Ala of sacrum

Ala of sacrum
Base of sacrum seen from above (ala labeled at center left)
Details
Latin	Ala ossis sacri
Identifiers
Dorlands /Elsevier	a_21/12118083
TA
TH	{{#property:P1694}}
TE	{{#property:P1693}}
FMA	{{#property:P1402}}
Anatomical terminology [[[d:|edit on Wikidata]]]

The ala of sacrum (plural alae) is a large triangular surface on either side of the body of the base of the sacrum. The alae support the psoas major muscles and the lumbosacral trunk which connects the lumbar plexus with the sacral plexus. In the articulated pelvis the alae are continuous with the iliac fossa.

It is slightly concave from side to side, and convex from the back and gives attachment to a few of the fibers of the iliacus.

The posterior quarter of the ala represents the transverse process, and its anterior three-quarters the costal process of the first sacral segment.

It serves as part of the border of the pelvic brim. The alae also form the base of the lumbosacral triangle.

Structures attached to the ala:

• Iliolumbar ligament at the lateral portion of tuberosity
• Lumbosacral ligament at the medial portion of the rough portion
• Origin of a few fibres of the illiacus from the smooth part

Structures in relation:

• Sympathetic trunk
• Lumbosacral trunk
• Iliolumbar artery (branch of posterior division of internal iliac artery)
• Obturator nerve

References

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)

External links

• pelvis at The Anatomy Lesson by Wesley Norman (Georgetown University)