ANATOMY (7). INTRODUCTION TO THE PELVIS. MOHAMMAD ALLOUH. BNB. 1 P a g e

Transcription

1 ANATOMY (7). INTRODUCTION TO THE PELVIS. MOHAMMAD ALLOUH. BNB 1 P a g e

2 Introduction to the Pelvis: Pelvic Wall & Pelvic Cavity pelvis (L, basin, sink ), is The region of the trunk that lies inferoposterior to abdomen & its cavity is continuous above with the abdominal cavity (abdominopelvic cavity). # physiological functions : 1- Bears the weight of upper body when standing or sitting on a chair ( because your body will be on a slope, so the whole weight of the body will not be on the lower limbs, it will be resting on the pelvis ). 2- Transmits weight from axial skeleton To lower appendicular skeleton During standing & walking. 3- Protects & supports pelvic viscera (i.e: Urinary Bladder, urethra, lower part of the ureter & internal. reprod. Organs: ovaries and uterus in female, seminal vesicles & prostate gland in males). 4- (imp) Provides attachments for muscles of:. locomotion (that produce the movement as you walk mainly the major flexors of the hip the iliopsoas that is attached to the iliac fossa, and extensors of the hip the gluteus attached to the iliac bone).. & posture (muscles of trunk) ext.oblique, int.oblique, transversus abdominis ). Why we said it s located inferioposterior to the abdomen: if you go through the thoracic cavity, abdominal cavity, and pelvic cavity you see its tilted backward a little bit, so it s not on the same side as the thoracic and abdominal cavities. 2 P a g e

3 the pelvis just like the thorax and the abdomen is made up of A WALL & A CAVITY. However, the main specialty in this type of walls is that it s mainly made by bones PELVIC GIRDLE and some muscle & some fascia & skin. Pelvic Wall: 1- Pelvic girdle (bony pelvis) made up of:.two HIP BONES,(anterolateral), each one is made of 3 bones: The V-shaped one is PUPIS. The L-shaped one is ISCHIAM. The largest one with a wing is ILIUM.. SACRUM & COCCYX (the tail bone), which are the two bones of the vertebral column posteriorly. The human body wall is made up of 4 imp structures: skin, fascia (superficial & deep), muscles and bones. You see specialty of one of these structures in each area you move, for ex: In the ABDOMEN the majority of its wall is made up by muscles and fascia. In the THORAX muscles and bones. In the PELVIS mainly by bones. 2- Pelvic Muscles (inferolat. Wall), they are imp in forming the floor of the pelvic cavity (the inferior wall of the pelvis), and some of the posterior & lateral wall. *P.S: the bones will be located all around anterior, lateral and posterior wall, while the inferior wall is mostly made of muscles. 3- Pelvic Fascia & Ligaments the deep fascia covering over the muscles (tough membranous fascia) the fascia will take the name of the muscle it covers. 3 P a g e

4 Pelvic cavity, divided into two areas, the greater and the lesser pelvis: 1- the greater (false) pelvis 2- the lesser (true) pelvis.the upper funnel-shaped area.called false because it s a misnomer.it s actually the lower part of the abdominal cavity.located between the two iliac wings within the iliac fossa. However it s not part of the pelvic cavity. the lower part (the inside part).. smaller # The real pelvic area that contains the pelvic viscera (UB, ureter, uterus ) #clinically has a major obstetrical & gynecological Significance. The light upper green area, that s wedged in btw the 2 iliac wings the darker lower green area, 4 P a g e

5 P.S: how to distinguish btw the false & the true pelvis?! By a bony landmark the pelvic brim.(the red dashed line). above the pelvic brim the false pelvis. below the pelvic brim the true pelvis. PELVIC BRIM: A bony edge (rim) that surrounds & define the PELVIC INLET (entrance to pelvis) and separates False from True pelvis. (Pelvic brim = pelvic inlet). Formed by: posteriorly Promontory & ala of sacrum. anteriorly Upper edge of symphysis pubis. laterally linea terminalis/iliopectineal line. iliopectineal line is made of 2 lines: (plz chick the pic in colors) 1- Arcuate line of ilium: that separate the body of the ilium from the wing of the ilium posteriolateral side of pelvic brim. 2- Pectineal line of the pubis: sup. Border of sup. Ramus & body of pubis. anteriolateral side of pelvic brim. # it s the line where the pectineal ligament of cooper is attached. # Also it s an attachment site (المشطية) for pectineus muscle Promontory means: the prominent part anteriorly of the upper margin of the first sacral vertebrae. Once you entered through the 1 st sacral vert. now you are in the true pelvis. At the level of L5 the false pelvis (abdominal cavity). 5 P a g e

6 How does the pectineal ligament form over the pectineal line? The inguinal ligament as it goes from anterior superior iliac spine all the way to the pubic tubercle, at the pubic tubercle, some of its fibers that reflected will separate again, and flatten to give the lacunar ligament. The lacunar ligament has a very sharp medial edge, that forms the medial border of femoral canal. Some of the fibers of the lacunar ligament will extend over the upper margin of the pubic bone (the superior pubic ramus), these fibers as they attach to the bone, they will form a linear elevation now it s called the pectineal ligament of cooper. 6 P a g e

7 The greater (false) pelvis: #Lower part of abdominal cavity that funnels in at its lower end to form the True pelvis. the lesser (true) pelvis: It has an inlet, outlet & cavity: (plz chick the pic below) 1- Pelvic inlet bounded by the pelvic brim. # BOUNDARIES: 2- pelvic outlet posteriorly the lumbar vertebrae ( mainly L5 & part of L4). Lat ischial tuberosity & laterally iliac fossae & iliacus muscle. Sacrotubular.lig Anteriorly the hypogastric region of the post tip of the coccyx anterior abdominal wall. # CONTENTS: lower abdominal viscera (ilium & colon) ant lower boarder of pubic arch If you want to draw the exact areas of pelvic outlet start from: tip of the coccyx to the ischial tuberosity (laterally) then anteriorly to the lower margin of pub,sym. Pelvic outlet (cont): some books refer to the sacrospinal ligament & sacrotubular ligament as part of the pelvic outlet. 7 P a g e

8 plz chick the pic again : ) this area in the pic (bounded by the red line) is the area of the true pelvis look, I m not gonna say it s the pelvic cavity now, it is the area of the true pelvis, this is the space within the true pelvis, remember this the doctor said. #the space of the true pelvis: Ant very shallow, demarcated by (upper & lower) borders of pubic symphysis. Post widen and deepen more & more to become the sacrum and the coccyx. Shallow anteriorly Deep posteriorly #clinical relations: (chick the pic above plz) usually in clinics, the obstetrician, when they ask you to determine the borders of pelvis you just draw a line to simplify first: a line from the promontory of the sacrum to the upper margin of pubic symphysis, that is : (the PELVIC INLET = the upper border of the true pelvis) Second: a line from tip of the coccyx to lower border of pubic symphysis, that s called: ( the PELVIC OUTLET = the lower border of the true pelvis ). Third: draw a curve line from midpoint of the pelvic inlet to the midpoint of the pelvic outlet, this curved line is called: (imp) (chick the pic in the following pg) 8 P a g e

9 (THE AXIS OF THE PELVIS ), it s very imp in obstetrics because, this is the bath that the child will take as it descends through the true pelvis during delivery. Another imp line is : the DIAGONAL CONJUCATE line: (diagonal means oblique) #from the promontory of the sacrum to the lower margin of the pub.sym. #it s around (5-inch/ 12-13cm) # during the vaginal examination (in pregnancy), when you insert your fingers with your thump attached to the pubic symphysis, your index finger should not reach the promontory of the sacrum. #If the diagonal conjugate was much shorter so you can palpate the promontory of the sacrum, this indicates that the true pelvis is narrow(contracted), this will lead to problems during delivery or labor, and by this the obstetrician may indicate cesarean section. So 2 important clinical landmarks: (remember them) 1- The axis of the pelvis. 2- The diagonal conjugate. 9 P a g e

10 4 diff shapes : The shape of the space of the true pelvis: 1. Gynecoid (like female): # Typical female pelvis #around half of females (41%) of females. # It s more wide laterally, than the anteriopost. dimension. 2. Android (has nth to do with the shape of gynacoid): # Typical male pelvis. #funnel-shaped & contracted outlet. #more common in white females. at transverse view looks heart-shaped at vertical (ant)veiw looks like a funnel 3. Anthropoid #long narrow oval shaped pelvis #more common in black women # more wide in anteriopost dimension. 4. Platypelloid (platy=plade, pelloid=like a pillow). #wide flattened pelvis. # v.rare less than 2% of women. In 1933 the two physician ( Caldwell and moloy) indicated the shapes of the true pelvis, into 4 diff shapes. Clinically imp because they determine the nature of delivery Gynecoid means like gynae (female) that s why we call it gynecology )علم النسائية ) 10 P a g e

11 Review, the bony pelvis or pelvic girdle it s composed of 4 bones: 2 hip bones sacrum coccyx we have 4 joints: 1) Anteriorly: which demarcating the border of the true pelvis, which is the symphysis pubis (or pubic symphysis). Pubic symphysis is a secondary cartilaginous joint; it is a cartilaginous because there is a fibro cartilaginous disc between the 2 pubic bones. This is a secondary cartilaginous joint between the 2 pubic bone anteriorly. (inside the circle) Why it is secondary not primary cartilaginous? The joint is 3 types: 1- Bone to bone with some collagen fibers, we call it fibrous. 2- Bone cartilage- bone, we call it cartilaginous (this joint is 2 types): A. Primary with no movement, like (xiphisternal joint). B. Secondary with limited movement, like (sternal angle). 11 P a g e

12 So, The pubic bones can move or they can a little bit spread from each other especially during delivery. the ligaments and the joints are very important because they provide a mechanism of expansion during delivery then the joints will get back togather again like spring ) الزنبرك )مثل, so it s a secondary cartilaginous not primary. 3- bone - space - bone, called synovial joint free range of movement (the types of the synovial joint regarding to the surfaces : saddle shape, gliding joint.. ) 2) Posteriorly: sacroiliac joint (right & left) important joint in expansion. it is a compound joint (2 joints): 1. Anteriorly : synovial joint, between iliac bone and sacrum, we call it the auricular surfaces like auricle,but this auricular is rough ),(خشن so its covered by articular cartilage that make smoothness. 2. Posteriorly: fibrous (sendesmosis). The fibrous have 2 types: 1- Fixed (suture). 2- Movable, the one that allow limited movement, called syndesmosis. so its combined joint. 12 P a g e

13 3) Posteroinferior: The sacro-coccygeal joint. something special about the bony girdle : in a LATERAL VIEW you will see it s tilted forward this tilting will make the: ant. surface facing ant.inf. post. Surface become post.sup. That s why when you look at the 2 nd pic you will see that the pelvis as it tilts, it will go a little bit post. ; (that s why the pelvic cavity is not in the same axis with the abd cavity, it s a little bit inf.post). This tilting will allow the ant.sup iliac spine to be in the same vertical plate with the upper margin of pubic symphysis. 13 P a g e

14 Anterior pelvic wall: #The shallowest #tilted forward #bears the weight of the visceral organs that lies on it (specially urinary bladder). #Formed by: 1-pubic bones (body & rami). 2- Symphysis pubis. #Bears the weight of urinary bladder. # The only separation btw the urinary bladder and the pubic bones is retropubic fat. (imp) So clinically any fracture or damage to the pubic bone or diastasis of the pubic sym (separation) that will lead most commonly to injury in the urinary bladder. so ant pelvic wall pubic bone & pubis sym. 14 P a g e

15 posterior pelvic wall: sacrum & coccyx & (imp) Piriformis muscle & fascia(piriformis facscia). Sacrum (sacred bone): Single wedge-shaped bone with forward concavity that formed by fusion of the 5 sacral vertebrae. -wider and less curved in female Coccyx (bird beak): Small triangular-shaped bone that formed by fusion of the 4 coccygeal Vertebrae. Piriformis (L, pear shaped) Origin: ant. surface of Sacrum, lat. To the sacral foramina. Passage: lat. through the greater sciatic foramen into the Gluteal Region so it goes from the true pelvis to the buttock region. Insertion: upper border of greater trochanter of femur. Action: lat. rotation of femur(thigh) at the hip joint. *it s an imp Landmark muscle of gluteal region: it separates the gtuteal reg. into superior and inferior compartments. So, Anterior pelvic wall are pubic symphysis & pubic bone. Posterior pelvic wall are sacrum, coccyx and piriformis. 15 P a g e

16 Now, Lateral pelvic wall : o Made of bony landmark, mostly part of the sacral and part of the ilium. o Along with these landmarks, Sacro-tuberous and sacrospinous ligaments are seen. o Obturator foramen covered by obturator membrane and it covers all the foramen except the superior par, called obturator canal (it allows the passage of veins, arteries and nerves). o Lateral wall formed of ischium, ilium bony component along with them the obturator internus muscle and the fascia covering it. 16 P a g e

17 Obturator internus muscle : o Originates from the inner surface of the obturator membrane and the bony margins of obturator foramen. Imp o It is a large muscle, form the most of the lateral wall of true pelvis. o From the origin point, it will move backward and converge (like triangle and it well give a small tendon) This tendon will leave the pelvis through lesser sciatic foramen Then it will turn at right angle laterally and move to obturator region (so it will move vertically and the tendon goes laterally) Then the tendon will accompanied with gemellus muscles into the medial border or surface of greater trochanter of the femur. So, this muscle is separated into upper and lower part by a thickening of the fascia covering it, coming from the pubic body to the ischial spine, this is called the tendinous arch 17 P a g e

18 In this picture you can see the greater sciatic foramen separated from greater sciatic foramen by sacrospinous ligament. You can see also the twin muscle ( the gemellus muscle) o Its action lateral rotation of the thigh. o Innervation: nerve to obturator internus muscle (L5, S1), it also supply the gemellus muscle. o It's covered by obturator fascia if you draw a line from the pubic body all the way until the area of ischial spine you will see the obturator fascia there,( is thickened), here it's called tendinous arch obturator fascia. Very important to know that this tendinous arch will form the attachment for the muscle that will form the inferior pelvic wall. 18 P a g e

19 inferior pelvic wall (pelvic floor) : o We refer it as pelvic diaphragm. ( all of them has the same meaning ) The fascia in green color that extend from the pubic to ischial spine is thickened and will become the tendinous arch of obturator fascia that will allow the attachment of levator ani muscle. - you can see here the superior part (upper part) of obturator internus ( the star). - between the upper and lower part of obturator internus the inferior pelvic wall hold them. in this part o It formed by 2 muscles, the important one called levator ani muscle (elevate the anus) the other one from the back called coccygeus muscle (ischiococcygeus, it come from ischial spine go to the sacrum and coccyx mainly). 19 P a g e

20 o Levator ani will attach to the tendinous arch of obturator fascia and it will separate the true pelvis into 2 cavities: 1. The main pelvic cavity (superior or above). 2. The perineum (below). o Pelvic diaphragm is very important because the tone of these muscles will carry all the contents of abdomen and pelvic cavity especially during downward pressure of inspiration. coccygeus muscle : o Its action help in flexing the coccyx so there is a movement between sacrum and coccyx. LEVATRO ANI Coccygeus 20 P a g e

21 Levator ani : o Divided into 3 main part : 1. Anterior part : are slips of muscles. these slips will go around the vagina forming a sphincter in female, called pubovaginalis or sphincter vaginae. and around prostate in male, called puboprostetae or levator prostatae. Very important, the is a gap or space anterior the levator ani allowing communication between the pelvic cavity and perineum called UROGENITAL HIATUS allowing of the passage of urethra and vagina. DSOME BOOKS LIKE SNELL, DON'T TALK ABOUT THE OTHER PARTS, HE JUST TALK ABOUT THE ANTERIOR PART ONLY CONSIDER IT AS THE MAIN PART. 2. Middle part: from pubic bone to the coccyx called pubococcygeus In addition, it has another part called puborectalis (doctor didn't mention it but it's in slides) 3. Posterior part: from ilium to coccyx called iliococcygeus. Here you can see the slips of muscle. o In levator ani there are 2 masses of fibers : Anterior the anal canal called perineum body. Posteriorly called anococcygeus body. 21 P a g e