Zhang el al. • CHINESE GROUSE MYOLOGY 
331 
FIG. 5. Anterior (right) and posterior views of the 
fourth layer of muscles of the shank of the Chinese Grouse. 
Abbreviations: EDL, M. extensor digitonim longus; EB, M. 
tibularis brevis: FDL. M. flexor digitoruni longus; FHI M. 
Hexor hallucis longus; IF. M. iliofihularis; PLA. M. 
plantaris; POP, M. popliteus. 
M. flexor cruris lateralis (Figs. 1, 2. 3; FCLP) 
and M. flexor cruris medialis form the caudal 
border of the thigh. M. flexor cruris lateralis arises 
mainly by fleshy fibers from the caudal end of the 
dorsolateral crest of the ilium, by aponeurosis 
bom the processus transversus of the first free 
caudal vertebra. The belly, passing downward and 
forward, joins in a tendinous raphe with a clearly 
developed pars aecessoria (Figs. 2. 3: FCL.A) at 
•be distal half of the thigh. Pars aecessoria extends 
forward from the raphe and inserts by fleshy 
fibers on the eaudolaieral surface of about the 
distal third of the femoral shaft. The main belly ol 
M. flexor cruris lateralis extends distally. and 
gives rise to a wide tendinous sheet in common 
with M. flexor cruris medialis. attaching to the 
medial surface of the proximal tibia. 
M. flexor cruris medialis (Figs. 1. 2. 3: FCM) is 
•he most medial muscle in the caudal part of the 
•high and arises partly aponeurotic from the ventral 
edge of the distal third of the ischium, caudal to the 
origin of M. pubo-ischio-femoralis. The flattened, 
band-shaped belly gives rise to a flat and wide 
aponeurosis passing between the internal and 
medial heads of M. gastrocnemius to its insertion 
on the medial surface of the proximal tibial shaft. 
M. caudofemoralis pars caudalis (Figs. 2, 3: 
CFC): M. caudofemoralis is composed of pars 
caudalis and pars pelvica. These two parts have 
separate origins and bellies, but share a common 
insertion on the eaudolaieral surface ol the 
proximal femoral shaft, just distal to that of M. 
ischiofemoralis. Pars caudalis arises b> a narrow 
tendon from a heavy tendinous sheet on the ventro¬ 
lateral surface of the pygostyle. The spindle-shaped 
belly extends forward between the superficial M. 
flexor cruris lateralis and the deep M. flexor cruris 
medialis. 
M. caudofemoralis pars pelvica (Figs. 2. 3: 
CFP) arises by fleshy fibers from the ventral edge 
of the distal fourth of the dorsolateral crest of the 
ilium. The belly is thin, strap-shaped, and nearly 
the same width as that of pais caudalis, presenting 
a small, dorsal, triangular tendinous area at the 
midway. 
M. ischiofemoralis (Figs. 2. 3: 1SF) is a deeply 
situated, roughly triangular shaped muscle. It 
arises fleshy from nearly the entire lateral surface 
of the ischium, beginning at the caudal margin of 
the foramen obturatum and extending to the 
caudal end of the bone. The bulky, fleshy belly 
converges on a strong, flat tendon, which attaches 
to the lateral surface ol the proximal femoral 
shaft. The area of insertion lies caudal to, and 
between the insertions ol Mm. iliotrochantericus 
cranialis and medius. 
M. obturatorius lateralis is a very small muscle 
that arises from the lateral surface of the pubis, 
just caudoventral to the acetabulum, cranial to the 
obturator foramen. The belly fuses w'ith the 
tendon of M. obturatorius medialis near its 
insertion on the trochanter of the femur. 
M. obturatorius medialis is a long, roughly 
oval-shaped muscle which originates fleshy from 
the medial surface of the postacetabular pelvis, 
including most of the ischium and the pubis, and 
the caudal part of the ilium. The fleshy belly 
converges on a stout tendon, which passes through 
the obturator foramen and inserts on the caudo- 
lateral side of the trochanter of the femur, caudal 
to the insertion of M. iliotrochantericus caudalis. 
M. pubo-ischio-femoralis (Figs. 2. 3: PIF) is 
composed of two separate bellies. Pars medialis is 
deeply situated and arises by aponeurosis from the 
