Table 4. Muscle actions, following results from Figs 9–20, to describe the major 3D potential functions of each ostrich pelvic limb muscle.

Blank cells indicate the muscle does not cross or act about the joint. “+” signs added to classifications indicate a major potential role in these functions based upon moment arm and muscle relative size (i.e., moment generation capacity), subjectively assessed. “/” combinations (F/E; M/L; AB/AD) indicate a strong sensitivity of muscle moment arm, and hence action, to joint angle. Annotation with an asterisk indicates a potential role for intrinsic stabilization about that axis of motion (see Discussion). “()” indicates that our model’s single origin for each muscle (or part thereof) did not allow such an action, but sub-parts of those muscles might have such actions if modelled in more detail.

	Action
Muscle	Hip F/E	Hip LAR	Hip Ab/Ad	Knee F/E	Ankle F/E	MTP F/E
IC	F+*	M	AD+	F/E
ILa	F/E	M/L	AB+	E+
ILp	E+	M/L	AB+	E+
AMB1	E*	L	AD	F
AMB2	F*	M/L	AD	E
FMTL				E+
FMTIM				E
FMTM				F
ILFBa	E	M	AB	F+
ILFBp	E+	M	AB	F+
ITCa	F/E*	M+	AB/AD
ITCp	F/E*	M+	AB/AD
IFE	F	M/L	AB
ITM	F/E*	M	AB/AD
ITCR	F/E*	M+	AB/AD
IFI	F	M/L	AD
FCM	E	M	AB	F
FCLP	E+	M+	AB+	F
FCLA	E	M	AB
ISF	F/E*	L	AB
PIFML	E	L	AB
OM	F+	L+	AB/AD*
CFP	E	L	AB
GL				F	E+
GIM				F	E
GM				(F/E)	E+
FL				E	F*	F
FDL					E+	F+
FPPD3				(F/E)	E+	F+
FPD3				(F/E)	E+	F+
FPD4				(F)	E+	F+
FHL				(F)	E	F
EDL					F+*	E+
TCf				0	F+*	E+
TCt					F+*	E+

Notes.

Classifications

E

extensor

F

flexor

M

medial (internal) rotator

L

lateral (external) rotator

AB

abductor

AD

adductor

0

no moment arm per se despite crossing the joint