The Wilson Journal of Ornithology 124(2):328-337, 2012 
DESCRIPTIVE ANATOMY OF THE PELVIC APPENDAGE MYOLOGY 
OF THE ENDEMIC CHINESE GROUSE (TETRASTES SEWERZOWI) 
ZIHUI ZHANG, 14 JAMES C. VANDEN BERGE, 2 AND YUE HUA SUN 34 
ABSTRACT. The musculature of the pelvic appendage of the Chinese Grouse ( Tetrastes sewerzowi) is described in 
detail. T. sewerzowi exhibits the same features as other tetraonids in the absence of M. adductor digiti II. and the rclativ: 
weak development of other intrinsic foot muscles, which are thought to be an adaptation to the extreme cold climate of the 
habitat of grouse. Myological modifications include weak development of the vincula between the flexor tendom to ire 
digits (M. flexor perforans digiti III and M. flexor perforans ct perforatus digiti HI. M. flexor digitorum longus. and M. 
Ilexor hall us longus). the proxirnolateral insertion of M. flexor perforans digiti II. the well-developed middle head of M. 
flexor perforans digiti IV. and the ossification of the insertion tendon of M. extensor brevis digiti IV. These features ar. 
suggested to be associated with the requirement of finer control over the individual digits while moving on the trc; 
especially a thin branch. Received 19 September 2011. Accepted 24 January 2012. 
I lie Chinese Grouse (Tetrastes sewerzowi) is 
the smallest (Johnsgard 1983. Sun el al. 2005), as 
well as the most southern grouse species among 
Tetraoninae, and is restricted to the high mountain 
forests along the Qinghai-Tibetan Plateau (Sun 
2000). It is recognized as the rarest, endangered 
grouse species, and has decreased in number due 
to deforestation of its habitat (Liu and Wang 
1987. Zheng and Wang 1998. Sun et al. 2003). It 
is one of the least known grouse (Johnsgard 1983, 
Storch 2000), although many contributions to our 
knowledge of the ecology, behavior, acoustics, 
morphometries, and mtDNA phylogeny of this 
species have been made since the 1990s (Sun and 
Fang 1997; Gutierrez el al. 2000; Sun 20(H)- Sun 
et al. 1999. 2003. 2005. 2007; Luechini ct al. 
2001; Drovetski 2002; Scher/inger et al. 2006: 
Wang et al. 2010). A detailed investigation of its 
myology was lacking until now. 
Gross myological differences and similarities 
may serve as a basis for study of the functional 
morphology of locomotion, as well as phyloge¬ 
netics and systematics at various taxonomic levels 
(Vanden Beige 1970; Zusi and Bentz 1982 
MeKitrick 1991; Raikow 1987, 1994a). Manv 
factors contribute to muscle function, including 
fiber arrangement. Fiber type, number of joints 
crossed, and the synergistic actions of muscle 
groups (Raikow 1994b). These factors are not 
BejS!''K' 8 , ™ Sr' C>W N ° rm “‘ 
Northwest Center for Medical Education Indiana 
University School of Medicine, Gary. IN 46408. USA 
Key Laboratory of Animal Ecology and Conservation 
s?^ a ""=“ ■= 
“ U '"' TC ■zhang@tom.com. 
considered here, and this study provides only j 
first detailed description of the musculature of the 
pelvic limb of the Chinese Grouse, as a basis tw 
studies on its arboreal mode of life. 
METHODS 
Four adult individuals that died from predatioi 
or during capture while attaching radio transmit¬ 
ters in Lianhuashan Natural Reserve of Gansu 
Province, China, were collected and fixed in v 
ethanol for dissections, which were perform^ 
under a stereomicroscope at 6X and 1-' 
magnifications. The descriptions here include thv 
location and nature (fleshy, tendinous) of the 
origin and insertion, muscle shape, fiber archils 
ture (e.g,. bipennate, unipennale), position, ai; 
size relative to adjacent structures, and .m 
additional details. Muscles were described 
proximal to distal, from superficial to deep 
layers, starting from a lateral view. Drawing' 
were made freehand. Nomenclature for '• 
musculature and the various bony structures w 
which Lhe muscles are attached follows thu' 
Nomina Anatomica Avium (Baumel et al. F 1 - 1 
DESCRIPTION 
M. iliotibialis cranialis (Fig. 1; IC) is the m 1 ' 
cranial superficial muscle in the thigh. Its one 11 
mainly fleshy from the cranial half of the cri- 
iliaca dorsalis. The Hat. strap-like belly P a> ' 
downward, and merges into the ligaments 
patellae which inserts on the crista patella^ 
the tibiotarsus. 
M. iliotibialis lateralis (Fig. 1: IL) is the im' 
extensive superficial muscle on the lateral flirty 
°1 the thigh. The origin, arising from die doN 
iliac crest and crista dorsolateralis ilii, is a P° K ’ 
328 
