Sacrum & Coccyx Flashcards
How many sacral vertebrae are there?
5
When does the sacrum fuse and what shape is the bone once fused?
Adolescence
Wedge shaped bone with anterior concavity
Where is the base of the sacrum and what does it articulate with?
Superior end
L5 (lumbosacral joint)
Where is the apex of the sacrum and what does it articulate with?
Inferior end
Coccyx
What do the articular surfaces of the sacrum articulate with?
Pelvis at the iliac bone (sacroiliac joints)
Anterior surface
How many transverse ridges are on the sacrum, and what do they represent?
4
Fusion of the 5 individual bodies
Anterior surface
Where do the ridges on the sacrum terminate?
Laterally at the intervertebral foramina (4 on each side)
*the foramina transmits nerves
Anterior surface
What are the upper lateral sides of the sacrum called?
Lateral masses
Anterior surface
What is the most superior part of the sacrum?
Ala
T/F
The anterior surface of the sacrum is concave
True
T/F
The posterior surface of the sacrum is convex
True
Posterior surface
What is on the midline of the sacrum?
Prominent crest with 4 spinous tubercles representing spinous processes
Posterior surface
What is below the fourth spinous tubercle?
Sacral hiatus (small gap)
T/F
Only the first sacral segment has superior articular processes for L5
True
T/F
The fifth sacral segment has inferior articulating processes that form the sacral cornua on either side of the hiatus
True
-wide superiorly
-narrow inferiorly
-superiorly articulated with the iliac bones (SI joints)
Lateral surface of sacrum
-formed by the upper surface of the first sacral vertebra
-anterior margin has sacral promontory
-behind the body is a triangular sacral canal
-superior articular facets face in and articulate with the inferior facets of L5
Base of sacrum
-has a small oval shaped articular surface for articulation with the coccyx
Apex of sacrum
Small triangular bone consisting of 4 segments usually fused
Coccyx
Has a body with transverse processes and superior articular processes called coccygeal cornua
First segment of coccyx
Segments only have bodies and decrease in size progressively
Segment 2,3,4 of coccyx
