Anatomy
A n a t E n r b r y o (l 1 9 8 5 )1 7 3 2 1 5 - 2 7 7
andEmbryology
t ; S p r i n g e r - \ ' e r l a gI 9 f l 5
Morphogenesisof the human gluteus maximus muscle arising
from two musclePrimordia
Miroslav Tichf and Milo5 Grim
Instituteof Anatomy,CharlesUniversityPrague,Czechoslovakia
Summary. In human embryos and fetusesa su.pernumerary
muscle was found situated on the distal margin of the gluteus maximus muscleand suppliedby the most distal main
branch of the inferior gluteui nerve.According to its origin
musand insertion it is being named the coccygeofemoralis
cle.
In embryos and fetusesof up to 40 mm in CR length
the coccygeofemoralismuscleis separatedby-loose connective tissue-fromneighbouring fetal muscles'Later on' close
contact betweenthe coccygeofemoralisand the distal margin of the fetal gluteus miiim,rt muscle develops'and duri"l tn" prenatai period both letal musclesgradually fuse'
Po-stnatally,the coccygeofemoralismuscle is incorporated
into the giuteusmaximus muscle of which the pars sacrolliaca cor-respondsto the fetal gluteus maximus itself and
the pars coccygearepresentsthe fetal coccygeofemoralis
muscle.
With respectto the generalprocessof musclemorphogenesis,the developmentalpattern describedfor the gluteus
iraximus muscle demonstrites that adult musclesmay be
formed by a fusion of severalfetal muscles'
Material and methods
Musclesof the pelvic regionwerestudiedin i8 human embryos and fetusesof 22 lo 215 mm crown-rump-length (CR
length),in 5 newbornsand in 5 adults of both sexes'The
peliic'part of the body of 18 embry-os-andfetusesof 22
io 85 mm CR length was fixed, embeddedin Paraplast,
and seriallysection;din the sagittal,frontal or transversal
olanes.The sectionswere stainedwith haematoxylinand
iosin. in 20 fetusesof 40 to 215 mm CR length' in newborns
and adults, superficial musclesof the gluteal region and'
in most cases.branchesof the inferior gluteal nerve were
microdissected.
Key words: Muscle morphogenesis- Human gluteusmaximus muscle- Coccygeofemoralismuscle
Introduction
The human gluteus maximus representsa muscle whose
anatomical description is well establishedbut the morphosenesis of which has not been fully clarified' Studies of
ihe variability of this musclesshowedthe occasionaloccurrence of an anomalousmusclewhich was more or lessconnectedwith the distal margin of the gluteusmaximusmuscle
and this has beendesignatedthe "coccy-femoralis" (Testut
1884)or "femoro-coccygeus"muscle(Le Double 1897)'
During the study of the developmentof the human external spi'incter ani muscle (Tichj' 1984), a fetal muscle
which correspondsin respectof its origin and insertion to
the "coccy-fimoralis" muscle was repeatedly.observed'In
this paper the resultsof a systematicstudy of the occurrence
and^ontogenesisof the "coccy-femoralis" muscle are presented.
Offprint requeststo: Dr. M. Tich!, Institute-of Anatomy' Charles
University,'U nemocnice3, 128 00 Praha2, Czechoslovakia
pelvis:
Figs. 1-3. Human fetal musclesin sagittal sections ol the
antesc sacrococcygeus
grn gluteusmaximus,c/'coccygeofemoralis,
l'
Fig'
externus'
ani
sphincter
to"
pubot..tilis,
p,
iio.l,
of +S m* bn length. HE, x 30' Figs'2, 3' Branchesof n'
Fetus "o""yg"ur,
into gm and cf muscles'
gluteus inferio. .nt", s.pu.utely (arror+'s)
Fetusof 30 mm CR length,HE, x 45
:16
r
gm
Fig.8. Schemeof the definitivegluteusmaximusmuscledivided
origin from two fetalmuscles
iniccordancewith its developmental
and its innervation
and a pars coccygea.
into a pars sacroiliaca
from n. gluteusinferior
Figs.z1-6.Dorsal views of microdissectedgluteus maximus (gz)
(l) musclesin a tttus 15 mm (4)' 75 mm
and coccygeofemoralis
border betweenthe two
(5) and 140mm (6) of CR length. ,4rrr,'rr'.r
muscles.Fig. 7. Ventral view of gluteusmarimus (grrr)and coccygeofemoralis({) musclesand their innervationby branches(arrox'.s)of n. gluteusinferior. Openurrott - n. cutaneuslemorisposterior. Fetusof 145mm CR leneth
Observations
In the pelvis, ventrolaterally from the chondral anlagen of
the coccygeal vertebrae, the primordium of a supernumerary muscl; was found in human embr)'os and letuses.This
primordium originates at the ventrolateral margin of the
chondral coccygealvertebrae and runs ventrolaterally to
insert on the femur, distal to the insertion of the primordium of the fetal gluteus maximus muscle. It can thus be
designatedthe coccygeofemoralismuscle.
In embryosand fetusesup to 45 mm CR length an indemusclewas regularlyfound bilapendentcoccygeofemoralis
terally. Its muscle belly was separatedb1' loose connective
tissuefrom other musclessituatedventrally from the coccygeal vertebrae(Fig. 1). Towards its insertion, it was delin'
eatedfrom the distal margin of the gluteusmaximus muscle
(Fig. 2). Both fetal muscleswere consistentlysupplied by
individual nerve branchesoriginating from the inferior gluteal nerve (Figs. 2, 3). By microdissection,the coccygeofemoralis musclemay be visualizedas a narrow band situated
along the distal margin of the gluteus maximus muscle
(Fig. a). The gap betweenthe two musclesin broader medially than laterally.
In fetusesof CR length 45 to 215 mm, the coccygeofefuse
moralis and fetal gluteusmaximus musclessuccessively
with
connecfilled
small
furrow
a
(Figs. 5, 6). Nevertheless,
tive tissuestill forms the borderline betweenthe two muscles. The coccygeofemoralismuscle is innervated by the
most distally situated main branch of the inferior gluteal
nerve, and the fetal gluteusmaximus muscleby one or two
proximal main branches(Fig. 7).
2'17
Previousstudiesof the developmentof the human gluIn nervbornsand in adults both musclesare completely
teus maximus muscle demonstrated a different extent of
fused.The coarsemuscle bundles typical for the gluteus
its prenatal rebuilding.According to Bardeen(1907)' the
maximusmusclemakeitdifficulttoidentif-"-theoriginal
of the gluteusmaximus muscledividesinto two porb o r d e r l i n e o f t h e t w o f e t a l m u s c l e s . B o t h p o r t i o n s c a n banlage
e
tions which are distinctly separatedin embryosbut only
artefrciallyseparatedonly if the dissectionis done between
rarely discerniblein adults. He consideredthe distal portion
origmusclebundlesoriginating from the coccyx and those
to representthe " femoro-coccygeus"muscleof lower mamthis
In
bone'
sacral
inating from the Jaudalind of the
mals.
Puzanov6(1961) showed that both portions of the
gluthe
of
coccygea
pars
and
-annJr, the pars sacroiliaca
gluteus
maximusmuscleare separatedin fetusesup to about
teus maximui muscle can be demonstrated(Fig' 8)'
130 mm in CR length, and subsequentlyfusetogether.Grdfenberg (1904) found an intrapelvic fetal muscle belly
Discussion
(" Beckenportion") of the gluteus maximus which was connectedwith its distal margin, and assumedthat it later disOur observationsshow that the human -sluteusmaximus
appears.This intrapelvic portion was not found by Bardeen
The
muscles'
fetal
two
muscle develops by the fusion of
(f907). Our findings lead to the conclusion that the fetal
part of the gluteus maximus muscle originating from the
coccygeofemoralismuscle occurring intrapelvically in its
rvhich
is
regucoccyxcorrespondsto a separatefetal muscle
medial part and along the distal margin of the fetal gluteus
has
which
and
fetuses
larly found in human em6ryos and
in its lateral part representsa separate
beentermedin accordancewith its courseas the coccygeofe- maximus muscle
prenatally fuseswith the fetal gluteus
which
entity
muscle
sucmoralis muscle.During the prenatal period this muscle
maximus
muscle.
gluteus
fetal
the
of
cessivelvfuses with the distal margin
With respectto the general processof musclemorphoborderline of the two
al
' 7 maximus muscle. Postnatally, the
genesis,
the developmentalpattern describedin the gluteus
fused musclesis masked by the coarse pattern of muscle
muscle is similar to that in the human pectoralis
maximus
Nevmuscle'
. bundlescharacteristicof the gluteusmaximus
major muscle (eihek 1959) or in certain musclesof the
'
ma.ximus
, ertheless,from the ontogenic aspect,the 'siuteus
human hand and foot (eih6k 1972), demonstrating that
can be divided into a pars sacroiliaca,corresponding to
a great many definitive adult musclesmay be formed by
reppars
coccygea
a
the fetal gluteusmaximus proper' and
fusion of severalmuscle primordia.
resentingthe human fetal coccygeofemoralismuscle'
No muscleentity correspondingto the fetal coccygeofemoralis muscle is included in normal human arlatomy'
References
However, Testut (1884) and Le Double (1897) described
an anomaloussupernumerarymusclealong the distal marThdses
AlezaisH (1900)Contributiond la myologiedesRongeurs.
gin of the gluteus maximus muscle on one or both sides
d la Fac.desSci.de Paris,S6rieA, No.371,F. Alcan,Paris,
i-n 12 humair subjectsand named it the "coccy-femoralis"
pp 221-227
and variationof the nervesand
(Testut 1884)or "femoro-coccygeus"muscle (Le Double
BardeenCR (1907)Development
of theinferiorextremityandof theneighboring
themusculature
1897).This muscle,according to Testut (1884).corresponds
regionsof the trunk in man.Am J Anat 6:25F390
to the caudofemoralismuscle of long-tailedmammals' ConE and S
hila of limb muscles.
BrashJC (1955)Neuro-vascular
trary to this, Leche (1900) consideredthese two terms to
pp 1-100
London,
Edinburgh,
Livingstone,
(1898)
represent two different muscles and Gegenbaur
eiirat R (1959)MusculuspectoralismajorundseineKomponenten
stressedthat the caudofemoralismuscleof animals and the
dei Menschen.(in Czech).es Morfologie
in dei Ontogenese
piriformis muscle of humans are homologous. We assume
7:147-191
that the fetal coccygeofemoralisdescribedin our study corof skeletonand intrinsicmusclesof
einat n (1972)Ontogenesis
and
thehumanhandand foot. Erg Anat Entw-Gesch46t:1-149
1 respondsto the anomalous "coccy-femoralis"muscle
Anatomieder WirbeltiereI,
I that its anomalouspostnatal persistencerepresentsonly an
GegenbaurC (1898)Vergleichende
W Engelmann,Leipzig,p 696
incomplete fusion with the gluteus maximus muscle.This
BeckenGrdfenbergE (1904)Die Entwicklungder menschlichen
view is supported by the opinion of Leche (1900) that in
Anat Hefte23:.429494
muskulatur.
apes,at least in the gorilla, the "femorococcygeus" muscle
In: Bronn'sKlassenund OrdS?iugethiere.
LecheW (1874-1900)
is incorporated into the gluteus maximus muscle mass. In
Band VI, Abt. V. Winter Leipzig'
nungendesThier-Reichs.
mus(1884)
felt
that the "coccy-femoralis"
contrast,Testut
pp 84G851
cle is normally not formed at all in anthropoids.
musculaire
Le DoubleAF (1897)Trait6 desvariationsdu systdme
"coccy-femorAccording to Alezais (1900),the separate
Frdres'Paris.pp360-362
de I'homme.Tome1, Schleicher
alis" muscle in mammals receives innervation from a
GH, Lau H, SchultzM. HimstedHW
MenningA, Schumacher
Nervenausbreitungen'
(1974) Zur Topographie
der muskuldren
branch of the inferior gluteal nerve.Studiesof innervation
Anat Anz135:302-314
6. UntereExtremitdt.Glutealmuskeln.
of the human gluteus maximus musclein adults has shown
of musstages
developmental
L (1961)Someinteresting
Puzanov6
that this muscle receivestwo or three main brancheslrom
(in Czech)'
culusgluteusmaximusin the humanontogenesis.
the inferior gluteal nerve, which further split in a brushlike
es Morfologie4:38V394
manner and enter the subsurlaceof the muscle(Brash 1955;
chezI'homme.G Masmusculaires
L (1884)Lesanomalies
Testut
ftbres
muscle
We
the
have found that
Menning et al. 1974).
Paris,pp 575-597
son,
originating from the coccyx are innervated from the main
ofthe sphincter
andorganization
Tichj'M (1984)Thedevelopment
most distal branch in a similar way to those of the fetal
ani externusand the adjacentpart of the levatorani muscle
coccygeofemoralismuscle. These data may serve as evi32:113-120
in man.FoliaMorphol(Prague)
dencefor the homology of the human fetal coccygeofemoralis musclewith the separatemuscletaking the samecourse
found in many adult mammals, and support a dual-devel9, 1985
AcceptedSeptember
opmental origin of the human gluteusmaximus muscle.