Pelvis Introductory Discussion

Lab Summary

An introduction to the bony pelvis is followed by a video of male and female pelvis to illustrate their similarities and differences. The detailed anatomy of the bony pelvis follows.

Lab Objectives

Describe the course of sciatic nerve as it leaves the pelvis.
Describe relationships of vessels and nerves of gluteal region to piriformis muscle.
Describe spinal nerves that contribute to lumbosacral plexus.
Name the main branches of internal iliac artery and regions they supply.
Name structures at trigone of bladder.
Describe relationships of inferior epigastric vessels and deep inguinal ring.
Describe the course and function of the pudendal nerve.

Lecture List

Introduction to Pelvis, Male and Female Pelvis, Skeletal Pelvis

Sex, Gender, and Anatomic Dissection

The vocabulary around sex and gender is rapidly shifting as visibility of transgender, intersex, and gender diverse individuals increases around the globe. Linguistic and social norms vary greatly across different cultural and geographic environments. Thus, while we establish our own uniform language around sex and gender within the scope of this course, we are aware terminology may vary in different contexts and cultures.

For the purpose of this course, we will use the phrase sex or “assigned sex” based on the appearance of external genitalia. Thus, male refers to individuals presenting with penis/testes; female refers to individuals presenting with vagina/uterus/ovaries. No intersex bodies are examined during this course.

The scope of this course is constrained to anatomical examination of cadavers and, thusly, focuses on assigned sex. Out of respect for the donors, we do not speculate about their personal gender identity.

The course does not address broader conversations of gender identity and expression. We still recommend familiarizing yourself with the intersections and differences between assigned sex, gender identity, and gender expression. In clinical settings, you will encounter individuals with any number of permutations of the identities outlined below.

Currently, gender-affirming surgery (surgical procedures to align a person’s primary and/or secondary sexual characteristics with their gender identity) is not discussed, though we hope to expand the scope of instruction in the future.

Sex and Gender Terminology

Sex: Assigned at birth based on appearance of external genitalia and/or chromosomal analysis

Assigned Male at Birth (AMAB)
Assigned Female at Birth (AFAB)
Intersex: Born with sexual characteristics that do not fit binary sex

Gender Identity: How an individual identifies themselves (binary or non-binary)

Gender Expression: How an individual wishes to be perceived publicly

Cisgender: Denoting or related to an individual whose sense of gender identity corresponds with their sex assigned at birth

Transgender: Denoting or related to an individual whose sense of gender identity differs with their sex assigned at birth

Gender Affirming Surgery: Surgical procedures to align an individual’s body with their gender identity

Introduction to Pelvis

Pelvis Gallery

2.1a) Pelvis composed of 3 fused bones – Ilium, ischium, and pubis + sacrum
2.1b) Sacroiliac joint transfers weight of the trunk, upper limbs, and head to pelvis
2.1c) Sacrotuberous and sacrospinous ligaments stabilize the sacrum
2.1d) Greater and lesser sciatic foramina are important doorways
2.1e) Internal iliac is the artery of the pelvis, perineum and gluteal regions
2.1f) Superior gluteal, inferior gluteal, and internal pudendal arteries leave the pelvis through the greater sciatic foramen
2.1g) Lumbar and sacral plexuses
2.1h) Origin of Pelvic Nerves
2.1i) Sciatic, gluteal, and pudendal nerves exit through the greater sciatic foramen
2.1j) Pudendal nerve passes around the sacrospinous ligament to enter the lesser sciatic foramen to reach perineum.
2.1k) Pelvic diaphragm
2.1l) Inferior view of pelvic diaphragm
2.1m) Urogenital diaphragm reinforces U-G hiatus

Male and Female Pelvis

Male and Female Pelvis Gallery

3.1a) Abdominal and pelvic cavities are continuous
3.1b) Inferior view of pelvic diaphragm
3.1c) Urogenital diaphragm
3.1d) Pelvic floor supports GI ,urinary, and reproductive organs
3.1e) Pelvic floor supports GI ,urinary, and reproductive organs
3.1f) The peritoneum covers the superior surface of the pelvic organs
3.1g) Fimbria of uterine tube and ovary are intraperitoneal
3.1h) Vagina, uterus, and uterine tube
3.1i) The uterus is normally anteverted and anteflexed
3.1j) Uterus positions
3.1k) Anterior to posterior pelvic dimensions
3.1l) Lateral dimensions of pelvis
3.1m) Mid sagittal male
3.1n) Sperm travels from testis to epididymis to vas deferent to ejaculatory duct to urethra.
3.1o) Male urethra
3.1p) External genitalia are attach to the U-G diaphragm
3.1q) External genitalia are attach to the U-G diaphragm
3.1r) Inferior view of female perineum
3.1s) Penile erectile tissue
3.1t) Muscles surround the root of the penis
3.1u) Muscles including the levator ani attach at the central perineal tendon
3.1v) Central perineal tendon in male
3.1w) Pudendal nerve (S2-S4) supplies motor and sensory innervation of the perineum
3.1x) Pudendal nerve (S2-S4) supplies the urethral and anal sphincters and sensation to the perineum
3.1y) Sympathetics and parasympathetics surround the prostate on their way to erectile tissue
3.1z) Vasography
3.1aa) Hysterosalpingogram
3.1ab) Sagittal female and male

Skeletal Pelvis

Skeletal Measurements

On a skeleton measure the following:

Pelvic inlet (sacral promontory to superior border of pubic symphysis)
Pelvic outlet (tip of coccyx to inferior border of pubic symphysis)
Diagonal conjugate (sacral promontory to inferior border of pubic symphysis)
Transverse dimension of outlet (distance between the ischial spines)

Are you able to determine differences between male and female?

4.1a) Pelvic inlet
4.1b) Pelvic outlet
4.1c) Diagonal conjugate
4.1d) Transverse dimension of outlet

Pelvimetry

Measure the pelvic inlet, pelvic outlet, diagonal conjugate and transverse dimension of outlet on the donor. Note the diagonal conjugate is a clinical estimation of the anterior to posterior dimension of the pelvic inlet.

Question 1: What are the importance of these measurements?

Answer

Pelvic dimensions are important for childbirth

Title: Pelvic dimensions Labels (left to right): Coccyx, pelvic outlet, diagonal conjugate, pubic symphysis (inferior border), pelvic inlet, pubic symphysis (superior border), sacral promontory — 4.2a) Pelvimetry

Pelvis Introductory Discussion

Contents

Key Structures

General Pelvic Anatomy

Female Pelvic Anatomy

Male Pelvic Anatomy

Resources

Pelvis Introductory Discussion

Lab Summary

Lab Objectives

Lecture List

Sex, Gender, and Anatomic Dissection

Sex and Gender Terminology

Introduction to Pelvis

Pelvis Gallery

Male and Female Pelvis

Male and Female Pelvis Gallery

Skeletal Pelvis

Skeletal Measurements

Pelvimetry