The Five Main Muscles for a Full Range of Natural Movement, Dynamic Alignment & Balance.

This fol­lows an in­tro­duc­tion to the me­dian plane and our midline anatomy as the refer­ences for al­ign­ment and bal­ance of the hu­man body.

Now think about how your body moves. Do you have a full range of nat­u­ral move­ment?

A Full Range of Nat­u­ral Move­ment.

The body’s full po­ten­tial, func­tion­ing at op­ti­mal.

Ex­am­ples of the body’s ca­pa­bil­ities.

Your Body Bub­ble.

Imag­ine the body’s ex­trem­ities trac­ing out a per­ime­ter—a bub­ble - as the body moves. The fingers, toes and head can only reach so far apart. The bub­ble is a finite space.

With a full range of nat­u­ral move­ment, move­ment flows through in­nu­mer­able po­si­tions in the largest pos­si­ble ‘body bub­ble’.

I’ve bor­rowed an illus­tra­tion!

The dis­tance be­tween the tips of all ex­trem­ities is great as phys­i­cally pos­si­ble when the body is free of phys­i­cal re­stric­tions, and the body dy­nam­i­cally al­igned and bal­anced with max­i­mal ex­ten­sion of midline anatom­i­cal struc­tures.

Anatomy of Align­ment and Balance (re­cap):

The linea alba and nuchal & supraspinous lig­a­ments are our main anatom­i­cal guides for body al­ign­ment.

Th­ese midline lin­ear struc­tures are strips of tough con­nec­tive tis­sue that we have no di­rect con­trol over. We can how­ever learn to fully util­ise the ad­ja­cent mus­cles.

Work­ing with the ad­ja­cent mus­cles (see be­low) in­creases:

  • Aware­ness of the sen­sory feed­back from these mus­cles, al­low­ing us to feel the rel­a­tive po­si­tion­ing of the midline anatomy. Part of our sense of pro­pri­o­cep­tion.

  • Vol­un­tary con­trol of the rele­vant mus­cles to work to­wards al­ign­ing the linea alba and nuchal & supraspinous lig­a­ments.

Ac­cord­ing to my Base-Line Hy­poth­e­sis Hu­man Health and Move­ment (see be­low for pt. 1) :

{For a less wordy in­tro­duc­tion to the anatomy try The 5 Main Mus­cles Made Easy.}

The 5 Main Mus­cles of Move­ment are:

Rec­tus Ab­do­mi­nis.

The left and right rec­tus ab­do­mi­nis mus­cles run par­allel to each other, ei­ther side of the linea alba, up the front of the ab­domen from pelvis to tho­rax.

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The rec­tus ab­do­mi­nis mus­cles at­tach to:

  • Pu­bic sym­ph­ysis and pu­bic crest of the pelvis.

  • Costal car­tilages of the 5th, 6th and 7th ribs (on the me­dial in­fe­rior costal mar­gins).

  • Pos­te­rior as­pect of xiphoid pro­cess of the ster­num.

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The rec­tus ab­do­mi­nis mus­cles con­sists of sev­eral pan­els’ of mus­cle be­tween strips of con­nec­tive tis­sue known as tend­i­nous in­ter­sec­tions.  Th­ese sec­tions of mus­cle are what gives the rec­tus ab­do­mi­nis the “6-pack” look, but the num­ber of pan­els can vary be­tween in­di­vi­d­u­als − 4, 8, and 10 packs can oc­cur.

The rec­tus ab­do­mi­nis mus­cles sit within their re­spec­tive rec­tus sheath formed by the aponeu­roses of the lat­eral ab­dom­i­nal mus­cles be­fore they merge to form the linea alba. Image text

My com­ments.

The rec­tus ab­do­mi­nis mus­cles—Our core pillar of strength. Our cen­tral Line. Strong and flex­ible, able to sup­port the rest of the body through a full range of move­ment when fully util­ised. Rib­bons of mus­cle that can bend and ro­tate at ev­ery level.

Like two stacks of blocks to be ac­ti­vated in se­quence from pelvis to chest.

Think longer and stronger with ev­ery in breath.

Fully en­gag­ing and elon­gat­ing the rec­tus ab­do­mi­nis mus­cles ex­tends the linea alba (our pri­mary guide for al­ign­ment) to its full po­ten­tial.



Trapez­ius.

The left and right trapez­ius mus­cles are the most su­perfi­cial mus­cle layer from mid-back (last tho­racic ver­te­bra) to the base of the skull, ex­tend­ing out to­wards each shoulder.

The trapezii (plu­ral) meet midline, at­tach­ing to the nuchal lig­a­ment and supraspinous lig­a­ment. image textThe trapezii are thin sheets of mus­cle, sculpted down the neck and to­wards the shoulders, at­tach­ing to both scapula (shoulder blade) and clav­i­cle (col­lar bone) of each arm.

Based on the di­rec­tion of the mus­cle fibres, cur­rent de­scrip­tions split each trapez­ius mus­cle into 3 func­tional sec­tions.



1. Up­per trapez­ius. (a.k.a. su­pe­rior trapez­ius, de­scend­ing trapez­ius)

At­taches to:

  • Base of the skull. Ex­ter­nal oc­cip­i­tal pro­tu­ber­ance and me­dial third of the su­pe­rior nuchal line of the oc­cip­i­tal bone via a thin fibrous lam­ina.

  • Nuchal lig­a­ment.

  • Lat­eral third of the clav­i­cle.

  • Spinal pro­cess of the 7th (last) cer­vi­cal ver­te­bra.

  • Supraspinous lig­a­ment.


2. Mid­dle trapez­ius. (a.k.a. trans­verse trapez­ius)

At­taches to:

  • Spinal pro­cesses of the 1st to 4th tho­racic ver­te­brae.

  • Supraspinous lig­a­ment.

  • Me­dial side of the acromion of the scapula.


3. Lower trapez­ius. (a.k.a. in­fe­rior trapez­ius, as­cend­ing trapez­ius)

At­taches to:

  • The spinal pro­cesses of the 5th to 12th (last) tho­racic ver­te­brae.

  • Supraspinous lig­a­ment.

  • Pos­te­rior crest of spine of the scapula.

  • Del­toid tu­ber­cle of spine of the scapula.

Image text

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Between the 6th cer­vi­cal and 3rd tho­racic ver­te­brae (the base of the nuchal lig­a­ment and start of the supraspinous lig­a­ment) the trapez­ius mus­cles are con­nected to the midline by a broad semi-el­lip­ti­cal aponeu­ro­sis, form­ing a tend­i­nous el­lipse be­tween the shoulder blades.

Tend­i­nous el­lipse of con­nec­tive tis­sue.

My com­ments.

The trapez­ius mus­cles—from the back of the head to mid-back, ex­tend­ing out to each shoulder.

A kite-shaped blan­ket of mus­cle that should be smooth and wrin­kle-free, sup­port­ing the head and arms through a full range of move­ment.

The trapez­ius mus­cles at­tach to the base of the skull via a thin sheet of con­nec­tive tis­sue (lam­ina) and there is a el­lipse of con­nec­tive tis­sue at the base of the neck/​be­tween the shoulder blades too.


Move­ment of the up­per body should be­gin from the lower trapezii. Think ex­ten­sion and ex­pan­sion from midline out­wards.

The mid­dle trapezii should spread wide al­low­ing the arms to fully ex­tend. Our up­per limb in­cludes the scapula.

The up­per trapezii should be free of ten­sions, al­low­ing the head to move through its full range of move­ment and al­ign­ment of the nuchal lig­a­ment.

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Pelvic Floor Mus­cles.

The “pelvic floor” are the mus­cles that span the pelvic canal. Also known as the pelvic di­aphragm.

Left and right sides of the pelvic floor are a mir­ror image, the line of sym­me­try the body’s midline.

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The pu­bic sym­ph­ysis (where the linea alba and rec­tus ab­do­mi­nis mus­cles at­tach to the pelvis) is lo­cated on the midline of the an­te­rior bor­der of the pelvic canal.

To de­scribe the pelvic floor in de­tail would be time-con­sum­ing—and frus­trat­ing. The anatomy is com­pli­cated with some con­tro­versy with re­gards to nomen­cla­ture, and is unim­por­tant to this pro­cess. Think of the pelvic floor mus­cles as one unit of two halves.

My com­ments.

The pelvic floor mus­cles—a bas­ket of mus­cles that should be tight and se­cure.

Ac­ti­vate your pelvic floor mus­cles and think of them at the root of all move­ment.

The solid Base for the the rest of the body.


Rec­tus Fe­moris.

The rec­tus fe­moris mus­cles at situ­ated at the front of each thigh, ex­tend­ing from pelvis to tibia.



The rec­tus fe­moris is tra­di­tion­ally de­scribed as part of the quadri­ceps fe­moris mus­cle group, along with the 3 vasti mus­cles (the vas­tus lat­er­alis, vas­tus in­ter­medius and vas­tus me­di­alis).  

The dis­tal ten­dons of the 4 quadri­ceps mus­cles merge to form the com­mon quadri­ceps ten­don, which at­taches to the patella (kneecap) and then con­tinues as the patel­lar lig­a­ment to the tibial tuberos­ity of the tibia. i.e. the quadri­cep mus­cles share a com­mon in­ser­tion but rec­tus fe­moris at­taches to the pelvis, whilst the 3 vasti mus­cles at­tach to the fe­mur. The rec­tus fe­moris is the only mus­cle of the quadri­ceps that crosses both the hip and knee joints.

. image text The pelvic at­tach­ments of the rec­tus fe­moris mus­cles are com­monly de­scribed as ”to the ilium of the pelvis via two heads—the straight head and the re­flected head” but it is not that sim­ple—vari­a­tions in the pelvic at­tach­ments have been ob­served.

  • The ten­don of the straight head at­taches to the an­te­rior in­fe­rior iliac spine.

  • The rec­tus fe­moris may also arise from the an­te­rior su­pe­rior iliac spine.

  • The ten­don of the re­flected head at­taches in a groove above the su­pe­rior rim of the ac­etab­u­lum and the fibrous cap­sule of the hip joint. The re­flected head may be ab­sent.

  • A 3rd head may be pre­sent, at­tach­ing to the iliofe­moral lig­a­ment deeply, and su­perfi­cially to the glu­teus min­i­mus ten­don as it at­taches to fe­mur.

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The heads of the rec­tus fe­moris merge into an aponeu­ro­sis (a tough, thin sheet of con­nec­tive tis­sue), from which the mus­cle fibres arise as the aponeu­ro­sis con­tinues dis­tally on the an­te­rior sur­face of the mus­cle.

The lower two-thirds of the pos­te­rior sur­face of the rec­tus fe­moris con­sists of a thick, broad aponeu­ro­sis that be­comes nar­rowed into a flat­tened ten­don at­tached to the patella.  This forms the su­perfi­cial, cen­tral part of the com­mon quadri­ceps ten­don.

My com­ments.

The rec­tus fe­moris mus­cles - a strong pole down the front of the thigh when en­gaged along their full length. Po­si­tion­ing the leg to the pelvis and al­ign­ing the hip and knee joints.

Feel each mus­cle con­tract be­tween it aponeu­roses—think of pul­ling your kneecaps up and push­ing down from your hip bone.


Glu­teus Max­i­mus.

Si­tu­ated at the pos­te­rior of the pelvic re­gion, the left and right glu­teus max­i­mus mus­cles are the largest skele­tal mus­cles in the body.

The su­perfi­cial mus­cle layer of the but­tocks, cov­er­ing and sur­rounded by a lot of com­pli­cated anatomy.



The glu­teus max­i­mus mus­cles at­tach to mul­ti­ple struc­tures, many more than the cur­rent stan­dard de­scrip­tion cov­ers.

At­tach­ments of the glu­teus max­i­mus:

  • The ilium of the pelvis (pos­te­rior to the pos­te­rior gluteal line {at­tach­ing to a nar­row, semilu­nar area with a rough sur­face}, and the pos­te­rior su­pe­rior iliac crest.

  • The sacrum (pos­te­rior in­fe­rior edge).

  • The coc­cyx (lat­eral sides of the pos­te­rior sur­face).

  • The aponeu­rotic fas­cia of the glu­teus medius mus­cle.

  • The sacro­tuber­ous lig­a­ment (pos­te­rior sur­face).

  • The tubero-iliac lig­a­ment (part of the long pos­te­rior {dor­sal} sacroiliac lig­a­ment).

  • The tho­ra­colum­bar fas­cia. (Through its at­tach­ment to the raphe of the tho­ra­colum­bar fas­cia, the glu­teus max­i­mus is cou­pled to the ip­silat­eral mul­ti­fi­dus mus­cle and to the con­tralat­eral latis­si­mus dorsi mus­cle.)

  • The iliotibial tract. Three-quar­ters of the fibres form a su­perfi­cial lam­ina (layer)which nar­rows and at­taches be­tween the two lay­ers of the ten­sor fas­cia latae, form­ing part of the iliotibial tract. (a.k.a. iliotibial band.)

  • Gluteal tuberos­ity of the fe­mur. Via an aponeu­ro­sis formed from the deeper mus­cle fibres. (The glu­teus max­i­mus at­taches be­tween the vas­tus lat­er­alis and ad­duc­tor mag­nus). .

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My com­ments.

The glu­teus max­i­mus mus­cles work in tan­dem with the rec­tus fe­moris mus­cles, sta­bil­is­ing the leg through a full range of move­ment.

The largest mus­cles of the body that po­si­tion the leg to torso when fully en­gaged.

“Buns of steel”—Hands on but­tocks. Feel these mus­cles con­tract and tighten.

The glu­teus max­i­mus mus­cles are su­perfi­cial to, and sur­rounded by, a lot of anatomy prone to pain syn­dromes (caused by these main mus­cles not be­ing ad­e­quately util­ised?).

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Based on my re­cov­ery from a life-time of pain, I be­lieve learn­ing to use these 5 (paired—left and right) main mus­cles move­ment to their full po­ten­tial is the key to bet­ter phys­i­cal health:

Base-Line Hy­poth­e­sis of Hu­man Health and Move­ment (part 1).

The body’s Base-Line mus­cles—the key to bet­ter health.

Pelvic floor—Base.

Rec­tus ab­do­mi­nis - Line.

image text

The Base-Line mus­cles from where the rest of the body ex­tends and is po­si­tioned rel­a­tive to, should be able to bend and ro­tate at ev­ery level, sup­port­ing the rest of the body through a full range of nat­u­ral move­ment. Our core pillar of strength.

Think solid Base and strong, flex­ible Line. (see be­low for how to start ‘breath­ing with your Base-Line’).

Fo­cus­ing on the Base-Line mus­cles, with the linea alba as the pri­mary refer­ence for body al­ign­ment, en­hances our sense of po­si­tion, move­ment and bal­ance - pro­pri­o­cep­tion. Con­nect­ing body and mind.

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Our Base-Line mus­cles are two of the ‘5 main mus­cles of move­ment’ which, when fully util­ised, provide the cen­tral frame­work for op­ti­mal func­tion­ing of the body. image text


Con­nect Your Base-Line to Your Legs.

Glu­teus max­i­mus & rec­tus fe­moris.

It should be pos­si­ble to move each leg through a full range of move­ment in a smooth and con­trol­led man­ner, with­out effort or strain, pos­si­ble when the glu­teus max­i­mus and rec­tus fe­moris mus­cles of each leg work in tan­dem.

En­gage­ment of these leg mus­cles is about feel­ing them con­tract and strengthen.   The rec­tus fe­moris a solid pole from shin to hip bone, al­ign­ing the hip and knee joints. The glu­teus max­i­mus the sta­bil­is­ing the legs to Base-Line sup­port.

Aim for a full en­gage­ment of both mus­cles, left and right sides, bal­anced in all po­si­tions.

Con­nect Your Base-Line to Your Up­per Body.

Trapez­ius.

image text

  • Do you have any con­nec­tion to your trapez­ius mus­cles?

  • Can you ac­ti­vate them from mid-back up? Push­ing your shoulders up from un­der, not pul­ling them up from above?

  • Can you feel your arms ex­tend out from midline? Your shoulders free to move and ro­tate?

  • Can you let your head re­lax for­wards? Fully, with­out ten­sion?

The whole of both trapez­ius mus­cles should be free to fully ex­tend in all di­rec­tions, with­out pain or ten­sion, sup­port­ing the head and arms through a full range of move­ment.

The trapez­ius mus­cles al­ign the nuchal and supraspinous lig­a­ments when they are fully util­ised. Our sec­ondary refer­ences for body al­ign­ment.


A Sim­ple Tech­nique—Breath­ing with your Base-Line.

  • Breathe in and up through your nos­trils.

  • Breathe out through your mouth.

  • En­gage your Base-Line mus­cles as you in­hale.


  • Be­gin with your Base pelvic floor.

Take as many breaths as you need to feel your pelvic floor mus­cles en­gag­ing. The base of the phys­i­cal body and start­ing point of the body map in the mind.

  • Then ac­ti­vate your cen­tral Line—rec­tus ab­do­mi­nis mus­cles.

Think of en­gag­ing and elon­gat­ing your rec­tus ab­do­mi­nis mus­cles sec­tion by sec­tion, in se­quence from pelvis to chest.

Stronger and longer with ev­ery in breath, ex­tend­ing the linea alba, our pri­mary guide for body al­ign­ment.

Don’t rush, just breathe. Wher­ever you are!

Be aware of when ‘the wrong’ ar­eas of mus­cle ac­ti­vate.  When you feel this hap­pen­ing—re­lax, breathe and fo­cus on your Base-Line mus­cles once more.

I used the roll-down ac­tion a lot—my go-to move. Feel­ing my Base-Line sup­port­ing the rest of my body, form­ing the widest pos­si­ble arc as I rol­led for­ward. Don’t worry about where your feet are to start, ev­ery­thing stems from your Base-Line.

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Main­tain­ing the body is not about do­ing spe­cific ex­er­cises or reach­ing cer­tain poses.

Work to­wards a full range of move­ment by fo­cus­ing on these five main mus­cles, start­ing with your Base-Line.

Pelvic floor Base, rec­tus ab­do­mi­nis Line.

When these main mus­cles of move­ment are free to be fully util­ised the rest ‘falls into place’ . The body is strong and move­ment flows when we can achieve dy­namic al­ign­ment and bal­ance. At least that’s what I’ve found. I just need a few oth­ers to find out for them­selves how less­wrong I am!

Part 3: Con­scious Pro­pri­o­cep­tion—Your Sense of Po­si­tion, Move­ment & Balance.


Back­ground Notes on Mus­cles:

Mus­cle En­gage­ment & Ac­ti­va­tion.

An ‘ac­tive’ mus­cle is tra­di­tion­ally is de­scribed as “con­tract­ing”, but this im­plies a re­duc­tion in length or de­crease in size which is of­ten not the case.

The 3 stan­dard clas­sifi­ca­tions of how a mus­cle ‘con­tracts’ are:

  • Con­cen­tric con­trac­tion (short­en­ing of mus­cle tis­sue).

  • Ec­cen­tric con­trac­tion (length­en­ing of mus­cle tis­sue).

  • Iso­met­ric con­trac­tion (mus­cle length re­mains the same).

I pre­fer to use ‘ac­ti­vat­ing’ and ‘en­gag­ing’ when it comes to dis­cussing the us­age of mus­cles. I like ‘en­gag­ing’ but I’ve had poor feed­back. I con­tinue my search for the perfect word—sug­ges­tions?!

Mus­cle Cells = Mus­cle Fibres.

Mus­cles con­sists of ‘hun­dreds of thou­sands’ (no figures available!) of elon­gated mus­cle cells (my­ocytes) sur­rounded by con­nec­tive tis­sue. Th­ese cells are com­monly known as mus­cle fibres.

Sev­eral mus­cle fibres.


Cross sec­tion of mus­cle tis­sue.


Areas of Mus­cle.

It is not “all or noth­ing” when a mus­cle works. Mus­cles con­sist of many over­lap­ping ar­eas of po­ten­tial ac­tivity. In an in­di­vi­d­ual mus­cle, some mus­cle fibres may be ac­tive whilst oth­ers are rest­ing—or spas­ming.

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Vol­un­tary Mus­cles.

Vol­un­tary mus­cles are mus­cles with “an ac­tion that is un­der the con­trol of the will”.

All stri­ated mus­cles (ex­cept the heart) are vol­un­tary i.e. we can con­sciously con­trol all our mus­cles if the con­nec­tion be­tween brain (com­mand cen­ter) and mus­cle is de­vel­oped.

Test Your­self …

Are you will­ing to do a bit of self-ex­per­i­men­ta­tion and con­sider how your body moves?

Find the main mus­cles—pal­pate them on your body.

Can you con­nect with them? Feel them? Ac­ti­vate them?

It may take a while for ‘ac­ti­va­tion sig­nals’ to to get to the right place, and the abil­ity to fully en­gage the whole of a mus­cle comes with prac­tice.

Time and effort.

To bal­ance the body. And mind.