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THE WILSON JOURNAL OF ORNITHOLOGY • Vo/. 124. No. 2. June 2012 
pertorans digiti IV and M. flexor perforans et 
perforatus digiti III. It is ossified for most of the 
length of the tarsometatarsus. uniting with the 
tendon of M. fibularis longus just below the 
hypotarsus. and sending a small branch to the 
tendon of M. flexor perforans et perforatus digiti 
III. Insertion is on the ventral surface of the distal 
end of the proximal phalanx and the proximal end 
of the second phalanx of the third toe. 
M. flexor perforans digiti II is a bipennate 
muscle and lies deep to M. flexor perforans digiti 
III and IV. It arises by two heads. One arises by 
aponeurosis from the intercondylar region of the 
femur, medial to the head of M. flexor perforans 
digiti IV; the other lateral head arises by fleshy 
fibers from the ansa m. iliofibularis. the lateral 
surface of the lateral condyle of the lemur, and the 
proximal part of the combined tendon. The belly 
of the medial head is strongly attached to that of 
the medial head of M. flexor perforans digiti III at 
the proximal half. The tendon is ossified for a 
considerable distance in the lower leg above the 
tibial cartilage, and for most of the length of the 
tarsometatarsus. It is perforated by the tendon of 
M. flexor perforans et perforatus digiti II and M. 
flexor digitorum longus at the base of the second 
toe, and inserts mainly on the ventrolateral side of 
the proximal end of phalanx I. digit II, 
M. flexor hallucis longus (Fig. 5: FHL) origi¬ 
nates by fleshy fibers from the intercondylar area 
of the femur. Its relatively weak belly lies lateral 
to, but is shorter than that of M. planiaris, and is 
confined to the proximal fourth of the tibiotarsus. 
With the exception of the distal-most part, nearly 
the entire slender tendon, including the part 
enclosed within the distal belly, is ossified in Lhe 
region of the tibiotarsus. The tendon passes 
through the tibial cartilage on the deep lateral 
side and then through a groove immediately 
lateral to the crista lateralis hypolarsi. The tendon 
is ossified again after emerging from the groove 
and passes diagonally toward the medial side over 
the caudal surface of the M. flexor digitorum 
longus near the base of the metatarsus I. The 
tendon of insertion splits into two unossified 
branches: the short, weak branch joins the lateral 
side ol the distal tendon of M. flexor digitorum 
longus; the other main branch perforates the M. 
flexor hallucis brevis near the base of digit I, and 
inserts on the ungual phalanx of the hallux. 
M. flexor digitorum longus (Figs. I, 2, 4 5 * 
p DL) is a unipennato muscle and the most deeply 
situated muscle on the caudal surface of the lower 
I IG. 6. Anterior (left) and posterior views of the 
intrinsic foot muscles of the Chinese Grouse. Abbrevia¬ 
tions: ABD2, M. abductor digiti II: ABD4, M. abductor 
digiti IV: LBD4, M. extensor brevis digiti IV: EIIL. M. 
extensor hallucis longus: KPD3. M. extensor pruprius digiti 
HI: FHB. M. flexor hallucis brevis. 
leg. I he distal part of the belly is visible 
superficially on the lateral surface of the lower 
leg. It arises by two fleshy heads, one from the 
lateral surface of the fibula, just proximal to the 
insertion of M. iliofibularis, the other from lhe 
caudal surface of the tibiotarsus and the adjacent 
tibular. The bellies arc separated by the insertion 
tendon of M. iliofibularis at the proximal end. and 
then merge extending about four-fifths the way 
down the lower leg. There is an ossified tendon 
embedded in the caudomedial surface along die 
distal hall of the belly. The tendon passes through 
a fibrous canal in the deepest medial side ot the 
tibial cartilage and then through the hypotarsus 
to the tarsometatarsus. After receiving a branch 
of M. flexor hallucis longus. it broadens and 
trifurcates, sending branches to insert on die 
ventroproximal surface of the ungual phalanges of 
the second, third, and fourth digits. 
M. extensor hallucis longus (Fig. 6; EHL) is 
unipennate muscle that arises bv fleshy libers 
from the craniomedial surface of the proximal 
halt of the tarsometatarsus. The tendon extends 
dislally along the medial side of the bone and then 
along the dorsal surface of the proximal phalanx 
of the hallux, inserting on the base of the ungual 
phalanx. 
M. flexor hallucis brevis (Fig. 6: FHB) arises 
by fleshy fibers from the caudomedial surface ol 
the proximal tarsometatarsus and the adjacent 
