallux).

Be prepared:  We get into weeds.  

Why the details? 

I refer to Einstein:

“It’s not that I’m so smart, it’s just that I stay with problems longer”.

We began this quest with problem feet.

To unpack where feet go wrong and how to prevent it, you first need to know what makes a foot right. 

We are on course to true the foot.  For that, you need  to know how the foot works.

The hallux ecosystem

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A muscular team holds the hallux in place, which protects the joint. 

Conversely, stable joints optimize each muscle’s size and function.

Joints and muscles resemble mutually beneficial relationships in nature.

Deep muscular teams are the unsung heroes. 

They hold joints fast.

Larger muscles (which get all the glory) operate inefficiently without this underlying support.

Deep teams of muscle underpin all movement-built joints.  Your

  • hip,
  • thumb, and
  • shoulder

also reflect this model.

Provision your pack:

The hiker’s pack includes a flashlight, a first aid kit, an extra pair of socks… 

Hikers pack to meet challenges ahead. 

Today’s adventure requires the word cloud, (right).

…and a machete for the weeds.

foot movements

Refresh your memory here, if necessary:

Guidebook to Navigating the Foot Pain Trail.

About muscles:

Muscles originate and insert at distinct points.  They cross a joint, sometimes two.    

Contraction moves the muscle’s insertion towards its origin, around a joint.

Muscles cooperate.

Each act as agonist, antagonist and synergist as they command, oppose, and modify the pull of their neighbors:

  • The agonist pulls the joint in one direction. Agonists do, like Batman.
  • Antagonists stretch under tension when the joint moves oppositely. They restrain movement. Antagonists oppose. Think of the Joker.
  • Neighboring muscles make actions stronger, and more precise. Neighbors are synergists — those who help. Remember Robin?

The local wildlife:

Four muscles anchor the hallux in four directions.  intrinsic to the foot, they both originate and insert there.

In their roles as agonist:

  • Flexor       Hallucis   Brevis (because there is a longus) (fhb)
  • Extensor   Hallucis  Brevis (also, there is a longus) (ehb)
  • ADductor  Hallucis   (aDh)
  • ABductor  Hallucis   (you get the idea) (aBh)

All four muscles  insert at the base of the first phalanx of the big toe. 

Look closely.   

Each muscle shortens (from insertion towards origin)

and pulls the big toe in the direction of their eponym. 

foot muscles

Flexor Hallucis Brevis

 

The drawing (right) shows two heads of fhb, that insert into the inner and outer sides at the base of the first phalanx of the great toe.

The drawing on the left show’s depth: You can just see the lateral head behind the medial head.  It also shows one of the two sesamoid bones that occur here.  

Sesamoid bones: 

 

Two boney plates develop within the end of each tendon of fhb, and enlarge or shrink with activity. 

Your knee cap provides another example of a sesamoid bone.

 

Sesamoid bones share a common purpose:  To shield. 

In the toe, they protect the muscle that passes between them from the ground. 

 

 

The presence of these bones testify to the ideal landing point for your body weight. 

Extensor Hallucis Brevis

Ehb supports the hallux position dorsally, counteracting the pull of fhb from underneath. 

Flexor and extensor hallucis brevis are antagonists.

 

 

 

Both flexor and extensor hallucis brevis subtend bigger siblings.

 

 

 

 

Extensor hallucis longus reaches past the e.h.brevis‘ insertion, to the end of the distant phalanx. 

 

 

 

 

 

 

 

When the dominant muscle (e.h. longus) is paralyzed, you can see e.h. brevis’ work:  The hallux extends only at the proximal phalanx.

 

The synergistic effect of the short muscles amplifies the action of their larger siblings.

 

 

E. hallucis b’s immediate neighbor is extensor digitorum brevis (edb), whose job it is to extend the next three toes.

 

 

 

 

So near, and alike its neighbor in appearance and function e. hallucis b. is often considered the most medial appendage of e. digitorum b.

 

 

 

Don’t miss this: 

The small difference in their points of origin makes e. hallucis b. a supinator (everts the sole up – skyward)

In contrast, originating lateral to the foot’s midline means e. digitorum b. acts as the antagonist, and pronates the foot (depresses the sole of the foot towards the ground).

Adductor Hallucis

Adductor hallucis has two parts. 

Keep the transverse head in mind. 

It will come up again in the fourth episode, when we explore the bridges and arches on the Foot Pain Trail. 

It functions more like a rope bridge.

 

Oblique Head

 

Note the depth .

Tie beams support a cathedral ceiling.

Similarly, the transverse head lifts the ceiling in the transverse arch.

ADh also aids its neighbor (fhb), helping to flex the big toe.

Abductor Hallucis 

Abh

  • lies in the first layer of the foot, which makes it easy to see. 
  • is the strongest of the intrinsic muscles. 
  • contributes fully 3% of the strength of the arch when it contracts. 

 

ABh also aids its neighbor (fhb), and helps to flex the big toe.

Neighboring muscles influence each other.  If one is stronger its pull dominates.  In the case of the big toe, these three muscles pulling side by side, together exert a strong flexion influence.  

     Now for that poser I asked you in the last episode:

When did you last move your big toe into abduction?

The answer is next.

Form dictates function. 

 

These muscles have short lever arms that attach just past the joint they cross.   

Short lever arms make the work they do more static than dynamic.

They maintain joint position.  Big muscles rely on this square footing to push off, and achieve a heavy lift.

Thus, your big toe won’t stray too far east (as the crow flies) through aBh. 

So, for the other three muscles that we discussed in this episode: flexor, extensor and adductor… hallucis brevis (of course).

Flexion and its opposite (extension) may be the most supported movements in the foot, but abduction and adduction forces keep the hallux on course.

 

A treat for tired feet:

 

Differentiating foot muscles is the first step to gaining control of them.

Touch constructs body-brain connections rapidly. 

Here are Blackman and Bootsma to take you through the palpation of the four muscles we introduced. 

Maybe one of the muscles in the discussion captured your interest more than another — so watch only one. 

If you decide to review all four videos, it will consume 15 1/2 minutes of your life.

foot

In this do it yourself guide to functional fabulous feet, it is time to start doing.

Follow Maggy Ashby, RMT's blog series on A guide to fabulous functional feet

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