Pelvis Cross-Sectional Anatomy PDF

Cross sectional anatomy - Pelvis 1  MEDICAL IMAGING DIVISION 2 Learning Objective CLO2- Identify normal cross-sectional anatomy of head, neck, chest, abdomen, and pelvis (Week 3-10) 50% Identify all major s...

Cross sectional anatomy - Pelvis 1  MEDICAL IMAGING DIVISION 2 Learning Objective CLO2- Identify normal cross-sectional anatomy of head, neck, chest, abdomen, and pelvis (Week 3-10) 50% Identify all major structures in contiguous axial, sagittal and coronal slices throughout the head and neck. Identify all major structures in contiguous axial and coronal slices throughout the chest. Identify all major structures in contiguous axial and coronal slices throughout the abdomen. Identify all major structures in contiguous axial and coronal slices throughout the pelvis. 2  MEDICAL IMAGING DIVISION 3 Objectives Identify the structures of the bony pelvis. Define the pelvic inlet and outlet. Describe the location of the bladder in relation to the reproductive organs and the course of the male and female urethras. Describe the location and function of the male and female reproductive organs. 3  MEDICAL IMAGING DIVISION 4 Outline Bony Pelvis Sacrum, Coccyx, and Os Coxae Pelvic Inlet and Outlet Viscera Bladder Rectum Female Reproductive Organs Male Reproductive Organs 4  MEDICAL IMAGING DIVISION 5 Bony Pelvis The bony pelvis is formed by the sacrum, coccyx, and two os coxae or innominate bones. 5  MEDICAL IMAGING DIVISION 6 Sacrum A triangular-shaped bone formed by the fusion of five vertebral segments. Sacral promontory A prominent ridge located on the anterior surface of the body of the first sacral segment. A bony landmark that separates the abdominal cavity from the pelvic cavity. Lateral mass (ala) The combination of the transverse processes of the five sacral segments. Articulates with the os coxae at the sacroiliac joints. Contains sacral foramina that allow for the passage of sacral nerves. 6  MEDICAL IMAGING DIVISION 7 7  MEDICAL IMAGING DIVISION 8 8  MEDICAL IMAGING DIVISION 9 Coccyx Articulates with the fifth sacral segment. Consists of three to five small fused bony segments. 9  MEDICAL IMAGING DIVISION 10 Os Coxae (Hip) The os coxae are made up of three bones: ilium, pubis, and ischium. 10  MEDICAL IMAGING DIVISION 11 Ilium The largest and most superior portion. Consists of a body and a large wing-like projection called the ala. Iliac fossa: The concave, anterior surface of the ala. Arcuate line Arch-shaped line. Located on the anterior surface of the ilium. Forms part of the pelvic brim. 11  MEDICAL IMAGING DIVISION 12 Cont’d Iliac crest The superior ridge of the ala. Slopes down to give rise to the superior and inferior iliac spines on both the anterior and posterior surfaces. Body of the ilium: Creates the upper portion of the acetabulum. Acetabulum: A deep fossa that articulates with the head of the femur. 12  MEDICAL IMAGING DIVISION 13 13  MEDICAL IMAGING DIVISION 14 14  MEDICAL IMAGING DIVISION 15 Pubis (Pubic Bone) Forms the lower anterior portion of the acetabulum. Consists of a body and superior and inferior pubic rami. Pubic symphysis: The midline meeting point of the bodies of the two pubic bones. Superior pubic ramus: Projects inferiorly and medially from the acetabulum to the midline of the body. Pectineal line A ridge located on the upper surface of the superior pubic ramus. Continuous with the arcuate line of the ilium, forming the pelvic brim. Inferior pubic ramus: Projects inferiorly and laterally from the body to join the ischium at an indistinct point (two together are 15 often referred to as the ischiopubic ramus).  MEDICAL IMAGING DIVISION 16 16  MEDICAL IMAGING DIVISION 17 Ischium The inferior portion of the os coxae. Composed of a body and two rami. Body: Forms the lower posterior portion of the acetabulum. Superior ischial ramus: Extends posteriorly and inferiorly to a roughened, enlarged area termed the ischial tuberosity. Inferior ischial ramus: Extends anteriorly and medially from the ischial tuberosity to join the inferior pubic ramus. 17  MEDICAL IMAGING DIVISION 18 Cont’d Ischial spine: Projects from the superior ischial ramus between two prominent notches on the posterior surface of the os coxae: Greater sciatic notch: Extends from the posterior inferior iliac spine to the ischial spine. Lesser sciatic notch: Extends from the ischial spine to the ischial tuberosity. Obturator foramen: A large opening formed by the union of the pubic rami and ischium. 18  MEDICAL IMAGING DIVISION 19 Pelvic Inlet and Outlet Pelvic brim: The boundary line of an oblique plane that extends from the upper anterior margin of the sacrum, along the arcuate line, to the upper margin (crest) of the pubic symphysis. Delineates the boundaries of the abdominal and pelvic cavities. False or greater pelvis: The region above the brim. True or lesser pelvis: The region below the brim. 19  MEDICAL IMAGING DIVISION 20 Cont’d Superior aperture (inlet) of the true pelvis Measured in the AP direction from the sacral promontory to the superior margin of the pubic bone. Pelvic outlet (inferior aperture) An opening bounded by the inferior edges of the pelvis. Measured in the AP direction from the tip of the coccyx to the inferior margin of the pubic symphysis Measured in the horizontal direction between the ischial spines. 20  MEDICAL IMAGING DIVISION 21 21  MEDICAL IMAGING DIVISION 22 VISCERA The pelvic cavity contains the bladder, rectum, and internal reproductive organs. 22  MEDICAL IMAGING DIVISION 23 23  MEDICAL IMAGING DIVISION 24 Bladder A pyramid-shaped muscular organ. Rests on the pelvic floor, immediately posterior to the symphysis pubis. Functions as a temporary reservoir for the storage of urine. Has the potential storage capacity of approximately 750 mL. In a normal adult, it takes approximately 200 to 250 mL of urine to accumulate before the urge to urinate is triggered. 24  MEDICAL IMAGING DIVISION 25 Trigone A triangular area formed by three openings in the floor of the bladder. Two of the openings are created by the ureters. The pelvic portions of the ureters run anterior to the internal iliac arteries and enter the posterolateral surface of the bladder at an oblique angle. The third opening is located in the apex of the trigone and is formed by the entrance to the urethra. 25  MEDICAL IMAGING DIVISION 26 Urethra A muscular tube that drains urine from the bladder. Passes through the urogenital diaphragm, which contains the urethral sphincter muscle responsible for the voluntary closure of the bladder. In females Short (3-4 cm). Located in front of the anterior vaginal wall and descends inferiorly and anteriorly to terminate at the external urethral opening. 26  MEDICAL IMAGING DIVISION 27 Cont’d In males Longer (18- 20cm). Extends from the inferior portion of the bladder to the tip of the penis. Subdivided into three regions: prostatic urethra, membranous urethra, and penile urethra. 27  MEDICAL IMAGING DIVISION 28 Cont’d Prostatic urethra: Passes through the middle of the prostate gland. Membranous urethra The shortest and narrowest portion of the urethra. Penetrates the urogenital diaphragm. Penile urethra The longest portion. Extends from the external urethral sphincter to the tip of the penis. 28  MEDICAL IMAGING DIVISION 29 29  MEDICAL IMAGING DIVISION 30 30  MEDICAL IMAGING DIVISION 31 31  MEDICAL IMAGING DIVISION 32 32  MEDICAL IMAGING DIVISION 33 33  MEDICAL IMAGING DIVISION 34 Rectum The terminal part of the large intestine. Extends from S3 to the tip of the coccyx. Approximately 15 cm long. It follows the AP curve of the sacrum and coccyx (sacral flexure) and ends by turning inferiorly and anteriorly to become the anal canal, which ends at the anus. 34  MEDICAL IMAGING DIVISION 35 Cont’d Rectal ampulla The upper third of the rectum. Has considerable distensibility. As fecal material collects in this area, it triggers the urge to defecate. Anal canal: The distal portion of the rectum. Anus: Marks the exit of the anal canal. Internal anal sphincter: Involuntary control the anus. External anal sphincter: Under voluntary control. 35  MEDICAL IMAGING DIVISION 36 36  MEDICAL IMAGING DIVISION 37 37  MEDICAL IMAGING DIVISION 38 Female Reproductive Organs Produce sex hormones and ova. Protect and support a developing embryo. Include the uterus, ovaries, uterine tubes, and vagina. 38  MEDICAL IMAGING DIVISION 39 39  MEDICAL IMAGING DIVISION 40 Uterus A pear-shaped muscular organ. Located in the anterior portion of the pelvic cavity between the bladder and the rectum. Protects the fetus during development. Can be subdivided into two anatomic regions: body and cervix. Body The largest division (the upper 2/3 of the uterus). Fundus The rounded superior portion of the body. Located just superior to the region where the uterine tubes enter the uterus. 40  MEDICAL IMAGING DIVISION 41 Cont’d Cornua Located in the lateral borders of the fundus. Where the uterine tubes attach to the uterus. Cervix The narrow inferior third of the uterus. Communicates with the vagina. Cervical canal The narrow lumen within the cervix. A conduit between the uterine cavity superiorly via the internal os and opens inferiorly into the vagina via the external os. 41  MEDICAL IMAGING DIVISION 42 Cont’d The wall of the uterus is composed of three layers: Endometrium The inner glandular tissue lining the inner wall. Lined by a mucous membrane that is continuous with the inner lining of the vagina and uterine tubes. Myometrium The middle, muscular layer and the thickest component of the uterine wall. Responsible for the main contractive force during childbirth. Perimetrium The outer layer consisting of a serous membrane that covers the fundus and posterior surface of the uterus. Firmly attached to the myometrium. 42  MEDICAL IMAGING DIVISION 43 43  MEDICAL IMAGING DIVISION 44 44  MEDICAL IMAGING DIVISION 45 Ovaries Small almond-shaped organs. Located on either side of the uterus. They lie in a depression on the lateral walls of the pelvis. Responsible for the production of ova and the production and secretion of estrogens and progesterone. 45  MEDICAL IMAGING DIVISION 46 Uterine (Fallopian) Tubes Slender, muscular tubes (approximately 8-20 cm long). Extend laterally from the body of the uterus to the inner abdominal wall near the ovaries. Provide a method of transport for ova to reach the uterus from the ovaries. At their distal end expand to form a funnel-shaped infundibulum. Infundibulum Has numerous 1- to 2-cm fingerlike projections called fimbriae, which spread loosely over the surface of the ovaries. During ovulation, the fimbriae trap the ovum and sweep it into the 46 uterine tubes.  MEDICAL IMAGING DIVISION 47 Cont’d The proximal portion of the uterine tubes opens into the uterus. The distal portion opens directly into the abdominal cavity, immediately superior to the ovaries. 47  MEDICAL IMAGING DIVISION 48 48  MEDICAL IMAGING DIVISION 49 49  MEDICAL IMAGING DIVISION 50 Vagina An 8- to 10-cm muscular tube. Extends anteroinferiorly from the cervix of the uterus to the external vaginal orifice. 50  MEDICAL IMAGING DIVISION 51 51  MEDICAL IMAGING DIVISION 52 Male Reproductive Organs Include the testis, epididymis, vas deferens, ejaculatory duct, seminal vesicle, prostate gland, bulbourethral gland, and penis. 52  MEDICAL IMAGING DIVISION 53 53  MEDICAL IMAGING DIVISION 54 Testes and Epididymis Suspended in the scrotal sacs. Produces sperm and male sex hormones. Epididymis A tightly coiled tubular structure located on the superoposterior surface of each testis. Head: Located on the upper pole of each testis. Body: Courses along the posterior surface to the tail. Tail: Located under the lower pole of each testis. Sperm are transmitted from the testis to the epididymis, where they are stored as they undergo the final stages of maturation. 54  MEDICAL IMAGING DIVISION 55 Vas Deferens (Ductus) and Ejaculatory Duct Vas deferens is a continuation from the tail of the epididymis. It is a long muscular tube that ascends in the posterior portion of the spermatic cord. It then leaves the spermatic cord and passes along the lateral pelvic wall over the ureter to the posterior surface of the bladder. Near its proximal end, it joins with the duct of the seminal vesicle to form the ejaculatory duct, which empties into the prostatic urethra. Each vas deferens, along with a testicular artery and vein, is surrounded by the tough connective tissue and muscle of the paired spermatic cords. 55  MEDICAL IMAGING DIVISION 56 56  MEDICAL IMAGING DIVISION 57 57  MEDICAL IMAGING DIVISION 58 Seminal Vesicles Paired accessory glands. Consist of coiled tubes that form two pouches, lateral to the vas deferens on the posterior inferior surface of the bladder. Lie superior to the prostate gland. Produce fructose and a coagulating enzyme for the seminal fluid that mixes with sperm before ejaculation. 58  MEDICAL IMAGING DIVISION 59 59  MEDICAL IMAGING DIVISION 60 Prostate Gland The largest accessory gland of the male reproductive system. Secretes a thin, slightly alkaline fluid that forms a portion of the seminal fluid. Located inferior to the bladder. Surrounds the prostatic urethra, which courses through the anterior portion of the gland. Has a base adjacent to the neck of the bladder and an apex. Composed of glandular and fibromuscular tissue. 60  MEDICAL IMAGING DIVISION 61 Cont’d Glandular tissue Comprises two-thirds of the prostate’s parenchymal tissue. Divided into zonal anatomy: central, periurethral, peripheral, transition zones and anterior fibromuscular stroma. Central zone Located at the base of the prostate between the peripheral and transition zones. Accounts for approximately 25% of the glandular tissue. Surrounds the ejaculatory ducts. 61  MEDICAL IMAGING DIVISION 62 Cont’d Peripheral zone The largest of the zones, comprising approximately 70% of the glandular tissue. Extends from the base to the apex along the posterior or rectal surface of the gland. Surrounds the distal urethra. Transition zone Forms only 5% of the glandular tissue. Consists of two small lobules that are located lateral to the proximal urethra. Enlarges in case of benign prostatic hypertrophy. 62  MEDICAL IMAGING DIVISION 63 Bulbourethral (Cowper’s) Glands Two small glands. Lie posterolateral to the membranous urethra. Secrete an alkaline fluid, which forms a portion of the seminal fluid, into the membranous urethra. 63  MEDICAL IMAGING DIVISION 64 64  MEDICAL IMAGING DIVISION 65 65  Thank you 800 MyHCT (800 www.hct.ac.ae 66 69428)