Pelvic Girdle

Pelvic girdle

Additional Images:

Pelvic Girdle

Functions of the Pelvic Girdle:

Protect the lower abdominal and pelvic organs
Articulate with the bones of the lower extremities
Provide attachment sites for muscles and ligaments of the trunk and lower extremity

Right and left pelvic bones:

Ilium
Ischium
Pubis

Posterior Wall:

Sacrum and coccyx

Features of Medial Aspect

Obturator foramen (space)

Round space created by the ischium and pubis.

IIlium (Iliac bone)

Iliac crest is the bony ridge of the ilium
Anterior and posterior superior iliac spines where crest terminates anteriorly and posteriorly
Anterior and posterior inferior iliac spines are inferior to superior spines

The iliac spines anchor muscles of the hip and thigh

Ala is the broad, flat portion of the ilium below the iliac crest
Iliac fossa is the concave portion of the ala, which gives a "bowl" shape to this region of the pelvis
Auricular surface and iliac tuberosity are areas of articulation the sacrum
Arcuate line is a rounded ridge of bone that sweeps from the auricular surface to the pubis

Pubis (Pubic bone)

Pectineal line is continuation of arcuate line; these lines are collectively referred to as the linea terminalis
Pubic tubercle is a knob-like projection that anchors the inguinal ligament (not shown)
Symphyseal surface is where the cartilaginous pubic symphysis attaches to the pubic bone anteriorly
Superior and inferior pubic rami are the straight portions of the pubis; they connect with the ilium, superiorly, and the ischium, inferiorly

Ischium (Ischial bone)

Ischial spine is a small projection of bone that points inferomedially
Ischial tuberosity is the large, roughened area of the bone where the hamstrings muscles attach
Ischial ramus joins with the inferior pubic ramus
Lesser sciatic notch is inferior to the ischial spine

Greater sciatic notch is bound by the ischial spine and the posterior inferior iliac spine*

Unique Features of Lateral Aspect:

Acetabulum is the deep, cup-like depression where the head of the femur (aka, thigh bone) articulates with the pelvic bone;it marks where ilium, ischium, and pubis meet and fuse
Lunate surface is the c-shaped smooth area inside the acetabulum

Gluteal surface of ala is marked by gluteal lines* (anterior, posterior, and inferior)

Additional key terminology and landmarks of the pelvis:

Pelvic brim is formed by the superior edges of the sacrum, arcuate and pectineal lines, and pubic symphysis

Encloses the pelvic inlet

Pelvic inlet, aka, aperture, is the circular opening between the abdominal and pelvic cavities (so, the brim comprises the edges of bone, the inlet is the space).

Pelvic inlet divides the pelvis into false and true pelvises:

Superiorly, the false (aka, greater) pelvis is bound by the alae of the ilium and the S1 vertebra; it contains the lower abdominal viscera. Inferior true (aka, lesser) pelvis contains the pelvic viscera and deep perineum.

Pelvic outlet is the diamond-shaped opening enclosed by the: pubic arch, ischial tuberosities, coccyx, and sacrotuberous ligaments.

Sexual Dimorphism

Photos from:

https://sites.google.com/a/umich.edu/bluelink/resources/bluelinks/labeled-bones-joints-and-movement-images

Pelvic Girdle

Related Tutorials