Quiz 15

inferior tip of the coccyx

"shelf"

labia majora

(homolog: crus of the penis)

superficial perineum

-scrotum is part of the superficial pernieum The superficial perineum is skin covering the perineum. It is the object of perineal care

pelvic outlet

15 degrees to horizontal Not flat - from inferior edge of pubic symphysis laterally to ischial tuberosities medially to the top of the coccyx -levator ani forms anatomical barrier here The pelvic outlet is defined by a line extending laterally from the inferior edge of the pubic symphysis to the left and right ischial tuberosities and then medially to tip of the coccyx. This is not a flat surface as the pelvic inlet is. It is about 15 degrees from the horizontal.

levator ani muscle

3 muscles combined but just need to know levator ani: -iliococcygeus -pubococcygeus -puborectalis gives minimal support to urogenital organs Nerve: S3, S4, and inferior rectal nerve (branch of pudendeal nerve) *Origin*: Inside pelvis from pubis to ischial spine *Insertion*: Deep surface of coccyx, levator ani from other side and structures passing through it *Action*: Supports pelvic viscera, lifts anal canal, forms sphincters for vagina and at anorectal junction The levator ani is primarily skeletal muscle, and is, therefore, under conscious control. It forms the anterior portion of the pelvic diaphragm and it is by far the majority of that diaphragm. Some anatomists consider the external sphincter ani to be part of the levator ani, while others consider it a separate structure. The levator ani provides minimal support to the urogenital organs. It also supports pelvic viscera, lifts anal canal, and forms a sphincter for the vagina. We will consider it to be one muscle. However, technically it is made, up of three muscles, the iliococcygeus, pubococcygeus, and puborectalis.

pelvic inlet

60 degrees to horizontal Relatively flat -may be called pelvic brim -from superior edge of pubic symphysis laterally to the iliopectineal (arcuate line or linea terminalis) line to sacral promontory -no anatomical barrier here (between abdomin & pelvis) The pelvic inlet is not an anatomical barrier, but rather an artificial surface separating the abdomen from the pelvis. Anteriorly it begins at the superior surface of the pubic symphysis and moves laterally along the iliopectineal line and then posteriorly to the sacral promontory. This is a relatively flat surface that is about 60 degrees from horizontal

arcuate line

Arcuate means shaped like an arch or bow. See iliopectineal line

sphincter ani

Has two parts: - internal sphincter ani (smooth muscle- part of anal canal wall) - external sphincter ani - three parts (skeletal muscle- often considered part of levator ani) *voluntary control*

vestibule

In cats the vestibule is a urogential sinus that forms where the vagina and urethra converge. In humans the vestibule is external to the urethra and vagina. Technically it is a space or cavity that serves as an entrance to a passageway.

1.5 inches

In females the distance from the urinary bladder to the urogenital diaphragm (greater distance for males due to prostate gland)

prostate gland

In truth, there is not one prostate gland, but rather 30 to 40 glands with many ducts (quack) that empty into the urethra. It is an accessory structure. The prostate fluid makes the semen less viscous so that it is easier to pump, as well as provide a number of essential materials that increase the likelihood that the spermatozoa will be successful in their journey to the oviduct. The prostate fluid makes up about 33% of the volume of the semen. We will expand on this information in lecture

gluteus maximus

Origin Gluteal surface of ilium, lumbar fascia, sacrum, sacrotuberous ligament Insertion Gluteal tuberosity of the femur and iliotibial tract Artery Superior and inferior gluteal arteries Nerve Inferior gluteal nerve (L5, S1 and S2 nerve roots) Actions External rotation and extension of the hip joint, supports the extended knee through the iliotibial tract, chief antigravity muscle in sitting and abduction of the hip Antagonist Iliacus, psoas major and psoas minor

transverse perineal muscle

Origin Inferior rami of the ischium Insertion The deep transverse perineal muscle of the opposite side Nerve Pudendal nerve

obturator internus muscle

Origin Ischiopubic ramus & obturator membrane Insertion Medial aspect of the greater trochanter Artery inferior gluteal artery Nerve Nerve to obturator internus (L5, S1, S2) Actions Abducts & laterally rotates the extended hip and abducts the flexed thigh at the hip, and stabilizes the hip during walking

60 degrees from horizontal

Pelvic inlet

15 degrees from horizontal

Pelvic outlet

anal canal

The anal canal is the most terminal part of the lower GI tract/large intestine, which lies between the anal verge (anal orifice, anus) in the perineum below and the rectum above

anterior urogenital triangle

The anterior urogenital triangle is defined by a line to each of the ischial tuberosities from the inferior end of the pubic symphysis as well as a line between the ischial tuberosities. This is where the urogenital arch is found

cervix

The cervix is a canal between the vagina and the body of the uterus and is considered to be part of the uterus. It produces mucus that fills the cavity, which presumably is helpful in preventing bacteria from entering the uterus. This mucus is an obstacle to spermatozoa, but during the mid cycle it becomes less viscous, thereby allowing spermatozoa to swim into the uterus

coccygeus muscle

The coccygeus is primarily skeletal muscle, and is, therefore, under conscious control. It forms the posterior portion of the pelvic diaphragm and is a small part of that diaphragm. It provides support for the pelvic viscera and the coccyx, and pulls the coccyx anteriorly after childbirth and defecation. Normally the coccyx moves posteriorly during childbirth and defecation

iliopectineal line

The iliopectineal line divides the false pelvis from the true pelvis. It forms part of the pelvic inlet or pelvic brim. Part of it is on the pubic bone just posterior to the pubic symphysis and part is on the ilium extending posteriorly toward the sacral promontory. It is also called the arcuate line

ilium

The ilium is the uppermost and largest region of the coxal bone

peritoneum

The peritoneum forms two abdominal organs, the greater omentum and the lesser omentum, that are primarily made of epithelial cells. They secrete a serous fluid that lubricates and reduces heat buildup. The peritoneum covers the abdominal wall (parietal peritoneum) as well as the organs (visceral peritoneum). The mesentery is peritoneum, as is the broad ligament of the uterus. The pleura of the thoracic cavity is much like the peritoneum

posterior anal triangle

The posterior anal triangle is defined by a line between the ischial tuberosities and a line from each ischial tuberosity to the coccyx. This is the area where the anus is found.

pubic symphysis

The pubic symphysis is a secondary cartilaginous joint (a joint made of hyaline cartilage and fibrocartilage) located between the left and right pubic bones near the midline of the body. More specifically, it is located above any external genitalia and in front of the bladder. The pubic symphysis can be found above the penis in males and above the vulva in females. In males, the joint connects to the ligament of the penis. In females, the joint is located near the clitoris

rectouterine pouch

The rectouterine pouch is a fold of the peritoneum that extends inferiorly between the rectum and the uterus. It sometimes fills with debris consisting mostly of dead cells. Sometimes, intraperitoneal infections lead to the accumulation of pus and blood in this pouch

rectovesical pouch

The rectovesical pouch is a fold of the peritoneum that extends inferiorly between the rectum and the urinary bladder. It sometimes fills with debris consisting mostly of dead cells. Sometimes, intraperitoneal infections lead to the accumulation of pus and blood in this pouch

sacral promontory

The sacral promontory is the anterior and superior margin of the first sacral vertebra. It forms the posterior portion of the pelvic inlet

scrotum

The scrotum is the sac that surrounds the testicle and part of the spermatic cord. It includes the dartos muscle that aids in thermoregulation of the testicle. There is a septum that provides for a separate space for each testicle

urinary bladder

The urinary bladder is a muscular sac in the pelvis, just above and behind the pubic bone. When empty, the bladder is about the size and shape of a pear. Urine is made in the kidneys, and travels down two tubes called ureters to the bladder. The bladder stores urine, allowing urination to be infrequent and voluntary

urogenital sinus

The urogenital sinus is a cavity through which both urinary and genital products may pass. The urogenital sinus of humans is found during the developmental stages of both sexes. It does not persist as a specific cavity after birth in humans, but does persist in females of other mammals. In humans it gives rise to part of the male urethra and in females part of the vagina, urethra, and vestibule.

vesicouterine pouch

The vesicouterine pouch is a fold of the peritoneum that extends inferiorly between the urinary bladder and the uterus. It sometimes fills with debris consisting mostly of dead cells. Sometimes, intraperitoneal infections lead to the accumulation of pus and blood in this pouch.

urethra

This is the duct that transports urine from the urinary bladder to the outside

ischial tuberosity

We sit on them!

homolog

a homologous structure have the same origin in the embryo, but may have very different outcomes in the adult. 3 homologous structures in the perineum: 1. clitoris/penis 2. the crus of the penis/labium majora 3. bulb of the penis/two labia minora

perineum

a space from the pelvic diaphragm to the surface of the skin superior boundary: pelvic outlet all structures in this space are included as part of the perineum The perineum is a space from the pelvic diaphragm to the surface of the skin. Its superior boundary is the pelvic outlet. All structures in this space are included as part of the perineum. Perineal care is usually cleaning the surface (skin)

sacrum

a triangular bone in the lower back formed from fused vertebrae and situated between the two hipbones of the pelvis

acetabulum

ball & socket joint Three bones meet in this structure The acetabulum is the hip socket, which forms a ball and socket joint with the head of the femur. It is part of the os coxa.

bulbospongiosus muscle

bulb of the penis is attached to the urogential diaphragm by the bulbospongiosus muscle

bulb

bulb of the penis is attached to the urogential diaphragm by the bulbospongiosus muscle Occasionally the bulb does not completely close- urethra empties directly to the outside (bulb is two pieces in development but should fuse before birth- if not urethra would empty right to outside...this condition can be corrected by surgery) (bulb of the penis homolog: two labia minora) The bulb of the penis is formed from the fusion of the two portions of the corpus spongiosum prior to birth. It is anchored to the perineal membrane, which is part of the urogenital diaphragm

os coxa (coxae)

composed of ilium, ischium & pubis AKA pelvic bone or innominate bone Fuse when 20-25 yrs old

innominate bone

composed of ilium, ischium & pubis AKA pelvic bone or os coxa (coxae) Fuse when 20-25 yrs old

perineal body

cut during episiotomy The perineal body is skin, connective tissue and some skeletal muscle tissue between the vagina and the rectum in females and between the scrotum and the rectum in males. This is the area most often cut when a woman is given an episiotomy.

episiotomy

cuts the perineal body normally about 2 inches in length -it may be midline (most common) -may be mediolateral (off to the side) -classified as a second degree tear An episiotomy is a surgical procedure performed on the perineal body or the adjacent area with the intent of reducing stress during childbirth on the infant. Recent research suggests that more often than not damage is done to the mother and the infant receives no significant benefit

pubis

either of a pair of bones forming the two sides of the pelvis

corpus spongiosum

erectile cylinder houses urethra There is one corpus spongiosum. It is an erectile cylinder on the anterior side of the shaft of the penis. It houses the urethra and ends distally as the glans penis. Proximally it is continuous with the bulb of the penis, which is anchored to the urogenital diaphragm by the bulbospongiosus muscle

corpus cavernosum

erectile cylinder (2) attached by muscle to the pelvis (follow the crus...it becomes this!) There are two corpora cavernosa. They are highly vascular erectile cylinders on the posterior side of the shaft of the penis. Proximally they are continuous with the crura of the penis, which are anchored to the pubic arch by the ischiocavernosus muscles. In the female there are also two corpora cavernosa. They are the only erectile cylinders in the clitoris and they are responsible for the erection of the clitoris during arousal. Proximally they are continuous with the labia majora

vagina

females have, males do not have a comparable structure. although they have the same tissue just in a different space potential space The vagina is a structure unique to females. It is an accessory sex organ in that it receives the penis during intercourse and is where semen is normally deposited. Part of it is derived from the urogenital sinus of the embryo. It is described by many authors as a potential space and is approximately 3 inches in length. Its walls have rugae that help in expansion without a huge increase in pressure during childbirth. It is an excretion duct for the uterus as well as being part of the birth canal. The inferior half is in the perineum, while the superior half is in the pelvis. The epithelial cells lining the vagina release glycogen into the lumen. This carbohydrate undergoes bacterial fermentation which produces lactic acid. The lactic acid discourages harmful bacteria but also is harmful to spermatozoa.

urogenital diaphragm

in the anterior urogenital triangle supports the urogenital organs - they attach to it (by a muscle) Kegel exercises are recommended to strengthen the levator ani muscles - helps prevent uterine prolapse bulb of the penis is attached to the urogential diaphragm by the bulbospongiosus muscle The urogenital diaphragm is a triangular musculofascial sheet found in the anterior urogenital triangle. It provides support for the urogenital organs that attach to it by means of the bulbospongiosus muscle. Included within the muscle is the external urethral sphincter and in the female it surrounds the vagina

funnel shaped pelvic inlet

male and prepubescent female pelvic cavity

heart shaped pelvic inlet

male and prepubescent female pelvic cavity

narrow oval pelvic outlet

male and prepubescent female pelvic cavity

narrow pubic arch (50-60 degrees)

male and prepubescent female pelvic cavity

clitoris

only has the two corpora cavernosa in it (not the corpus spongiosum) these two cylinders are responsible for erection of the clitoris (homolog:penis)

superior edge of pubic symphysis

pelvic inlet is measured from here to the iliopectineal line to sacral promontory

inferior edge of pubic symphysis

pelvic outlet is measured from here to ischial tuberosities medially to the tip of the coccyx

cylinder shaped pelvic cavity

post pubescent female pelvic cavity

round pelvic outlet

post pubescent female pelvic cavity

wide oval pelvic inlet

post pubescent female pelvic cavity

wide pubic arch (80-85 degrees)

post pubescent female pelvic cavity

pelvic brim

see pelvic inlet

ischiocavernosus muscle

the crura of the penis are anchored to the ischium by the ischiocavernosus muscle- they help pump semen out of the urethra too anchors the crura to the ischium

crus (crura)

the crura of the penis are anchored to the ischium by the ischiocavernosus muscle- they help pump semen out of the urethra too (crus of the penis- homolog: labium majora) the crura of the penis. They are actually the proximal ends of the corpora cavernosa, and with the associated muscle (ischiocavernosus) anchor the penis to the pubic arch. In the female the same structures exist and they anchor the labia major to the pubic arch

ischium

the curved bone forming the base of each half of the pelvis

deep perineum

the deep perineum is the space between the pelvic diaphragm and the superficial perineum

labia minora

two (homolog: bulb of the penis)

pelvic diaphragm

two parts: 1. levator ani 2. coccygeus Extends across diamond shape of pelvic outlet Prevents organs from falling out The pelvic diaphragm is a muscular barrier at the inferior end of the pelvic cavity. It is primarily composed of the levator ani (the anterior portion) and to a lesser extent by the coccygeus muscle (posterior portion). This barrier helps support the pelvic and abdominal viscera. The urethra and vagina pass through an archway in the anterior portion of the levator ani (the urogenital arch) and the anal canal passes through the levator ani posteriorly

kegel (kiegel or pubococcygeus) exercises of the levator ani muscle

urogenital diaphragm- supports the urogenital organs - they attach to it (by a muscle) Kegel exercises are recommended to strengthen the levator ani muscles - helps prevent uterine prolapse Kegel exercises (pubococcygeus exercises) are designed to strengthen the muscles of the pelvic diaphragm and perineum. This helps prevent uterine prolapse as well as improve urinary bladder control. They are called elevator exercises because people often do them while they ride in elevators to pass the time.