anatomyphysiologyblog - Perineum: Boundaries, divisions, perineal fascia in addition to perineal pouches
Perineum
The perineum refers to the areas both externally on the surface as well as internally equally a shallow compartment of the body. The compartmental surface area of perineum lies inferior to the pelvic outlet as well as is separated from the principal pelvic cavity past times the pelvic diaphragm. In other words the pelvis is divided into principal pelvic cavity inward a higher house as well as perineum below past times the pelvic diaphragm.
Extent as well as boundaries of Perineum
When viewed from below amongst lower limbs abducted, the perineum is diamond-shaped surface area that includes mons pubis anteriorly, insides of the thighs laterally as well as the gluteal folds as well as upper goal of natal fissure posteriorly as well as presents next osseofibrous boundaries:
Anteriorly – pubic symphysis
Anterolaterally – ischiopubic ramus
Laterally – ischial tuberosities
Posterolaterally – sacrotuberous ligament
Posteriorly – tip of the coccyx
Division of Perineum
An imaginary transverse trouble joining the anterior ends of the ischial tuberosities divides the perineum into ii triangles:
Anal triangle lies posterior to this trouble as well as contains the anus or lower goal of anal canal as well as ischiorectal fossa.
Urogenital triangle lies anterior to this trouble as well as contains origin of the scrotum as well as penis inward males or the external genitalia inward females.
Perineal Body
The mid-point of the imaginary transverse trouble joining the ischial tuberosities is the key signal of the perineum as well as overlies the Perineal trunk that provides attachment for the perineal muscles.
The perineal trunk lies deep to the peel as well as subcutaneous tissue inward the midline at the junction of anal as well as urogenital triangles, behind the lobby of the vagina or bulb of the penis as well as inward front end of the anus as well as anal canal. It is attached to the posterior edge of perineal membrane. The pernieal trunk is variable inward size amongst relatively petty obese deep to the overlying skin.
Structurally perineal trunk is an irregular fibromuscular mass, containing both collagenous as well as elastic fibers as well as both skeletal as well as smoothen muscles. It is the site of convergence of several muscles as well as receives them inward 3 strata:
Superficial stratum: bulbospongiosus, superficial transverse perenei as well as superficial business office of external anal sphincter
Intermediate stratum: sphincter urethrae as well as deep transverse perenei, as well as deep business office of external anal sphincter
Deep stratum: levator ani
Perineal fascia:
The perineal fascia consists of superficial and deep layers.
The superficial perineal fascia i time to a greater extent than tin live divided into superficial obese layer as well as deep membranous layer (as inward example of lower business office of anterior abdominal wall).
The superficial obese layer (Camper fascia) is continuous amongst the obese inward the share of anal triangle (or ischiorectal fossa), the superficial fascia of the thighs as well as the obese superficial layer of abdominal wall. In male, it is replaced inward scrotum amongst smoothen dartos muscle.
The membranous layer (Colles’ fascia) is attached posteriorly to the posterior goal of perineal membrane as well as the perineal body. On each side it is attached to the margins of pubic arch as well as to the deep fascia i.e. fascia lata of the uppermost business office of the thigh on medial aspect. Anteriorly, the membranous layer is continuous amongst dartos fascia as well as amongst the like layer of abdominal wall i.e. Scarpa’s fascia.
The deep perineal fascia (investing or Gallaider’s fascia) tightly invest the ischiocavenous, bulbospongiosus as well as superficial transverse perneal muscles. The deep perineal fascia is fused amongst the suspensory ligament of the clitoris inward females as well as the deep fascia of the abdomen inward males.
Urogenital diaphragm as well as Perineal membrane:
The urogenital diaphragm is a triangular musculofascial diaphragm situated inward the anterior business office of the perineum inward the share of urogenital triangle, hence filling inward the gap of pubic arch. It consists of:
Two muscles
External urethral sphincter and
Deep transverse perineal muscles
Two fasciae
Superior fascial layer
Inferior fascial layer
Thus, nosotros tin enjoin that the urogenital diaphragm is composed of ii muscles (sphincter urethrae as well as deep transverse perineal muscles) enclosed within the ii fascial layers (superior as well as inferior) of urogenital diaphragm.
The ii layers of fascia fuse anteriorly as well as posteriorly amongst each other as well as amongst the membranous layer of the superficial fascia as well as the perineal trunk posteriorly. On each side, the layers of the diaphragm are attached to the pubic arch.
Structures piercing the urogenital diaphragm
The urogenital diaphragm is pierced past times urethra inward both manlike mortal as well as woman mortal as well as past times equally good past times vagina behind the urethra inward female.
Actions of Urogenital diaphragm:
It provides back upwardly to prostate gland or the urinary bladder. Sphincter urethrae exert voluntary command to micturition. It equally good constricts the vagina inward female.
Perineal Membrane
The inferior layer of fasica of urogenital diaphragm is known equally Perineal membrane. Thus the perineal membrane is a sparse sail of tough deep fascia stretching betwixt the ii sides of the pubic arch as well as covers the anterior business office of the pelvic outlet. Immediately superior to the perineal membrane (on its superior surface) runs the deep transverse perineal mjuscles along the posterior appear of the membrane. Above the middle of the membrane, the external urethral sphincter surrounds the urethra.
Perineal Pouches
Superficial Perineal Pouch
The superficial perineal puch is a potential infinite betwixt the membranous layer of perineal fascia as well as the perineal membrane.
Contents of superficial perineal pouch in Male:
Root (bulb as well as crura) of the penis as well as the muscles associated amongst it (ischiocavernous as well as bulbospongiosus)
Proximal business office of spongy urethra
Superficial transverse perineal muscles
Branches of internal pudendal artery
Posterior scrotal branches of the perieneal branch
Transverse perineal branches of the perieneal branch
Posterior scrotal branch of Perineal branch of the pudendal nerves
Perineal branch of posterior cutaneous nervus of thigh
Contents of superficial perineal pouch in Female:
Root (crura) of the clitoris as well as musculus associated amongst it (ischiocavenous)
Bulbs of the lobby as well as surrounding musculus (bulbospongiosus)
Superficial transverse perineal muscles
Branches of the internal pudendal artery
Posterior labial branches of the perieneal branch
Transverse perineal branches of the perieneal branch
Posterior labial branch of Perineal branch of the pudendal nerves
Perineal branch of posterior cutaneous nervus of thigh
Greater vestibular glands
Deep Perineal Pouch
The deep perineal pouch is the infinite betwixt the superior as well as inferior layers of fascia of urogenital diaphragm.
Contents of deep perineal pouch inward Males:
Intermediate or membranous business office of manlike mortal urethra
External urethral sphincter muscles
Bulbourethral glands
Deep transverse perineal muscles
Related vessels
Deep artery of penis
Dorsal artery of penis
Artery to bulb of penis
Urethral artery
Dorsal nervus of penis
Contents of deep perineal pouch inward Females:
Proximal business office of urethra
External urethral sphincter muscle
Deep transverse perineal muscles
Related vessels as well as nerves
Deep artery of clitoris
Dorsal artery of clitoris
Artery to bulb of vestibule
Urethral artery
Dorsal nervus of clitoris
REFERENCES:
Following resources are used spell preparing this post service (readers are strongly recommended to become through them for to a greater extent than details):
Gray's Anatomy
K. L. Moore's Clinically Oriented Anatomy
R. Snell's Clinical Anatomy