Distinguish Between False And True Pelvis

The pelvis, a basin-shaped structure located at the base of the spine, is a critical component of the human skeletal system. It supports the weight of the upper body, facilitates movement, and protects vital organs. Understanding the nuances of pelvic anatomy, particularly the distinction between the false and true pelvis, is crucial for healthcare professionals, fitness enthusiasts, and anyone interested in human anatomy. This comprehensive article delves into the differences between the false and true pelvis, their respective functions, clinical significance, and common conditions affecting them.

Demystifying the Pelvis: False vs. True

The pelvis is divided into two main regions: the false pelvis (also known as the greater pelvis) and the true pelvis (also known as the lesser pelvis). These regions are separated by an important anatomical landmark called the pelvic brim or linea terminalis. Understanding this division is fundamental to comprehending pelvic function and its role in various physiological processes, especially during pregnancy and childbirth.

The False Pelvis: Gateway to the Abdomen

The false pelvis is the superior portion of the pelvic region, situated above the pelvic brim. It is essentially a part of the abdomen and plays a significant role in supporting the abdominal organs.

• Boundaries: The false pelvis is bounded by the iliac bones laterally, the lumbar vertebrae posteriorly, and the abdominal wall anteriorly.
• Function: Its primary function is to support the intestines and transmit the weight of the upper body to the lower limbs. It provides a broad surface for muscle attachment, contributing to posture and movement.
• Contents: The false pelvis houses parts of the intestines, particularly the ileum and sigmoid colon. It also contains major blood vessels and nerves that supply the lower abdomen and lower limbs.
• Clinical Significance: The false pelvis can be involved in various abdominal conditions, such as appendicitis, diverticulitis, and bowel obstruction. Its bony structure can be affected by fractures or tumors, causing pain and affecting mobility.

The True Pelvis: The Foundation of Childbirth

The true pelvis lies below the pelvic brim and forms a bony canal through which the fetus passes during childbirth. It is a crucial structure in obstetrics and gynecology.

• Boundaries: The true pelvis is bounded by the sacrum and coccyx posteriorly, the ischium and pubis laterally and anteriorly, and the pelvic brim superiorly.
• Function: The true pelvis supports the bladder, rectum, and reproductive organs. In females, it forms the birth canal and plays a vital role in pregnancy and childbirth.
• Contents: The true pelvis houses the urinary bladder, rectum, and internal reproductive organs (uterus, ovaries, and fallopian tubes in females; prostate gland and seminal vesicles in males).
• Clinical Significance: The true pelvis is involved in various conditions, including pelvic inflammatory disease (PID), ectopic pregnancy, prostate cancer, and childbirth complications. Its dimensions are critical for successful vaginal delivery, and abnormalities can lead to dystocia (difficult labor).

Key Differences Summarized

To clearly differentiate between the false and true pelvis, consider the following table:

The Pelvic Brim: The Dividing Line

The pelvic brim (also known as the linea terminalis or inlet of the pelvis) is an oval-shaped bony ridge that marks the boundary between the false and true pelvis. It is formed by the following structures:

• Sacral promontory: The anterior and superior edge of the sacrum.
• Ala of the sacrum: The wing-like lateral extensions of the sacrum.
• Arcuate line: A curved ridge on the inner surface of the ilium.
• Pectineal line (pecten pubis): A ridge on the superior ramus of the pubis.
• Pubic crest: The superior border of the pubic bone.
• Symphysis pubis: The cartilaginous joint between the two pubic bones.

The pelvic brim is a crucial landmark for obstetricians, as it defines the entrance to the birth canal. Its shape and dimensions can influence the progress of labor and delivery.

Clinical Significance in Obstetrics

The true pelvis is of paramount importance in obstetrics, as its dimensions determine the feasibility of vaginal delivery. Key pelvic measurements include:

• Inlet diameter: The anteroposterior diameter of the pelvic inlet, measured from the sacral promontory to the symphysis pubis. A normal inlet diameter is approximately 11 cm.
• Midpelvis diameter: The transverse diameter of the midpelvis, measured between the ischial spines. A normal midpelvis diameter is approximately 10.5 cm.
• Outlet diameter: The anteroposterior diameter of the pelvic outlet, measured from the coccyx to the inferior margin of the symphysis pubis. A normal outlet diameter is approximately 9.5 cm.

If these diameters are significantly reduced, a condition known as cephalopelvic disproportion (CPD) may occur, where the baby's head is too large to pass through the mother's pelvis. In such cases, a Cesarean section may be necessary.

Pelvic Shapes and Their Obstetrical Implications

The shape of the true pelvis also influences the ease of childbirth. Based on the classification developed by Caldwell and Moloy, there are four basic pelvic types:

• Gynecoid: This is the classic female pelvis, with a rounded inlet, wide subpubic arch, and straight side walls. It is the most favorable for vaginal delivery.
• Android: This pelvis is heart-shaped or wedge-shaped, with a narrow subpubic arch and convergent side walls. It is more common in males and is associated with difficult labor.
• Anthropoid: This pelvis is oval-shaped, with a long anteroposterior diameter and a narrow transverse diameter. It is associated with occiput posterior positions and prolonged labor.
• Platypelloid: This pelvis is flattened, with a wide transverse diameter and a short anteroposterior diameter. It is relatively rare and can lead to transverse arrest of labor.

Common Conditions Affecting the Pelvis

Several conditions can affect the false and true pelvis, leading to pain, dysfunction, and complications. These include:

• Pelvic Fractures: Pelvic fractures can result from high-energy trauma, such as motor vehicle accidents or falls from height. They can be associated with significant bleeding, nerve damage, and organ injury. Treatment may involve surgery and prolonged rehabilitation.
• Pelvic Inflammatory Disease (PID): PID is an infection of the female reproductive organs, usually caused by sexually transmitted bacteria. It can lead to chronic pelvic pain, infertility, and ectopic pregnancy.
• Endometriosis: Endometriosis is a condition in which the tissue that normally lines the uterus (endometrium) grows outside the uterus. It can cause pelvic pain, heavy bleeding, and infertility.
• Pelvic Floor Dysfunction: Pelvic floor dysfunction refers to a range of conditions that affect the muscles and ligaments that support the pelvic organs. It can lead to urinary incontinence, fecal incontinence, and pelvic organ prolapse.
• Prostate Cancer: Prostate cancer is a common malignancy in men that can affect the prostate gland, which is located within the true pelvis. It can cause urinary symptoms, sexual dysfunction, and bone pain.
• Osteoarthritis: Osteoarthritis can affect the hip joint and the sacroiliac joint, both of which are located near the pelvis. It can cause pain, stiffness, and limited range of motion.
• Sacroiliac Joint Dysfunction: The sacroiliac (SI) joint connects the sacrum to the ilium. Dysfunction of this joint can cause lower back pain, buttock pain, and referred pain to the groin and legs.

Diagnostic Tools and Imaging Techniques

Various diagnostic tools and imaging techniques are used to evaluate the pelvis and diagnose conditions affecting it. These include:

• Physical Examination: A thorough physical examination, including palpation of the pelvic bones and assessment of range of motion, can provide valuable information about pelvic structure and function.
• X-rays: X-rays can be used to visualize fractures, dislocations, and bony abnormalities of the pelvis.
• Computed Tomography (CT) Scans: CT scans provide detailed cross-sectional images of the pelvis, allowing for the evaluation of bony structures, soft tissues, and blood vessels.
• Magnetic Resonance Imaging (MRI): MRI provides high-resolution images of the soft tissues of the pelvis, including muscles, ligaments, nerves, and blood vessels. It is particularly useful for evaluating pelvic floor dysfunction, endometriosis, and tumors.
• Ultrasound: Ultrasound can be used to visualize the pelvic organs, including the uterus, ovaries, bladder, and prostate gland. It is often used in obstetrics to monitor fetal development.
• Hysterosalpingography (HSG): HSG is an X-ray procedure used to evaluate the uterus and fallopian tubes. It is often used to investigate infertility.
• Cystoscopy: Cystoscopy is a procedure in which a thin, flexible tube with a camera attached is inserted into the bladder to visualize its lining. It is used to evaluate bladder conditions, such as bladder cancer and interstitial cystitis.

Maintaining Pelvic Health

Maintaining pelvic health is crucial for overall well-being and function. Here are some tips for promoting pelvic health:

• Maintain a Healthy Weight: Obesity can put extra stress on the pelvic floor muscles, increasing the risk of pelvic floor dysfunction.
• Practice Good Posture: Good posture helps to align the pelvis and spine, reducing stress on the pelvic joints and muscles.
• Perform Pelvic Floor Exercises (Kegels): Kegel exercises can strengthen the pelvic floor muscles, improving bladder control and sexual function.
• Avoid Straining During Bowel Movements: Straining during bowel movements can weaken the pelvic floor muscles. Ensure adequate fiber intake and stay hydrated to promote regular bowel movements.
• Practice Safe Sex: Practicing safe sex can reduce the risk of sexually transmitted infections that can lead to pelvic inflammatory disease.
• Seek Medical Attention for Pelvic Pain: Persistent pelvic pain should be evaluated by a healthcare professional to determine the underlying cause and receive appropriate treatment.
• Regular Exercise: Regular exercise can improve overall health and fitness, including pelvic health. Choose exercises that are low-impact and do not put excessive stress on the pelvic joints.
• Proper Lifting Techniques: When lifting heavy objects, use proper lifting techniques to avoid straining the back and pelvis.
• Avoid Smoking: Smoking can weaken the pelvic floor muscles and increase the risk of urinary incontinence.

Frequently Asked Questions (FAQ)

• What is the difference between the male and female pelvis?

  The female pelvis is generally wider, shallower, and has a larger pelvic inlet and outlet than the male pelvis. These differences are adaptations for childbirth. The subpubic angle is also wider in females.

• Can pelvic floor exercises help with back pain?

  Yes, pelvic floor exercises can help with back pain, especially if the pain is related to sacroiliac joint dysfunction or pelvic instability. Strengthening the pelvic floor muscles can improve core stability and support the spine.

• What are the risk factors for pelvic floor dysfunction?

  Risk factors for pelvic floor dysfunction include pregnancy, childbirth, obesity, chronic constipation, chronic coughing, and aging.

• How can I tell if I have pelvic floor dysfunction?

  Symptoms of pelvic floor dysfunction include urinary incontinence, fecal incontinence, pelvic pain, pelvic pressure, and painful intercourse. If you experience any of these symptoms, consult a healthcare professional.

• Is it possible to correct cephalopelvic disproportion (CPD)?

  No, cephalopelvic disproportion (CPD) cannot be corrected. If a woman is diagnosed with CPD, a Cesarean section is usually recommended to deliver the baby safely.

• What is the role of the obturator foramen?

  The obturator foramen is a large opening in the hip bone formed by the ischium and pubis. It allows the passage of nerves and blood vessels to the lower limb. While it's a significant anatomical feature, it doesn't directly delineate the false and true pelvis.

• Can posture affect the pelvic alignment?

  Yes, posture can significantly affect pelvic alignment. Prolonged sitting, slouching, or incorrect lifting techniques can lead to pelvic imbalances and pain. Maintaining good posture and practicing exercises to strengthen core and pelvic muscles are essential for proper alignment.

Conclusion: Understanding Your Pelvis

The distinction between the false and true pelvis is fundamental to understanding pelvic anatomy and its role in supporting the body, protecting organs, and facilitating childbirth. While the false pelvis primarily supports abdominal organs, the true pelvis is crucial for reproductive function and vaginal delivery. Understanding the dimensions and shapes of the true pelvis is essential for obstetricians in managing labor and delivery. Various conditions can affect the pelvis, leading to pain and dysfunction, but proper diagnosis and treatment can help to restore pelvic health and function. By maintaining a healthy lifestyle, practicing good posture, and performing pelvic floor exercises, individuals can promote pelvic health and overall well-being. This comprehensive knowledge empowers individuals to take proactive steps in understanding and caring for their pelvic health.