Sacrum: Central piece of the pelvis, connecting upper and lower parts of the axial skeleton.
Pelvic Girdles: Comprised of two os coxa, joined anteriorly by the pubic symphysis.
Position: Sits at the base of the vertebral column.
Structure of the Sacrum
Anterior Surface: Primary view of the sacrum in study.
Posterior Surface:
Features structures akin to spinous processes found on the vertebral column.
Includes the Median Sacral Crest.
Development
Initially, the sacrum is made of individual segments resembling small vertebrae.
Fusion: Segments fuse into a single, solid bone during development.
Key Anatomical Features
Sacral Canal:
Located at the top.
Passage for the cauda equina part of the spinal cord.
Sacral Hiatus:
Base opening, exit point for coccygeal nerves.
Sacral Foramen:
Openings on anterior and posterior surfaces.
Pathway for sacral nerves exiting from the sacral canal.
Sacral Promontory:
Anterior portion, base of the sacrum.
Widest point of the sacrum.
Apex: Bottom point of the sacrum.
Sacral Ala: Structures on either side of the sacral promontory.
Summary
The sacrum is a critical part of the pelvis, with various structures that serve as pathways for nerves and support for the vertebral column. Understanding its anatomy is crucial for comprehending the connectivity and functionality within the skeletal system.