CH. 8 - PELVIS

uterus

-Is a pear-shaped muscular organ located in the anterior portion of the pelvic cavity. -The _____ is the reproductive organ responsible for protecting and nourishing the fetus during development.

os coxae

Are made up of three bones: ilium, pubis, and ischium

coccyx

Articulating with the fifth sacral segment is the _____, which consists of three to five small fused bony segments

vas deferens

As a continuation from the tail of the epididymis, the _____ is a long muscular tube that ascends in the posterior portion of the spermatic cord and traverses the inguinal canal. Near its proximal end it joins with the duct of the seminal vesicle to form the ejaculatory duct, which empties into the prostatic urethra.

external anal sphincter

Consists of a ring of skeletal muscle fibers and is under voluntary control

psoas muscles

Extend along the lateral surfaces of the lumbar vertebrae and act to flex the thigh or trunk

the pubis (pubic bone)

Forms the lower anterior portion of the acetabulum and consists of a body and superior and inferior pubic rami

urethra, urethral

In both genders, the _____ passes through the urogenital diaphragm, which contains the _____ sphincter muscle responsible for the voluntary closure of the bladder

scrotum

Is a muscultendinous pouch that encloses the testis, epididymis, and lower portions of the spermatic cord. The _____ facilitates sperm formation by distending the testes outside the peritoneum in a cooler environment, in effect regulating the temperature of the testes.

urinary bladder

Is a pyramid-shaped muscular organ that rests on the pelvic floor, immediately posterior to the symphysis pubis, it functions as a temporary reservoir for the storage of urine. (In a normal adult, it takes approximately 200 to 250 mL of urine to accumulate before the urge to urinate is triggered. However, the bladder has the potential storage capacity of approximately 750 mL.)

sacrum

Is a triangular-shaped bone formed by the fusion of five vertebral segments

penis (the external reproductive organ)

Is attached to the pubic arch via suspensory ligaments. It has two parts: the root, which is attached to the pubic arch, and the body, which remains free. Three cylindric masses of erectile tissue compose the root of the penis: two corpora cavernosa and the corpus spongiosm. The distal end of the cylindric masses forms the glans penis, which surrounds the external urethral meatus.

bony pelvis

Is formed by the sacrum, coccyx, and two os coxae or innominate bones

vagina

Is located between the bladder and the rectum and functions as a receptacle for sperm and as the lower portion of the birth canal.

female reproductive system

Is responsible for producing sex hormones and ova and functions to protect and support a developing embryo.

progesterone

Is responsible for the uterine changes in preparation of pregnancy, such as thickening of the uterine lining and decreasing contractions of the uterine muscle.

anal canal

Is the distal portion of the rectum and contains small longitudinal folds called rectal or anal columns.

rectum

Is the terminal part of the large intestine extending from S3 to the tip of the coccyx, approximately 15 cm long. It follows the anteroposterior curve of the sacrum and coccyx and ends by turning inferiorly and anteriorly.

ilium

Largest and most superior portion, consists of a body and a large winglike projection called the ala

pectineal line

Located on the upper surface of the superior pubic rams is a ridge termed the _____, which is continuous with the arcuate line of the ilium, forming the pelvic brim

anus

Marks the exit of the anal canal and is under the involuntary control of the internal anal sphincter, a circular muscle layer within the rectal wall.

ischial spine

Projects from the superior ischial ramus between two prominent notches on the posterior surface of the os coxae

superior pubic ramus

Projects inferiorly and medially from the acetabulum to the midline of the body

pelvis

Provides structural support for the body and encloses the male and female reproductive organs. Because of its role as a support mechanism for the body, it has a large amount of musculoskeletal anatomy, which, together with the differences in male and female anatomy, makes this area challenging to learn.

the rectus abdominis, psoas, and internal and external oblique muscles

Several of the muscles visualized in the pelvis are actually abdominal muscles, such as:

seminal vesicles

The _____ are paired accessory glands consisting of coiled tubes that form two pouches, lateral to the vas deferens, on the posterior inferior surface of the bladder. They lie superior to the prostate gland and produce fructose and a coagulating enzyme for the seminal fluid that mixes with sperm before ejaculation.

uterine (fallopian) tubes

The _____ are slender, muscular tubes extending laterally from the body of the uterus to the peritoneum near the ovaries. Fimbriae spread loosely over the surface of the ovaries. During ovulation, the fimbriae trap the ovum and sweep it into the uterine tubes. The proximal portion of the uterine tubes open into the uterus. The proximal portion of the uterine tubes open into the uterus, and the distal portion opens directly into the peritoneal cavity, immediately superior to the ovaries, thereby providing a direct route for pathogens to enter the pelvic cavity. The uterine tubes provide a method of transport for ova to reach the uterus from the ovaries.

descending aorta

The _____ bifurcates at the level of the fourth lumbar vertebra into the right and left common iliac arteries. Each common iliac artery bifurcates at the upper margin of the sacroiliac joint into the internal and external iliac arteries. The smaller internal iliac artery extends posteromedially into the pelvis just medial to the external iliac vein and branches into an anterior and posterior trunk.

pelvic cavity

The _____ contains bladder, rectum, and internal reproductive organs.

prostate

The _____ has a base adjacent to the neck of the bladder and an apex that is in contact with the urogenital diaphragm.

epididymis

The _____ is a tightly coiled tubular structure located on the superoposterior surface of each testis. Sperm are transmitted from the testis to the epididymis, where they are stored as they undergo the final stages of maturation.

pelvic outlet (inferior aperture)

The _____ is an opening bounded by the inferior edges of the pelvis and is measured from the tip of the coccyx to the inferior margin of the pubic symphysis

prostate gland

The _____ is the largest accessory gland of the male reproductive system. It secretes a thin, slightly alkaline fluid that forms a portion of the seminal fluid. The _____ is located inferior to the bladder and surrounds the prosthetic urethra, which courses through the anterior portion of the gland.

superior aperture (inlet)

The _____ of the true pelvis is measured in the anteroposterior direction from the sacral promontory to the superior margin or crest of the pubic bone

ischium

The _____, the inferior portion of the os coxae, like the pubis, is composed of a body and two rami. The body of the _____ forms the lower posterior portion of the acetabulum

pubic symphysis

The bodies of the two pubic bones meet at the midline to form the _____

acetabulum

The body of the ilium creates the upper portion of the _____, which is a deep fossa that articulated with the head of the femur

arcuate line

The concave, anterior surface of the ala is termed the iliac fossa, which is separated from the body by the _____. This arch shaped line, which is located on the anterior surface of the ilium, forms part of the pelvic brim.

sacral promontory

The first sacral segment has a prominent ridge located on the anterior surface of the body termed _____, which acts as a bony landmark separating the abdominal cavity from the pelvic cavity

neck of the bladder

The inferior angle of the bladder is a funnel-shaped narrowing formed by the convergence of the inferolateral and posterior surfaces and is called the _____, which is continuous with the urethra. It contains the muscular internal urethral sphincter, which provides for involuntary control over the release of urine from the bladder.

sacral foramina

The lateral mass contains _____ that allow for the passage of sacral nerves

cervical canal

The narrow lumen within the cervix, called the _____, is a conduit between the uterine cavity superiorly via the internal os and opens inferiorly into the vagina via the external os. The wall of the uterus is composed of three layers: the endometrium is the inner glandular tissue lining the inner wall; the myometrium is the middle, muscular layer and the thickest component of the uterine wall; and the perimetrium is the outer layer consisting of a serous membrane that covers the fundus and posterior surface of the uterus.

ovaries

The paired _____ are small almond-shaped organs located on either side of the uterus. The _____ are responsible for the production of ova and the production and secretion of estrogens and progesterone. Estrogens are responsible for the development and maintenance of female characteristics and reproductive organs.

seminiferous tubules

The paired testes are suspended in the fleshy, pouchlike scrotal sac. Each testis is an ovoid organ that produces sperm and male sex hormones. Each testis is made up of several hundred lobules, with each lobule containing 1 to 4 _____, approximately 800 _____ in total.

pelvic brim

The pelvis is divided into the false (greater pelvis) and the true (lesser pelvis) by an oblique plane that extends from the upper anterior margin of the sacrum, along the arcuate line, to the upper margin of the pubic symphysis. The boundary line of this plane is called the _____, which delineates the boundaries of the abdominal and pelvic cavities. The region above the _____ is called the false pelvis, and the region below the brim is called the true pelvis, which can be subdivided by the pelvic diaphragm into the main pelvic cavity and the perineum.

ischial tuberosity

The superior ischial ramus extends posteriorly and inferiorly to a roughened, enlarged area termed the _____. From the _____, the inferior ischial ramus extends anteriorly and medially to join the inferior pubic ramus.

iliac crest

The superior ridge of the ala is termed the _____; it slopes down to give rise to the superior and inferior iliac spines on both the anterior and posterior surfaces

lateral mass (ala)

The transverse processes of the five sacral segments combine to form the _____, which articulates with the os coxae at the sacroiliac joints

posterolateral angles

The two _____ mark the point where the ureters enter the bladder

obturator foramen

The union of the pubic rami and ischium surrounds a large opening termed the _____, which is enclosed by the obturator muscles

the rectal ampulla

The upper third of the rectum, _____, has considerable distensibility. As fecal material collects in this area, it triggers the urge to defecate.

body, cervix

The uterus can be subdivided into two anatomic regions: _____ and _____ The body is the largest division, comprising the upper two thirds of the uterus. The rounded superior portion of the body is called the fundus. The narrow inferior third of the uterus is called the cervix.

8 to 10 cm muscular tube

The vagina is an _____ extending anteroinferiorly from the cervix of the uterus to the external vaginal orifice. The vaginal vault or fornix is the upper vaginal area surrounding the cervical os like a ring and is commonly divided into anterior and posterior fornices.

the principal organs of the female reproductive system

are located within the pelvic cavity and include the uterus, ovaries, uterine tubes, and vagina

The principal structures of the male reproductive system

testis, epididymis, vas deferns, ejaculatory duct, seminal vesicle, prostate gland, bulbourethral gland, and penis. All these structures, except the testes and penis are located within the pelvic cavity.