The Pronators and Supinators

Donald Sammut Hand Surgeon KCH Upper Limb Anatomy plus lecture notes

Pronation(and(supination(of(the(hand(occurs(by(movement(at(two(articulations((between(radius(and(ulna((Beyond(the(elbow).((This(involves(the(radius(spiralling(around(the(ulna((This(is(not(to(be(confused(with(the(rotation(that(is(possible(when(the(elbow(is(extended((and(there(is(contribution(by(humerus(and(scapula,(as(well(as(radio?ulnar(movement.((With(humero?scapular(contribution,(the(hand(can(be(rotated(through(nearly(360°(

Pronation(and((Supination(of(the((forearm(

Plus(Humeral(rotation(and(Scapular(movement(

Range:((

Elbow(flexed:(140°(to(150(°((With(elbow(extended(and(adding((Humeral(rotation(and(scapular(movement:((350°(((

Power((

Supination(>(Pronation(Antigravity(

Pronation(is(often(aided(by(gravity((the(hand(readily(falls(into(pronation)((Supination(is(often(anti?gravity((Both(are(indispensable(contributors(to(the(versatility(of(the(upper(limb((in(orientating(the(hand(in(space((Supination(is(the(more(powerful,(a(fact(that(is(made(use(of(in(the(design(of((screw(and(bolt(thread.(Screwing(into(wood(is(usually(harder(than((undoing(a(screw,((Thread(tightens(clockwise,(which(would(be(achieved(by(supination((of(a(hand(holding(a(screwdriver.((((

The(typical(action(of(pronation(and(supination(is(the(turning(of(a(key(in(a(lock(The(hand(clamps(on(to(the(key(The(forearm(rotates.((

Supination( Pronation(

Supination((Avge(75°(

Pronation((Avge(64°(

In(pronation(and(supination,(the(ulna(is(static.(The(Radius(spirals(around(the(ulna((Actually(the(ulna(abducts(and(adducts(slightly(during(supination(and(pronation,((so(the(radius(does(not(describe(a(symmetrical(spiral.(This(is(of(no/minimal(clinical(relevance.(((

RADIUS(ULNA(

RADIUS( ULNA(

Interosseous((Membrane(

Static((Ulna(

The(Proximal(Radio?Ulnar(Joint((Uni?axial(pivot(joint(

(Radial(head(with(radial(notch(of(Ulna(((and(Capitulum(of(Humerus(

The(Distal(Radio?Ulnar(Joint((Uni?axial(pivot(joint(

The(proximal(radio?ulnar(joint(

The(Radius(articulates(with(the(ulnar(radial(notch(proximally(and(also,((by(a(shallow(facet,(with(the(capitulum(of(the(Humerus(The(anular(ligament(is(a(strong(transmitter(of(force(from(the(hand,((via(the(radius(and(on(into(the(ulna(and(humerus.((It(also(ensures(that(the(radial(head(remains(congruous(with(the(radial(notch((in(the(proximal(Ulna(

Humerus

Radial Fossa

Capitulum

Lateral epicondyle

Medial epicondyle

Trochlea

Coronoid fossa

Radial head

Radial Neck

Radial Tuberosity

Coronoid Process

Ulnar Tuberosity

TROCHLEA

CAPITULUM

Anular Ligament

The(distal(radio?ulnar(joint(

The(distal(radio?ulnar(joint((The(radius(glides(around(the(convex(head(of(the(ulna(which(articulates((with(the(ulnar(notch(in(the(distal(radius.((The(radius(is(held(in(this(accurate(arc(around(the(ulnar(head(by(the(triangular(fibrocartilage.(This(triangle(is(strongest(and(thickest(dorsal(and(volar.((These(two(parts(act(like(spokes(of(a(wheel,(ensuring(that(the(radius((and(ulna(remain(congruous.((The(central(part(is(not(crucial(to(structure(and(stability(and(is((frequently(perforated(or(deficient(in(later(life(without(compromise(of(function.(

TFCC(Triangular(

Fibro?Cartilaginous(Complex(

Rupture(of(the(Triangular(Fibrocartilage(results(in(loss(on(congruity((and(instability(of(the(distal(radio?ulnar(joint((DRIUJ)(

The(interosseous(membrane(connects(radius(to(ulna((It(also(spirals(as(the(radius(spirals(around(the(ulna.((It(is(relatively(slack(in(full(pronation(and(in(full(supination.(It(is(tight(in(neutral((Mid(pronation/Mid(supination)((The(hand(hangs(from(the(radius(and(the(ulna(does(not(participate(in(wrist(articulation.((Weight(is(transmitted(via(the(radius(and(then,(partly(directly(into(the(humerus(and((partly(through(the(ulna(which(hangs(from(the(humerus(via(the(very(strong((bony(articulation(of(the(Olecranon.((The(interosseous(membrane(probably(does(not(participate(significantly(in((load(transmission.(

Transmission((of((force(

Collateral(Ligament(

Anular((Ligament(

Interosseous(Membrane((tense(in(neutral)(

SUPINATION(Biceps(Brachii(Supinator(

Two(powerful(muscles(produce(supination((Biceps(Brachii(inserts(into(the(radial(tuberosity.(The(tendon(winds(round(the(radius((in(full(pronation(and(unwinds(forcefully(when(powerful,(fast(supination(is(required.(It(also(has(attachment(into(the(deep(fascia(of(the(forearm(via(the(bicipital(aponeurosis,((which(gives(it(purchase(on(the(forearm(with(a(better(moment(arm((Supinator(has(two(heads,((One(transverse(connecting(ulna(to(radius(One(oblique(connecting(humerus(to(radius.(Both(produce(powerful(supination(of(the(radius(on(the(ulna(

Biceps(Brachii(

Biceps(Tendon(Bicipital(Aponeurosis(

BICEPS(BRACHII(

Insertion((Biceps(Brachii((((((Radial(Tuberosity((+((via(Bicipital(Aponeurosis(into(Deep(fascia(of(forearm(

The(bicipital(aponeurosis(crosses(the(path(of(the(median(nerve(and(brachial(artery(in(the(cubital(fossa.((It(can(be(a(cause(of(proximal(compression(of(the(median(nerve(

Biceps:(Puts(in(the(Corkscrew…(

Biceps:(Puts(in(the(Corkscrew…and(pulls(out(the(cork.(

Supinator(Superficial(layer((Humeral(Head)((Anterior(view((((•  Lateral(Epicondyle(•  Radial(Collateral(((((((Ligament(•  Anular(Ligament((((((Lateral(aspect(of(Proximal(1/3rd((Radius(

Supinator(Superficial(layer((Humeral(Head)((Posterior(view((((

Supinator(Deep(layer((Ulnar(head)((Anterior(view((((((Supinator(Crest(Of((Ulna(((((Lateral(aspect(of(Proximal(1/3rd(Radius((

Supinator(Deep(layer((Ulnar(head)((Posterior(view(((((((

Supinator(Deep(and(superficial(Layers((

Anterior( Posterior(

Pronation( Supination(

Pronation( Supination(

The(posterior(interosseous(nerve((nerve(of(the(extensor(compartment(of(the(forearm)(leaves(the(main(radial(nerve(as(a(terminal(branch(beneath(Brachioradialis(and(travels(between(the(two(heads(of(Supinator(to(reach(the(back(of(the((interosseous(membrane(

The Arcade of Frohse also The Supinator arch

Fritz(Frohse:(Anatomist(1871(?(1916(

Hypertrophy(of(the(supinator(can(cause(compression(of(the(posterior(interosseous(nerve((Under(the(Arcade(of(Frohse,(or(the(‘Supinator(Tunnel’)((This(presents(clinically(as(weakness(of(thumb(extension(and(extension(of(the(digits.(When(invited(to(extend(the(wrist,(the(patient(will(extend(and(deviate(to(the(radial(side((because(the(Mobile(wad((with(ECRL(and(ECRB(are(unaffected)(

PRONATION(Pronator(Teres(

Pronator(Quadratus(

Pronation(is(produced(by(two(Muscles((Pronator(Teres(lies(proximal(in(the(forearm.(It(consists(of(two(heads,((between(which(the(median(nerve(enters(the(forearm.(It(forms(the(medial(border(of(the(cubital(fossa.(((Pronator(Quadratus(is(quadrangular(and(lies(in(the(distal(quarter(of(the(forearm,((between(radius(and(ulna(and(deep(on(the(interosseous(membrane.((

Pronator((Teres(((Humeral(Head:((•  Common(Flexor(Origin(•  Medial(Intermuscular((

(Septum(Ulnar(Head:(Medial(Side(Coronoid(((((Lateral(edge(Midway(Radius(

(

Pronator((Quadratus(

Distal(ulna(((((Distal(radius((

FDP( FPL(

PQ(

One(can(test(separately((for(Pronator(Teres(and(Pronator(Quadratus.((Since(Pronator(Teres(crosses(the(elbow,(flexing(the(elbow(will(slacken(it(and(render(it(weak.((Pronation(with(elbow(flexed(tests(mainly(Pronator(Quadratus.((To(test(Pronator(Teres,(the(elbow(is(held(extended(and(one(ensures(that(there(is(no((pronation(occurring(by(internal(and(external(rotation(of(the(humerus.(((

Summary((Supination:((Biceps(Brachii:((Into(Radial(tuberosity(via(strong(tendon(which(strongly(rotates(the(radius(into(supination(and(via(Bicipital(aponeurosis(into(deep(fascia((Supinator:(Superficial(and(Deep(Heads(

( (Humero/Ulnar(to(Radius,(upper(third(( (Ulnar(to(Radius(upper(third.((

((((

Pronation:((Pronator(Teres:(2(heads:(Humero/Ulnar(to(Radius(midway(down(lateral(border((Pronator(Quadratus:(Distal(Ulna(to(distal(Radius.(

www.donaldsammut.com