384 The Nerves and Muscles of the Leg 
Witson, J. F.—Abnormal distribution of nerve to quadratus femoris in man. 
Journal of Anatomy and Physiology, Vol. 23, p. 354, 1889. 
WINDLE, B. C. A., and Parsons, F. G.—Morphology of the femoral head of the 
biceps flexor cruris. Journal of Anatomy and Physiology, Vol. 34, 
1900. 
DESCRIPTION OF PLATES. 
PLATE I, 
Two figures, repeated from this journal (Vol. I, Plate II), to illustrate 
early stages in the differentiation of the inferior extremity. 
Fic. 1. Embryo II, length 7 mm., age about four weeks. - 
Fie. 2. Embryo CLXIII, length 9 mm., age about four and a half weeks. 
For description of figures see text, p. 264. 
PLATE II. 
Four sections through the base of the posterior limb to illustrate different 
stages in the development of the nerves and musculature. 
Fic. 1. Section passing through the right limb-bud in embryo II, length 
7 mm., age 26 days. The tips of the neighboring myotomes do not extend 
into the mass of tissue of which the limb-buds are composed and in which 
as yet no specific differentiation is visible. 33 diam. 
Fig. 2. Secton passing transversely through the base of the right limb- 
bud of embryo CIX, length 11 mm., age about five weeks. At the center of 
the limb-bud the acetabular region of the skeleton appears as a condensed 
mass of tissue. About this the femoral, obturator, and sciatic nerves may be 
seen extending into the limb bud. Myogenous tissue is fairly well marked 
near the femoral and sciatic nerves. 25 diam. 
Fic. 3. Transverse section passing through the acetabular region of left 
leg of embryo CXLIV, length 14 mm., age about five and one-half weeks. The 
femoral, obturator, gluteal, and sciatic nerves may be seen extending into 
the limb bud, and in the vicinity of these nerves the anlages of the iliopsoas, 
pectineus, adductor, hamstring, and gluteal muscles. 25 diam. 
Fic. 4. Transverse section passing through the acetabular region of em- 
bryo CXLYV, length 33 mm., age about two months. The femoral, obturator, 
inferior gluteal, and sciatic nerves may be seen entering the limb. The 
chief fasciculi of the iliopsoas, pectineus, adductor, and gluteus maximus 
muscles are separated by an amount of connective tissue relatively greater 
than in the adult. 10 diam. 
PLATE III. 
Three figures to illustrate the skeletal, muscular, and nervous apparatus 
of the right posterior extremity of embryo CIX, length 11 mm., age about five 
weeks. The nerves are represented black; the muscle anlages by stippling; 
the skeletal structures, light grey; the skin of the leg, transparent. About 
17 diam. 
Fie. 1. Median view. The urachus is shown in outline. 
Fig. 2. Lateral view. 
