Chapter V: Part 5

Wilcox (1948), studying a loon, did not find any peroneal supply to M. extensor iliotibialis lateralis or to M. gluteus profundus. He found a femoral, rather than a peroneal, supply to M. piriformis. He found an obturator, instead of a tibial, supply to M. flexor ischiofemoralis. (In some of my specimens I found a tiny blood vessel, appearing much like a nerve, emerging from the obturator foramen and entering M. flexor ischiofemoralis.) Wilcox reports an innervation of M. caudofemoralis pars caudifemoralis from the pudendal plexus, in addition to the usual sciatic one. Wilcox did not distinguish tibial and peroneal components in the thigh. In the shank and foot he misidentified the peroneal nerve as the tibial nerve and therefore gave erroneous innervations for all the muscles supplied by this nerve, except for M. adductor digiti IV, which actually should be supplied by the tibial nerve.

Howell (1938) studied only the hip and thigh musculature of the chicken. He overlooked the femoral nerve supply for M. gluteus profundus.

Romer (1927) studied only the hip and thigh muscles of the chick. He did not distinguish tibial and peroneal components in the thigh. He did not mention any sciatic supply for M. gluteus profundus.

Appleton (1928), studied (in various birds) only those muscles of the hip and thigh that are innervated by the tibial and peroneal nerves. He terms the former "ischiadicus ventralis" and the latter "ischiadicus dorsalis." His findings did not differ from mine.

Many differences in the innervation of specific muscles are reported in the literature, even in the same species (by different workers). Some of these differences may be real; others are probably misinterpretations. Consequently more work needs to be done before a complete understanding can be obtained of the innervation of the leg muscles of birds. Especially needed are studies of the tibial-peroneal nerve relationship, perhaps approached by a method other than gross dissection.

SUMMARY

The muscles and nerves were dissected in eight legs of the Lesser Prairie Chicken (_Tympanuchus pallidicinctus_), six legs of the Greater Prairie Chicken (_T. cupido pinnatus_), three legs of Attwater's Prairie Chicken (_T. c. attwateri_), and six legs of the Sharp-tailed Grouse (_Pedioecetes phasianellus jamesi_) for the purpose of obtaining information on individual variation as well as variation between these closely related species. Relatively little information is available regarding the nerves of the leg of birds and little is known about individual variation and variation between closely related forms in the muscles of the leg of birds.

All osteological terms used in the present paper are defined and those of the pelvis are illustrated. New terms were coined for some structures for which no names could be found in the literature. Terms were also coined for the major divisions of the femoral and sciatic nerves. With three exceptions, my muscle terminology follows that of Fisher (1946) and Fisher and Goodman (1955). Their term femoritibialis externus is not used here; the muscle so named is considered to be a part of M. vastus lateralis. Fisher's accessory head of M. flexor cruris lateralis is considered to be a distinct muscle--M. femorocruralis. Usage of the term obturator internus is avoided because the muscle so named is considered not to be homologous with the mammalian muscle of the same name; the entire obturator complex is called M. obturator, and is subdivided into four parts.

The typical (most common) condition of the nerves and muscles in _Tympanuchus pallidicinctus_ is described in detail. Variations from this condition among the other birds studied are then described. All muscles of one leg of _T. pallidicinctus_ are illustrated. Several variations in the muscles are also illustrated. The lumbosacral plexus and nerves of the leg in several specimens that show variations are illustrated.

Considerable individual variation was found in both the muscles and the nerves of the leg of the species studied. Certain muscles were more variable than others. Mm. flexor digitorum longus, obturator, caudofemoralis, and extensor hallucis longus showed the greatest number of variations. Mm. vastus medialis, femoritibialis internus, flexor perforatus digiti III, extensor brevis digiti III, and abductor digiti IV did not exhibit any variations considered significant. Certain legs showed a greater number of variations from the typical condition than did others.

Although most of the variations were minor, some were major. M. extensor proprius digiti III was present in two legs of _Pedioecetes_ but absent in the other legs studied. A fleshy muscle slip connected M. caudofemoralis pars caudifemoralis with the tendinous raphe between Mm. flexor cruris lateralis and femorocruralis in two legs, whereas in others this connection was tendinous or even absent altogether. M. flexor cruris lateralis had an accessory slip arising from the caudal musculature in one leg. A vinculum connected the insertional tendons of Mm. flexor perforans et perforatus digiti II and flexor perforatus digiti II in one leg.

In most specimens there was as much variation between the muscles of the right and left legs of one individual as there was between individuals. The same was true for the nerves, except for the lumbosacral plexus, in which there was no significant variation between the right and left sides of any individual. The peroneal and obturator nerves varied less than the other nerves.

No constant differences in the muscles or nerves was found between _T. cupido pinnatus_ and _T. c. attwateri_. One constant difference was found between _T. cupido_ and _T. pallidicinctus_: the fleshy origin of M. extensor iliotibialis lateralis in _T. cupido_ was thicker (associated with a thicker edge of the lateral iliac process).

Although no constant differences in the nerves were found between _Pedioecetes_ and _Tympanuchus_ (both species), 17 constant differences in the muscles were found between these two genera. Study of additional specimens possibly would show enough individual variation in some of these differences to reduce the number of constant differences to fewer than 17. Seven of these differences pertain to features of a single muscle--M. flexor cruris medialis. Some of the other differences are associated with the thinner and much less pronounced lateral iliac process in _Pedioecetes_. The picture of the differences between _Tympanuchus_ and _Pedioecetes_ that this study presents is radically different from that presented by the study of Hudson, _et al._ (1959).

The important differences in innervation between previous studies and the present one are discussed.

All of the muscles under consideration have been grouped as either dorsal or ventral muscles, according to their embryonic origin, as described by Romer (1927) and Wortham (1948). This grouping probably represents accurately the phylogenetic origin of these muscles. The dorsal muscles probably were originally supplied by dorsal nerves--the femoral and peroneal--and the ventral muscles probably were originally supplied by ventral nerves--the obturator and tibial. This primitive muscle-nerve relationship has been relatively constant.

Several previous workers have reported some dorsal muscles supplied by ventral nerves and _vice versa_. Those findings should be viewed with suspicion until verified, because the proximal parts of the tibial and peroneal nerves are intimately associated and their relationship is easily misinterpreted. I found a branch of the tibial nerve that is closely associated with, and distributed with, the peroneal nerve. That branch of the tibial nerve has been mistakenly considered a part of the peroneal nerve by some workers. My study revealed no definite exceptions to the expected innervation.

TABLE 1. SYNONYMY OF THE MUSCLES OF THE LEG OF BIRDS

===============+===============+============+==============+============== | | Howell | Fisher & | Gadow (1891) | Hudson (1937) | (1938) |Goodman (1955)| Holmes ---------------+---------------+------------+--------------+-------------- ilio-tibialis |ilio-tibialis |extensor |extensor |extensor | | iliotibia- | ilio-tibia- | iliotibialis | | lis latera-| lis | lateralis | | lis | lateralis | ---------------+---------------+------------+--------------+-------------- ilio-tibialis |sartorius |extensor |extensor |extensor internus s. | |iliotibialis| ilio-tibia- | iliotibialis sartorius | |anterior | lis anterior| anticus ---------------+---------------+------------+--------------+-------------- ambiens |ambiens |ambiens |ambiens |ambiens ---------------+---------------+------------+--------------+-------------- femori-tibialis| | |femoritibialis|vastus externus | | | externus | lateralis | | | |(a) pars | | | | postica ---------------+ | +--------------+ {|femori-tibialis|vastus |vastus |(b) pars femori- {| externus | lateralis | lateralis | lateralis tibialis {+---------------+------------+--------------+-------------- medius {|femori-tibialis|} {|vastus |vastus {| medius |} {| medialis | medialis ---------------+---------------+}vastus {+--------------+-------------- femori-tibialis|femori-tibialis|} medialis{|femoritibialis|femoritibialis internus | internus |} {| internus | internus ---------------+---------------+------------+--------------+-------------- ilio-fibularis |biceps femoris |extensor |extensor |extensor | | iliofibu- | ilio- | ilio- | | laris | fibularis | fibularis ---------------+---------------+------------+--------------+-------------- ilio-femoralis |glutaeus medius|piriformis |piriformis |piriformis externus | et minimus | | | ---------------+---------------+------------+--------------+-------------- ilio-trochante-|ilio-trochante-|gluteus |gluteus |gluteus ricus | ricus | profundus | profundus | profundus posterior | posterior | | | ---------------+---------------+------------+--------------+-------------- ilio-trochante-|ilio-trochante-|iliacus |iliacus |iliacus ricus | ricus | | | anterior | anterior | | | ---------------+---------------+------------+--------------+-------------- ilio-trochante-|ilio-trochante-| |ilio-trochan- |iliotrochante- ricus medius | ricus medius | | tericus | ricus medius | | | medius | ---------------+---------------+------------+--------------+-------------- ilio-trochante-|iliacus |psoas |psoas |psoas ricus | | | | internus | | | | ---------------+---------------+------------+--------------+-------------- caud-ilio- |semitendinosus |flexor |flexor cruris |flexor cruris flexorius | | cruris | lateralis | lateralis | | lateralis |(a) main head | ---------------+---------------+------------+ +-------------- accessorius |accessorius |femorocru- |(b) accessory |femorocruralis semitendinosi| semitendinosi| ralis | heads | ---------------+---------------+------------+--------------+-------------- ischio- |semimembranosus|flexor |flexor cruris |flexor cruris flexorius | | cruris | medialis | medialis | | medialis | | ---------------+---------------+------------+--------------+-------------- caud-ilio- |piriformis | |caudofemoralis|caudofemoralis femoralis | | | | (a) pars |(a) pars |caudofemo- |(a) pars |(a) pars caudi- | caudi- |ralis | caudi- | caudifemo- femoralis | femoralis | | femoralis | ralis | +------------+ | (b) pars ilio- |(b) pars ilio- |flexor ilio-|(b) pars ilio-|(b) pars femoralis | femoralis | femoralis | femoralis | iliofemo- | | | | ralis ---------------+---------------+------------+--------------+-------------- ischio- |ischio- |flexor |flexor ischio-|flexor femoralis | femoralis | ischiofe- | femoralis | ischiofemo- | | moralis | | ralis ---------------+---------------+------------+--------------+-------------- {|adductor longus|adductor |adductor |adductor {| et brevis | superfi- | superfici- | superficialis {|(a) pars | cialis | alis | pub-ischio- {| anterior | | | femoralis {| +------------+--------------+-------------- {|(b) pars |adductor |adductor |adductor {| posterior | profundus | profundus | profundus ---------------+---------------+------------+--------------+-------------- obturator |obturator |} {|obturator |} | internus |} {| internus |} ---------------+---------------+} obturator{+--------------+} obturator accessorii M. |obturator |} {|obturator |} obturatoris | externus |} {| externus |} ---------------+---------------+------------+--------------+-------------- gastrocnemius |gastrocnemius | |gastrocnemius |gastrocnemius ---------------+---------------+------------+--------------+-------------- flexor |flexor | |flexor perfo- |flexor perfo- perforans et | perforans et | | rans et per-| rans et per- perforatus | perforatus | | foratus | foratus digiti II | digiti II | | digiti II | digiti II ---------------+---------------+------------+--------------+-------------- flexor |flexor | |flexor perfo- |flexor perfo- perforans et | perforans et | | rans et per-| rans et per- perforatus | perforatus | | foratus | foratus digiti III | digiti III | | digiti III | digiti III ---------------+---------------+------------+--------------+-------------- flexor |flexor | |flexor |flexor perfo- perforatus | perforatus | | perforatus | ratus digiti digiti IV | digiti IV | | digiti IV | IV ---------------+---------------+------------+--------------+-------------- flexor |flexor | |flexor |flexor perfo- perforatus | perforatus | | perforatus | ratus digiti III | digiti III | | digiti III | digiti III ---------------+---------------+------------+--------------+-------------- flexor |flexor | |flexor |flexor perfo- perforatus | perforatus | | perforatus | ratus digiti digiti II | digiti II | | digiti II | II ---------------+---------------+------------+--------------+-------------- flexor hallucis|flexor hallucis| |flexor hallu- |flexor hallu- longus | longus | | cis longus | cis longus ---------------+---------------+------------+--------------+-------------- plantaris |plantaris | |plantaris |plantaris ---------------+---------------+------------+--------------+-------------- flexor |flexor | |flexor digi- |flexor digito- profundus | digitorum | | torum longus| rum longus s. perforans | longus | | | ---------------+---------------+------------+--------------+-------------- popliteus |popliteus | |popliteus |popliteus ---------------+---------------+------------+--------------+-------------- peroneus |peronaeus | |peroneus |peroneus superficialis| longus | | longus | longus ---------------+---------------+------------+--------------+-------------- tibialis |tibialis | |tibialis |tibialis anticus | anterior | | anterior | anticus ---------------+---------------+------------+--------------+-------------- extensor |extensor | |extensor |extensor digitorum | digitorum | | digitorum | digitorum communis | longus | | longus | longus ---------------+---------------+------------+--------------+-------------- peroneus |peronaeus | |peroneus |peroneus profundus | brevis | | brevis | brevis ---------------+---------------+------------+--------------+-------------- extensor |extensor | |extensor |extensor hallucis | hallucis | | hallucis | hallucis brevis | longus | | longus | longus ---------------+---------------+------------+--------------+-------------- abductor |abductor | |abductor |abductor digiti II | digiti II | | digiti II | digiti II ---------------+---------------+------------+--------------+-------------- extensor brevis|} {| |extensor |extensor bre- digiti III |} extensor {| | brevis | vis digiti |} {| | digiti III | III ---------------+} proprius {+------------+--------------+-------------- extensor |} digiti {| |extensor |extensor proprius |} III {| | proprius | proprius digiti III |} {| | digiti III | digiti III ---------------+---------------+------------+--------------+-------------- extensor brevis|extensor brevis| |extensor |extensor bre- digiti IV | digiti IV | | brevis | vis digiti | | | digiti IV | IV ---------------+---------------+------------+--------------+-------------- flexor brevis |lumbricalis | | |lumbricalis digiti III | | | | ---------------+---------------+------------+--------------+-------------- abductor |abductor | |abductor |abductor digiti IV | digiti IV | | digiti IV | digiti IV ---------------+---------------+------------+--------------+-------------- flexor hallucis|flexor hallucis| |flexor |flexor hallu- brevis | brevis | | hallucis | cis brevis | | | brevis | ---------------+---------------+------------+--------------+-------------- adductor |adductor | |adductor | digiti II | digiti II | | digiti II | ---------------+---------------+------------+--------------+-------------- adductor |adductor | | | digiti IV | digiti IV | | | ---------------+---------------+------------+--------------+--------------

TABLE 2. RELATIVE SIZES (IN PERCENTAGES) OF SOME MUSCLES IN TYMPANUCHUS AND PEDIOECETES

===========================+=======================+======================
| _Tympanuchus_ | _Pedioecetes_
Muscle +-----+---------+-------+------+--------+------
| Ave.| Range | No.[1]| Ave. | Range |No.[1]
---------------------------+-----+---------+-------+------+--------+------
Iliacus: width of fleshy | | | | | |
origin (divided by length| | | | | |
of ilium) | .10 | .08-.11 | 13 | .19 | .17-.19| 6
---------------------------+-----+---------+-------+------+--------+------
Flexor cruris lateralis: | | | | | |
maximum width of exposed | | | | | |
part (divided by length | | | | | |
of ilium) | .22 | .19-.27 | 13 | .31 | .27-.36| 6
---------------------------+-----+---------+-------+------+--------+------
Flexor cruris medialis: | | | | | |
width of origin (divided | | | | | |
by length of ilium) | .11 | .08-.16 | 13 | .22 | .19-.23| 6
---------------------------+-----+---------+-------+------+--------+------
Flexor cruris medialis: | | | | | |
width of insertion | | | | | |
(divided by length of | | | | | |
tibiotarsus) | .09 | .08-.13 | 13 | .17 | .15-.17| 4
---------------------------+-----+---------+-------+------+--------+------
Adductor superficialis: | | | | | |
width of origin (divided | | | | | |
by length of ilium) | .20 | .17-.23 | 13 | .13 | .10-.16| 5
---------------------------+-----+---------+-------+------+--------+------
Femorocruralis: distance of| | | | | |
proximal end of origin | | | | | |
from proximal end of | | | | | |
femur (divided by length | | | | | |
of femur) | .59 | .55-.63 | 13 | .40 | .38-.43| 6
---------------------------+-----+---------+-------+------+--------+------
Extensor digitorum longus: | | | | | |
length of fleshy belly | | | | | |
(divided by length of | | | | | |
tibiotarsus) | .73 | .64-.83 | 13 | .59 | .50-.62| 4
---------------------------+-----+---------+-------+------+--------+------

FOOTNOTES:

[Footnote 1: No. = number of legs.]

TABLE 3. OCCURRENCE OF INDIVIDUAL VARIATIONS IN MUSCLES

===========================+===============+===========+======+===========
| T.p. | T.c.p. |T.c.a.| P.p.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+-+-+-+-
|1|1|2|2|3|3|4|5|1|1|2|2|3|4|1|1|2 |1|1|2|3|3|4
|L|R|L|R|L|R|L|R|L|R|L|R|L|L|L|R|L |L|R|L|L|R|L
---------------------------+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+-+-+-+-
Ambiens | | | | | | | | | | | | | | | | | | | | | | |
origin partly fleshy | | | | | | | | | | | | | | | |x| | | | | | |
| | | | | | | | | | | | | | | | | | | | | | |
Vastus lateralis | | | | | | | | | | | | | | | | | | | | | | |
no vincula | | | | | | | | | | | |x| |x| | | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | |
Extensor iliofibularis | | | | | | | | | | | | | | | | | | | | | | |
insertional tendon double | | | | | | | | | |x| | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | |
Piriformis | | | | | | | | | | | | | | | | | | | | | | |
posteroproximal corner | | | | | | | | | | | | | | | | | | | | | | |
tendinous | |x| | | | | | | | |x| | | |x|x| |x| | | | |
insertion fused to flexor | | | | | | | | | | | | | | | | | | | | | | |
ischiofemoralis | | | | | | | | | | | |x| | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | |
Iliotrochantericus medius | | | | | | | | | | | | | | | | | | | | | | |
not notched | | | | |x|x| | | | | | | | |x| | | | | | | |
anterior part with fleshy | | | | | | | | | | | | | | | | | | | | | | |
origin | | | | | | | | | | | | | |x| | | |x| |x| | |x
insertion fused to gluteus| | | | | | | | | | | | | | | | | | | | | | |
profundus | | | | | | | | | | | | | | | |x| | | | | | |
muscle split | | | | | | | | | | | | | | | | | |x| | | | |
| | | | | | | | | | | | | | | | | | | | | | |
Flexor cruris lateralis | | | | | | | | | | | | | | | | | | | | | | |
accessory slip present | | | | | | | | | | | |x| | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | |
Flexor cruris medialis | | | | | | | | | | | | | | | | | | | | | | |
origin from pubis | | | | | | | | | | | | |x| | |x| | | | | | |
insertion partly fleshy | | | | | | | | | | | | | | | | | | |x|x| |x|x
insertional tendon split | | | | | | | | | | | | | | | | | | |x| | | |
| | | | | | | | | | | | | | | | | | | | | | |
Caudofemoralis | | | | | | | | | | | | | | | | | | | | | | |
accessory slip fleshy | |x|x| | | | | | | | | | | | | | | | | | | |
tendinous area in belly of| | | | | | | | | | | | | | | | | | | | | | |
pars caudifemoralis | | | | | | | | |x|x| | | |x| | | | | | | | |
origin from pubis | | | | | | | | | |x| | | | | | | | | | | | |
insertion entirely | | | | | | | | | | | | | | | | | | | | | | |
tendinous | | | | | | | | | | | | | | | | | | | | | |x|
| | | | | | | | | | | | | | | | | | | | | | |
Flexor ischiofemoralis | | | | | | | | | | | | | | | | | | | | | | |
insertion partly fleshy |x| | | | | |x| | | | | | | | | | | | |x| | |
| | | | | | | | | | | | | | | | | | | | | | |
Adductor superficialis | | | | | | | | | | | | | | | | | | | | | | |
groove for flexor cruris | | | | | | | | | | | | | | | | | | | | | | |
medialis present | | |x|x| |x| |x| | | | | | | | | | | | | | |
completely fused with | | | | | | | | | | | | | | | | | | | | | | |
adductor profundus | | | | | | | | | | | | | | | |x| | | | | | |
| | | | | | | | | | | | | | | | | | | | | | |
Adductor profundus | | | | | | | | | | | | | | | | | | | | | | |
proximal part of insertion| | | | | | | | | | | | | | | | | | | | | | |
tendinous | | | | | | | | | | | | | | | |x| | | | | | |
distal end of insertion | | | | | | | | | | | | | | | | | | | | | | |
tendinous | | | | | | | | | | | |x| | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | |
Obturator | | | | | | | | | | | | | | | | | | | | | | |
independent slip of pars | | | | | | | | | | | | | | | | | | | | | | |
antica present | | | |x| | | | | |x| | | | | | | | | | | | |
slip of pars antica fused | | | | | | | | | | | | | | | | | | | | | | |
to pars postica | | | | | | |x| | | | | | | | | | | | | |x| |
independent slip of pars | | | | | | | | | | | | | | | | | | | | | | |
dorsalis present | | | | | | | |x| | | | | | |x|x| | |x| | | |
pars dorsalis fused with | | | | | | | | | | | | | | | | | | | | | | |
pars antica | | | | | | | | | | | | | | | | | |x| | | | |
| | | | | | | | | | | | | | | | | | | | | | |
Gastrocnemius | | | | | | | | | | | | | | | | | | | | | | |
pars interna overlaps | | | | | | | | | | | | | | | | | | | | | | |
peroneus longus | | | | | | | | | | | | | | |x| | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | |
Flexor perforans et | | | | | | | | | | | | | | | | | | | | | | |
perforatus digiti II | | | | | | | | | | | | | | | | | | | | | | |
anterior head entirely | | | | | | | | | | | | | | | | | | | | | | |
tendinous | | | | | | | |x| | | | | | | | | | | | | | |
vinculum joins flexor | | | | | | | | | | | | | | | | | | | | | | |
perforatus digiti II |x| | | | | | | | | | | | | | | | | | | | | |
origin from superficial | | | | | | | | | | | | | | | | | | | | | | |
surface of patellar | | | | | | | | | | | | | | | | | | | | | | |
tendon | | | | | | | | | | | | |x| | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | |
Flexor perforans et | | | | | | | | | | | | | | | | | | | | | | |
perforatus digiti III | | | | | | | | | | | | | | | | | | | | | | |
accessory head present | | | | |x|x| | | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | |
Flexor perforatus digiti II| | | | | | | | | | | | | | | | | | | | | | |
roof of hypotarsal canal | | | | | | | | | | | | | | | | | | | | | | |
bony | | | | | | | | |x| | | | | | | | | | | |x|x|
| | | | | | | | | | | | | | | | | | | | | | |
Plantaris | | | | | | | | | | | | | | | | | | | | | | |
accessory head present | | | | |x| | | | | | | | | | | | | | | | | |
origin from medial | | | | | | | | | | | | | | | | | | | | | | |
collateral ligament | | | | | | | | | | | | | | | | |x | | | | | |
| | | | | | | | | | | | | | | | | | | | | | |
Flexor digitorum longus | | | | | | | | | | | | | | | | | | | | | | |
notched for peroneal nerve| | |x|x| | |x|x| | | | | | | | | | | | | |x|
origin from tendon of | | | | | | | | | | | | | | | | | | | | | | |
extensor iliofibularis | | | | | |x| | | | | | | | | | | | | | | | |
third dorsal slip present | | | | | | | | | | | | | | | | | | | | | | |
in digit IV | | |x|x| | | | | | | | | | |x|x|x | |x|x|x|x|
third dorsal slip present | | | | | | | | | | | | | | | | | | | | | | |
in digit III | | |x|x|x| | | | | | | |x|x|x|x|x |x|x| | |x|x
second dorsal slip present| | | | | | | | | | | | | | | | | | | | | | |
in digit II | | |x|x|x| | | | | | |x| |x|x|x|x |x|x| | |x|x
vinculum joins flexor | | | | | | | | | | | | | | | | | | | | | | |
perforatus digiti IV | | | | | | | | | | | | | | | | | | | |x|x|x|x
| | | | | | | | | | | | | | | | | | | | | | |
Peroneus longus | | | | | | | | | | | | | | | | | | | | | | |
origin from patellar | | | | | | | | | | | | | | | | | | | | | | |
tendon |x|x| | |x|x| | | | | | | | | | | | | | | | |x
| | | | | | | | | | | | | | | | | | | | | | |
Tibialis anticus | | | | | | | | | | | | | | | | | | | | | | |
accessory insertion absent| | | | | | |x| | | | | | | | | | | | | | |x|
| | | | | | | | | | | | | | | | | | | | | | |
Extensor digitorum longus | | | | | | | | | | | | | | | | | | | | | | |
lateral branch of tendon | | | | | | | | | | | | | | | | | | | | | | |
not ossified |x| | | |x|x| |x| | | | | | | | | |x|x|x|x|x|x
origin from posterior | | | | | | | | | | | | | | | | | | | | | | |
surface of outer cnemial| | | | | | | | | | | | | | | | | | | | | | |
crest | | | | | | | | | | | | | | | | | |x| x | | |x
| | | | | | | | | | | | | | | | | | | | | | |
Extensor hallucis longus | | | | | | | | | | | | | | | | | | | | | | |
origin lateral to | | | | | | | | | | | | | | | | | | | | | | |
retinaculum | |x| | | | | | | | | | | | | | | |x| | | | |
distal fibers of distal | | | | | | | | | | | | | | | | | | | | | | |
head insert | | | | | | | | | | | | | | | | | | | | | | |
independently | | | | |x| | | | | | | | | | | | |x|x| |x| |x
accessory bundle present | | | | | | | | | | | | | | |x| | | | | | | |
entire distal head inserts| | | | | | | | | | | | | | | | | | | | | | |
independently | | | | | | | | | | | | | | | | | | | |x| | |
| | | | | | | | | | | | | | | | | | | | | | |
Abductor digiti II | | | | | | | | | | | | | | | | | | | | | | |
accessory insertion | | | | | | | | | | | | | | | | | | | | | | |
present | | | | | | | | | | | | |x| | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | |
Extensor proprius digiti | | | | | | | | | | | | | | | | | | | | | | |
III present | | | | | | | | | | | | | | | | | |x| | | | |x
---------------------------+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+-+-+-+-

TABLE 4. NUMBER OF MUSCULAR VARIATIONS IN COMMON BETWEEN THE LEGS STUDIED

=========+========+===============++===========++======++===========+===== | Other | T.p. || T.c.p. ||T.c.a.|| P.p. | | leg +---------------++-----------++------++-----------+ No Leg |of same |1|1|2|2|3|3|4|5||1|1|2|2|3|4||1|1|2 ||1|1|2|3|3|4|other |specimen|L|R|L|R|L|R|L|R||L|R|L|R|L|L||L|R|L ||L|R|L|L|R|L| legs ---------+--------+-+-+-+-+-+-+-+-++-+-+-+-+-+-++-+-+--++-+-+-+-+-+-+----- T.p. 1L | 1 |-|-| | |2|2|1|1|| | | | | | || | | ||1|1|2|1|1|2| 1 T.p. 2R | 6 | | |-|-|2|1|1|2|| |1| |1|1|2||3|3|3 ||2|3|1|1|4|2| 0 T.p. 3L | 4 |2|1|2|2|-|-| |1|| | | |1|1|2||3|2|2 ||4|4|1|2|3|5| 1 T.c.p. 1R| 1 | | | |1| | | | ||-|-| | | |1|| | | || | | | | | | 2 T.c.p. 2R| 0 | |1|1|1|1| | | || | |-|-| |2||1| |1 ||1|1| | |1|1| 3 T.c.a. 1R| 5 | |2|3|3|2| | |1|| | |1|1|2|2||-|1|3 ||3|4|1|1|3|2| 3 P.p. 1L | 4 | | |2|2|3| |2| || | |1|1|1|3||3|-|2 ||-|-|3|2|3|7| 2 P.p. 3R | 4 | | |4|4|2| | |1||1| | |1|1|2||3|3|3 ||3|5|4|-|-|5| 1 ---------+--------+-+-+-+-+-+-+-+-++-+-+-+-+-+-++-+-+--++-+-+-+-+-+-+-----

TABLE 5. OCCURRENCE OF INDIVIDUAL VARIATIONS IN NERVES

===========================+===============+===========+======+===========
| T.p. | T.c.p. |T.c.a.| P.p.
+---------------+-----------+------+-----------
|1|1|2|2|3|3|4|5|1|1|2|2|3|4|1|1|2 |1|1|2|3|3|4
|L|R|L|R|L|R|L|R|L|R|L|R|L|L|L|R|L |L|R|L|L|R|L
---------------------------+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+-+-+-+-
Lumbosacral plexus | | | | | | | | | | | | | | | | | | | | | | |
two fureal nerves | | |x|x| | | | | | | | | | |x|x| | | | |x|x|x
S9 with three branches | | | | | | | |x| | | | | | | | | | | | | | |
prefixed | | | | | | | | | | | | |x| |x|x|x | | |x|x|x|x
sciatic nerve with six | | | | | | | | | | | | | | | | | | | | | | |
roots | | |x|x| | | | | | | | |x| |x|x|x | | |x|x|x|x
obturator nerve from S2 | | | | | | | | | | | | | | | | | | | | | | |
and S3 only | | | | | | | | | | | | | | | | |x | | | |x|x|x
femoral nerve mainly from | | | | | | | | | | | | | | | | | | | | | | |
S2-S4 | | | | | | | | | | | | |x| |x|x|x | | |x|x|x|x
| | | | | | | | | | | | | | | | | | | | | | |
Femoral nerve | | | | | | | | | | | | | | | | | | | | | | |
anterior division | | | | | | | | | | | | | | | | | | | | | | |
innervates | | | | | | | | | | | | | | | | | | | | | | |
extensor iliotibialis | | | | | | | | | | | | | | | | | | | | | | |
lateralis | | | | | | |x|x| |x|x| |x| | | | | | | | | |
dorsal division fused with| | | | | | | | | | | | | | | | | | | | | | |
anterior division |x| | | | | | | | | | | | | | | | | |x| |x| |x
dorsal division fused with| | | | | | | | | | | | | | | | | | | | | | |
middle division | | |x|x| |x| | | | | | | | |x| | | | |x|x| |
two branches to iliacus | | |x| | | | | | | | | | | | | | | | | |x| |
middle division anasto- | | | | | | | | | | | | | | | | | | | | | | |
moses with anterior | | | | | | | | | | | | | | | | | | | | | | |
division | | |x|x| | | | | | | | | |x|x|x| | | | | | |
anterodorsal division does| | | | | | | | | | | | | | | | | | | | | | |
not go through femoral | | | | | | | | | | | | | | | | | | | | | | |
notch | | | | |x|x| | | | | | | | | | | | | | | | |
branch of anterior divi- | | | | | | | | | | | | | | | | | | | | | | |
sion perforates iliacus | | | | | | | | | | | | | | | |x| | | | | | |
cutaneous branch perfo- | | | | | | | | | | | | | | | | | | | | | | |
rates extensor ilioti- | | | | | | | | | | | | | | | | | | | | | | |
bialis lateralis | | | | | | | | | | |x|x| | | | | | | | | | |
branch of middle division | | | | | | | | | | | | | | | | | | | | | | |
perforates vastus | | | | | | | | | | | | | | | | | | | | | | |
medialis | | | | | | | | | | | | | |x| | | | | | | | |
branch to vasti innervates| | | | | | | | | | | | | | | | | | | | | | |
extensor iliotibialis | | | | | | | | | | | | | | | | | | | | | | |
lateralis | | | | | | | | | | |x| | | | | | | | | | | |
anterior branch of ante- | | | | | | | | | | | | | | | | | | | | | | |
rior division cutaneous | | | | | | | | | | | | | | | | | |x|x| | | |x
| | | | | | | | | | | | | | | | | | | | | | |
Sciatic nerve | | | | | | | | | | | | | | | | | | | | | | |
twig to pars caudifemora- | | | | | | | | | | | | | | | | | | | | | | |
lis independent | | |x| | | | | | | | | | | | | | | | | | | |
branch to flexor cruris | | | | | | | | | | | | | | | | | | | | | | |
lateralis does not | | | | | | | | | | | | | | | | | | | | | | |
perforate caudofemoralis|x|x| |x| | | | |x|x|x|x|x| | | |x | | | | | |
paraperoneal nerve enters | | | | | | | | | | | | | | | | | | | | | | |
peroneal sheath |x| |x|x| | |x| | | | | | | | | | |x|x| | | |
cutaneous peroneal branch | | | | | | | | | | | | | | | | | | | | | | |
perforates gastrocnemius| | | | | | | | | | | | | | | | | | | | | | |
pars externa | | | | | | |x| | | | | | | | | | | | | | | |
cutaneous peroneal branch | | | | | | | | | | | | | | | | | | | | | | |
absent | | |x|x| | | |x| | | | | | | | | | | | | | |
distal cutaneous tibial | | | | | | | | | | | | | | | | | | | | | | |
branch absent | | | | | | | |x| | | | | | | | | | | | | | |
twig to tail present | | |x| | |x| |x| | | | | | | |x|x | |x| | |x|
nonmuscular peroneal twig | | | | | | | | | | | | | | | | | | | | | | |
deep to vastus lateralis| | | | | | | | | | | | | | | | | | | | | | |
pars postica | | |x|x| | | |x| | | | | | | | |x | | | | | |
branch to flexor cruris | | | | | | | | | | | | | | | | | | | | | | |
medialis from posterior | | | | | | | | | | | | | | | | | | | | | | |
tibial division | | | | | | | | | | | | |x| | | | |x|x| | | |
extra twigs join cutaneous| | | | | | | | | | | | | | | | | | | | | | |
tibial branches | | | | | | | | | | | | |x| | | | | | | | | |
branch to flexor cruris | | | | | | | | | | | | | | | | | | | | | | |
medialis an independent | | | | | | | | | | | | | | | | | | | | | | |
division | | | | | | | | | | | | | | | | | | | |x|x|x|
branch to flexor cruris | | | | | | | | | | | | | | | | | | | | | | |
medialis perforates | | | | | | | | | | | | | | | | | | | | | | |
flexor | | | | | | | | | | | | | | | | | | | | | | |
ischiofemoralis | | | | | | | | | | | | | | | | | | |x| | | |
two twigs to flexor | | | | | | | | | | | | | | | | | | | | | | |
ischiofemoralis | | | | | | | | | | | | | | | | | | |x|x|x|x|x
independent extra branch | | | | | | | | | | | | | | | | | | | | | | |
innervates extensor | | | | | | | | | | | | | | | | | | | | | | |
iliofibularis | | | | | | | | | | | | | | | | | | | | |x| |
branch to femorocruralis | | | | | | | | | | | | | | | | | | | | | | |
innervates gastrocnemius| | | | | | | | | | | | | | | | | | | | | | |
pars media | | | | | | | | | | | | | | | | | | | | | |x|
| | | | | | | | | | | | | | | | | | | | | | |
Peroneal nerve | | | | | | | | | | | | | | | | | | | | | | |
superficial and deep | | | | | | | | | | | | | | | | | | | | | | |
peroneal nerves do not | | | | | | | | | | | | | | | | | | | | | | |
join |x| | | |x| |x|x| | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | |
Tibial nerve | | | | | | | | | | | | | | | | | | | | | | |
independent extra branch | | | | | | | | | | | | | | | | | | | | | | |
innervates flexor | | | | | | | | | | | | | | | | | | | | | | |
perforatus digiti IV | | | | |x|x| | | | | | | | | | | | | | | | |
anastomosis involving | | | | | | | | | | | | | | | | | | | | | | |
posterior division | | | | |x|x| | | | | | | | | | | | | | | | |
branch to gastrocnemius | | | | | | | | | | | | | | | | | | | | | | |
pars externa an | | | | | | | | | | | | | | | | | | | | | | |
independent division | | | | | |x| | | | | | | | | | | | | | | | |
branch to gastrocnemius | | | | | | | | | | | | | | | | | | | | | | |
pars media innervates | | | | | | | | | | | | | | | | | | | | | | |
femorocruralis |x| | | | |x| | | | | | | | | | | | | | | | |
extra branch innervates | | | | | | | | | | | | | | | | | | | | | | |
flexor perforatus | | | | | | | | | | | | | | | | | | | | | | |
digiti III | | | | | | | | | | | | | | | |x| | | | | | |
branch to gastrocnemius | | | | | | | | | | | | | | | | | | | | | | |
pars interna perforates | | | | | | | | | | | | | | | | | | | | | | |
plantaris | | | | | | | | | | | | | | |x| | | | | | | |
branch to gastrocnemius | | | | | | | | | | | | | | | | | | | | | | |
pars interna innervates | | | | | | | | | | | | | | | | | | | | | | |
plantaris | | | | | | | | | | | | | | | | | | | | |x| |
---------------------------+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+-+-+-+-

TABLE 6. NUMBER OF NERVE VARIATIONS IN COMMON BETWEEN THE LEGS STUDIED

=========+========+===============++===========++======++===========+===== | Other | T.p. || T.c.p. ||T.c.a.|| P.p. | | leg +---------------++-----------++------++-----------+ No Leg |of same |1|1|2|2|3|3|4|5||1|1|2|2|3|4||1|1|2 ||1|1|2|3|3|4|other |specimen|L|R|L|R|L|R|L|R||L|R|L|R|L|L||L|R|L ||L|R|L|L|R|L| legs ---------+--------+-+-+-+-+-+-+-+-++-+-+-+-+-+-++-+-+--++-+-+-+-+-+-+----- T.p. 1L | 1 |-|-|1|2|1|1|2|1||1|1|1|1|1| || | |1 ||1|2| |1| |1| 0 T.p. 2L | 5 |1| |-|-| |2|1|3|| | | | | |1||2|2|2 ||1|2|1|2|1| | 1 T.p. 3R | 3 |1| |2|1|-|-| |1|| | | | | | ||1|1|1 || |1|1|1|1| | 1 T.c.p. 1R| 1 |1|1| |1| | |1|1||-|-|2|1|2| || | |1 || | | | | | | 0 T.c.p. 2L| 2 |1|1| |1| | |1|1||1|2|-|-|2| || | |1 || | | | | | | 1 T.c.a. 1R| 1 | | |2|1| |1| |1|| | | | | |1||-|-|1 || |1| | |1| | 2 P.p. 1R | 3 |2| |2|1| |1|1|1|| | | | |1| || |1|1 ||-|-|1|2|2|3| 1 P.p. 3L | 2 |1| |2|1| |1| | || | | | | | ||1| | || |2|3|-|-|2| 2 ---------+--------+-+-+-+-+-+-+-+-++-+-+-+-+-+-++-+-+--++-+-+-+-+-+-+-----

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