The Bony Pelvis.pdf
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The document provides a detailed examination of the pelvic anatomy, including its boundaries, divisions into greater and lesser pelvis, and their respective contents. It outlines the structural components of the bony pelvis, the pelvic joints, and their functions, particularly in relation to childbirth. Additionally, it discusses the importance of pelvic measurements in obstetrics to assess the likelihood of vaginal delivery.
The Bony Pelvis.pdf
- 1. Dr. NDAYISABA CORNEILLE CEO of CHG MBChB,DCM,BCSIT,CCNA Supported BY
- 2. PELVIS • The pelvis is the lower part of the trunk of the human body between the abdomen and the thighs. • Topographically it is made up of a bony and ligamentous framework which is lined internally and externally by soft tissue and it is closed inferior by a layer of muscle and fascia which constitute the pelvic floor. • The perineum lies below the pelvic floor. Dr Ndayisaba Corneille 2
- 3. Boundaries of the Pelvis • The pelvis in its broadest sense is an anatomical region bounded behind by the sacrum and coccyx, on each side and anteriorly by the innominate bones which are the hip bones, or pelvic bones. • These bones form the skeletal base for the lower limb. Dr Ndayisaba Corneille 3
- 4. DIVISION OF THE PELVIS • An imaginary plane passing through the linea terminalis (Pelvic Brim) divides the entire pelvis into two parts: – an upper larger part which is referred to as the greater pelvis also known as the false pelvis or the pelvis major and – a lower smaller part which is referred to as the lesser pelvis, also known as the true pelvis or the minor pelvis Dr Ndayisaba Corneille 4
- 5. • The linea terminales is formed by the – anterior border of the base of the 1st sacrum formed by (the sacral Promontory and margin of the ala), – the arcuate line of the ilium and – the pectineal line of the pubis. Dr Ndayisaba Corneille 5
- 6. THE GREATER PELVIS (FALSE, MAJOR PELVIS) • This is the part of the pelvis lying above the linea terminalis. • Posterior lies the 5th Lumber vertebrate • laterally it is bounded by the iliac fossa while • anteriorly where the ilium is deficient it is bounded by the lower part of the anterior abdominal wall. Dr Ndayisaba Corneille 6
- 7. CONTENTS OF THE GREATER PELVIS…………………. • It is generally considered part of the abdominal cavity (because of this, it is also called the false pelvis). • The greater pelvis contains – Part of the ileum, – Ceacum, – Appendix and – Sigmoid colon Dr Ndayisaba Corneille 7
- 8. LESSER PELVIS • It is part of the pelvis lying below and behind the linea terminalis. • It is said to have superior aperture or Pelvic inlet , Pelvic cavity and an inferior aperture or Pelvic outlet • The true pelvis in females is modified to serve as the birth carnal. Dr Ndayisaba Corneille 8
- 9. CONTENTS OF LESSER PELVIS • The lesser pelvis contains the rectum, bladder, and some of the internal genitalia (sex organs). • The rectum lies in the curve of the sacrum and coccyx; the bladder is in front, behind the pubic symphysis. • In the female, the uterus and vagina occupy the interval between these viscera. Dr Ndayisaba Corneille 9
- 10. The superior aperture: Pelvic Inlet • The superior aperture is formed posteriorly by the anterior surface of the base of the body of the 1st sacrum, • on each side (laterally) it is bounded by the arcuate line and the pectineal line • while anteriorly it is bounded by the pubic crest and the anterior continuation of the pectineal line. Dr Ndayisaba Corneille 10
- 11. Pelvic Outlet • The pelvic outlet also known as the inferior aperture is bounded – posterior by the tip of coccyx, – lateral by the ischial tuberosity and – anteriorly by the pubic arch which is formed by the ventral rami of the pubic and the ischial bone as they unite anteriorly. Dr Ndayisaba Corneille 11
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- 13. OBSTETRICAL OUTLET: • This outlet has greater practical significance, because it includes the narrow pelvic strait through which the fetus must pass. • It is otherwise known as bony outlet. • Shape: it is diamond shaped. • It is bounded by the lower border of the symphysis pubis anteriorly, the ischial spines laterally, and the tip of the sacrum posteriorly Dr Ndayisaba Corneille 13
- 14. THE PELVIC CAVITY • The pelvic cavity is the continuation of the abdominal cavity into the Pelvis through the Pelvic brim or Pelvic inlet. It extends from the pelvic brim above to the Pelvic outlet below. • The Abdominal cavity continues inferiorly into the Pelvic cavity as such they are sometimes referred to as Abdominopelvic cavity Dr Ndayisaba Corneille 14
- 15. Pelvic cavity…………………… • its shape is almost rounded. It consist of – Anterior border: Symphysis pubis – Posterior border: Sacral hollow – Lateral border: Soft tissues • It has two openings: a Superior and Inferior Aperture or Outlet • This cavity is a short, curved canal, deeper on its posterior than on its anterior wall. Dr Ndayisaba Corneille 15
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- 17. THE BONY PELVIS • The bony pelvis is the irregular bony griddle between the femoral heads and the fifth lumbar vertebra. • It is massive because its primary function is to withstand compression and other forces due to body weight, abdominal powerful musculature and lower limb musculature. • It is of great importance in obstetric, forensic and anthropological applications. Dr Ndayisaba Corneille 17
- 18. The bony pelvis……………….. • The bony pelvis is formed by : – the hipbone (pelvic bone) in front and at the sides, and – the sacrum and coccyx behind. Dr Ndayisaba Corneille 18
- 19. Pelvic Bone • The two hip bones are joined at the pubic symphysis • Hip bones articulate with the sacrum at the sacroiliac joints and the femur at the hip joint • It is composed of Ilium, ischium and pubis and they fused at the acetabulum. Dr Ndayisaba Corneille 19
- 20. THE PUBIS: • It forms the anterior part of the pelvic bone. • Its body forms 1/5th of the acetabulum. • Its symphyseal surface unites with the opposite side to form the pubic symphysis. • The superior and inferior pubic rami participate in the formation of the obturator foramen. • Its inferior ramus fuses with the ischial ramus to form the ischiopubic ramus. Dr Ndayisaba Corneille 20
- 21. HIP BONES: PUBIS • Body of pubis • Superior ramus of pubis • Inferior ramus of pubis • Pubis crest • Pubic tubercle • Pecten pubis (pectineal line of pubis) • Subpubic angle Dr Ndayisaba Corneille 21
- 22. The Ischium • It is V-shape and forms the posterior inferior part of the pelvic bone. • It presents a roughened projection. The ischial tuberosity that protrudes posteroinferiorly from the body of the ischium. • It is the site for attachment of the sacrotuberous ligament; origin of the inferior gemellus muscle, quadratus femoris muscle and the hamstring muscles. • Its posterior margin is marked by a prominent ischial spine that separates the lesser sciatic notch below from the greater sciatic notch above. Dr Ndayisaba Corneille 22
- 23. HIP BONE: ISCHIUM • Body of ischium • Superior Ischial Ramus • Inferior ischial ramus • Ischial spine • Ischial tuberosity Dr Ndayisaba Corneille 23
- 24. The Ilium • It Is the most superior in position. • It presents the iliac crest which runs between the antero- and postero- superior iliac spines, below each of these are the corresponding inferior spines. • Its inner aspect bears the large auricular surface which articulates with the sacrum. Dr Ndayisaba Corneille 24
- 25. HIP BONE: ILIUM • Ala of ilium • Body of ilium • Iliac crest • Iliac fossa • Anterior superior iliac spine (ASIS) • Anterior inferior iliac spine (AIIS) • Posterior superior iliac spine (PSIS) • Posterior inferior iliac spine (PIIS Dr Ndayisaba Corneille 25
- 26. THE SACRUM • It is formed by five fused sacral vertebrae whose transverse processes and fused costal processes forms the alar plate or the lateral mass. • Anteriorly, is the anterior sacral foramina which transmits the ventral primary rami of the sacral spinal nerve Dr Ndayisaba Corneille 26
- 27. Posterior View • Posteriorly the spinal processes fuse to form the median sacral crest • Present also is a posterior sacral foramina which transmits the dorsal primary rami, • Caudally is the sacral hiatus which is formed due to the unfused laminar of the 5th sacral vertebrae. It is the sight for caudal anesthesia. • It is located at the surface by an important landmark formed by the sacral cornua formed by the pedicle of the 5th sacral vertebrae. • Second sacral vertebrate marks the end of dura and arachnoid mater as well as the subarachnoid space Sacral Canal Dr Ndayisaba Corneille 27
- 28. Abnormalities of Sacral Bone • Sacralization is a common irregularity of the spine, where the transverse process of the fifth lumbar vertebra fuse with the sacrum • The fifth lumbar vertebra may fuse fully or partially on either side of the sacrum, or on both sides. • Lumbarisation is where the 1st sacral vertebra fuses with the 5th Lumbar Vertebra • Sacralization and lumbarization are congenital anomalies that occurs in the embryo. • Unilateral or Bilateral lumbarisation • Unilateral or Bilateral sacralisation Dr Ndayisaba Corneille 28
- 29. THE COCCYX • Coccyx is a vestigial tail. It consists of four fused vertebra forming a small triangular bone. • its base articulates with the lower end of the sacrum. Dr Ndayisaba Corneille 29
- 30. FUNCTIONS OF BONY PELVIS • 1) To protect pelvic viscera • 2) To support the weight of the body - transfer the weight of the upper body from the axial to the lower appendicular skeleton • 3) Provides attachment for muscles • 4) In females, it provide bony support for the birth canal Dr Ndayisaba Corneille 30
- 31. Pelvic joints • There are four pelvic joints • Two sacroiliac joints • One sacro- coccygeal joint • One Pubic symphysis Dr Ndayisaba Corneille 31
- 32. Pubic Symphysis • It is a secondary cartilaginous joint • Articular surface is covered with hyaline articular cartilage • Disc of fibro-cartilage lies between the articular surface • A cavity may develop in the disc but it is not lined with synovial membrane • There is normally very little movement at the pubic symphysis, except during the latter months of pregnancy Dr Ndayisaba Corneille 32
- 33. Sacroiliac Joint • Modified synovial plane joint • Articular surfaces are rough • It bound by the Anterior and Posterior sacroiliac ligaments which is one of the strongest ligaments in the body • This articulation is almost immobile, except during pregnancy Dr Ndayisaba Corneille 33
- 34. Sacroiliac Joint Accessory Ligaments • Sacrotuberous ligaments • Sacrospinous ligaments • Iliolumbar ligaments • The sacrotuberous and sacrospinous ligaments converts the greater and lesser sciatic notches to Foraminae GS F LSF Dr Ndayisaba Corneille 34
- 35. Sacro coccygeal joint • The sacro coccygeal joint: this joint is formed where the base of the coccyx articulate with the tip of the sacrum • During labour the coccyx moves backwards at the sacrococcygeal joint to give more space for the delivery of the baby this is called nodding. • Fracture of a fused sacrococcygeal joint or at the fused coccygeal joints or arthritis in these joints causes a painful condition known as coccygodynia. Dr Ndayisaba Corneille 35
- 36. Movement in the Pelvic Joint • In the non-pregnant state there is very little movement in these joints, but during pregnancy endocrine activity causes the ligaments to soften, which allows for slight movement. • This may provide more room for the fetal head as it passes through the pelvis. • The symphysis pubis may separate slightly in later pregnancy. If it widens appreciably, the degree of movement permitted may give rise to pain on walking. • The sacro-coccygeal joint permits coccyx to be deflected backward during the birth of the head Dr Ndayisaba Corneille 36
- 37. MEASUREMENT OF THE FEMALE PELVIS • These values are of great importance in obstetrics for predicting the likelihood of a vaginal delivery. • Accurate measurements of the mothers pelvic inlet and outlet is determined in other to know if the size and position of the fetal head could cause complications during delivery. • These measurements include: Dr Ndayisaba Corneille 37
- 38. MEASUREMENT OF THE PELVIC INLET: • Conjugate Diameter: – True conjugate – Diagonal Conjugate – Obstetric Conjugate • Transverse Diameter • Anatomical Transverse Diameter • Obstetric Transverse Diameter • Oblique Diameter • Right Oblique Diameter • Left Oblique Diameter • Sacrocotyloid diameter Dr Ndayisaba Corneille 38
- 39. True conjugate • This is the anterior posterior diameter from the sacral promontory to the superior margin of the pubic symphysis. It is about 11 to 11.5cm in females, but in Dr Ndayisaba Corneille 39
- 40. Diagonal Conjugate • This is measured from the sacral promontory to the inferior margin of the pubic symphysis. It is about 12cm. Vaginal Examination to Determine Diagonal Conjug Dr Ndayisaba Corneille 40
- 41. Obstetric Conjugate • Obstetric Conjugate: This is the least A.P diameter from the sacral promontory to a point a few millimeters below the superior margin of the pubic symphysis. It is about 10.5cm. • It is shortest AP diameter through which the head must pass. • It cannot be measured clinically • For clinical purposes, obstetric conjugate is estimated indirectly by subtracting 1.5 to 2 cm from diagonal conjugate • If the Obstetric conjugate is less than 10 cm, it is called contracted pelvic inlet. Dr Ndayisaba Corneille 41
- 42. Transverse Diameters: Anatomical and Obstetric T D • Anatomical Transverse Diameter is the widest distance across the pelvic brim. It is about 13 to 13.5cm in females and in males it is about 12.5cm. • The largest diameter of pelvic inlet = Transverse diameter Dr Ndayisaba Corneille 42
- 43. Obstetric transverse diameter • It bisects the true conjugate and is slightly shorter than the anatomical transverse diameter. Dr Ndayisaba Corneille 43
- 44. Oblique Diameters: Right and Left O. D. • The right oblique diameter passes from the right sacroiliac joint to the left iliopectineal eminence and the left oblique extends from the left sacroiliac joint to the right iliopectineal eminence. Each measures about 12cm. Dr Ndayisaba Corneille 44
- 45. The Sacrocotyloid diameter • The sacrocotyloid diameter is measured from the sacral promotory to the iliopectineal eminence, on the same side, and is approximately 9c ms Dr Ndayisaba Corneille 45
- 46. Diameters of the Pelvic cavity • The cavity extends from the brim above to the outlet below. It is almost circular in shape. • The anterior wall is formed by the pubic bones and symphysis pubis and its depth is 4cm. • The posterior wall is formed by the curve of the sacrum which is 12cm in length. • The diameters, similar in direction to Dr Ndayisaba Corneille 46
- 47. MEASUREMENT OF THE PELVIC OUTLET • The pelvic outlet is slightly smaller than the pelvic brim, but it would be unusual for a fetal head to be able to pass through the brim and not be able to pass through the outlet. • Antero-posterior diameter (13cm): it Extend from lower border of symphysis pubis to the tip of coccyx. • Oblique diameter (12): it extend from Rt. or Lt. Sacro spinous ligament to the contralateral Obturator foramen • Transverse diameter (11cm): between the ischial spines. Dr Ndayisaba Corneille 47
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- 49. ORIENTATION OF THE PELVIC • In the anatomical position, the pelvis should be placed in such a way the anterior superior iliac spine lies on the same vertical plane with the top of the pubic symphysis. • Though in the living the female anterior superior iliac spine is tilted a bit forward as a result of this the lumbar curvature becomes more curved and the buttock becomes more prominent. Dr Ndayisaba Corneille 49
- 50. VARIATION OF THE PELVIS • The general shape of the pelvis is grouped into four base on Caldwell- Moloy Classification of Pelvic Types 1. The Gynaecoid: 2. The Android: 3. Platypelloid: 4. Anthropoids: Dr Ndayisaba Corneille 50
- 51. • Gynaecoid pelvis(50%) • Anthropoid pelvis (25%) • Android pelvis (20%) • Platypelloid pelvis (5%) Dr Ndayisaba Corneille 51
- 52. Gynaecoid pelvis: (50%) • It is commonly known as the female pelvis because that type occurs most frequently in women. • Most suitable for childbirth. • Wider brim. • Ischial spines are blunt • Sub pubic angle is greater than 90 degrees • Sub-pubic arch is wide enough to accommodate the examiners four knuckles or clenched fist Dr Ndayisaba Corneille 52
- 53. Android pelvis: (20%) • It is commonly known as male pelvis because it occurs more frequently in men. • Heart shaped brim • Anterior posterior diameter is shorter • Transverse diameter is wider • Childbirth is difficult Dr Ndayisaba Corneille 53
- 54. SEX DIFFERENTIATION • This is of great important in forensic anthropology in order to determine the sex of the pelvis in medicolegal situations. • When presented with a pelvis for identification emphasis should be laid on: 1. Pubic arch: to note its prominence as a result of attachment of crus of the penis or clitoris. 2. The size of the acetabulum: which is larger in male than in female. 3. The distance between the acetabulum, ilium and the pubic symphysis: which is longer in females than in males. 4. The size of the facet base of the sacrum in relation to the ala of the sacrum (smaller in female and larger in male). 5. Subpubic angle it is the angle of the pubic arch which is larger in female than in male. Dr Ndayisaba Corneille 54
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- 56. MUSCLES OF THE LATERAL PELVIC WALL Obturator Internus Muscle and Piriformis Dr Ndayisaba Corneille 56
- 57. Obturator Internus Muscle • Origin: It takes its origin from the deep surface of obturator membrane and its associated bony surface, its fibers converge and pass through the lesser sciatic foramen. • Insertion: Inserted into the greater trochanter of the femur just above the trochanteric fossa. • Nerve Supply: Nerve to Obturator internus (L5, L11, L12). • Action: Because of its posterior medial insertion it helps in abduction of the flexed hip and in lateral rotation. OIM Dr Ndayisaba Corneille 57
- 58. Piriformi s PIRIFORMIS It is a triangular shaped muscle which serves as an important landmark in the gluteal region. Its position should be compared with that of P minor. Origin: From the anterior surface of 2nd – 4th sacral vertebrae, lateral to the anterior sacral foramina, INSERTION: It passes to be inserted into the greater trochanter of the femur just above the insertion of the Obturator internus muscle. Nerve Supply: Branches from ventral rami of L5, S1 – S3. Action: lateral rotator and abduction of the femur Dr Ndayisaba Corneille 58
- 59. THE MUSCLES OF THE PELVIC FLOOR • The pelvic floor is composed of – the pelvic diaphragm, • The pelvic floor separates the pelvic cavity from the perineum. • The muscles that forms the pelvic floor is – the levator ani and – the coccygeus muscle Dr Ndayisaba Corneille 59
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- 61. LEVATOR ANI • The levator ani muscle is made up of two parts, – the lateral portion and – medial portion. Dr Ndayisaba Corneille 61
- 62. the lateral portion of Levator ani • The lateral portion arises from the posterior and lateral aspect of the pelvic bone and from the arcus tendinus which is a condensation of the fascia that covers the obturator internus muscle (the white line). • The part of the lateral portion which arises from Pubic bone passes backward forming a sling around the anorectal junction this part of the levator ani is referred to as the puborectalis. • It functions as a pinch valve and keeps the anorectal junction at 90O angle, thereby maintaining the continence of feces within the rectum. Part of the puborectalis insert into the external anal sphincter to reinforce it. Dr Ndayisaba Corneille 62
- 63. the lateral portion of Levator ani……… • The parts of the lateral portion arising from the pubis and part of the arcus tendinus passes downward and backward as the pubococcygeus to meet at the midline behind the perineal body to form the anococcygeal rephae. • This raphae extends from the tip of the coccyx to the anorectal junction • The part that arises from the ischial spines and the posterior aspect of the tendinous arch is referred to as the iliococcygeus muscle it is attached to the posterior aspect of the tendinous arch Dr Ndayisaba Corneille 63
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- 65. The medial portion of the levator ani • The medial portion arises from the pubic bone close to the median plane. • The medial portion of the levator ani is also called the Prerectal fibers of puborectalis. • It forms a sling around the prostate in males (puboprostatea or around the vagina- pubovaginae or vaginal sphincter) • Some part of it inserts into the perineal body while some of it blends with the longitudinal muscle of the anal canal as the puboanalis. Dr Ndayisaba Corneille 65
- 66. • Nerve Supply: A branch from the pudendal nerve known as the inferior rectal branch and branches from the ventral rami of the 4th sacral Nerve. • Action: It helps to support the pelvic viscera while the puborectalis function during defecation process. Dr Ndayisaba Corneille 66
- 67. THE COCCYGEUS MUSCLE • It is a triangular shaped muscle. It arises from the ischial spine to be inserted into the coccyx and the adjacent part of the sacrum. • It over lies the sacrospinous ligament • Nerve Supply: Ventral branches of S4 and S5 • Action: It helps to pull forward the coccyx during defecation. Dr Ndayisaba Corneille 67
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- 69. Functions • The roles of the pelvic floor muscles are: • pelvic floor support as well as aid in the sphincteric action on rectum and vagina. Aids defecation, micturition and parturition by increasing intra-abdominal pressure. • Support of abdominopelvic viscera (bladder, intestines, uterus etc.) through their tonic contraction. • Resistance to increases in intra-pelvic/abdominal pressure during activities such as coughing or lifting heavy objects. • Urinary and faecal continence. The muscle fibres have a sphincter action on the rectum and urethra. They relax to allow urination and defecation Dr Ndayisaba Corneille 69
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- 71. Episiotomy • To avoid this pressure damage on pelvic and perineal floor, during childbirth episiotomy is normally employed to avoid tearing the muscles. • Age, number of normal vaginal deliveries, weight, chronic cough, family history of pelvic floor dysfunction are notable risk factors. • Damaged pelvic floor can be repaired surgically and the muscles can be strengthened through pelvic floor exercises called kegel exercises. Dr Ndayisaba Corneille 71
- 72. END Dr Ndayisaba Corneille THANKS FOR LISTENING By DR NDAYISABA CORNEILLE MBChB,DCM,BCSIT,CCNA Contact us: [email protected]/ [email protected] whatsaps :+256772497591 /+250788958241 72