Download Gross Anatomy of the male and female bony pelvis

Anatomy of the male and female
bony pelvis
Dr. Munirah Batarfi
MD, MSc, & PhD
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Bony pelvis
Components of the pelvic bone: A. Medial surface. B. Lateral
surface.
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Bony pelvis (Cont’d)
Sacrum and coccyx. A. Anterior view. B. Posterior view. C.
Lateral view.
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Pelvic joints
Lumbosacral joints and associated ligaments: A. Lateral view.
B. Anterior view.
The lumbosacral joints are reinforced by strong iliolumbar and lumbosacral
ligaments
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Pelvic joints (Cont’d)
Sacro-iliac joints and associated ligaments: A. Lateral view.
B. Anterior view.
C. Posterior view.
The sacro-iliac joints transmit
forces from the lower limbs to
the vertebral column. They are
synovial Joints and supported
by:
• anterior sacro-iliac ligament,
• interosseous sacro-iliac
ligament,
• posterior sacro-iliac
ligament,
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Pelvic ligaments
Sacrospinous and sacrotuberous ligaments:
A. Medial view of right side of pelvis.
B. Function of the ligaments.
The sacrospinous and sacrotuberous ligaments stabilize the sacrum on the pelvic
bones by resisting the upward tilting of the inferior aspect of the sacrum.
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Gender differences in the bony pelvis
Structure of the bony pelvis. A. In women. B. In men.
The angle formed by the pubic arch can be approximated by the angle between
the thumb and index finger for women and the angle between the index finger and middle
finger for men as shown in the insets.
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Pelvic outlet
Pelvic inlet
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The pelvic types
The pelvic types shown in this Figure: A and C are most common in males, B
and A in white females, B and C in black females, whereas D is uncommon in
both sexes. The gynecoid pelvis is the normal female type (Fig. B);
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Pelvic measurements
In pregnancy, accurate transverse and
sagittal measurements of the mother's
pelvic inlet and outlet can help in
predicting the likelihood of a successful
vaginal delivery.
These measurements include:
• the sagittal inlet (between the
promontory and the top of the pubic
symphysis);
• the maximum transverse diameter of
the inlet;
• the bispinous outlet (the distance
between ischial spines); and
• the sagittal outlet (the distance
between the tip of the coccyx and the
inferior margin of the pubic
symphysis).
Pelvic Diameters (Conjugates)
The acceptable values for these are 11,
11.5, 9, and 10 cm, respectively.
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Pelvic Fractures
Fractures of the bony pelvic ring are almost always multiple
fractures or a fracture combined with a joint dislocation.
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Apertures in the pelvic wall
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Muscles of pelvic wall
Obturator internus and piriformis muscles (medial view of right side of
pelvis).
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Pelvic diaphragm
• The pelvic diaphragm is the muscular part of the pelvic floor.
• Shaped like a bowl or funnel and attached superiorly to the pelvic walls,
• consists of the levator ani and the coccygeus muscles.
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Sacral plexus
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Sacral and coccygeal plexuses
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Arteries of the pelvis
Internal iliac artery
Branches of the anterior trunk of the internal
iliac artery:
A. Male
B. Female
Branches of the posterior trunk of the internal iliac
artery:
•
•
•
the iliolumbar artery,
the lateral sacral artery,
the superior gluteal artery
Branches of the anterior trunk of the internal iliac artery include:
the superior vesical artery, the umbilical artery, the inferior vesical artery, the middle rectal artery, the uterine
artery, the vaginal artery, the obturator artery, the internal pudendal artery, and the inferior gluteal artery.
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The perineum
The perineum is a diamond-shaped region between
the thighs and is divided descriptively into an anterior
urogenital (UG) triangle and a posterior anal triangle.
The boundaries of the perineum include the
following:
● Pubic symphysis anteriorly
● Ischial tuberosities laterally (lateral margins are
demarcated by the ischiopubic rami anteriorly
and the sacrotuberous ligaments posteriorly)
● Coccyx posteriorly
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Borders and ceiling of the perineum
Boundaries of the perineum
•
The ceiling of the perineum is the pelvic
diaphragm (the levator ani and coccygeus
muscles); and its narrow lateral walls are
formed by the walls of the pelvic cavity below
the attachment of the levator ani muscle.
Perineal membrane
•
•
The urogenital triangle is
associated with the openings of
the urinary systems and the
reproductive systems and
functions to anchor the external
genitalia.
The anal triangle contains the
anus and the external anal
sphincter.
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ANAL TRIANGLE
External anal sphincter
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Ischio-anal fossae
Ischio-anal fossae and their anterior recesses
B. Inferior view
A. Anterolateral view with left pelvic wall removed
• The lateral wall of each fossa is
formed mainly by the ischium,
obturator internus muscle, and the
sacrotuberous ligament.
• The medial wall is the levator ani
muscle.
• The medial and lateral walls
converge superiorly where the
levator ani muscle attaches to the
C. Anterolateral view with
fascia overlying the obturator
pelvic walls and diaphragm
internus muscle.
removed.
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UROGENITAL TRIANGLE
Erectile tissues of clitoris and penis
A. Clitoris
B. Penis
The urogenital triangle of the
perineum is the anterior half
of the perineum and is
oriented in the horizontal
plane. It contains the roots of
the external genitalia and the
openings of the urogenital
system.
The urogenital triangle is
defined:
• laterally by the ischiopubic
rami;
• posteriorly by an
imaginary line between
the ischial tuberosities;
• anteriorly by the inferior
margin of the pubic
symphysis.
The urogenital triangle
includes deep & superficial
perineal pouches
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Perineal membrane and deep
perineal pouch
.
A. Inferior view
C. Medial view
B. Superolateral view
• The perineal membrane is a thick fascial, triangular
structure attached to the bony framework of the
pubic arch .It is oriented in the horizontal plane and
has a free posterior margin. The perineal
membrane is related above to a thin space called
the deep perineal pouch which contains a layer of
skeletal muscle and various neurovascular
elements.
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Muscles in the deep perineal pouch
A. In women
B. In men
Perineal body
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Urethera and its relation with the perineum
Urethra:-
A. In women
B. In men
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Superficial perineal pouch
Muscles in the superficial perineal pouch
:.
A. In women
B. In men
The superficial perineal
pouch contains:
erectile structures that
join together to form the
penis in men and the
clitoris in women; and
skeletal muscles that
are associated mainly
with parts of the erectile
structures attached to
the perineal membrane
and adjacent bone.
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Pudendal nerve in the perineum
The pudendal nerve has three major terminal branches:
• Inferior rectal
• Perineal nerves
• Dorsal nerve of penis or clitoris
which are accompanied by branches of the internal
pudendal artery.
A. In men
B. In women
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Pudendal nerve in the
perineum (Cont’d)
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Injury to the Pelvic Floor in females
The perineum, levator ani, and pelvic fascia may be injured during childbirth
(Fig. A); the pubococcygeus, the main and most medial part of the levator ani, is
torn most often (Fig. B). This part of the muscle is important because it encircles
and supports the urethra, vagina, and anal canal. Weakening may alter the position
of the neck of the bladder and the urethra. These changes may cause urinary
stress incontinence, characterized by dribbling of urine when intra‐abdominal
pressure is raised during coughing and lifting.
Disruption of the Perineal Body can occur during childbirth, removing support
from the pelvic floor. As a result, prolapse of pelvic viscera, including prolapse of
the bladder (through the urethra) and prolapse of the uterus and/or vagina (through
the vaginal orifice) may occur.
Injury to the Pelvic Floor in females
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Episiotomies
Median episiotomies is directed toward the anus, and sphincter
damage or anovaginal fistulae are potential sequelae.
Mediolateral episiotomies : do not appear to increase the incidence of
severe laceration and are less likely to be associated with damage to
the anal sphincters and canal.
Episiotomies
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References:
• Gray's Anatomy for Students- Second edition
• Netter’s Clinical Anatomy, Second edition
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