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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 124. No. 2. June 2012 
FIG. 3. Lateral view of a third layer of muscles of the 
ihigh of the Chinese Grouse. Abbreviations: CPC, M. 
caudofemoralis pars caudalis: CFP. VI. caudofemorulis pars 
pelvica; FCLA. Pars accessoria of M. flexor cruris lateralis: 
FCLP, M. flexor cruris lateralis; FCM, M. flexor cruris 
medialis; FTM, M. femorotibialis medius: ISF, M. 
ischiofemondis; ITCR. M. iliotrochantericus cranialis; 
ITM, M. iliotrochantericus medius; PIF, M. pubo-ischio- 
femoralis. 
iliotibialis lateralis, and originates by fleshy fibers 
from the fossa iliaca dorsalis. The bulky belly 
converges on a short, flat and wide tendon, which 
inserts on the lateral surface of trochanter femoris. 
M. iliotrochantericus cranialis (Figs. 2. 3; 
ITCR) originates by tendinous and fleshy fibers 
from the cranial two-thirds of the lateral crest of 
the ilium. The insertion is by a wide, flat tendon 
on the lateral surface of the proximal femur, distal 
to the insertion of M. iliotrochantericus medius. 
M. iliotrochantericus medius (Fig. 3; ITM) is 
the weakest of die iliotrochanteric muscles. It 
arises fleshy from the caudal third of the lateral 
crest of the ilium and inserts by a thinner tendon 
on the lateral side of the femur between the 
insertions of M. iliotrochantericus caudalis and M. 
iliotrochantericus cranialis. 
M. iliofemoral is exlcrnus (Fig. 2: IFE) is a 
small, flattened, triangular muscle, which arises 
directly from (lie dorsal ridge of the ilium, cranial 
and dorsal to the acetabulum. The belly is closely 
attached to that ot M, iliotrochantericus caudalis 
and terminates on a small tendon which attaches 
on the caudoluteral aspect, between the tendons of 
M. iliotrochantericus cranialis and M. iliotrochan- 
tericus medius. 
FIG. 4. Lateral (left) and medial (right) views of the 
third layer of muscles of the shank of the Chinese Grouse. 
Abbreviations: AIF. Ansa m. iliofibularis: AM. M. 
ambiens; F,DL, M. extensor Jigitorutn longus: FB. M. 
lihularis brevis; FDL, M. flexor digitorum longus; FPD3. 
VI. flexor perloruns digiti III: FPD4. VI. flexor perforans 
digiti IV; IF. M. iliofibularis; PLA. M. planlans; TC. M. 
tibialis cranialis. 
M. iliofemoralis internus is the smallest of ail 
the thigh muscles and arises by fleshy fibers from 
the lateral crest of the ilium, just medial to the 
origin of M. iliotrochantericus medius. The thin, 
band-like belly passes diagonally caudolaterally 
to insert on the caudomedial side of the shaft of 
the femur, proximal to M. femorotibialis internus. 
M. femorotibialis externus (Fig. 2; FTE) lies 
deep to M. iliotibialis cranialis and M. iliotibialis 
lateralis, and is the largest of the three parts of this 
complex and arises primarily by fleshy fibers 
from the cranial and lateral surfaces of the 
femoral shaft throughout nearly its entire length. 
The belly is notched to accommodate the tendon 
of insertion of M. iliotrochantericus cranialis at 
the proximal end. and gives rise to a dense 
aponeurosis distally for the formation of the 
patellar ligament. 
M. femorotibialis medius (Fie. 3: FTM) an>es 
hv fleshy fibers from the distal half of the lateral 
surface of the femoral shall. The belly is closely 
attached to the overlying M. femorotibialis 
externus on the caudal edge. 
M. femorotibialis internus is the weakest of the 
three parts of the M. femorotibialis complex and 
originates by fleshy fibers from slightly more than 
half of the distal part of the medial surface of the 
femoral shaft The belly increases in size as it 
passes distally and inserts by a flat tendon on the 
craniomedial surface of the head of the tibiotarsus. 
