Anatomical Model of the Female Pelvis – Key Features

This detailed anatomical model accurately represents the structure and function of the female human pelvis, designed for both educational and clinical applications.

Bone Composition:

• Includes paired iliac (coxal) bones, sacrum, and coccyx

• Features L1 and L2 lumbar vertebrae to demonstrate spinal articulation

• Provides complete representation of pelvic skeletal anatomy

Structural Characteristics:

• Distinctive funnel-shaped architecture divided into:

  • Greater pelvis (false pelvis): Upper, flared portion

  • Lesser pelvis (true pelvis): Lower, narrower cavity

• Anatomically accurate female morphology:

  • Wider, more circular pelvic inlet

  • Broader subpubic angle

  • Shorter, more everted sacrum

• Designed to reflect obstetric adaptations for childbirth

Functional Attributes:

• Supports weight transfer between trunk and lower limbs

• Provides attachment points for major muscle groups

• Protects reproductive organs and lower abdominal viscera

• Facilitates bipedal locomotion and spinal stability

Educational & Clinical Applications:

• Essential teaching tool for:

  • Medical and nursing education

  • Physical therapy programs

  • Midwifery training

• Valuable clinical reference for:

  • Obstetric and gynecological practice

  • Orthopedic assessments

  • Surgical planning

• Enables detailed study of:

  • Pelvic dimensions and variations

  • Biomechanical relationships

  • Pathological conditions

The human spine anatomical model, commonly referred to as the spine, represents the central support structure of the human skeleton, extending from the skull’s base to the pelvis.

Structure and Composition:
Comprised of 33 vertically stacked vertebrae, separated by intervertebral discs that function as shock absorbers.

Segments:
Divided into five regions: 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, the sacrum (5 fused vertebrae), and the coccyx (3-4 fused vertebrae).

Functions:
Serves three primary roles:
– **Static**: Maintains upright posture.
– **Dynamic**: Enables trunk and head mobility.
– **Protective**: Shields the spinal cord within the spinal canal.

Role:
Supports body weight, facilitates a wide range of movements, and acts as an anchor for muscles and ligaments.

### **Human Urinary System – Key Features**

The urinary system consists of specialized organs that work together to filter blood, remove waste, and maintain fluid and electrolyte balance.

**Kidneys**
– Paired, bean-shaped organs that filter blood to eliminate waste (e.g., urea, excess salts).
– Regulate blood pressure, electrolyte levels, and red blood cell production.

**Ureters**
– Two narrow tubes that transport urine from the kidneys to the bladder.

**Bladder**
– A muscular, expandable sac that stores urine (capacity: ~600 mL).
– Contracts during urination to expel urine.

**Arteries & Veins**
– Represented in red (arteries) and blue (veins) on models.
– Supply blood to the kidneys for filtration and oxygenate urinary tissues.

**Urethra**
– The final passageway for urine excretion from the bladder to the exterior.

The birthing pelvis is the female bony structure essential for childbirth, providing both structural support and a dynamic passageway for fetal delivery.

Anatomical Composition

• Comprises four fused bones:

  • Paired iliac bones (forming the pelvic girdle)

  • Sacrum (posterior base of the spine)

  • Coccyx (tailbone)

• Connects the spine to the lower limbs, ensuring stability and weight distribution.

Shape & Structural Divisions

• Funnel/hourglass shape with distinct regions:

  • Upper flare (false pelvis): Wider, supports abdominal organs.

  • Lower flare (true pelvis): Narrower, forms the birth canal.

• Superior strait: The narrowing between these regions, a critical landmark for obstetric assessment.

Obstetric Straits & Key Measurements

The pelvis features three key straits, each with critical diameters for fetal passage:

1. Upper strait:

   • Promontoretropubic diameter (anteroposterior measurement).

2. Middle strait:

   • Median transverse diameter (widest point between ischial spines).

3. Lower strait:

   • Interspinous diameter (between ischial tuberosities).

• These measurements determine cephalopelvic disproportion (CPD) and delivery feasibility.

Dynamic Adaptability

• Not rigid: Hormonal changes (relaxin, progesterone) increase ligament laxity late in pregnancy.

• Pubis symphysis and sacroiliac joints slightly widen, expanding the birth canal by up to 10–15%.

Role in Childbirth

1. Guides fetal descent: The baby navigates through the pelvic inlet, mid-cavity, and outlet.

2. Facilitates rotation: Bone contours help the fetus rotate into optimal positioning (e.g., occiput anterior).

3. Enables vaginal delivery: Optimal pelvic dimensions and adaptability prevent obstructed labor.

The Birthing Pelvis: Structure and Function in Childbirth

The female birthing pelvis serves as the crucial bony framework that enables successful vaginal delivery. This specialized structure combines anatomical precision with dynamic adaptability to facilitate the birth process.

Bony Architecture:

• Composed of four interconnected bones:

  • Paired ilium bones (forming the sides)

  • Sacrum (posterior wall)

  • Coccyx (tailbone)

• Forms a complete pelvic ring connecting the spine to the femurs

• Provides structural support while allowing necessary movement

Morphological Features:

• Distinctive hourglass configuration with:

  • Expanded false pelvis (greater pelvis) superiorly

  • Constricted true pelvis (lesser pelvis) inferiorly

  • Demarcated by the pelvic brim (superior strait)

• Exhibits characteristic female adaptations:

  • Wider subpubic angle (>90°)

  • Broader, more circular inlet

  • Shorter sacral curvature

Obstetric Dimensions:
Three critical planes determine fetal passage:

1. Pelvic Inlet (Superior Strait):

   • Key diameter: Promontoretropubic (11.5-13 cm)

2. Midpelvis:

   • Crucial measurement: Median transverse (10.5 cm)

3. Pelvic Outlet:

   • Important span: Interspinous (10-11 cm)

Dynamic Adaptations:

• Hormonally-mediated changes (relaxin, progesterone):

  • Increased sacroiliac joint mobility

  • Pubic symphysis widening (2-3 mm)

  • Ligamentous relaxation

• Permits up to 10-15% expansion of birth canal dimensions

Parturition Mechanics:

1. Fetal Engagement: Head enters pelvic inlet

2. Descent: Progressive movement through planes

3. Rotation: Internal adjustment to navigate contours

4. Expulsion: Final passage through outlet