Pelvis & perineum WB4 Flashcards
What bony landmarks create boundaries of the perineum
Name the orange and green triangle & name the bony porminance that separates each triangle
Orange= urogenital
Green = anal
Ischial tuberosities seperate each triangle
A thin sheet of deep fascia stretches between right and left sides of the pubic arch, below the pubic symphysis.
What is the name given to this fascia?
Perineal fascia
Function of the external anal sphincter & its innervation
Voluntary control of defacation: innervated by branches of the pudendal nerve
Function of the superficial transverse perineal muscle & its innervation
Flexes and stabiles perineal body; innervated by branches of the pudendal nerve (S2-S4)
Function of the deep transverse peirneal muscle & its innervation
Forms the urogenital diaphragm and anchors the perineal body, thus supporting the pelvic vescera
innervated by branches to the peuodendal nerve (S2-S4)
Function of the external urethral sphincter & its innervation
Compress the urethra to maintain urinary continence
Innervated by branches of the pudendal nerve (S2-S4)
Function of the bulbospongiosus muscle (male)
The muscle is relaxed during micturition but when contracted will stop the flow of urine.
- It aids in fully emptying the urethra after urination.
- It contracts rhythmically during ejaculation to create a series of wave-like contractions within the corpus spongiosum; this facilitates movement of ejaculate through the urethra.
- branches of pudendal nerve (S2-S4)
Function & innervation of the bulbospongiosus muscle in females
Compresses the vestibular bulb and expresses the secretions of the greater vestibular glands. Constricts the vaginal orifice and anterior fibers compress the deep dorsal vein of the clitoris, restricting venous return and allowing clitoral erection.
Branches of the pudendal nerve (S2-S4)
Function of the Ischiocavernosus (Male) and its innervation
Steady contraction of the muscle may help in impeding venous return from the corpora cavernosa of the penis, aiding in maintenance of erection.
- The muscle also undergoes rhythmic contraction in conjunction with bulbospongiosus during ejaculation.
- The contractions serve to help maintain the erection and possibly to aid in moving the ejaculate through the urethra.
innervated by branches of the pudendal nerve (S2-S4)
Function & innervation of the Ischiocavernosus (Female)
Compresses the corpus cavernosum, restricting venous return and allowing clitoral erection in the female.
Innervated by branches of the pudendal nerve (S2-S4)
What is the perineal body & name the muscles that converge at it
Perineal body= central point of perineum, site of convergence of bulbospongiosus, external anal sphincter, superficial & deep transverse perineal muscles and ischiocavenosus.
- Levator ani (part of the pelvic floor).
- Bulbospongiosus muscle.
- Superficial and deep transverse perineal muscles.
- External anal sphincter muscle.
- External urethral sphincter muscle fibres.
Label these mucles/structures
What is the urogenital triangle?
The urogenital triangle is the anterior half of the perineum. It is bounded by the pubic symphysis, ischiopubic rami, and a theorectical line between the two ischial tuberosities. The triangle is associated with the structures of the urogenital system – the external genitalia and urethra.
Structurally, the urogenital triangle is complex, with a number of fascial layers and pouches. Unlike the anal triangle, the urogenital triangle has an additional layer of strong deep fascia; the perineal membrane. This membrane has pouches on its superior and inferior surfaces.
Complete the diagram
What are the 3 parts of the make urethra
What is the narrowest and widest part of the male uerthra?
Which are the widest and narrowest parts of the male urethra and why?
Widest part: prostatic part; most dilatable
Narrowest part: membranous part; the least dilatable
What can put the male urethra at risk of becoming narrowed?
Enlargment of the prostate
Label
Name the two layers of fascia which make up the pelvic diaphragm and their function
Superficial and inferior fascia, make up the pelvic diaphram. These provide additional support for the pelvic organs within the perineum.
Where do the ducts of the bulbo-urethral glands open into?
The proximal part of the spongy urethra