46 
DR. PETTIGREW ON THE MUSCULAR ARRANGEMENTS 
concomitant or companion loop embraces the cervix posteriorly, and 
assists in forming the posterior lip of the sphincter vesicse. 
1c n, K n\ k" n". Terminal expansions or loops representing very oblique 
spiral figure-of-eight fibres, forming the lower two-thirds of the fourth or 
central layer posteriorly. Their companion loops occur on the posterior 
aspect of the cervix, and are principally concerned in the formation of 
the posterior lip of the sphincter {m l , m! 1! , m" l"). The sphincter and 
the other portions of the fourth or central layer, as will be seen from 
this explanation, are not composed of circular fibres as is generally 
believed. 
Diagram 3 represents the various sets of fibres occurring on the posterior aspect of the 
bladder, as seen in layers 1, 2, 3, & 4. 
op. Longitudinal or vertical fibres forming layer 1. 
qrst. Slightly oblique spiral figure-of-eight fibres embracing urachus and 
urethra anteriorly, and forming layer 2. 
u v w x. Oblique spiral figure-of-eight fibres embracing upper third of 
bladder and lower portion of cervix anteriorly, and forming layer 3. 
yy'zz!. Very oblique spiral figure-of-eight fibres embracing lower two-thirds 
of bladder and upper portion of cervix anteriorly, and forming the fourth 
or central layer. 
Diagram 4 shows the same as diagram 3, and, in addition, the manner in which the 
sphincter and fourth or central layer is formed anteriorly. 
u x. Terminal expansion or loop representing the spiral oblique fibres which 
spread out on the upper third of the bladder anteriorly, and assist in 
forming the central, transverse, or circular layer in this direction. Its 
companion loop embraces the cervix anteriorly, and assists in forming the 
anterior lip of the sphincter. 
y z, y' z 1 , y" z". Terminal expansions or loops representing the very oblique 
spiral figure-of-eight fibres, forming the lower two-thirds of the fourth 
or central layer anteriorly. Their companion loops occur on the 
anterior aspect of the cervix, and are principally concerned in the 
formation of the sphincter, zy', z y', z y'. 
Diagram 5 represents the various sets of fibres occurring on the left lateral aspect of the 
bladder, as seen in layers 1, 2, 3, & 4. 
a b , op. Anterior and posterior longitudinal fibres, as seen in layer 1. 
cd e,st. Slightly oblique spiral figure-of-eight fibres embracing urachus (x) 
and urethra, as seen in layer 2. 
g h A', i i'j. Oblique spiral figure-of-eight fibres spreading out on upper third of 
right side of bladder and right side of sphincter, as seen in layer 3. 
k Im n. Very oblique spiral figure-of-eight fibres embracing lower two-thirds 
of right side of bladder and right side of sphincter. 
