The majority of the osteological terms used in the present p

UNIVERSITY OF KANSAS PUBLICATIONS

MUSEUM OF NATURAL HISTORY

Vol. 12, No. 9, pp. 363-474, 20 figs.

October 25, 1963

Variation in the Muscles and Nerves

of the Leg in Two Genera of Grouse

(Tympanuchus and Pedioecetes)

BY

E. BRUCE HOLMES

UNIVERSITY OF KANSAS

LAWRENCE

1963

UNIVERSITY OF KANSAS PUBLICATIONS

MUSEUM OF NATURAL HISTORY

Institutional libraries interested in publications exchange may obtain

this series by addressing the Exchange Librarian, University of Kansas

Library, Lawrence, Kansas. Copies for individuals, persons working in a

particular field of study, may be obtained by addressing instead the

Museum of Natural History, University of Kansas, Lawrence, Kansas. There

is no provision for sale of this series by the University Library, which

meets institutional requests, or by the Museum of Natural History, which

meets the requests of individuals. Nevertheless, when individuals

request copies from the Museum, 25 cents should be included, for each

separate number that is 100 pages or more in length, for the purpose of

defraying the costs of wrapping and mailing.

* An asterisk designates those numbers of which the Museum's supply (not

the Library's supply) is exhausted. Numbers published to date, in this

series, are as follows:

Vol. 1. Nos. 1-26 and index. Pp. 1-638, 1946-1950.

*Vol. 2. (Complete) Mammals of Washington. By Walter W. Dalquest. Pp.

1-444, 140 figures in text. April 9, 1948.

Vol. 3. *1. The avifauna of Micronesia, its origin, evolution, and

distribution. By Rollin H. Baker. Pp. 1-359, 16 figures

in text. June 12, 1951.

*2. A quantitative study of the nocturnal migration of birds.

By George H. Lowery, Jr. Pp. 361-472, 47 figures in text.

June 29, 1951.

3. Phylogeny of the waxwings and allied birds. By M. Dale

Arvey. Pp. 473-530, 49 figures in text, 13 tables.

October 10, 1951.

*4. Birds from the state of Veracruz, Mexico. By George H.

Lowery, Jr., and Walter W. Dalquest. Pp. 531-649, 7

figures in text, 2 tables. October 10, 1951.

Index. Pp. 651-681.

*Vol. 4. (Complete) American weasels. By E. Raymond Hall. Pp. 1-466,

41 plates, 31 figures in text. December 27, 1951.

Vol. 5. Nos. 1-37 and index. Pp. 1-676, 1951-1953.

*Vol. 6. (Complete) Mammals of Utah, _taxonomy and distribution_. By

Stephen D. Durrant. Pp. 1-549, 91 figures in text, 30 tables.

August 10, 1952.

Vol. 7. Nos. 1-15 and index. Pp. 1-651, 1952-1955.

Vol. 8. Nos. 1-10 and index. Pp. 1-675, 1954-1956.

Vol. 9. *1. Speciation of the wandering shrew. By James S. Findley.

Pp. 1-68, 18 figures in text. December 10, 1955.

2. Additional records and extension of ranges of mammals

from Utah. By Stephen D. Durrant, M. Raymond Lee, and

Richard M. Hansen, Pp. 69-80. December 10, 1955.

3. A new long-eared myotis (Myotis evotis) from

northeastern Mexico. By Rollin H. Baker and Howard J.

Stains. Pp. 81-84. December 10, 1955.

4. Subspeciation in the meadow mouse, Microtus

pennsylvanicus, in Wyoming. By Sydney Anderson. Pp.

85-104, 2 figures in text. May 10, 1956.

5. The condylarth genus Ellipsodon. By Robert W. Wilson.

Pp. 105-116, 6 figures in text. May 19, 1956.

6. Additional remains of the multituberculate genus

Eucosmodon. By Robert W. Wilson. Pp. 117-123, 10 figures

in text. May 19, 1956.

7. Mammals of Coahulia, Mexico. By Rollin H. Baker. Pp.

125-335, 75 figures in text. June 15, 1956.

8. Comments on the taxonomic status of Apodemus peninsulae,

with description of a new subspecies from North China.

By J. Knox Jones, Jr. Pp. 337-346, 1 figure in text, 1

table. August 15, 1956.

9. Extensions of known ranges of Mexican bats. By Sydney

Anderson. Pp. 347-351. August 15, 1956.

10. A new bat (Genus Leptonycteris) from Coahulia. By Howard

J. Stains. Pp. 353-356. January 21, 1957.

11. A new species of pocket gopher (Genus Pappogeomys) from

Jalisco, Mexico. By Robert J. Russell. Pp. 357-361.

January 21, 1957.

12. Geographic variation in the pocket gopher, Thomomys

bottae, in Colorado. By Phillip M. Youngman. Pp. 363-384,

7 figures in text. February 21, 1958.

13. New bog lemming (genus Synaptomys) from Nebraska. By J.

Knox Jones, Jr. Pp. 385-388. May 12, 1958.

14. Pleistocene bats from San Josecito Cave, Nuevo León,

México. By J. Knox Jones, Jr. Pp. 389-396. December 19,

1958.

15. New subspecies of the rodent Baiomys from Central

America. By Robert L. Packard. Pp. 397-404. December 19,

1958.

16. Mammals of the Grand Mesa, Colorado. By Sydney Anderson.

Pp. 405-414, 1 figure in text. May 20, 1959.

17. Distribution, variation, and relationships of the montane

vole, Microtus montanus. By Sydney Anderson. Pp. 415-511,

12 figures in text, 2 tables. August 1, 1959.

(Continued on inside of back cover)

UNIVERSITY OF KANSAS PUBLICATIONS

MUSEUM OF NATURAL HISTORY

Vol. 12, No. 9, pp. 363-474, 20 figs.

October 25, 1963

Variation in the Muscles and Nerves

of the Leg in Two Genera of Grouse

(Tympanuchus and Pedioecetes)

BY

E. BRUCE HOLMES

UNIVERSITY OF KANSAS

LAWRENCE

1963

UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, Henry S. Fitch,

Theodore H. Eaton, Jr.

Volume 12, No. 9, pp. 363-474, 20 figs.

Published October 25, 1963

UNIVERSITY OF KANSAS

Lawrence, Kansas

PRINTED BY

JEAN M. NEIBARGER, STATE PRINTER

TOPEKA, KANSAS

1963

[Illustration]

29-5835

Variation in the Muscles and Nerves

of the Leg in Two Genera of Grouse

(Tympanuchus and Pedioecetes)

BY

E. BRUCE HOLMES

CONTENTS

PAGE

Introduction 367

Materials and Methods 368

Terminology 369

Acknowledgments 375

Skeleton 375

Nerves 376

Lumbosacral Plexus 376

Femoral Nerve 377

Obturator Nerve 379

Sciatic Nerve 379

Peroneal Nerve 382

Tibial Nerve 384

Muscles 396

M. Extensor Iliotibialis Lateralis 398

M. Extensor Iliotibialis Anticus 405

M. Ambiens 408

M. Vastus Lateralis 408

M. Vastus Medialis 410

M. Femoritibialis Internus 410

M. Extensor Iliofibularis 411

M. Piriformis 412

M. Gluteus Profundus 413

M. Iliacus 414

M. Iliotrochantericus Medius 415

M. Psoas 416

M. Flexor Cruris Lateralis 416

M. Flexor Cruris Medialis 417

M. Caudofemoralis 418

M. Flexor Ischiofemoralis 420

M. Adductor Superficialis 420

M. Adductor Profundus 421

M. Obturator 422

M. Femorocruralis 425

M. Gastrocnemius 426

M. Flexor Perforans et Perforatus Digiti II 427

M. Flexor Perforans et Perforatus Digiti III 429

M. Flexor Perforatus Digiti IV 430

M. Flexor Perforatus Digiti III 432

M. Flexor Perforatus Digiti II 433

M. Flexor Hallucis Longus 435

M. Plantaris 435

M. Flexor Digitorum Longus 436

M. Popliteus 438

M. Peroneus Longus 438

M. Tibialis Anticus 439

M. Extensor Digitorum Longus 440

M. Peroneus Brevis 441

M. Extensor Hallucis Longus 442

M. Abductor Digiti II 443

M. Extensor Brevis Digiti III 444

M. Extensor Proprius Digiti III 444

M. Extensor Brevis Digiti IV 445

M. Lumbricalis 445

M. Abductor Digiti IV 446

M. Flexor Hallucis Brevis 446

Discussion and Conclusions 446

Analysis of Individual Variation 446

Muscles 447

Nerves 449

Analysis of Variation Between Species 451

Comparison with Other Studies of Innervation 452

Summary 457

Literature Cited 473

LIST OF ILLUSTRATIONS

PAGE

FIG. 1. Pelvis of _Tympanuchus pallidicinctus_.

A. Lateral view. × 1. B. Ventral view. × 1-1/8. 370

FIG. 2. Ventral views of the lumbosacral plexus of

_Tympanuchus pallidicinctus_.

Sympathetic ganglionated chain removed. Numbers indicate

synsacral spinal nerves. × 2. A. T.p. 1L. B. T.p. 2L. 386

FIG. 3. Ventral views of the lumbosacral plexus.

Sympathetic ganglionated chain removed. Numbers indicate

synsacral spinal nerves. × 2. A. _Tympanuchus cupido pinnatus_

3L. B. _Pedioecetes phasianellus jamesi_ 4L. 387

FIG. 4. Semidiagrammatic ventral views of the femoral

nerve, showing the distribution of the branches. × 3. 1,2,

M. extensor iliotibialis anticus; 3, cutaneous; 4-6, M. extensor

iliotibialis lateralis; 7,8, M. iliacus; 9, M. gluteus

profundus; 10-12, fused Mm. vastus lateralis and vastus

medialis; 13,14, M. vastus medialis; 15, M. ambiens;

16, M. femoritibialis internus; 17, nonmuscular; 18, M.

psoas; 19, M. iliotrochantericus medius. A. _Tympanuchus

cupido pinnatus_ 3L. B. _Pedioecetes phasianellus

jamesi_ 3L. 388

FIG. 5. Semidiagrammatic ventral views of the femoral

nerve, showing the distribution of the branches. × 3. 1,2, M.

extensor iliotibialis anticus; 3, cutaneous; 5,6, M. extensor

iliotibialis lateralis; 7,8, M. iliacus; 9, M. gluteus

profundus; 10,11, fused Mm. vastus lateralis and vastus

medialis; 13, M. vastus medialis; 15, M. ambiens; 16,

M. femoritibialis internus; 17, nonmuscular; 18, M. psoas;

19, M. iliotrochantericus medius. A. _Tympanuchus

pallidicinctus_ 2L. B. _Tympanuchus cupido attwateri_ 1R. 389

FIG. 6. Semidiagrammatic dorsolateral view of the sciatic

nerve of _Pedioecetes phasianellus jamesi_ 3R, showing

the distribution of the branches. × 2-1/2. 1, M. gluteus

profundus; 2, M. piriformis; 3, M. extensor iliotibialis

lateralis; 4-7, M. extensor iliofibularis; 8, M. flexor cruris

medialis; 9, cutaneous; 10, to pudendal plexus; 11, M. flexor

cruris lateralis; 12, M. caudofemoralis pars caudifemoralis;

13-15, M. caudofemoralis pars iliofemoralis; 16,17, M. flexor

ischiofemoralis; 18,19, M. femorocruralis (branch of tibial

nerve); 20, cutaneous; 21, M. gastrocnemius pars media (branch

of tibial nerve); 22, cutaneous. 390

FIG. 7. Semidiagrammatic dorsolateral view of the sciatic

nerve of _Tympanuchus pallidicinctus_ 2L, showing the

distribution of the branches. × 2-1/2. 1, M. gluteus profundus;

2, M. piriformis; 3, M. extensor iliotibialis lateralis; 4, 7,

M. extensor iliofibularis; 8, M. flexor cruris medialis; 9,

cutaneous; 10, to pudendal plexus; 11, M. flexor cruris

lateralis; 12, M. caudofemoralis pars caudifemoralis; 13-15,

M. caudofemoralis pars iliofemoralis; 17, M. flexor

ischiofemoralis; 18, M. femorocruralis (branch of tibial nerve);

22, cutaneous; 23, nonmuscular (branch of peroneal nerve). 391

FIG. 8. Semidiagrammatic dorsolateral view of the

sciatic nerve of _Tympanuchus cupido pinnatus_ 3L,

showing the distribution of the branches. × 2-1/2. 1,

M. gluteus profundus; 2, M. piriformis; 3, M. extensor

iliotibialis lateralis; 4,7, M. extensor iliofibularis;

8, M. flexor cruris medialis; 9, cutaneous; 11, M. flexor

cruris lateralis; 12, M. caudofemoralis pars caudifemoralis;

13, M. caudofemoralis pars iliofemoralis; 17, M. flexor

ischiofemoralis; 18, M. femorocruralis (branch of tibial

nerve); 20, cutaneous; 22, cutaneous. 392

FIG. 9. Semidiagrammatic dorsolateral view of the

sciatic nerve of _Pedioecetes phasianellus jamesi_ 3L,

showing the distribution of the branches. × 2-1/2. 1,

M. gluteus profundus; 2, M. piriformis; 3, M. extensor

iliotibialis lateralis; 4,5,7, M. extensor iliofibularis;

8, M. flexor cruris medialis; 9, cutaneous; 11, M. flexor

cruris lateralis; 13,14, M. caudofemoralis pars iliofemoralis;

16,17, M. flexor ischiofemoralis; 18,19, M. femorocruralis

(branch of tibial nerve); 20, cutaneous; 22, cutaneous. 393

FIG. 10. A,B. Semidiagrammatic drawings of the peroneal

nerve of _Tympanuchus pallidicinctus_ 1L, showing the

distribution of the branches. × 2. C. Semidiagrammatic drawing

of the distal part of the peroneal nerve of _Tympanuchus

cupido attwateri_ 1R, showing the distribution of the

branches. × 2. 1,2, M. tibialis anticus (tibial head); 3,4,

M. tibialis anticus (femoral head); 5, M. extensor digitorum

longus; 6, nonmuscular; 7,8, M. peroneus longus; 9, M. peroneus

brevis; 10,11, M. extensor hallucis longus (proximal head);

12, M. extensor hallucis longus (distal head); 13-15, nonmuscular

(to toes); 16, M. abductor digiti II; 17, M. extensor brevis

digiti III; 18, M. extensor brevis digiti IV. 394

FIG. 11. A,B. Semidiagrammatic drawings of the tibial

nerve (excluding the paraperoneal branch) of _Tympanuchus

pallidicinctus_, showing the distribution of the branches.

× 2. A. T.p. 1L. B. T.p. 3R. C. Semidiagrammatic drawing

of the distal part of the paraperoneal branch of the tibial

nerve of _Pedioecetes phasianellus jamesi_ 2L, showing

the distribution of the branches. × 2. 1, M. femorocruralis;

2, M. gastrocnemius pars media; 3, M. popliteus; 4, M. plantaris;

5, M. flexor digitorum longus; 6-8, nonmuscular; 9-11, M.

gastrocnemius pars interna; 12,13, M. flexor hallucis longus;

14-16, M. flexor perforatus digiti IV (medial head); 17, M.

flexor perforatus digiti III (medial head); 18-20, M. flexor

perforatus digiti II; 21, M. flexor perforatus digiti IV

(lateral head); 22-24, M. flexor perforatus digiti IV

(anterolateral head); 25, M. flexor perforatus digiti III

(anterolateral head); 26, M. flexor perforans et perforatus

digiti III; 27,28, M. flexor perforans et perforatus digiti II;

29, M. gastrocnemius pars externa; 30,31, M. abductor digiti IV;

32,33, M. flexor hallucis brevis; 34,35, nonmuscular (to toes). 395

FIG. 12. _Tympanuchus pallidicinctus_ 2L. Lateral

view of the superficial muscles of the left leg. × 1. 397

FIG. 13. _Tympanuchus pallidicinctus_ 2L. Medial

view of the superficial muscles of the left leg. × 1. Articular

capsule shown by concentrically arranged dashes. 398

FIG. 14. _Tympanuchus pallidicinctus_ 2L. Lateral

view of the muscles of the left leg. The following muscles have

been removed: extensor iliotibialis lateralis, extensor

iliotibialis anticus, gastrocnemius pars externa and pars

interna, and peroneus longus. × 1. 399

FIG. 15. _Tympanuchus pallidicinctus_ 2L. Medial

view of the muscles of the left leg. The following muscles have

been removed: extensor iliotibialis lateralis, extensor

iliotibialis anticus, ambiens, flexor cruris lateralis (in part),

flexor cruris medialis (in part), gastrocnemius pars externa

and pars interna, and peroneus longus. × 1. 400

FIG. 16. _Tympanuchus pallidicinctus_ 2L. Lateral

view of the muscles of the left leg. The following muscles,

in addition to those listed for Fig. 14, have been removed:

ambiens, vastus lateralis pars lateralis, vastus medialis (except

for part of patellar tendon), extensor iliofibularis, flexor

cruris lateralis (in part), flexor perforans et perforatus

digiti II, and flexor perforans et perforatus digiti III. × 1. 401

FIG. 17. _Tympanuchus pallidicinctus_ 2L. Lateral

view of the muscles of the left leg. The following muscles, in

addition to those listed for Fig. 16, have been removed: vastus

lateralis pars postica, gluteus profundus, flexor cruris medialis

(in part), caudofemoralis, flexor perforatus digiti IV, and

tibialis anticus. × 1. 402

FIG. 18. _Tympanuchus pallidicinctus_ 2L. Lateral

view of the muscles of the left leg. The following muscles, in

addition to those listed for Fig. 17, have been removed: patellar

tendon, iliacus, iliotrochantericus medius, flexor cruris

lateralis, flexor cruris medialis, flexor ischiofemoralis,

adductor superficialis, femorocruralis, gastrocnemius pars media,

flexor perforatus digiti III, flexor perforatus digiti II, flexor

hallucis longus, plantaris, flexor digitorum longus, popliteus,

and extensor digitorum longus. × 1. 403

FIG. 19. _Tympanuchus pallidicinctus_ 2L. A.

Posterior view of the muscles of the left shank. The following

shank muscles, in addition to those listed for Fig. 17, have

been removed: gastrocnemius pars media, flexor perforatus

digiti III, and flexor perforatus digiti II. × 1. B. Posterior

view of the proximal end of the shank, showing the most deeply

situated muscle. × 1. C. Lateral view of the head of the left

femur and the middle part of the pelvis, showing the deepest

part of M. obturator. × 1. D. Medial view of the posteroventral

part of the left side of the pelvis, showing the intrapelvic part

of M. obturator. × 1. E. Anterior view of the left

tarsometatarsus, showing the dorsal intrinsic muscles of the

foot. × 1-1/2. F. Posterior view of the left tarsometatarsus,

showing the ventral intrinsic muscles of the foot. × 1-1/2. 404

FIG. 20. A-D. Dorsal views of M. iliotrochantericus

medius, showing its relationship to femoral notch. × 1. In D,

note absence of femoral notch and location of branch of femoral

nerve. A. _Tympanuchus pallidicinctus_ 2L. B. _T. cupido

pinnatus_ 4L. C. _Pedioecetes phasianellus jamesi_ 1L.

D. _T. pallidicinctus_ 3L.

E. Medial view of distal end of M. flexor cruris medialis of

_P. p. jamesi_ 4L. × 1. Part of insertion is covered by

medial collateral ligament.

F,G. Lateral views of posteroproximal corner of M. extensor

iliotibialis lateralis (removed from specimen). × 1. F.

_T. pallidicinctus_ 2L. G. _P. p. jamesi_ 3L.

H,I. Dorsolateral views of M. piriformis. × 1. H. _P.

p. jamesi_ 1L. I. _T. cupido attwateri_ 1L.

J. Lateral view of M. caudofemoralis pars caudifemoralis

(removed from specimen) of _T. c. pinnatus_ 4L. × 1.

K. Lateral view of extrapelvic part of M. obturator of

_T. pallidicinctus_ 3L (bones not shown). × 2.

L,M. Region surrounding obturator foramen of _T.

pallidicinctus_ 3L, showing points of attachment of three

parts of M. obturator (muscles removed). × 3. L. Lateral

view. M. Medial view.

N. Anterior view of left tarsometatarsus of _P. p.

jamesi_ 4L, showing dorsal intrinsic muscles of foot.

× 1-1/2. Tendon of M. extensor digitorum longus has been

removed. 406

INTRODUCTION

The purposes of this study were: (1) to obtain information on individual

variation in the anatomy of the muscles and nerves of the leg of

_Tympanuchus cupido pinnatus_ (Greater Prairie Chicken), _T. c.

attwateri_ (Attwater's Prairie Chicken), _T. pallidicinctus_ (Lesser

Prairie Chicken), and _Pedioecetes phasianellus jamesi_ (Sharp-tailed

Grouse); (2) to determine whether or not the two species of the genus

_Tympanuchus_ differ constantly in the myology of the leg; and (3) to

determine what constant differences in the myology of the leg exist

between the two closely related genera _Tympanuchus_ and _Pedioecetes_.

These particular birds were chosen because they are closely related, and

closely resemble one another in habitats occupied and in patterns of

behavior. It was desired to study examples that showed as few adaptive

differences as possible among the grouse. Series of each of the three

species of grouse were readily obtainable, making it possible to draw

comparisons at the level of individuals, subspecies, species, and

genera.

The study here reported on was begun in the spring of 1957 and was

completed in the autumn of 1961.

Prior work on the muscles of the leg of birds has been reviewed by

Hudson (1937) and Hudson, _et al._ (1959). Only papers dealing with the

innervation of the leg in birds are reviewed below.

DeMan (1873) treated the nerves of _Paradisea papuana_, _Corvus

monedula_, and the chicken; he also commented briefly on a few

other species. Jhering (Ihering, 1873) briefly described the

lumbosacral plexus in approximately a dozen birds, but illustrated

only two. Gadow (1880) described the nerves in _Struthio_, _Rhea_,

and _Casuarius_; his paper contains some excellent illustrations of

nerves. Unfortunately, the text is marred by numerous confusing

typographical errors. Carlsson (1884) described the nerves of

_Eudyptes chrysolopha_, _Alca torda_, _Mergulus alle_, and _Mormon

arcticus_. Gadow (1891) described the nerves in a study that

included a large variety of birds, but published few illustrations.

DuToit (1913) described the lumbosacral plexus of the chicken.

Romer (1927) gave the innervation of the hip and thigh muscles in

the chicken, but did not cover the lumbosacral plexus. Appleton

(1928) gave the innervation, in various birds, only of those

muscles of the hip and thigh that are supplied by the tibial and

peroneal nerves; he did not include the lumbosacral plexus.

Sudilovskaya (1931) described the nerves of _Struthio_, _Rhea_, and

_Dromaeus_ (_Dromiceius_). Unfortunately, his illustrations are

almost useless as far as the nerves are concerned. Boas (1933)

described the lumbosacral plexus in a large number of birds. His

extensive account includes numerous good illustrations. Howell

(1938) listed the innervation of the hip and thigh muscles in the

chicken; he did not include the lumbosacral plexus. Fisher (1946)

listed the innervation of the muscles of vultures, but did not

include the lumbosacral plexus. Wilcox (1948) gave the innervation

of the muscles of _Gavia immer_, but did not include the lumbosacral

plexus. Fisher and Goodman (1955) described the nerves in the Whooping

Crane. Papers by Chomiak (1950) and Yasuda, _et al._ (1959), both

dealing with the chicken, were not examined.

MATERIALS AND METHODS

Complete dissections of the muscles and nerves were made in eight legs

(of five specimens) of the Lesser Prairie Chicken (_Tympanuchus

pallidicinctus_), six legs (of four specimens) of the Greater Prairie

Chicken (_T. cupido pinnatus_), three legs (of two specimens) of

Attwater's Prairie Chicken (_T. cupido attwateri_), and six legs (of

four specimens) of the Sharp-tailed Grouse (_Pedioecetes phasianellus

jamesi_).

For convenience and simplicity of reference, each specimen has been

designated by a symbol consisting of the first letter of the genus and

of the species (and also of the subspecies in _T. cupido_) plus a

number. The letter "L" or "R" is added to indicate the left or right

leg. Thus the symbol T.p. 1L refers to the left leg of specimen number

one of _T. pallidicinctus_.

All specimens are in the University of Kansas Museum of Natural History.

The catalogue number of each specimen, and the legs of it that were

dissected, are listed below.

T.p. 1L,R KU38520 T.c.p. 4L KU38518

T.p. 2L,R KU38521 T.c.a. 1L,R KU36617

T.p. 3L,R KU38522 T.c.a. 2L KU36618

T.p. 4L KU38523 P.p. 1L,R KU38526

T.p. 5R KU38524 P.p. 2L KU38527

T.c.p. 1L,R KU38515 P.p. 3L,R KU38528

T.c.p. 2L,R KU38516 P.p. 4L KU38529

T.c.p. 3L KU38517

The specimens were injected in the field either with formalin (10%) or

embalming fluid, except for those of _T. c. attwateri_, which were

frozen; the latter were later injected with embalming fluid. Injection

in all the birds was by hypodermic syringe into all major muscle masses,

into the body cavities, and subcutaneously in the neck, wings, and feet.

In those specimens injected with embalming fluid, the body cavities were

injected with formalin. The embalming fluid consisted of 70 per cent

alcohol, glycerin (or propylene glycol), and formalin (full strength) in

the approximate ratio of 78:20:2, respectively. This fluid gave good

preservation; these specimens had the advantages of lacking almost

entirely the irritating odor of formalin and of having pliable tissues.

The skin of those specimens originally injected with formalin was slit

in several places and they were transferred to crocks containing

embalming fluid (without the formalin). After a period of many weeks,

with two changes of fluid, most of the formalin odor was eliminated and

the muscles were sufficiently pliable to be easily dissected. All

specimens were kept in containers filled with embalming fluid. No mold

ever appeared, even though no phenol or other chemical was added.

To facilitate comparison, two or three specimens were frequently

dissected simultaneously. The nerves and smaller muscles were dissected

with the aid of a stereoscopic microscope mounted on a long movable arm.

In order satisfactorily to expose the lumbosacral plexus the posterior

half of the sternum and pectoral muscles, as well as the abdominal

viscera, were removed.

To insure more nearly accurate proportions, drawings of the pelvis and

of some of the muscles were made with the aid of photographs of the

several specimens listed above.

TERMINOLOGY

_Skeleton_

The majority of the osteological terms used in the present paper are

those used by Howard (1929); however, many skeletal features are not

named by Howard. Since names for most of these parts were not found in

the other literature examined, it was necessary for me to propose terms

for them. Most of this new terminology pertains to the pelvis. All of

the osteological terms used in the present paper, whether used by Howard

or not, are briefly defined below. Those of the pelvis are illustrated

in fig. 1. Most of the remaining terms are illustrated by Howard (1929).

PELVIS

The _median dorsal ridge_ is the blunt ridge in the midline of the

anterior part of the synsacrum formed by the neural spines of the

vertebrae. The _antitrochanter_, on the posterodorsal rim of the

acetabulum, is a pyramid-shaped projection that articulates with the

proximal end of the femur. The _anterior iliac crest_ is a ridge along

the dorsomedial border of the ilium, beginning almost at the anterior

end of that bone; the crest curves laterally as it extends posteriorly

and (for purposes of the present definition) ends at the level of the

posterior edge of the antitrochanter, where the crest is continuous with

the lateral iliac process. The _lateral iliac process_ is a pronounced,

laterally or ventrolaterally, projecting ridge on the ventrolateral

surface of the ilium posterior to the level of the antitrochanter; the

process does not extend as far as the posterior end of the ilium. The

_lateral ischiatic ridge_ is a relatively slight ridge continuous with

the posterior end of the lateral iliac process and curves

posteroventrally across the lateral surface of the posterior part of the

ischium; the ridge extends to the ventral edge of the ischium in some

individuals and not in others. The _dorsolateral iliac ridge_ begins at

the lateral edge of the ilium near the posterior end of the lateral

iliac process and curves posteromedially and somewhat dorsally,

extending to the posterior edge of the ilium. The _lateral iliac fossa_

is the concavity below the overhanging lateral iliac process. The

_ilio-ischiatic fenestra_ is a large oblong opening behind the

acetabulum between the ilium and the ischium. The _obturator foramen_ is

a small oval opening posteroventral to the acetabulum between the

ischium and the pubis. The _ventral ischiatic tubercle_ is the angle

formed by the ventrally projecting ischium at the point (near its

midlength) where the ischium overlaps and lies lateral to (and fused to)

the pubis. The _pectineal process_ is an anterolaterally directed

projection of the ventrolateral edge of the ilium anteroventral to the

acetabulum. The _femoral notch_ of the ilium is a shallow notch in the

ventrolateral edge of the ilium approximately halfway between the last

rib and the pectineal process. The _oblique iliac crest_ is a pronounced

blunt ridge on the ventral surface of the ilium and extends from the

posterolateral corner of the last synsacro-thoraco-lumbar vertebra to

near the anteroventral border of the ilio-ischiatic fenestra. The

_internal ilio-ischiatic crest_ is more or less continuous with the

oblique iliac crest and extends posteriorly along the dorsal border of

the ischium (forming the ventral border of the ilio-ischiatic fenestra),

and then curves sharply dorsomedially onto the ventral surface of the

ilium. The _iliac recess_ is a concavity dorsolateral to the sharply

curving posterior end of the internal ilio-ischiatic crest.

[Illustration: FIG. 1. Pelvis of _Tympanuchus pallidicinctus_. A.

Lateral view. × 1. B. Ventral view. × 1-1/8.]

The terminology applied to the synsacral vertebrae by different authors

varies. The terminology proposed by DuToit (1913) is employed in the

present account. See my fig. 1B. This terminology differs considerably

from that used by Howard (1929). DuToit divides the fused synsacral

vertebrae into the following five groups, listed in anteroposterior

sequence: (1) _synsacro-thoracic_, which bear movable ribs; (2)

_synsacro-thoraco-lumbar_, which lack movable ribs but possess well

developed laterally directed parapophyses, in addition to the more

dorsally directed diapophyses; (3) _synsacro-lumbar_, which lack

parapophyses, although possessing inconspicuous diapophyses; these

vertebrae are shortened anteroposteriorly and are so firmly fused

together that often the number present can be determined only by

counting the intervertebral foramina; (4) _synsacro-sacral_, which have

much more pronounced transverse processes than do the synsacro-lumbar

vertebrae; these transverse processes are expanded distally where they

fuse with the ilium and represent both parapophyses and diapophyses

partly or completely fused together plus sacral ribs (detectable only in

the embryo); there are considered to be two of these vertebrae; they are

situated at approximately the level of the acetabulum; (5)

_synsacro-caudal_, which include the remainder of the fused vertebrae;

no marked gross morphological features differentiate the synsacro-sacral

and the synsacro-caudal groups of vertebrae. The boundaries between all

but the last two groups of vertebrae are usually, but not always, easily

determined. It may be difficult to determine whether a vertebra with

rudimentary parapophyses belongs to the synsacro-thoraco-lumbar or the

synsacro-lumbar group. Sometimes a parapophysis will be better developed

on one side of a vertebra than on the other.

FEMUR

The _trochanter_ is a large squarish tuberosity on the lateral surface

of the proximal end of the femur. The _trochanteric ridge_ is a sharp,

longitudinal (relative to the femur) ridge forming the anterior edge of

the trochanter. The _obturator ridge_ is a short, blunt, longitudinal

ridge forming the posterior edge of the trochanter. The _anterior

intermuscular line_ is a slight ridge extending distally from the

trochanteric ridge. The _posterolateral intermuscular line_ is a slight

ridge extending distally from the obturator ridge. The _posterior

intermuscular line_ is a slight, longitudinal ridge on the mid-posterior

surface of the femur. The _internal condyle_ is a large rounded

articular prominence on the medial side of the distal end of the femur.

On the lateral side of the distal end of the femur are two articular

prominences--the lateralmost, smaller one is the _fibular condyle_,

separated by the _fibular groove_ (visible from posterior aspect only)

from the larger and more medial _external condyle_. The _popliteal area_

is a depression on the posterior surface of the distal part of the femur

immediately proximal to the condyles.

TIBIOTARSUS AND FIBULA

The _inner cnemial crest_ is pronounced and directed anteriorly on the

anterior surface of the proximal end of the tibiotarsus. The _outer

cnemial crest_ is pronounced and directed anterolaterally on the

anterolateral surface of the proximal end of the tibiotarsus. The

_rotular crest_ is transverse and forms the anterior border of the

proximal end of the tibiotarsus; the crest extends between the dorsal

ends of the two cnemial crests and also extends medial to the inner

cnemial crest. The _fibular crest_ is longitudinal on the lateral

surface of the tibiotarsus and fuses with the middle part of the fibula.

The _fibular tubercle_ is small and on the lateral surface of the fibula

near the level of the middle of the fibular crest. The _anteromedial

intermuscular line_ is a slight ridge extending from the inner cnemial

crest down the anteromedial surface of the tibiotarsus. The

_anterolateral intermuscular line_ is a slight ridge extending from the

fibular crest down the anterolateral surface of the tibiotarsus. The

_supratendinal bridge_ is a transverse bony arch over a longitudinal

groove near the distal end of the anterior surface of the tibiotarsus.

TARSOMETATARSUS

The _hypotarsus_ is a large, pronounced, squarish protuberance on the

posterior surface of the proximal end of the tarsometatarsus and

contains grooves and canals for the passage of the flexor tendons. The

longitudinal ridges forming the lateral and medial edges of the

posterior surface of the hypotarsus are termed _calcaneal ridges_. The

_posterior metatarsal crest_ is long and sharp; it is continuous with

the medial calcaneal ridge that extends most of the way down the

posterior surface of the tarsometatarsus medial to the midline; there is

an opening between this crest and the tarsometatarsus immediately distal

to the hypotarsus. The _medial metatarsal depression_ is large; it is on

the medial surface of the proximal end of the tarsometatarsus. The

_anterior metatarsal groove_ is a longitudinal groove in the midline of

the proximal part of the anterior surface of the tarsometatarsus. The

three _trochleae_ are large rounded articular prominences at the distal

end of the tarsometatarsus; there is one at the base of each of the

digits II, III, and IV. The term _distal foramen_ (as used by Howard)

refers to a short, anteroposteriorly directed canal that perforates the

tarsometatarsus a short distance proximal to the intertrochlear notch

between the trochleae for digits III and IV. Beginning at the middle of

this canal and extending distally at a right angle to it is the

_intertrochlear canal_, which opens via the terminal foramen into the

intertrochlear notch between the trochleae for digits III and IV.

_Nerves_

For ease of description I have coined terms for the major divisions of

the femoral and sciatic nerves.

_Muscles_

My terminology follows that of Fisher (1946) and Fisher and Goodman

(1955) except for Mm. femoritibialis externus, flexor cruris lateralis

(accessory head), and obturator internus et externus. Fisher (1946:547)

states that most of his names for the hip and thigh muscles are those of

Howell (1938) and the names for the shank and foot muscles are those of

Hudson (1937). Fisher deviates, without explanation, from Howell's

terminology in respect to Mm. vastus medialis and femoritibialis

internus, M. caudofemoralis, M. flexor cruris lateralis, and Mm.

obturator internus and obturator externus. Fisher's synonymy of these

muscles (1946: table 42) is in error. Fisher understandably deviates

from Hudson in respect to Mm. extensor brevis digiti III and extensor

proprius digiti III (see Holmes, 1962), although Fisher's synonymy is in

error here. See my table 1.

I am not using Fisher and Goodman's term femoritibialis externus;

this muscle is here considered as a part of M. vastus lateralis. A

great deal of confusion surrounds the terminology of the muscle

complex here termed Mm. vastus lateralis and vastus medialis.

Hudson (1937), Hudson, _et al._ (1959), Fisher (1946), and Fisher

and Goodman (1955) have used different terminology for this

complex. Most of the confusion stems from Gadow's (1891) unclear

description of this complex, which he subdivided into two units

termed Mm. femori-tibialis externus and femori-tibialis medius.

Many birds have three parts to this complex. It is difficult to

determine how to apply Gadow's two terms to these three parts. As

nearly as I can determine, the correct method is that of Hudson,

_et al._ (1959); but because Gadow's terms have been used in

different ways (even by the same worker), it seems best to abandon

these terms. Berger (1956:272) believes that the muscle unit that

Fisher and Goodman term M. femoritibialis externus represents a

head of M. vastus lateralis; I am accepting his opinion. For the

three parts of the complex under discussion, I am using the terms

M. vastus medialis and M. vastus lateralis pars lateralis and pars

postica.

Fisher (Fisher, 1946; Fisher and Goodman, 1955) considers the

muscle here termed M. femorocruralis as an accessory head of M.

flexor cruris lateralis. The two muscle units in question are

closely associated; they insert broadly on opposite sides of a

common tendinous raphe. Howell (1938:73) considers this to be a

secondary fusion of unrelated muscles. Romer (1927:366) states that

in the chick embryo M. femorocruralis is in reality a shank muscle

that migrates into the thigh during development. Therefore,

Fisher's usage of a single name for these two unrelated muscles is

unsatisfactory. I am using Howell's terminology in which the name

flexor cruris lateralis represents the main head only of Fisher's

M. flexor cruris lateralis and the name femorocruralis represents

Fisher's accessory head.

Gadow (1891) divides the obturator complex into two muscles (or

muscle groups), which he terms M. obturator and Mm. accessorii M.

obturatoris. He states that the former is homologous with the

mammalian obturator internus and the latter with the obturator

externus. Hudson (1937), accepting Gadow's homologies, renamed

these muscles M. obturator internus and M. obturator externus.

Nearly all subsequent workers have followed Hudson's terminology,

with its implication that these muscles are homologous with the

mammalian muscles of the same name. Howell (1938) is an exception.

He points out (pp. 78, 79) that the obturator internus of Hudson is

homologous with the obturator externus of mammals. His evidence is

convincing: "In origin the obturator is somewhat suggestive of the

mammalian obturator internus, for which it has uniformly been

mistaken. That the latter interpretation is incorrect, however, is

attested by the facts that it receives twigs of n. obturatorius

within the pelvis, passes _through_ the obturator foramen rather

than dorsal to the border of the ischium, and it is segregated from

any muscle with tibial innervation. Insertion has shifted only to a

slight and unimportant degree as compared with that of the

mammalian obturator externus, and beyond question it is the

equivalent of that muscle. The stimulus for a longer muscle, has

been the same, resulting in the extension of origin to within the

pelvis of the externus in birds and the internus in mammals, but

the obturator internus is an extension of a part of the gemellus

mass and this does not occur in any vertebrate class but Mammalia."

Howell applies the term M. obturator to the entire obturator

complex.

Romer (1927), studying the development of the thigh musculature in chick

embryos, concluded that the entire obturator complex is homologous with

the mammalian obturator externus plus quadratus femoris. He considered

the avian M. flexor ischiofemoralis to be the homologue of the mammalian

obturator internus.

Gadow, in his work on the ratites (1880:34), states that M. obturator

(obturator internus of Hudson) cannot be homologous to the mammalian

obturator internus, but must represent the obturator externus. His

reasoning is as follows: "Als M. pectineus kann man diesen Muskel nicht

auffassen, da er auf der Aussenfläche des Trochanter major inserirt,

ferner auch nicht als M. obturator internus der menschlichen Anatomie,

da er nicht vom Plexus ischiadicus, sondern vom Plexus cruralis aus

innervirt wird. Seiner Innervation und Insertion nach wäre er nur mit

dem M. obturator externus zu vergleichen, wobei er seinen Ursprung im

Verhältniss zum Menschen nur bedeutend weiter auf das Os ischii und Os

pubis distalwärts ausgedehnt hätte und so allerdings der Lage nach mit

Ausnahme seines Insertionsdrittels ein 'internus' geworden wäre."

Since Gadow gives different homologues for M. obturator in two of his

works (1880 and 1891), one would suspect that he had changed his opinion

in the interim; however, there is no evidence that he did so. In 1880 he

gives supporting evidence (quoted above) for his view; in 1891 he does

not. After describing (1891:173) how the origin of M. obturator in bird

ancestors presumably migrated from a location outside the pelvis to a

position inside the pelvis prior to the meeting of the pubis and ischium

external to the muscle, he states: "Eine ähnliche Entwicklung ist für

den _Obturator internus_ der Säugethiere anzunehmen, welchem der _M.

obturator_ der Vögel entspricht." A similar development in mammals is

impossible, owing to the different relationship of the muscle to the

pelvic bones in this class. Gadow says nothing more about the mammalian

homologue of M. obturator. In view of this discrepancy, Gadow can hardly

be considered as a supporter of the idea that the avian M. obturator is

homologous with the mammalian obturator internus.

The evidence is conclusive, it seems to me, that the obturator internus

of Hudson is not homologous with the mammalian obturator internus.

Therefore, the term obturator internus is inappropriate for the avian

muscle and must be abandoned. I shall follow Howell (1938) in naming the

entire obturator complex M. obturator. This term, of course, is not used

in the sense in which it is used by Gadow. The use of the term obturator

externus for the entire complex is avoided because it may not correspond

exactly to the mammalian obturator externus. As mentioned previously,

Romer considers the avian muscle to be homologous not only with the

mammalian obturator externus but also with the quadratus femoris.

I am following the policy of Wilcox (1948) and Berger (1952) in

latinizing the term anterior, changing it to anticus. When preceded by

the feminine word pars, the feminine ending is used (antica).

In table 1 my terminology is compared with that of Fisher and Goodman

(1955), Howell (1938), Hudson (1937), and Gadow (1891). The terminology

of Fisher (1946) is identical with that of Fisher and Goodman (1955)

except that in his earlier work Fisher did not describe or name M.

femoritibialis externus, and M. lumbricales of his earlier work is not

mentioned in his later work. The terminology of Hudson, _et al._ (1959)

is identical with that of Hudson (1937) except that the manner in which

the femoritibialis complex is subdivided is identical with that of Gadow

(1891) and different from that in Hudson's earlier work; also the

abbreviations p. ext. and p. int. are substituted in his later paper for

pars anterior and pars posterior, respectively, of M. adductor longus et

brevis.

ACKNOWLEDGMENTS

I gratefully acknowledge the generous help of Professor A. Byron

Leonard, under whose guidance this study was conducted and thank

Professor E. Raymond Hall, Professor Howard A. Matzke, and Dr. Irwin

Baird for numerous helpful suggestions and criticisms.

For help in collecting specimens I thank J. R. Alcorn, W. C. Glazener

(through the courtesy of the Texas Game and Fish Commission), Dr.

Harrison B. Tordoff, Jerry Tash, William Brecheisen, and Louis

Brecheisen. I thank also Edwin Gebhard of the Kansas Forestry, Fish and

Game Commission for help in locating the Lesser Prairie Chickens.

I am grateful for the assistance of Mrs. Chester Alexander and Dr. L. C.

Dahl in translating a Russian and a Dutch reference, and thank George

Young and James Bee for making equipment used in my study.

All of the original drawings except fig. 1 were made by me, although the

final inking of figs. 12 through 19 was done by Bret Waller. Fig. 1 was

drawn by Kay Swearingen.

I was aided in this study during the summer of 1960 by a research grant

from the University of Kansas.

SKELETON

Although no special study was made of the skeleton, certain conspicuous

variations are discussed here.

There are a few pronounced differences between the pelvis of

_Tympanuchus_ and that of _Pedioecetes_. Whereas in the former the thick

lateral iliac process has a pronounced overhang with the ventral edge

lateral to the ischium (fig. 1), in _Pedioecetes_ there is no overhang

at all and the edge of this process is much thinner. The ischium in

_Pedioecetes_ is wider (in dorsoventral extent), especially posteriorly,

than in _Tympanuchus_. In _Tympanuchus_ the posteroventral margin of the

ischium is rounded and is free from the pubis, whereas in _Pedioecetes_

it is pointed and fused with the pubis.

In _Tympanuchus cupido_ (both subspecies) the lateral iliac process

extends farther ventrally than in _T. pallidicinctus_, approaching or

extending ventral to the level of the pubis in the former species; also

the edge of this process is thicker in _T. cupido_.

All specimens studied have a single synsacro-thoracic vertebra. The

number of combined synsacro-thoraco-lumbar and synsacro-lumbar vertebrae

is eight in each specimen of _Tympanuchus_ and in one specimen of

_Pedioecetes phasianellus jamesi_ and is seven in three specimens of the

latter. In most specimens of _Tympanuchus_ there are three

synsacro-thoraco-lumbar and five synsacro-lumbar vertebrae, although in

two specimens (_T. pallidicinctus_) there are four of each group; in one

of these latter two specimens the parapophysis on one side of the fourth

synsacro-thoraco-lumbar vertebra is small. The first (of five)

synsacro-lumbar vertebra has a rudimentary parapophysis on one side in

one specimen of _Tympanuchus_ and on both sides in another specimen. One

specimen of _Pedioecetes phasianellus jamesi_ has five synsacro-lumbar

vertebrae and the others have four; all have three

synsacro-thoraco-lumbar vertebrae.

NERVES

For each nerve (or plexus) the condition found in most specimens of the

Lesser Prairie Chicken (_T. pallidicinctus_) is described first.

Following this, variations from the typical _T. pallidicinctus_

condition are given for _T. pallidicinctus_, then for _T. cupido_ (both

subspecies considered together), and finally for _P. p. jamesi_.

=_Lumbosacral Plexus_=, Figs. 2, 3

_T. pallidicinctus_

DESCRIPTION.--Eight spinal nerves contribute to the lumbosacral plexus.

These are the second through the ninth synsacral spinal nerves (S2 to

S9). The entire ventral ramus of each of these nerves, excepting S2 and

S9, contributes to this plexus. The ventral ramus of S2 divides into two

branches, only the posterior of which contributes to the plexus; the

anterior branch directly innervates muscles of the abdominal wall (as

does the entire ventral ramus of S1). The ventral ramus of S9 divides

into two branches, only the anterior of which contributes to this

plexus; the posterior branch contributes to the more posteriorly

situated pudendal plexus.

Each root of the plexus corresponds to a single spinal nerve except one

spinal nerve (S5--the furcal) that contributes a root to both the

femoral nerve and the sciatic nerve; thus typically the plexus has nine

roots (but see below). The four anteriormost roots (S2 to S5) contribute

to the femoral nerve, although the contribution from S2 is small. S3 and

S4 contribute to the obturator nerve. The five posteriormost roots (S5

to S9) contribute to the sciatic nerve, although the contribution from

S9 is relatively small.

INDIVIDUAL VARIATION.--In all specimens (of all species) examined, the

right and left sides of the plexus in any one individual were

practically identical. In T.p. 2 (fig. 2B), there appear to be two

furcal nerves; S5 is typical, but a small branch of S4 apparently also

contributes to the sciatic nerve. In T.p. 5, S9 is unique in dividing

into three branches; the anterior two join the sciatic nerve separately;

the posterior one joins the pudendal plexus as usual.

_T. cupido_

INDIVIDUAL VARIATION.--S2 or S5, or both, may contribute to a limited

extent to the obturator nerve. In T.c.p. 3 (fig. 3A) and T.c.a. 1 and 2,

much of the plexus has shifted one segment anteriorly, relative to the

synsacral vertebrae (the so-called prefixed condition); the roots of the

femoral nerve are S2, S3, and S4 (all large); the furcal nerve is S4 (in

T.c.a. 1, S5 gives an extremely small root to the femoral nerve, thus

making two furcal nerves); six roots (S4 to S9) contribute to the

sciatic nerve; S3 and S4 remain as the main contributors to the

obturator nerve except in T.c.a. 2 in which only S2 and S3 contribute to

it.

_P. p. jamesi_

INDIVIDUAL VARIATION.--In P.p. 1, the plexus resembles the typical

condition in _T. pallidicinctus_. In P.p. 2, 3, and 4, the plexus is

prefixed. P.p. 2 resembles T.c.p. 3. In P.p. 3 and 4 (fig. 3B) there are

two furcal nerves (S4 and S5); S2 to S4 are the main contributors to the

femoral nerve; only S2 and S3 contribute to the obturator nerve; S4 to

S9 contribute to the sciatic nerve (the anteriormost and posteriormost

roots are small).

=_Femoral Nerve_=, Figs. 4, 5

_T. pallidicinctus_