Gross anatomy of the pelvic wall and perineum practica Flashcards
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?
Pectinate line
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?
ischiocavernosus muscle