Flashcards in Gross anatomy of the pelvic wall and perineum practica Deck (46):
Which bones comprise the bony pelvis?
hip (coxal) bones, sacrum, coccyx
Which bones, and which of their parts, contribute to the pelvic inlet (superior pelvic aperture or pelvic brim)?
The pelvic inlet is formed by the sacral
promontory, arcuate line of the ilium and pectin pubis of the pubic bone.
What does the pelvic inlet divide?
The superior pelvic aperture (pelvic brim, inlet) divides the pelvis into the greater pelvis (pelvis major, false pelvis) above and the lesser pelvis (pelvis minor, true pelvis) below.
Compare the shape of the pelvic inlet in females and males.
The female compared to male pelvis (on average) has wider superior and inferior pelvic apertures, wider pubic arch, wider greater sciatic notch, narrower depth of true pelvis and thinner, lighter bones.
Define and identify the conjugate (anteroposterior) diameters, including the true, obstetric, and diagonal; the oblique diameter; and the transverse diameter.
The true conjugate (superior pubic symphysis to sacral promontory) can only be measured only on radiographic films. Its normal measurement is 11 cm or more. The diagonal conjugate (inferior pubic symphysis to sacral promontory) can be estimated using an internal examination, it is normally 11.5 cm or more. The obstetric conjugate is the shortest of the three measurements (sacral promontory to thickest part of the pubic symphysis) and measures 10 cm or more. The inlet is said to be contracted when any of these diameters is smaller than norm
What are the bony and ligamentous boundaries of the anal triangle?
The anal triangle is formed my the ischial tuberosities and the coccyx. The sides are formed by the sacrotuberous ligaments.
What is the anal triangle composed of?
The anal triangle is composed of the anal canal and sphincters, surrounded by adipose tissue in the ischioanal fossa.
List the borders of the ischioanal fossa
erineal skin, ischial tuberosities, obturator internus, levator ani, external anal sphincter
What are the contents of the ischioanal fossa?
Mostly fat and pudendal canal
What structure represents the transition zone between innervation, lymphatic drainage and epithelium in the anal canal?
What type of muscle forms the internal and external anal sphincters?
The internal anal sphincter is smooth muscle, which is continuous with the inner circular muscle layer of the rectum.
The external anal sphincter is skeletal muscle.
What is the difference in blood supply, innervation and lymphatic drainage above and below the pectinate line
Above the line: blood supply is from the inferior mesenteric artery (sup rectal a) and veins drain to portal system, lymph to internal iliac nodes and nerves are autonomic.
Below the line: blood is from the internal iliac artery (middle and inf rectal aa) and veins drain to caval venous system. Lymph to superficial lymph nodes, somatomotor/sensory innervation.
What is the pecten?
A transition area from the columnar epithelium of the rectum to a stratified squamous epithelium, below the pectinate line..
What are the different parts of the external anal sphincter?
Subcutaneous, superficial and deep.
Which part of the external anal sphincter blends with the puborectalis m?
The deep part.
Which part of the external anal sphincter has attachments to the perineal body and coccyx?
The superficial has attachments to the perineal body and coccyx via the anococcygeal ligament.
What are the bony boundaries of the urogenital triangle?
pubic symphysis, ischiopubic ramus and a line between ischial tuberosities.
Which muscle is closely related to the crus of the clitoris?
Which muscle is closely related to the bulb of the vestibule?
Where are the greater vestibular glands (of Bartholin) located? Where do their ducts open?
Superficial perineal pouch. Their ducts open near the external opening of the vagina
To which glands in the male are the greater vestibular glands (of Bartholin) homologous?
The paired bulbourethral (Cowper's) glands (?)
What forms the roof of the superficial perineal pouch?
The perineal membrane is the roof (superior border) of the superficial perineal pouch, and the floor (inferior border) of the deep perineal pouch.
In the deep perineal pouch, what is the urethra surrounded by?
sphincter urethrae muscle
What muscles exist in the deep perineal pouch?
The sphincter urethrae muscle, the compressor urethrae and the urethrovaginal muscle (the deep transverse perineal muscle in females appears to have been replaced by a sheet of smooth muscle)
What muscles attach to the perineal body?
The superficial part of the external anal sphincter, as well as many muscles that support the pelvic viscera.
Name the four parts of the urethra.
What structures surround the four different parts of the urethra?
1. Intramural: bladder
2. Prostatic: prostate
3. Membranous: deep pouch
4. Spongy: corpus spongiosum
With which parts of the body of the penis are the crura and bulb continuous?
The bulb of penis is continues into body of penis as corpus spongiosum.
The crura is continuous with the corpora cavernosa.
Which muscle is closely related to each crus of the penis?
Ischiocavernosus covers the crura.
Which muscle is closely related to the bulb of the penis?
Bulbuspongiosus covers the bulb.
Which muscles are located in the deep perineal pouch (m)?
Inferior part of the external urethral sphincter and
a few threads of muscle from the sphincter to the
ischiopubic ramus (but not a ‘true’ compressor
urethrae), the deep transverse perineal muscle (a
skeletal muscle strip at the posterior edge of the
Which part of the urethra is in the deep perineal pouch?
Intermediate part of the urethra.
Where are the bulbourethral glands (of Cowper) located?
The Bulbourethral glands are
located within or next to the sphincter or in the
deep transverse perineal m
Into which part of the urethra do the bulbourethral gland ducts open?
The ducts join the spongy urethra
To which glands in the female are the bulbourethral glands homologous?
Greater Vestibular (Bartholin’s) glands
Which muscles contribute to the pelvic diaphragm?
The levator ani, the coccygeus
What are the parts of the levator ani?
The levator ani is divided into three parts:
What are the functions of the pelvic diaphragm?
It separates the pelvic cavity from the perineum below (diamond shaped region between thighs and buttocks). The pelvic diaphragm is the floor of abdominopelvic cavity – supports pelvic viscera, allows passage of faecal material, urine and babies and contains sphincters for continence.
Which muscle is located on the lateral wall of the true pelvis?
How does the obturator internus exit the pelvis and where does it insert?
It exits the pelvis through lesser sciatic foramen and inserts into the trochanteric fossa. I
What is the innnervation and action of the obturator internus?
Lateral rotator of thigh Innervation – nerve to obturator internus (L5-S2).
Which muscle is located on the anterior surface of the sacrum?
What is the origin, and insertion of the piriformis? How does it exit the pelvis?
origin - anterior surface of sacrum, exits pelvis through greater sciatic foramen and inserts onto the greater trochanter of femur.
What is the innervation and action of the piriformis?
Lateral rotator of thigh
Innervation - ant rami S1-2 (nerve to piriformis).
What ligaments reinforce the sacroiliac joint?