- The pelvis is the part of the trunk that is inferoposterior to the abdomen, and is the area of transition between the trunk and the lower limbs.
- The pelvic cavity is the inferior most part of the abdominopelvic cavity.
- Anatomically, the pelvis is the part of the body surrounded by the pelvic girdle
Pelvic Orientation
- The front of the symphysis pubis and the anterior superior iliac spines lie in the same vertical plane.
- This means that the pelvic surface of the symphysis pubis faces upward and backward and the anterior surface of the sacrum is directed forward and downward.
PELVIC GIRDLE
The pelvic girdle is a basin-shaped ring of bones that connect the vertebral column to the two femurs. The primary functions are:
- Bear the weight of the upper body when sitting and standing.
- Transfer that weight from the axial to the lower appendicular skeleton for standing and walking.
- Provide attachment for the powerful muscles of locomotion and posture and those of the abdominal wall, withstanding the forces generated by their actions.
- Contain and protect the pelvic viscera and the inferior abdominal viscera, while permitting passage of their terminal parts to the perineum.
- Provide support for the uterus and attachment for the erectile bodies of the external genitalia.
- Provide attachment for the muscles and membranes that assist the functions listed above by forming the pelvic floor and filling gaps that exist in or around it.
Bones of Pelvic Girdle
- In the mature individual, the pelvic girdle is formed by three bones:
- Right and left hip bones: large, irregularly shaped bones, each of which develops from the fusion of three bones, the ilium, ischium, and pubis.
- Sacrum: formed by the fusion of five, originally separate, sacral vertebrae.
False Pelvis
The boundaries are:
- The lumbar vertebrae behind, the iliac fossae and the iliacus muscles laterally, and the power part of the anterior abdominal wall anteriorly.
- The false pelvis flares out at the upper end and is considered part of the abdominal cavity.
True Pelvis
- The anatomy of the true pelvis in females is important for obstetrics because it forms the bony canal through which the child passes during birth.
- The true pelvis in both sexes has an inlet, an outlet, and a cavity
Pelvic Brim (Inlet)
- The pelvic brim is formed by the sacral promontory behind, the iliopectineal lines laterally, and the symphysis pubis anteriorly.
Pelvic outlet
- Its boundaries are the coccyx posteriorly, the ischial tuberosities laterally, and the pubic arch anteriorly.
- It has three notches:
- Pubic arch anteriorly,
- Greater and lesser Sciatic notch, converted into foramen by sacrotuberous and sacrospinal ligaments
- So the outlet becomes diamond shaped
Pelvic cavity
- This short, curved canal, with a shallow anterior wall and a much deeper posterior wall, lies between the inlet and the outlet.
Differences of male and female pelvis
Morphological groups of pelvis
A and C are most common in males,
B and A in white females,
B and C in black females
D is uncommon in both sexes
The gynecoid pelvis is the normal female type. its pelvic inlet typically has a rounded oval shape and a wide transverse diameter.
An platypelloid (masculine or funnel-shaped) pelvis in a woman may present hazards to vaginal delivery.
- The true (obstetrical) conjugate from the middle of the sacral promontory to the posterosuperior margin (closest point) of the pubic symphysis. (11 to 11.5cm)
- The diagonal conjugate is the distance between the sacral promontory and the lower margin of pubic symphysis. (13 to 13.5cm)
It is measured by palpating the sacral promontory with the tip of the middle finger, using the other hand to mark the level of the inferior margin of the pubic symphysis on the examining hand
