Female Pelvis: Practical Explanation (Nursing Lecture) - Notes

1. Summary

This video provides a practical, detailed explanation of the female pelvis, crucial for understanding childbirth. It covers the anatomy of the female pelvis, including its bones, joints, and ligaments. The lecture distinguishes between the false and true pelvis and highlights important landmarks. A significant portion is dedicated to explaining the various diameters of the pelvic brim (inlet), cavity, and outlet, which are critical for assessing the passage of the fetus during birth.

2. Key Takeaways

* The female pelvis is a bony canal essential for fetal passage during birth.

* It is comprised of specific bones: ilium, ischium, pubis, and sacrum.

* Key joints within the pelvis include the sacroiliac joints and the pubic symphysis.

* Ligaments play a vital role in stabilizing the pelvic joints.

* The pelvis is divided into the false pelvis (superior) and the true pelvis (inferior), with the true pelvis being the birth canal.

* Understanding pelvic landmarks is crucial for clinical assessment.

* Pelvic diameters (anteroposterior, transverse, oblique) at the brim, cavity, and outlet are essential for predicting the likelihood and ease of vaginal birth.

3. Detailed Notes

00:00 - Introduction to the Female Pelvis

* **Definition:** The female pelvis is a bony canal through which the fetus must pass during birth.

* **Components:** It consists of a brim, cavity, and outlet.

* **Scope of the video:** Covers bones, joints, ligaments, and diameters.

01:18 - Female Pelvis Bone

* The pelvis is formed by four bones:

* **Two Hip Bones (Innominate Bones):** Each hip bone is formed by the fusion of three bones:

* **Ilium:** The largest part, forms the upper and posterior part of the hip bone. Features include the iliac crest and iliac fossa.

* **Ischium:** Forms the lower and posterior part. Features include the ischial tuberosity (which bears body weight when sitting) and the ischial spine.

* **Pubis:** Forms the anterior and inferior part. Features include the pubic crest and pubic tubercle. The two pubic bones meet at the pubic symphysis.

* **Sacrum:** A triangular bone formed by the fusion of five sacral vertebrae, located at the posterior pelvis.

* **Coccyx:** The tailbone, formed by the fusion of typically 3-5 coccygeal vertebrae, attached to the sacrum.

09:17 - Female Pelvis Joints

* **Sacroiliac Joints:** (2) These are strong, weight-bearing joints formed between the sacrum and the ilium. They are synovial joints.

* **Sacrococcygeal Joint:** The joint between the sacrum and the coccyx.

* **Pubic Symphysis:** The joint formed by the articulation of the two pubic bones anteriorly. It is a cartilaginous joint.

09:54 - Female Pelvis Ligaments

* Ligaments provide strength and stability to the pelvic joints. Key ligaments include:

* **Anterior and Posterior Sacroiliac Ligaments:** Reinforce the sacroiliac joints.

* **Sacrospinous Ligament:** Extends from the sacrum to the ischial spine, dividing the greater and lesser sciatic foramina.

* **Sacrotuberous Ligament:** Extends from the sacrum to the ischial tuberosity.

* **Anterior and Posterior Pubic Ligaments:** Reinforce the pubic symphysis.

11:21 - False Pelvis (Pelvis Major)

* **Location:** The superior, wider part of the pelvic cavity, above the pelvic brim.

* **Boundaries:** Formed by the lumbar vertebrae posteriorly, the iliac wings laterally, and the abdominal wall anteriorly.

* **Function:** Primarily supports abdominal organs (e.g., intestines). Not directly involved in childbirth.

11:44 - True Pelvis (Pelvis Minor)

* **Location:** The inferior, narrower part of the pelvic cavity, below the pelvic brim.

* **Boundaries:** Formed by the sacrum and coccyx posteriorly, the ischium and pubis laterally and anteriorly.

* **Function:** This is the actual birth canal through which the fetus must pass. It has an inlet, cavity, and outlet.

12:32 - Landmarks of the Female Pelvis

* These are anatomical points used for measurement and assessment. Important landmarks include:

* **Promontory:** The anterior and upper border of the first sacral vertebra.

* **Sacral Promontory:** (Same as above)

* **Sacroiliac Joints**

* **Anterior Superior Iliac Spines (ASIS)**

* **Iliac Crests**

* **Pubic Symphysis**

* **Pubic Arch**

* **Ischial Spines:** Palpable internally, important for determining descent of the fetal head.

* **Ischial Tuberosities:** Can be measured externally to assess pelvic width.

* **Coccyx:** The tip of the tailbone.

13:23 - Diameters of Brim/Inlet of the Female Pelvis

* The pelvic inlet is the upper opening of the true pelvis. It is heart-shaped in females.

* **Anteroposterior (AP) Diameter (Conjugate):**

* **Anatomical Conjugate:** From the sacral promontory to the superior aspect of the pubic symphysis.

* **Obstetric Conjugate:** The *most important* diameter. Measured from the sacral promontory to the *closest* point on the posterior aspect of the pubic symphysis. **Average:** ~11 cm.

* **Diagonal Conjugate:** From the sacral promontory to the inferior aspect of the pubic symphysis. Can be measured clinically (by palpation) and used to estimate the obstetric conjugate (Diagonal Conjugate - 1.5 to 2 cm = Obstetric Conjugate).

* **Transverse Diameter:** The widest diameter at the inlet, running between the widest points of the pelvic brim on either side. **Average:** ~13.5 cm.

* **Oblique Diameters (2):**

* **Right Oblique:** From the right sacroiliac synchondrosis to the left iliopubic eminence. **Average:** ~12.5 cm.

* **Left Oblique:** From the left sacroiliac synchondrosis to the right iliopubic eminence. **Average:** ~12.5 cm.

15:51 - Diameters of the Cavity of the Female Pelvis

* The pelvic cavity is the space between the inlet and the outlet.

* **Anteroposterior Diameter:** From the anterior surface of the sacrum to a point midway between the symphysis pubis and the tip of the coccyx.

* **Transverse Diameter:** The widest diameter, measured between the ischial spines. This is often referred to as the **interspinous diameter**. **Average:** ~10.5 cm. This is a critical measurement as it represents the narrowest part of the mid-pelvis.

* **Oblique Diameters:** Less significant in the cavity compared to the inlet and outlet.

16:54 - Diameters of the Outlet of the Female Pelvis

* The pelvic outlet is the lower opening of the true pelvis. It is diamond-shaped.

* **Anteroposterior Diameter:** From the pubic symphysis to the tip of the coccyx. **Average:** ~13 cm (this measurement increases if the coccyx can be pushed back during birth).

* **Transverse Diameter (Bi-ischial Diameter):** Measured between the inner aspects of the ischial tuberosities. **Average:** ~11 cm.

* **Anteroposterior Diameter (Pubic bone to anus):** Another AP measurement for the outlet.

* **Intertuberous Diameter:** (Same as Transverse Diameter of the Outlet).

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**Note:** The video emphasizes the practical application of these measurements in nursing and obstetrics for assessing the adequacy of the pelvis for vaginal delivery. It's important to note that averages can vary, and clinical judgment is paramount.