Pelvis Lab 6B

Lab 6B: Female and Male Pelvic Organs and Kidney

Lab Overview

The pelvis has already been sagittally sectioned into left and right sides for you.
Study pelvic osteology. Osteology is critical for keeping oriented in the 3D complexity of the pelvic region.
Study the pelvic organs.
View the broad ligament in the female pelvis and understand the different parts.
Dissect the spermatic cord and testis (male).
Section the kidney and view its gross internal structures.

Short List of Structures - 6B

Greater and Lesser Sciatic Notch
Broad Ligament of Uterus and Mesosalpinx (female) or Ductus Deferens (male)
Round ligament of the Uterus (female) or Seminal Vesicle (male)
Urethra (be sure to bisect the full length of the urethra)
Uterine tube (female) or Epididymis (male)
Major and Minor Calyces of the Kidney

Osteology of the Pelvis

Use an articulated skeleton, models, and individual bones to study the osteology of the pelvis. A deep understanding of this complex, 3D skeletal structure is critical for remaining oriented when working with the hemisected pelvises.

Each pelvic bone (os coxa) is formed by three bones (ilium, ischium, and pubis), which fuse during childhood along lines that intersect in the acetabular fossa. The sacrum is not fused to os coxa.

Anterior view

Right lateral view of pelvic bone (os coxa)

Identify the following:

Acetabulum — articular socket on the lateral surface of each os coxa, which, together with the head of the femur, forms the hip joint
Obturator foramen (FIG. 1)— located inferior and anterior to the acetabulum; most of the foramen is closed by a flat connective tissue membrane called the obturator membrane; a small obturator canal remains open superiorly between the membrane and adjacent bone, providing communication between the lower limb and the pelvic cavity for the obturator n., a., and v.
Greater sciatic notch — posterior margin of the os coxa, superior to the ischial spine
Lesser sciatic notch — posterior margin of the os coxa, inferior to the ischial spine

Learn the names of the following landmarks on the three bones of the pelvis. Knowing these landmarks will make learning all other pelvic anatomy much easier:

Ilium — the most superior of the os coxa bones; articulates with the sacrum (Figure 35-2)
- - Iliac crest — thickened, superior margin of the ilium that serves as an attachment for muscles and fascia
  - Anterior superior iliac spine — anterior termination of the iliac crest
  - Anterior inferior iliac spine — inferior to the anterior superior iliac spine
  - Posterior superior iliac spine — posterior termination of the iliac crest
  - Iliac fossa — the iliacus muscle sits here

Figure 1.4

Anterior Superior View Posterior Inferior view

Ischium — the most inferior of the os coxa bones
- - Ischial tuberosity — the most prominent feature of the ischium, a large tuberosity on the posteroinferior aspect of the bone; an important site for lower limb muscle attachments and for supporting the body when sitting
  - Ischial spine — on the posterior margin of the ischium; separates the lesser and greater sciatic notches
  - Ischial ramus — projects anteriorly and superiorly to join with the inferior ramus of the pubis; the ischial ramus and inferior pubic ramus are fused and therefore are often called the ischiopubic ramus or conjoint ramus

Pubis — the most anterior of the os coxa bones
- - Superior pubic ramus — projects laterally and superiorly to join with the ilium; has notches for the external iliac a. and v., femoral n., and iliopsoas m./tendon
  - Inferior pubic ramus — a ramus that projects laterally and interiorly to join with the ramus of the ischium; the inferior pubic ramus and ischial ramus are termed the ischiopubic ramus
  - Pubic symphysis — a fibrocartilagenous pad of cartilage that joins the left and right pubic bones
  - Pubic tubercle — The pubic tubercle is a prominent tubercle on the superior ramus of the pubis bone of the pelvis. The pubic tubercle is the inferior attachment of the inguinal ligament.

Anterior Superior view

Right Sagittal Oblique view

Surface Anatomy

The following can be palpated externally (good for studying):

Prone position:

gluteal fold
intergluteal cleft
posterior superior iliac spine
iliac crest
ischial tuberosity

Supine Position

anterior superior iliac spine
pubic tubercle
pubic symphysis
inguinal ligament

Overview of the pelvic organs (both sexes)

Identify as many structures as you can in the hemisected pelvis before you begin dissecting. Then, carefully peel off the peritoneum to reveal the organs, ducts, vasculature, and nerves. You may have to clean off fat as well. Clean any feces out of the rectum as you identify structures. Some of the vasculature will not be visible until the organs are removed .

If you have a female cadaver, you should only peel the peritoneum off of one side of the pelvis. Leave the peritoneum intact on the other side to preserve the broad ligament.

Structures you can see without removing peritoneum:

- Ureters — paired tubes that drain urine from the kidneys; course interiorly along both sides of the posterior abdominal wall to the pelvic brim; cross anterior to the common/external iliac vessels on their way into the pelvis to the urinary bladder
- Urinary bladder — a reservoir for urine; located in the true pelvis, retroperitoneal; rests on the pelvic floor, posterior to the pubic symphysis. If the bladder is empty it will be collapsed against the pubic symphysis and difficult to see. The smooth musculature in the wall of the bladder is the Detrusor musculature.
- Ductus (=vas) deferens in the male — follow the ductus deferens from the deep inguinal ring to the posterior surface of the bladder; crosses over the ureter; push the bladder anteriorly and the rectum posteriorly to follow to the prostate gland. This may be difficulty to see in some cadavers without removing the peritoneum.
- Round ligament of the uterus in the female — follow the round ligament from the deep inguinal ring to the anterior and superior surface of the uterus; the round ligament is located between the layers of the broad ligament. It is a remnant of the fetal gubernaculum.
- Common Iliac a. and v. — bifurcate at the sacroiliac joint into the internal and external iliac aa. and vv., respectively
- Gonadal aa. (testicular/ovarian) — follow their course along the posterior abdominal wall from the deep inguinal ring (male) or from the ovaries (female); use forceps to reveal these vessels but note that they were cut when the cadavers were sectioned into superior and inferior halves. In older female cadavers the arteries will be very small, and may not be visible. They run to the ovary in a fold of peritoneum that is called the suspensory ligament of the ovary.
- Left gonadal v. — observe its course from the deep inguinal ring in males or from the ovaries in females to where it was cut when the cadaver was sectioned
- Right gonadal v. — observe its course from the deep inguinal ring in males or from the ovaries in females to where it was cut when the cadaver was sectioned

If you have a female, proceed to the “Uterine ligaments” section. If you have a male, proceed to the “Spermatic cord, testis and scrotum”

Anterior View (female)

Left Sagittal View (female)

Right Sagittal View (male)

Uterine Ligaments (female)

This section is mostly looking, not dissecting. Begin by moving the uterus and rectum to different positions to identify the following components of the broad ligament:

Note: If the uterus is absent (hysterectomy), go to another female cadaver that has a uterus to observe the following structures:

- Broad ligament — a drape of parietal peritoneum over the female reproductive organs. During development the uterus and ovaries push up into the peritoneum, so they appear to have a mesentery. Technically the peritoneum that forms the broad ligament is parietal peritoneum, but you will hear the ovaries and the fundus of the uterus referred to as “intraperitoneal”. The broad ligament has anterior and posterior sheets
- Mesosalpinx — the part of the broad ligament that wraps around the uterine (fallopian) tube; most superior part of the broad ligament, between the uterine tube and ovary; bilateral
- Mesovarium — the part of the broad ligament that suspends the ovary; posterior (perpendicular) extension of the broad ligament; to reveal the mesovarium, pull the ovary posteriorly 90 degrees to the plane of the mesosalpinx and broad ligament; bilateral

Superior view of the intact pelvis (female)

The remainder of the broad ligament is inferior to the ovary and mesosalpinx.

- Round ligament of the uterus — courses from the anterolateral surface of the uterine wall, inferior to the origin of the uterine tube, to the deep inguinal ring and ends by attaching to the mons pubis; bilateral. Remnant of the fetal gubernaculum.
- Ovarian ligament — courses from the posterolateral surface of the uterine wall, inferior to the origin of the uterine tube, to the medial pole of the ovary (also a remnant of the gubernaculum); contains the ovarian branches of the uterine a. and v.; bilateral
- Suspensory ligament of the ovary — courses from the pelvic brim to the lateral pole of the ovary; formed by the peritoneum where it drapes the ovarian vessels; bilateral
- Ovary- organ that produces ovum

Identify the following structures:

Bladder — superior and posterior to the pubic symphysis
Ureters — enter the lateral sides of the bladder; use forceps to dissect along the ureter to find its entry into the posterolateral surface of the bladder
Trigone — internal triangular space between the two ureteral orifices and the internal urethral orifice (you will see only half of the trigone)
Uterus — posterior to the bladder; identify the fundus, body, and cervix of the uterus, as well as the following:
Uterine tubes — extend laterally from the upper part of the body of the uterus
Fimbria — finger-like projections from the distal end of the uterine tube; the end is open
Ovaries — almond-shaped; the lateral pole is cupped by the fimbriated end of the uterine tube
Cervix — protrudes into the vaginal canal; external os opens into the vagina; use forceps to reveal the cervical canal and external os
Vagina — anterior wall, posterior wall, and two lateral fornices; use forceps to reveal the fornices
Urethra — between the clitoris and vagina; use forceps to reveal the urethra

Prostate, Spermatic cord, Testis and Scrotum (male)

Prostate Gland - a gland that surrounds the first part of the urethra (hence "prostatic urethra". It produces fluids that make up some of the volume of the semen.
Seminal Vesicles (= seminal gland) - the seminal vesicle is an outgrowth from the vas deferens. It is a highly coiled tubular structure that produces much of the volume of the semen.
Ejaculatory duct - the ejaculatory duct is the terminal portion of the vas deferens, and sits between the seminal vesicle and the prostatic urethra.
Urethra - The tube that drains the urinary bladder, it is divided into 3 parts anatomically.
- Prostatic urethra - the initital part of the urethra that is surrounded by the prostate gland. The prostatic urethra is where the ejaculatory duct empties into the urethra.
- Membranous urethra - a very short segment of the urethra as it passes through the body wall.
- Spongy urethra (= penile urethra) - the continuation of the membranous urethra in the penis, surrounded by corpus spongiosum erectile tissue.

Spermatic Cord and Scrotum Overview

The spermatic cord and scrotum are surrounded by fascial coverings that are continuous with and derived from the abdominal wall.

Scrotal sac - hangs inferior to the pubis and the root of the penis

Use a scalpel to make superficial vertical incisions of the skin along the left and right sides of the scrotum to fully reveal the spermatic cord on both sides

Spermatic cord - begins at the deep inguinal ring, lateral to the inferior epigastric vessels, and ends in the scrotum at the posterior border of the testis.

Scrotum — Tissue Layers

Superficial scrotal (Dartos) fascia - very thin layer that is continuous with Scarpa's fascia; devoid of fat; forms the scrotal septum; use forceps to dissect into the fascia to find the following structures of the spermatic cord:
1. External spermatic fascia - outer layer of spermatic fascia; continuous with the external oblique aponeurosis; deep to the Dartos fascia
2. Cremasteric fibers/fascia — middle layer of spermatic fascia; composed of loose connective tissue and thin fibers of cremasteric m. derived from the internal oblique m.; deep to the external spermatic fascia; best seen by looking for muscle strands while holding the cord in front of a light source
3. Internal spermatic fascia - innermost layer of spermatic fascia; continuous with the transversalis fascia; deep to the cremasteric fibers/fascia

Spermatic Cord — Contents

Use forceps to reveal and identify the following structures within the spermatic cord:

Ductus deferens (male) - muscular tube that conveys sperm from the epididymis to the ejaculatory duct. Palpate this firm, tubular structure (the hardest structure) within the spermatic cord. Follow the ductus deferns through the body wall and into the pelvis to the bladder.
Testicular a. - arises from the aorta; in the spermatic cord, the artery courses with the pampiniform plexus of veins
Pampiniform plexus of veins - venous network that drains into the right or left testicular v.
Genital branch of the genitofemoral n. - motor supply to he cremaster m.; may not be evident
Testis - organ that produces spermatozoa

Tunica vaginalis (visceral and parietal) - fibrous drape that surrounds the testis; extension of parietal peritoneum that forms a sleeve around much of the testis

Testis

Use forceps to reveal and identify the following:

Tunica vaginalis - derived from the parietal peritoneum; covers most of the testis; has a parietal layer (fused with the internal spermatic fascia) and visceral layer (bound to the anterolateral surface of the testis and epididymis). Covers the anterior, medial, and lateral surfaces of the testis, but not the posterior surface
Gubernaculum testis - connective tissue band between the inferior pole of the testis and the scrotum; remnant of the embryologic tissue that attached the inferior pole of the testis to the inferior surface of the scrotal sac

With scissors, open the tunica vaginalis to inspect the interior of the serous sac of the testis

Epididymis - attached to the posterior surface of the testis; observe its head, body, and tail regions; the ductus deferens begins at the tail of the epididymis

With a scalpel, cut the testis longitudinally into left and right portions but leave the epididymis intact

Tunica albuginea - deep to the visceral layer of the tunica vaginalis; tough, white layer of connective tissue that is the capsule of the testis; observe the numerous pyramidal lobules of the testis that are created by septa from the tunica albuginea
Seminiferous tubules - fine, threadlike tubes that produce sperm

Clinical Correlation: Testicular Torsion

Testicular torsion is a medical emergency in which the spermatic cord twists and cuts off blood supply to the testicle. The resulting ischemia causes rapid onset testicular pain, nausea, and vomiting, and the affected testicle may be higher than its normal position.

Individuals with the rare bell-clapper deformity are predisposed to testicular torsion because their tunica vaginalis attaches too high on the spermatic cord, leaving the testicle free to rotate (see image). ALthough the testicle can sometimes be manually rotated out of torsion, most cases require emergent surgery.

Kidney dissection

NOTE: The condition of the kidneys varies a lot between cadavers. In some you will be able to the gross structures well, in others not so much.

CUT: Use a scalpel or sharp knife to make a coronal section through the kidney (i.e. split the kidney into anterior and posterior halves, as in the figure to the left). You may need to clean fat away from the area of the renal sinus.

FIND: Identify the following internal structures:

(you are responsible for all the bold terms)

Fibrous capsule – Also called the renal capsule. The dense connective tissue that surrounds the kidney.
Renal cortex – the outer third of the kidney, this is where the glomeruli are located, appears as a continuous band of tissue that completely surrounds the renal medulla.
Renal columns - extensions of the renal cortex that project into the inner aspect of the kidney.
Renal medulla – the middle third of the kidney, divided by the renal columns into triangular-shaped Renal Pyramids. Contains the loop of Henle.
Renal papilla - the inner, pointed tip of each renal pyramid.

Minor calyx – part of the collecting system that receives urine from the renal papilla, one minor calyx for each papilla.
Major calyx – part of the collecting system that receives urine from two to four minor calyces.
Renal pelvis – formed by the union of all the major calyces. Two to four minor calyces unite to form a major calyx, and the major calyces unite to form the renal pelvis.
Ureter - the continuation of the renal pelvis, drains into the urinary bladder.

Spend some time looking at a cadaver of the opposite sex from your group's cadaver. If you finish everything early, go back and study and quiz each other on the osteology. To the extent possible, identify the same bones and landmarks in the cadaver as can be seen on the skeleton and plastic pelvis.

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