The PelvisThe PelvisLectured by Bien Eli Nillos, MDLectured by Bien Eli Nillos, MD

1.1. No. of bones composing the bony No. of bones composing the bony pelvispelvis

2.2. What divides the true pelvis from What divides the true pelvis from false pelvisfalse pelvis

3 – 5. What comprises the answer to No. 3 – 5. What comprises the answer to No. 2? (anterior, lateral and posterior)2? (anterior, lateral and posterior)

6. What is the floor of the pelvis?6. What is the floor of the pelvis?

7 – 8. What comprises answer to No. 87 – 8. What comprises answer to No. 8For no. 9 – 10, answer whether it is a male of female For no. 9 – 10, answer whether it is a male of female

pelvis being described.pelvis being described.

9. Pelvic inlet is heart shaped9. Pelvic inlet is heart shaped

10. False pelvis is shallower. 10. False pelvis is shallower.

The PelvisThe Pelvis

The region of the trunk that lies The region of the trunk that lies below the abdomen. The abdominal below the abdomen. The abdominal and pelvic cavities are continuous.and pelvic cavities are continuous.

Surface LandmarksSurface Landmarks

Iliac CrestIliac Crest Anterior Superior Iliac Spine – upper Anterior Superior Iliac Spine – upper

lateral end of the fold of the groinlateral end of the fold of the groin Posterior Superior Iliac Spine – Posterior Superior Iliac Spine –

posterior end of the iliac crest, lies at posterior end of the iliac crest, lies at the bottom of a small skin dimple the bottom of a small skin dimple and on a level with the second sacral and on a level with the second sacral spine.spine.

Pubic Tubercle – upper border of the Pubic Tubercle – upper border of the pubispubis

Symphysis Pubis – cartilaginous joint Symphysis Pubis – cartilaginous joint that lies in the midline between the that lies in the midline between the bodies of the pubic bones. bodies of the pubic bones.

Pubic Crest – ridge of bone on the Pubic Crest – ridge of bone on the superior surface of the pubic bone, superior surface of the pubic bone, medial to the pubic tuberclemedial to the pubic tubercle

Spinous Process of the Sacrum – Spinous Process of the Sacrum – fused in the midline to form the fused in the midline to form the median sacral crestmedian sacral crest

Sacral Hiatus – posterior aspect of Sacral Hiatus – posterior aspect of the lower end of the sacrumthe lower end of the sacrum

Coccyx – inferior surface and tip can Coccyx – inferior surface and tip can be palpated in the natal cleft about 1 be palpated in the natal cleft about 1 inch behind the anusinch behind the anus

PelvisPelvis

Composed of four bones: 2 Composed of four bones: 2 innominate bones, sacrum and innominate bones, sacrum and coccyxcoccyx

Pelvic brim: sacral promontory Pelvic brim: sacral promontory behind, iliopectineal lines laterally, behind, iliopectineal lines laterally, symphysis pubis anteriorly. symphysis pubis anteriorly.

Above the brim is the FALSE PELVIS Above the brim is the FALSE PELVIS (greater pelvis).(greater pelvis).

Below the brim is the TRUE PELVIS Below the brim is the TRUE PELVIS (lesser pelvis)(lesser pelvis)

The Lesser or True Pelvis (pelvis minor).The Lesser or True Pelvis (pelvis minor).—The lesser pelvis is that part of the —The lesser pelvis is that part of the pelvic cavity which is situated below pelvic cavity which is situated below and behind the pelvic brim. Its bony and behind the pelvic brim. Its bony walls are more complete than those of walls are more complete than those of the greater pelvis. For convenience of the greater pelvis. For convenience of description, it is divided into an description, it is divided into an inletinlet bounded by the superior circumference, bounded by the superior circumference, and and outletoutlet bounded by the inferior bounded by the inferior circumference, and a circumference, and a cavitycavity..

The Superior Circumference.—The The Superior Circumference.—The superior circumference forms the brim superior circumference forms the brim of the pelvis, the included space being of the pelvis, the included space being called the superior aperture or inlet called the superior aperture or inlet

The superior aperture is somewhat The superior aperture is somewhat heart-shaped, obtusely pointed in heart-shaped, obtusely pointed in front, diverging on either side, and front, diverging on either side, and encroached upon behind by the encroached upon behind by the projection forward of the promontory projection forward of the promontory of the sacrum.of the sacrum.

It has three principal diameters: It has three principal diameters: antero-posterior, transverse, and antero-posterior, transverse, and oblique.oblique.

The The anteroposterior or conjugate anteroposterior or conjugate diameterdiameter extends from the extends from the sacrovertebral angle to the sacrovertebral angle to the symphysis pubis; its average symphysis pubis; its average measurement is about measurement is about 110 mm110 mm. in . in the female. the female.

The The transverse diametertransverse diameter extends extends across the greatest width of the across the greatest width of the superior aperture, from the middle of superior aperture, from the middle of the brim on one side to the same the brim on one side to the same point on the opposite; its average point on the opposite; its average measurement is about measurement is about 135 mm135 mm. in . in the female. the female.

The The oblique diameteroblique diameter extends from extends from the iliopectineal eminence of one the iliopectineal eminence of one side to the sacroiliac articulation of side to the sacroiliac articulation of the opposite side; its average the opposite side; its average measurement is about measurement is about 125 mm.125 mm. in in the female.the female.

The Lower CircumferenceThe Lower Circumference—The —The lower circumference of the pelvis is lower circumference of the pelvis is very irregular; the space enclosed by very irregular; the space enclosed by it is named the inferior aperture or it is named the inferior aperture or outlet, is bounded behind by the outlet, is bounded behind by the point of the coccyx, and laterally by point of the coccyx, and laterally by the ischial tuberosities.the ischial tuberosities.

The diameters of the outlet of the The diameters of the outlet of the pelvis are two: pelvis are two: antero-posterior antero-posterior and transverse.and transverse.

The The antero-posterior diameterantero-posterior diameter extends from the tip of the coccyx to extends from the tip of the coccyx to the lower part of the pubic the lower part of the pubic symphysis; its measurement is from symphysis; its measurement is from 90 to 115 mm. in the female.90 to 115 mm. in the female.

The The transverse diametertransverse diameter, , measured between the posterior measured between the posterior parts of the ischial tuberosities, is parts of the ischial tuberosities, is about 115 mm. in the female.about 115 mm. in the female.

In the erect posture, the pelvis is In the erect posture, the pelvis is placed obliquely with regard to the placed obliquely with regard to the trunk: the plane of the superior trunk: the plane of the superior aperture forms an angle of from 50° aperture forms an angle of from 50° to 60°, and that of the inferior to 60°, and that of the inferior aperture one of about 15° with the aperture one of about 15° with the horizontal plane.horizontal plane.

The pelvic surface of the symphysis The pelvic surface of the symphysis pubis looks upward and backward, pubis looks upward and backward, the concavity of the sacrum and the concavity of the sacrum and coccyx downward and forward. coccyx downward and forward.

The position of the pelvis in the erect The position of the pelvis in the erect posture may be indicated by holding posture may be indicated by holding it so that the anterior superior iliac it so that the anterior superior iliac spines and the front of the top of the spines and the front of the top of the symphysis pubis are in the same symphysis pubis are in the same vertical plane.vertical plane.

Muscles of the PelvisMuscles of the Pelvis

PiriformisPiriformis– Origin: front of Origin: front of

sacrumsacrum– Insertion: greater Insertion: greater

trochanter of femurtrochanter of femur– Action: lateral Action: lateral

rotator of femur at rotator of femur at hip jointhip joint

Obturator Internus:Obturator Internus:– Origin: obturator Origin: obturator

membrane and membrane and adjoining part of hip adjoining part of hip bonebone

– Insertion: greater Insertion: greater trochanter of femurtrochanter of femur

– Action: lateral Action: lateral rotator of femur at rotator of femur at hip jointhip joint

Levator ani:Levator ani:– Origin: body of pubis, fascia of obturator Origin: body of pubis, fascia of obturator

internus, spine of ischiuminternus, spine of ischium– Insertion: perinela body, anococcygeal Insertion: perinela body, anococcygeal

body, walls of prostate, vagina, rectum body, walls of prostate, vagina, rectum and anal canaland anal canal

– Action: supports pelvic organsAction: supports pelvic organs

Anterior fibers – levator Anterior fibers – levator prostatae/sphincter vaginaeprostatae/sphincter vaginae

Intermediate fibers – puborectalis, Intermediate fibers – puborectalis, pubococcygeus, anococcygeal bodypubococcygeus, anococcygeal body

Posterior fibers - iliococcygeusPosterior fibers - iliococcygeus

Coccygeus:Coccygeus:– Origin: spine of ischiumOrigin: spine of ischium– Insertion: lower end of sacrum; coccyxInsertion: lower end of sacrum; coccyx– Action: assists levator ani to support Action: assists levator ani to support

pelvic organspelvic organs

Male and Female PelvisMale and Female Pelvis

Urinary BladderUrinary Bladder Receptacle for storage of urineReceptacle for storage of urine

UreterUreter Crosses the pelvic inlet in front of the Crosses the pelvic inlet in front of the

bifurcation of the common iliac arterybifurcation of the common iliac artery

Vas DeferensVas Deferens Conveys mature sperm from epididymis Conveys mature sperm from epididymis

to the ejaculatory duct and the urethrato the ejaculatory duct and the urethra

ProstateProstate Inverted pyramid, fibromuscular Inverted pyramid, fibromuscular

glandular organ.glandular organ.

OvaryOvary

Almond-shaped organAlmond-shaped organ

Uterine (Fallopian) TubesUterine (Fallopian) Tubes 4 inches long, four parts: infundibulum, 4 inches long, four parts: infundibulum,

ampulla, isthmus, intramuralampulla, isthmus, intramural

UterusUterus

CervixCervix

VaginaVagina