The iliolumbar ligament is a strong

ligament A ligament is the fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the: * Peritoneal li ...

passing from the tip of the

transverse process The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic i ...

of the fifth

lumbar vertebra The lumbar vertebrae are, in human anatomy, the five vertebrae between the rib cage and the pelvis. They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse p ...

to the posterior part of the inner lip of the

iliac crest The crest of the ilium (or iliac crest) is the superior border of the wing of ilium and the superiolateral margin of the greater pelvis. Structure The iliac crest stretches posteriorly from the anterior superior iliac spine (ASIS) to the posterior ...

(upper margin of ilium).

Course

It forms the thickened lower border of two of the layers of the

thoracolumbar fascia The thoracolumbar fascia (lumbodorsal fascia or thoracodorsal fascia) is a deep investing membrane throughout most of the posterior thorax and abdomen although it is a thin fibrous lamina in the thoracic region. Above, it is continuous with a simil ...

. Occasionally, a small ligamentous band stretches from the tip of the transverse process of the fourth vertebra down to the iliac crest behind the main ligament. Usually, fibrous strands are found between this latter process and the iliac crest, but these are only considered a true ligament when dense enough. It radiates as it passes laterally and is attached by two main bands to the

pelvis The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The ...

. The lower bands run to the base of the

sacrum The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part ...

, blending with the

anterior sacroiliac ligament The anterior sacroiliac ligament consists of numerous thin bands, which connect the anterior surface of the lateral part of the sacrum to the margin of the auricular surface of the ilium and to the preauricular sulcus. See also *Posterior sacroi ...

; the upper is attached to the crest of the ilium immediately in front of the

sacroiliac articulation The sacroiliac joint or SI joint (SIJ) is the joint between the sacrum and the ilium bones of the pelvis, which are connected by strong ligaments. In humans, the sacrum supports the spine and is supported in turn by an ilium on each side. The j ...

, and is continuous above with the

lumbodorsal fascia The thoracolumbar fascia (lumbodorsal fascia or thoracodorsal fascia) is a deep investing membrane throughout most of the posterior thorax and abdomen although it is a thin fibrous lamina in the thoracic region. Above, it is continuous with a simil ...

. In front, it is in relation with the

psoas major The psoas major ( or ; from grc, ψόᾱ, psóā, muscles of the loins) is a long fusiform muscle located in the lateral lumbar region between the vertebral column and the brim of the lesser pelvis. It joins the iliacus muscle to form the iliop ...

; behind, with the muscles occupying the

vertebral groove The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordate ...

; above, with the Quadratus lumborum.

Function

The iliolumbar ligament strengthens the

lumbosacral joint The lumbosacral joint is a joint of the body, between the last lumbar vertebra and the first sacral segment of the vertebral column The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral colum ...

assisted by the

lateral lumbosacral ligament Lateral is a geometric term of location which may refer to: Healthcare * Lateral (anatomy), an anatomical direction *Lateral cricoarytenoid muscle *Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral co ...

, and, like all other vertebral joints, by the posterior and

anterior longitudinal ligament The anterior longitudinal ligament is a ligament that runs down the anterior surface of the spine. It traverses all of the vertebral bodies and intervertebral discs on their ventral side. It may be partially cut to treat certain abnormal curvatur ...

s, the

ligamenta flava The ligamenta flava (singular, ''ligamentum flavum'', Latin for ''yellow ligament'') are a series of ligaments that connect the ventral parts of the laminae of adjacent vertebrae. They help to preserve upright posture, preventing hyperflexion, a ...

, and the interspinous and

supraspinous ligament The supraspinous ligament, also known as the supraspinal ligament, is a ligament found along the vertebral column. Structure The supraspinous ligament connects the tips of the spinous processes from the seventh cervical vertebra to the sacrum. Abo ...

s. It reduces the range of movement of the lumbosacral joint.

References

External links

* () {{Authority control Ligaments of the torso