Charity Callis Anatomy & Physiology Clinical Anatomy 1 - #4 Page 1

For this assignment read in Oxorn Foote Human Labor and Birth, chapters 1-4. You can find the book HERE. This book may be used for other assignments as well.

One of the important aspects of midwifery are the anatomical structures themselves. Knowing the bones, joints, ligaments, and other structures of the human body are useful and at times necessary. There is no easy way to learn them except by looking at them and ensuring they are familiar to you. When the midwife asks you as the birth assistant an anatomical question or where in the pelvis the baby is it will be important to note the correct locations. In this first part you should familiarize yourself in the book with the various names and locations of the pelvis and surrounding organs both specifically and generally.

A. Pelvis

1. Name the innominate bones (those that are fused together and don’t move).

The Ilium, Ischium and Pubis are the innominate bones on each side of the pelvis.

2. Describe the sacrum. Triangular bone, consists of five vertebrae fused together (rarely there are four or six), anterior pelvic surface is concave, posterior surface is convex, a portion protrudes slightly into the pelvic cavity reducing the diameter of the inlet. The sacral promontory can be pushed back to widen the pelvic inlet and increase the diameter for birth.

3. Describe the coccyx. Tail bone, composed of four vertebrae, the coccygeus/levator ani/sphincter muscles are attached to the anterior part of the coccyx

4. Give the difference between the primary and accessory ligaments.

PRIMARY LIGAMENTS

1) Anterior sacroiliac – short, transverse, running from the preauricular sulcus o the ilium to the anterior aspect of the ala of the sacrum 2) Interosseus sacroiliac – short, strong transverse bands that extend from the rough part behind the auricular surface on the ilium to the adjoining area in the sacrum 3) Short posterior sacroiliac – strong, transverse bands that lie behind the interosseus ligaments 4) Long posterior sacroiliac – each attached to the posterosuperior spine on the ilium and to the tubercles on the third and fourth sacral vertebrae

ACCESSORY LIGAMENTS

1) Sacrotuberous ligaments – attached on one side to the posterior superior iliac spine; posterior inferior spine; tubercles on the third, fourth, and fifth sacral vertebrae; and lateral border of the coccyx. On the other side, the sacrotuberous ligaments are attached to the pelvic aspect of the ischial tuberosity. 2) Sacrospinous ligament – triangular. The base is attached to lateral parts of the fifth sacral and first coccygeal vertebrae, and the apex is attached to the ischial spine.

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5. What is the sacroiliac joint? The joint / area where the sacrum and ilium are connected. There are two of them in your lower back, and they sit on each side of your spine. Their main job is to carry the weight of your upper body when you stand or walk and shift that load to your legs.

6. Describe the Symphysis Pubis. Secondary joint, made of cartilage, between left and right superior rami of the pubis and hip bones, located in from and below the bladder. In the female, it is close to the clitoris. This area expands and helps make way for a baby to come through the pelvis at birth.

7. What is the sacrococcygeal Joint and why is it important? The sacrococcygeal joint is a hinge joint between the fifth sacral and the first occygeal vetebrae. It allows both flexion and extension. Extension, by increasing the diameter of the outlet of the pelvis. Because it is mobile, it performs movements of extension and flexion. This is most important in birth to allow for the baby to pass through without breaking any of mama’s bones.

8. How does the mobility of the pelvis change during pregnancy? During pregnancy, progesterone and relaxin hormones are released to make the joints and ligaments soften (hypermia). Bones separate by 1-12mm. This allows for the expansion of the pelvis during labor as the fetus makes its way down to be born.

9. What are the differences in the male and female pelvis? At birth of a boy or girl, there is no difference between male and female. At puberty, androgen is essential for development of the male-type pelvis. Some of the differences are as follows:  Male: thicker, heavier, narrow deeper, longer and narrower sacrum, pelvis has a heart shaped inlet, v- shaped pubic arch, coccyx is immovable  Female: delicate-thin and light, Ilia are less sloped, wider, pelvic inlet larger more rounded, more oval shaped, shallow, coccyx is more moveable

10. Explain how the adolescent female and adult female pelvis differ. How and why does this happen?  Adolescent: smaller, anthropoid shape  Adult: gynecoid shape

Girls growth in stature decelerates rapidly in the first year after menarche and ceases within 1 or 2 years. The pelvic basin, on the other hand, continues to grow more slowly and consistently during late adolescence. It’s at that time that the pelvis changes from anthropoid toa gynecoid shape. Maturation of the reproductive system and attainment of adult size do not indicate that the growth and development of the pelvis are complete.

B. Pelvic Floor

1. What is the pelvic floor and what are its functions? The pelvic floor is a muscular diaphragm that separates the pelvic cavity above from the perineal space below. It is formed by the levator ani and coccygeus muscles and is covered completely by parietal facia. The urethra and vagina pass through the urogenital hiatus. The rectal hiatus is posterior and the rectum and anal canal pass through it. Its functions is to support the pelvic internal organs, to build up intraabdominal pressure (diaphragm, abdominal wall, pelvic floor must contract together), and help at the birth of the anterior rotation of the presenting part and directs it downward/forward along with the birth passage.

2. Part of the pelvic floor consists of the Levator Ani. This is further subdivided into two main muscles. One of these is the pubococcygeus muscle. What is this muscle and what does it do/why is it important? Ensure you cover all three sections completely. The PC muscle is made up of pubovaginalis, puborectalis and pubococcygeus proper. The pubovaginalis portion acts as a sling around the vagina and is the main support for the female pelvic organs. The puborectalis portion forms a loop around the anal canal and rectum, suspending the rectum and controlling the Charity Callis Anatomy & Physiology Clinical Anatomy 1 - #4 Page 3

descent of the feces. The pubococcygeus proper is composed of the lateral fibers of the PC muscle. It has a Y-shaped insertion into the lateral margins of the coccyx, it helps control the passage of feces.

3. What happens to the pelvic floor during parturition? Why do you think this is the case? When the presenting part has reached the proper level during second stage, the central point of the perineum becomes thin. The levator ani and the anal sphincter muscles relax, and the muscles of the pelvic floor are drawn over the advancing head.

C. Perineum

1. What is the perineum and what are the two triangles? The perineum is a diamond-shaped space that lies below the pelvic floor. It is divided into two triangles: anteriorly, the urogenital triangle; posteriorly, the anal triangle.

2. What anatomical parts are contained within the Urogenital Triangle? Opening of the vagina, terminal part of the urethra, crura of the clitoris with the ischiocavernosus muscles, vestibular bulbs covered by the bulbocavernousus muscles, Bartholin’s glands and their ducts, urogenital diaphragm, muscles that constitute the central point oaf the perineum, perineal pouches, blood vessels, nerves and lymphatics

3. What is the urogenital diaphragm? What does it contain? Is a triangular ligament, likes in the anterior triangle of the perineum, composed of muscle tissue covered by facia. The two muscles are the deep transverse perineal and the sphincter of the membranous urethra. The superior layer of fascia is thin and weak. The inferior fascial layer is a strong fibrous membrane. It extends from a short distant beneath the arcuate pubic ligament to the ischial tuberosities. The fascial layers fuse superiorly and form the transverse perineal ligament. Inferiorly, they join in the central point of the perineum.

4. What is the job of the Sphincter of Membranous Urethra? The sphincter of the membranous urethra lies between the facial layers of the urogenital diaphragm. It is also called the compressor of the urethra. It helps to control the flow of urine in the urethra.

5. What is the Anal Triangle and what does it contain? Contains the following: lower end of the anal canal and its sphincters, anococcygeal body, ischiorectal fossa, blood vessels, lymphatics and nerves

6. What are the two jobs of the Sphincter Ani Externus? Two jobs of the sphincter ani externus:  The superficial portions surround the anal orifice. Its fibers are voluntary and act during defecation (pooping) or in an emergency.  The deep part is and involuntary muscle that surround the lower part of the anal canal and acts as a sphincter for the anus.

7. What comprises the Perineal Body and what is the biggest issue with this area in childbirth? The perineal body, aka the perineum is what the fetal head stretches during childbirth. When delivery of the baby is rushed or when there’s medical intervention, often times the perineum tears. An episiotomy is often given to a mama when in labor in this area. In natural labor and birth, this area stretches beautifully, and some midwives can help mama ease or “breathe” the baby out often resulting in a perineum that is intact during birth.

D. Uterus and Vagina

1. What is the uterus? Describe its size, purpose, and location. The uterus is a muscular organ. It houses the fetus during pregnancy and afterwards pushes and squeezes the baby out. It is located in the pelvis and when the woman is not pregnant, it is the size of a pear. When she’s pregnant it changes to accommodate a fetus, sometimes up to 10-12lbs. Charity Callis Anatomy & Physiology Clinical Anatomy 1 - #4 Page 4

2. Name the three layers of the uterus. 1) Perimetrium 2) Myometrium 3) Endometrium

3. Describe each of the three uterine layers. The three layers of the uterus are the 1) Perimetrium, outer layer – longitudinal fibers 2) Myometrium, inner layer whose fibers run (for the most part) in a circular direction 3) Endometrium, a thick middle layer whose fibers are arranged in an interlacing pattern and through which the blood vessels course. When these fibers contract and retract after the fetus have been expelled, the blood vessels are kinked and constricted. This is how postpartum hemorrhaging is controlled.

4. What is the isthmus? What role does it play and how does it change in pregnancy? The isthmus lies between the body of the uterus and the cervix. In pregnancy, the isthmus plays an important role. As the uterus grows, the isthmus increases in length and becomes soft and compressible. It is the thick tube-like portion of the birth canal connecting the opening of the cervix to the uterus.

5. Explain the role of the cervix and vagina in pregnancy as well as the different features and layers. The vagina is a fibromuscular membranous tube surrounded by the vulva, inferiorly, the uterus superiorly, the bladder anteriorly, and the rectum posterior. The wall of the vagina is made up of four layers: mucosa (epithelial layer), submucosa (rich in blood vessels), muscularis (behind the third layer), outer connective tissue layer connects the vagina to the surrounding structures. It is where sperm travels to fertilize the mother’s egg through the cervix. The cervix is the baby door. After an egg if fertilized the cervix remains closed with a mucus plug to protect from germs during pregnancy. When the cervix is ripe, the mucus plug is expelled in early labor. The cervix dilates and the internal os gradually disappears, and the cervical canal also becomes part of the uterine segment, leaving only the external os. The baby is born through the vagina as it stretches to accommodate the fetal head and body.

6. What is uterine prolapse? Discuss the complications, treatments, etc with this abnormality. Uterine prolapse is when the pelvic floor muscles and ligaments stretch and weaken and no longer provide enough support for the uterus. As a result, the uterus slips down into or protrudes out of the vagina. Complications include (antepartum) abortion, cervical edema, ulceration, and sepsis, urinary retention and infection, possible prolonged bed rest, (intrapartum) cervical dilation beginning outside the vagina, edema and fibrosis causing cervical dystocia, lacerations of the cervix, obstructive labor possibly leading to uttering rupture, (postpartum) infection is increased. Treatments are as follows (antepartum) bed rest in the Trendelenburg position to reduce edema and permit the repositioning of the uterus, Pessary to maintain the position of the uterus, (intrapartum) most patients have a normal delivery, but arrest of progress may happen, if cervical dystocia develops several procedures may be considered a) incisions of the cervix b) Pitocin augmentation of labor c) c-section.

7. What are the three main uterine complications in labor and delivery? The three main uterine complications in labor and delivery are retained placenta, subinvolution of the placental cite, postpartum hemorrhage.

8. What is a unicornuate and bicornuate uterus? An unicornuate uterus is one that is malformed, missing one “horn” or side. Removal of the contralateral ovary and rudimentary horn may be followed by a successful pregnancy. A bicornuate uterus is where there is a deep indention at the top of the fundus, a heart shaped uterus. Abortion, incompetent cervix, PROM, preterm labor, abnormal presentation, and c-section are all common outcomes. Labor proceeds to vaginal delivery in many cases. Occasionally, the nonpregnant horn may rupture during labor.