322
UNIT TWO
Scrotum
Ischiocavernosus
Clitoris
Urethral orifice
Vaginal orifice
Anus
Bulbospongiosus
Superficial
transversus
perinei
Levator ani
Gluteus maximus
External anal
sphincter
Penis
Anus
Coccyx
Rectum
Vagina
Urethra
Symphysis pubis
Coccygeus
Urogenital diaphragm
Levator ani
(b)
(a)
(c)
The
sphincter urethrae
(sf
ngk
ter u-re
thre
¯) are muscles
that arise From the margins oF the pubic and ischial bones.
Each arches around the urethra and unites with the one on
the other side. Together they act as a sphincter that closes
the urethra by compression and opens it by relaxation, thus
helping control the fl
ow oF urine.
which helps maintain an erection oF the penis in the male
and oF the clitoris in the Female.
The
ischiocavernosus
(is
ke-o-kav
er-no
sus) muscle is
a tendinous structure that extends From the ischial tuberos-
ity to the margin oF the pubic arch. It assists erection oF the
penis in males and the clitoris in Females.
TABLE
9.10
|
Muscles of the Abdominal Wall
Muscle
Origin
Insertion
Action
Nerve Supply
External oblique
Outer surfaces of lower ribs
Outer lip of iliac crest and
linea alba
Tenses abdominal wall and
compresses abdominal contents
Intercostal nerves 7–12
Internal oblique
Crest of ilium and inguinal ligament
Cartilages of lower ribs, linea
alba, and crest of pubis
Same as above
Intercostal nerves 7–12
Transversus abdominis
Costal cartilages of lower ribs, processes
of lumbar vertebrae, lip of iliac crest, and
inguinal ligament
Linea alba and crest of pubis
Same as above
Intercostal nerves 7–12
Rectus abdominis
Crest of pubis and symphysis pubis
Xiphoid process of sternum
and costal cartilages
Same as above; also F
exes
vertebral column
Intercostal nerves 7–12
FIGURE 9.36
External view of muscles of (
a
) the male pelvic outlet and (
b
) the female pelvic outlet. (
c
) Internal view of female pelvic and
urogenital diaphragms.
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