Anatomy of the Pelvic Wall and Cavity

Hello everyone, this is Dr. Adel Bondok, professor of anatomy and neuroscience, Mansoor University, Egypt. Today I will talk about the pelvic wall and the pelvic cavity. So, let's start by the pelvic wall. The pelvic wall is formed of bones, joints, ligaments, membranes and muscles. Regarding the bones, we have four bones, two hip bones, sacrum and the coccyx regarding the joints between the bones we have the pubic symphysis the lumbosacral joint the sacro coccygeal joint and the sacroiliac joint then we have ligaments fixing the hip bone with the sacrum sacro tuberous ligament and the sacrospinous ligament and we have membranes these membranes closing the obturator membrane obturator membrane and the perineal membrane closing the sub-pubic space. And then we have four muscles. Four muscles, two on the side wall of the pelvis, piriformis and obturator internus, and two in the pelvic floor, levator and coccygeus, and they are called the pelvic diaphragm. So this is the wall of the pelvis. Regarding the bones, two hip bones, sacrum and coccyx. the joints pubic symphysis between the two hip bones sacroiliac joint between the sacrum and ilium lumbosacral between the sacrum and l5 and the sacrococcygeal between the sacrum and the coccyx we have two ligaments one between the sacrum and hip bone secret tuberous and one between the ischial spine and sacrum sacrospinous ligament we have two membranes obturator membrane closing the the opti rate of riemann and the period membrane closing the subpubic space or subpubic angle and we have four muscles two on the side wall of the pelvis and two in the pelvic floor these are the ligaments sacrospinous ligament between the sacrum and the ischial spine and and the sacro-tuborous ligament between the ischial tuberosity and the sacrum. then the anatomical position of the pelvis regarding the anatomical position of the pelvis this is the anterior superior iliac spine and this is the pubic symphysis the anterior superior iliac spine and the pubic symphysis are on the same vertical plane and the upper border of the pubic symphysis and the tip of the coccyx on the same horizontal plane so anatomically the anterior severe elect spine and the pubic symphysis are the same vertical plane and the upper border of the pubic symphysis and the tip of the coccyx are on the same horizontal plane regarding the sacrum the sacrum is formed of five pieces and these five pieces are fused together and are separated by the anterior sacral foramina for anterior sacral foramina the first piece of the sacrum the body of the first piece this is the first piece of the sacrum the body of the first piece is projecting anterior to form the poromontory this poromontory is more projecting in the male than in the female and the lateral mass is called the ela of the sacrum This is the back of the sacrum and these are the posterior sacral foramina and in the midline we have median sacral crest and at the lower end of the sacrum there is a hiatus called the sacral hiatus and here the sacral canal okay then we'll talk about the articulation of the sacrum the sacrum articulates with l5 this is a lumbosacral joint articulates with the coccyx this is the sacrococcygeal joint and articulates with the ilium of the bone this is the sacroiliac joint so remember the midline joints midline joints are secondary cartilaginous joints so lumbosacral joint with l5 and it is secondary cartilaginous joint sacrococcygeal joint with the coccyx and it is also secondary cartilaginous joint sacroilgic joint is with the ilium of the hip bone and it is plain synovial joint it permits gliding or sliding movement Then this is the pelvic surface of the sacrum. You should know the anterior relations of the pelvic surface of the sacrum. So the pelvic surface of the sacrum is related to many structures. First one muscles. We have three muscles. One attached to the ilia of the sacrum. This is the iliacus. And one attached to the middle three pieces of the sacrum, the piriformis. and one attached to the last piece of the sacrum, the coccygeus. Then artery, nerve, artery, nerve. Artery in the midline, this is the median sacral artery ending by glomus coxigeum. Then laterally, sympathetic chain, and these are the sympathetic ganglia. The two sympathetic chains fuse to form one ganglion called ganglion impar. Then arteries entering the sacral canal, lateral sacral arteries. Then nerves coming out of the sacral canal, the ventral rimai of the upper fourth sacral nerves. Then the ilia of the sacrum is related to two nerves and one artery, the two nerves, lumbosacral trunk. obturator nerve and iliolumbar artery and in front of the last three pieces of the sacrum the rectum so the sacrum is related anteriorly to three muscles iliagus, piriformis coccygeus three arteries Median sacral artery, lateral sacral arteries and iliolumbar artery, four nerves, sympathetic chain, ventral rami of the upper four sacral nerves, lumbosacral trunk and obturator. and then the viscera, the rectum in front of the last lower three pieces of the sacrum and the relation of the ili of the sacrum, iliacus and lumbosacral trunk, obturator nerve and iliolumbar artery. This is the sacral hiatus. Sacral hiatus. It permits the passage of phylum terminale, which is the continuation of the pia mater, the fifth sacral nerve, and the coccygeal nerve. This sacral hiatus is important clinically because you can insert anesthetics through the sacral hiatus to perform epidural anesthesia and this type of anesthesia is called caudal anesthesia. We have four main differences between male sacrum and female sacrum. The female sacrum is shorter and wider, the male is longer and narrower. The promontory is less prominent in the female sacrum. male, more prominent in the male. The female sacrum is curved, sharply curved at S3. The male sacrum is nearly straight, and the articular surface in the female reaches S2, in the male reaches S3. Then the sacral canal, this is the sacral canal. It doesn't permit the passage of the spinal cord because the spinal cord ends at the lower level of L1. So what are the contents? of the sacral canal. First content is this red filament phylum terminale which is a continuation of the pia mater. Then these nerve roots sacral and coccygeal nerve roots called the coda equina coda equina similar to the horse tail coda equina and then dura and arachnoid matter dura and arachnoid descend in the sacral canal till sc2 so this the dural sac ends at sc2 then branches of the lateral sacral arteries venous plexus and fat again this is the the secret canal And these are the contents of the sacral canal. But before talking about the contents, this is the lower end of the spinal cord called the conus medullaris opposite lower border of L1. And this is the sacral canal phylum terminale. then these nerve roots called the cauda equina then the dura and the arachnoid this is the dura matter this is the arachnoid matter they end opposite SC2 branches of lateral sacral arteries venous plexus and fat these are the ligaments sacro-tubulus ligament and the sacrospinous ligament these two ligaments are very important because they fix the sacrum to the hip bone they fix the sacrum to the hip bone and they prevent tilting of the sacrum by the effect of the body weight We have four muscles in the wall of the pelvis. Two on the side wall of the pelvis and two in the floor of the pelvis. The two muscles on the side wall of the pelvis, this is the piriformis muscle in front of the sacrum. and this is the obturator internus on the inner surface of the obturator membrane. So, piriformis in front of the sacrum, obturator internus on the inner surface of the obturator membrane. We have two muscles. closing the pelvic outlet forming the pelvic diaphragm levator in eye this one levator in eye and the coccygeus muscle this one so the four muscles are two on the side wall of the pelvis piriformis and obturator internus two in the pelvic floor called the pelvic diaphragm levator in eye and coccygeus so the pelvic diaphragm is formed mainly by the levator in eye This is the rectum, this is the anal canal, this is a coronal section. So this is the pelvic floor, pelvic floor, pelvic diaphragm. And this is the side wall of the pelvis. This muscle is obturator internus, obturator internus, and this muscle is the levator. levator and eye forming the pelvic diaphragm. This is the obturator internus. Okay, obturator internus by reformus, levator and eye coxaegeus. This is the obturator internus. The obturator internus is covered by a fascia called obturator fascia. This obturator fascia is thickened to form the white line. This white line gives origin to levator and eye. And this obturator fascia splits to form the pudendal canal. So we have two features in the obturator fascia, white line and the pudendal canal. White line is thickening in the obturator. and gives origin to levator ani and the pudendal canal splitting of the obturator fascia in the lateral wall of the ischiorictal fossa we'll talk about it later on this is the pelvic floor formed of two muscles this is the levator ani and this is the coccygeus this is the pelvic floor in the female this is the levator ani muscle formed of three parts We'll talk about it in another presentation. and this is the coccygeus. So the pelvic floor, pelvic diaphragm is formed of two muscles, mainly by the levator in the eye and coccygeus muscle, assisted by the coccygeus muscle. It is a rudimentary muscle in man. So we finished with the wall of the pelvis, now let us talk about the pelvic cavity. The pelvic cavity has inlet and outlet. Between the inlet and outlet there is a cavity, the space. So let us talk about the pelvic inlet. Pelvic inlet, the boundaries, it is bounded anteriorly by the upper border of the pubic symphysis. it is bounded posteriorly by the promontory and the ala of the sacrum on each side this line is called the iliopectineal line so the boundaries of the pelvic inlet anteriorly upper border of the pubic symphysis posteriorly promontory of the sacrum and the ala of the sacrum on each side iliopectineal line again this is the pelvic inlet it is also called the pelvic brim so what is pelvic brim pelvic brim is the pelvic inlet anteriorly it is the upper border of the pubic symphysis posteriorly it is the sacral promontory and ala of the sacrum on each side is the iliopectinial line this is the pelvic outlet pelvic outlet it is bounded anteriorly by the lower border of the pubic symphysis it is bounded posteriorly by the tip of the coccyx on each side anteriorly it is a pubic arch and posteriorly is a securitubris ligament So the boundaries of the pelvic outlet, anteriorly lower border of the pubic symphysis, posteriorly it is the tip of the coccyx, on each side the pubic arch anterior, securitubus ligament posterior. So the pubic symphysis shares in bounding the pelvic inlet and the pelvic outlet. and this is the pelvic cavity this is hip bone hip bone and this is the pelvic inlet the pelvic cavity is divided by the pelvic inlet into upper part and the lower part the upper part is called false pelvis and the lower part is called the true pelvis actually the false pelvis is part of the abdominal cavity and it contains abdominal organs and the true pelvis below the pelvic inlet It's called the true pelvis. So the true pelvis, which contains the pelvic organs, is located between pelvic inlet and the pelvic outlet. So between inlet and outlet is the true pelvis. This true pelvis contains the pelvic organs. What are the female pelvic organs? The female pelvic organs are the most posterior organ is the rectum. This one. So, Most anterior organ is the urinary bladder and in between this is the uterus. ovary, uterine tube and this canal it is the vagina. The female genital organs are, sorry, the female pelvic organs, rectum posterior, urinary bladder anterior, uterus, uterine ovary, uterine tube, vagina in the middle. So actually the rectum and urinary bladder are present in both males and females. Now the male pelvic organs. The most posterior organ again is the rectum. And the most anterior organ is the urinary bladder. Between the urinary bladder and rectum here, seminal vesicle and vas deferens. And below the urinary bladder is the prostate gland. So the male pelvic organs, rectum posterior, urinary bladder anterior, seminal vesicle and the vast difference in between and the prostate gland below the urinary bladder. And thank you very much, best wishes and good luck and see you again.

The pelvic wall is formed of bones, joints, ligaments, membranes and muscles. Regarding the bones, we have four bones, two hip bones, sacrum and the coccyx regarding the joints between the bones we have the pubic symphysis the lumbosacral joint the sacro coccygeal joint and the sacroiliac joint then we have ligaments fixing the hip bone with the sacrum sacro tuberous ligament and the sacrospinous ligament and we have membranes these membranes closing the obturator membrane obturator membrane and the perineal membrane closing the sub-pubic space. And then we have four muscles.

Four muscles, two on the side wall of the pelvis, piriformis and obturator internus, and two in the pelvic floor, levator and coccygeus, and they are called the pelvic diaphragm. So this is the wall of the pelvis. Regarding the bones, two hip bones, sacrum and coccyx.

the joints pubic symphysis between the two hip bones sacroiliac joint between the sacrum and ilium lumbosacral between the sacrum and l5 and the sacrococcygeal between the sacrum and the coccyx we have two ligaments one between the sacrum and hip bone secret tuberous and one between the ischial spine and sacrum sacrospinous ligament we have two membranes obturator membrane closing the the opti rate of riemann and the period membrane closing the subpubic space or subpubic angle and we have four muscles two on the side wall of the pelvis and two in the pelvic floor these are the ligaments sacrospinous ligament between the sacrum and the ischial spine and and the sacro-tuborous ligament between the ischial tuberosity and the sacrum. then the anatomical position of the pelvis regarding the anatomical position of the pelvis this is the anterior superior iliac spine and this is the pubic symphysis the anterior superior iliac spine and the pubic symphysis are on the same vertical plane and the upper border of the pubic symphysis and the tip of the coccyx on the same horizontal plane so anatomically the anterior severe elect spine and the pubic symphysis are the same vertical plane and the upper border of the pubic symphysis and the tip of the coccyx are on the same horizontal plane regarding the sacrum the sacrum is formed of five pieces and these five pieces are fused together and are separated by the anterior sacral foramina for anterior sacral foramina the first piece of the sacrum the body of the first piece this is the first piece of the sacrum the body of the first piece is projecting anterior to form the poromontory this poromontory is more projecting in the male than in the female and the lateral mass is called the ela of the sacrum This is the back of the sacrum and these are the posterior sacral foramina and in the midline we have median sacral crest and at the lower end of the sacrum there is a hiatus called the sacral hiatus and here the sacral canal okay then we'll talk about the articulation of the sacrum the sacrum articulates with l5 this is a lumbosacral joint articulates with the coccyx this is the sacrococcygeal joint and articulates with the ilium of the bone this is the sacroiliac joint so remember the midline joints midline joints are secondary cartilaginous joints so lumbosacral joint with l5 and it is secondary cartilaginous joint sacrococcygeal joint with the coccyx and it is also secondary cartilaginous joint sacroilgic joint is with the ilium of the hip bone and it is plain synovial joint it permits gliding or sliding movement Then this is the pelvic surface of the sacrum. You should know the anterior relations of the pelvic surface of the sacrum. So the pelvic surface of the sacrum is related to many structures.

First one muscles. We have three muscles. One attached to the ilia of the sacrum. This is the iliacus.

And one attached to the middle three pieces of the sacrum, the piriformis. and one attached to the last piece of the sacrum, the coccygeus. Then artery, nerve, artery, nerve. Artery in the midline, this is the median sacral artery ending by glomus coxigeum.

Then laterally, sympathetic chain, and these are the sympathetic ganglia. The two sympathetic chains fuse to form one ganglion called ganglion impar. Then arteries entering the sacral canal, lateral sacral arteries.

Then nerves coming out of the sacral canal, the ventral rimai of the upper fourth sacral nerves. Then the ilia of the sacrum is related to two nerves and one artery, the two nerves, lumbosacral trunk. obturator nerve and iliolumbar artery and in front of the last three pieces of the sacrum the rectum so the sacrum is related anteriorly to three muscles iliagus, piriformis coccygeus three arteries Median sacral artery, lateral sacral arteries and iliolumbar artery, four nerves, sympathetic chain, ventral rami of the upper four sacral nerves, lumbosacral trunk and obturator.

and then the viscera, the rectum in front of the last lower three pieces of the sacrum and the relation of the ili of the sacrum, iliacus and lumbosacral trunk, obturator nerve and iliolumbar artery. This is the sacral hiatus. Sacral hiatus.

It permits the passage of phylum terminale, which is the continuation of the pia mater, the fifth sacral nerve, and the coccygeal nerve. This sacral hiatus is important clinically because you can insert anesthetics through the sacral hiatus to perform epidural anesthesia and this type of anesthesia is called caudal anesthesia. We have four main differences between male sacrum and female sacrum. The female sacrum is shorter and wider, the male is longer and narrower. The promontory is less prominent in the female sacrum.

male, more prominent in the male. The female sacrum is curved, sharply curved at S3. The male sacrum is nearly straight, and the articular surface in the female reaches S2, in the male reaches S3.

Then the sacral canal, this is the sacral canal. It doesn't permit the passage of the spinal cord because the spinal cord ends at the lower level of L1. So what are the contents? of the sacral canal.

First content is this red filament phylum terminale which is a continuation of the pia mater. Then these nerve roots sacral and coccygeal nerve roots called the coda equina coda equina similar to the horse tail coda equina and then dura and arachnoid matter dura and arachnoid descend in the sacral canal till sc2 so this the dural sac ends at sc2 then branches of the lateral sacral arteries venous plexus and fat again this is the the secret canal And these are the contents of the sacral canal. But before talking about the contents, this is the lower end of the spinal cord called the conus medullaris opposite lower border of L1. And this is the sacral canal phylum terminale. then these nerve roots called the cauda equina then the dura and the arachnoid this is the dura matter this is the arachnoid matter they end opposite SC2 branches of lateral sacral arteries venous plexus and fat these are the ligaments sacro-tubulus ligament and the sacrospinous ligament these two ligaments are very important because they fix the sacrum to the hip bone they fix the sacrum to the hip bone and they prevent tilting of the sacrum by the effect of the body weight We have four muscles in the wall of the pelvis.

Two on the side wall of the pelvis and two in the floor of the pelvis. The two muscles on the side wall of the pelvis, this is the piriformis muscle in front of the sacrum. and this is the obturator internus on the inner surface of the obturator membrane. So, piriformis in front of the sacrum, obturator internus on the inner surface of the obturator membrane. We have two muscles.

closing the pelvic outlet forming the pelvic diaphragm levator in eye this one levator in eye and the coccygeus muscle this one so the four muscles are two on the side wall of the pelvis piriformis and obturator internus two in the pelvic floor called the pelvic diaphragm levator in eye and coccygeus so the pelvic diaphragm is formed mainly by the levator in eye This is the rectum, this is the anal canal, this is a coronal section. So this is the pelvic floor, pelvic floor, pelvic diaphragm. And this is the side wall of the pelvis. This muscle is obturator internus, obturator internus, and this muscle is the levator. levator and eye forming the pelvic diaphragm.

This is the obturator internus. Okay, obturator internus by reformus, levator and eye coxaegeus. This is the obturator internus.

The obturator internus is covered by a fascia called obturator fascia. This obturator fascia is thickened to form the white line. This white line gives origin to levator and eye. And this obturator fascia splits to form the pudendal canal.

So we have two features in the obturator fascia, white line and the pudendal canal. White line is thickening in the obturator. and gives origin to levator ani and the pudendal canal splitting of the obturator fascia in the lateral wall of the ischiorictal fossa we'll talk about it later on this is the pelvic floor formed of two muscles this is the levator ani and this is the coccygeus this is the pelvic floor in the female this is the levator ani muscle formed of three parts We'll talk about it in another presentation.

and this is the coccygeus. So the pelvic floor, pelvic diaphragm is formed of two muscles, mainly by the levator in the eye and coccygeus muscle, assisted by the coccygeus muscle. It is a rudimentary muscle in man.

So we finished with the wall of the pelvis, now let us talk about the pelvic cavity. The pelvic cavity has inlet and outlet. Between the inlet and outlet there is a cavity, the space.

So let us talk about the pelvic inlet. Pelvic inlet, the boundaries, it is bounded anteriorly by the upper border of the pubic symphysis. it is bounded posteriorly by the promontory and the ala of the sacrum on each side this line is called the iliopectineal line so the boundaries of the pelvic inlet anteriorly upper border of the pubic symphysis posteriorly promontory of the sacrum and the ala of the sacrum on each side iliopectineal line again this is the pelvic inlet it is also called the pelvic brim so what is pelvic brim pelvic brim is the pelvic inlet anteriorly it is the upper border of the pubic symphysis posteriorly it is the sacral promontory and ala of the sacrum on each side is the iliopectinial line this is the pelvic outlet pelvic outlet it is bounded anteriorly by the lower border of the pubic symphysis it is bounded posteriorly by the tip of the coccyx on each side anteriorly it is a pubic arch and posteriorly is a securitubris ligament So the boundaries of the pelvic outlet, anteriorly lower border of the pubic symphysis, posteriorly it is the tip of the coccyx, on each side the pubic arch anterior, securitubus ligament posterior. So the pubic symphysis shares in bounding the pelvic inlet and the pelvic outlet. and this is the pelvic cavity this is hip bone hip bone and this is the pelvic inlet the pelvic cavity is divided by the pelvic inlet into upper part and the lower part the upper part is called false pelvis and the lower part is called the true pelvis actually the false pelvis is part of the abdominal cavity and it contains abdominal organs and the true pelvis below the pelvic inlet It's called the true pelvis.

So the true pelvis, which contains the pelvic organs, is located between pelvic inlet and the pelvic outlet. So between inlet and outlet is the true pelvis. This true pelvis contains the pelvic organs. What are the female pelvic organs? The female pelvic organs are the most posterior organ is the rectum.

This one. So, Most anterior organ is the urinary bladder and in between this is the uterus. ovary, uterine tube and this canal it is the vagina. The female genital organs are, sorry, the female pelvic organs, rectum posterior, urinary bladder anterior, uterus, uterine ovary, uterine tube, vagina in the middle.

So actually the rectum and urinary bladder are present in both males and females. Now the male pelvic organs. The most posterior organ again is the rectum.

And the most anterior organ is the urinary bladder. Between the urinary bladder and rectum here, seminal vesicle and vas deferens. And below the urinary bladder is the prostate gland. So the male pelvic organs, rectum posterior, urinary bladder anterior, seminal vesicle and the vast difference in between and the prostate gland below the urinary bladder. And thank you very much, best wishes and good luck and see you again.

Transcript for:Anatomy of the Pelvic Wall and Cavity

Transcript for:
Anatomy of the Pelvic Wall and Cavity