The ligamenta flava (singular, ''ligamentum flavum'', Latin for ''yellow ligament'') are a series of

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 l ...

s that connect the ventral parts of the laminae of adjacent

vertebra 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 characteristi ...

e. They help to preserve

upright posture Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' 'double' ...

, preventing hyperflexion, and ensuring that the

vertebral column 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 ...

straightens after flexion. Hypertrophy can cause spinal stenosis.

Structure

Each ligamentum flavum connects the laminae two adjacent vertebrae. They begin with the junction of the axis and third cervical vertebra, continuing down to the junction 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 ...

and 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 o ...

. They are best seen from the interior of the

vertebral canal The spinal canal (or vertebral canal or spinal cavity) is the canal that contains the spinal cord within the vertebral column. The spinal canal is formed by the vertebrae through which the spinal cord passes. It is a process of the dorsal body ...

. when looked at from the outer surface they appear short, being overlapped by the

lamina of the vertebral arch 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 ...

. Each ligament consists of two lateral portions which commence one on either side of the roots of the

articular processes The articular processes or zygapophyses ( Greek ζυγον = " yoke" (because it links two vertebrae) + απο = "away" + φυσις = " process") of a vertebra are projections of the vertebra that serve the purpose of fitting with an adjacent vert ...

, and extend backward to the point where the laminae meet to form the spinous process; the posterior margins of the two portions are in contact and to a certain extent united, slight intervals being left for the passage of small vessels. Each consists of yellow

elastic tissue Elastic fibers (or yellow fibers) are an essential component of the extracellular matrix composed of bundles of proteins (elastin) which are produced by a number of different cell types including fibroblasts, endothelial, smooth muscle, and ai ...

, the fibers of which, almost perpendicular in direction, are attached to the

anterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...

surface of the lamina above, some distance from its inferior margin, and to the posterior surface and upper margin of the lamina below. In the

neck The neck is the part of the body on many vertebrates that connects the head with the torso. The neck supports the weight of the head and protects the nerves that carry sensory and motor information from the brain down to the rest of the body. In ...

region the ligaments are thin, but broad and long; they are thicker in the

thoracic The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the crea ...

region, and thickest in the

lumbar In tetrapod Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosa ...

region. They are thinnest between the atlas bone (C1) and the axis bone (C2), and may not be present in some people. They become longer inferiorly in the cervical spine, as the distance between adjacent laminae increases. Anatomy of the Neck Sagittal Color MRI

Function

The marked elasticity of the ligamenta flava serves to preserve

, and to assist the

in resuming it after flexion. The

elastin Elastin is a protein that in humans is encoded by the ''ELN'' gene. Elastin is a key component of the extracellular matrix in gnathostomes (jawed vertebrates). It is highly elastic and present in connective tissue allowing many tissues in the bo ...

, fairly unique to the ligamenta flava among other

ligaments 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 ...

, prevents buckling of the ligament into the spinal canal during extension, which would cause

spinal cord compression Spinal cord compression is a form of myelopathy in which the spinal cord is compressed. Causes can be bone fragments from a vertebral fracture, a tumor, abscess, ruptured intervertebral disc or other lesion. When acute it can cause a medi ...

Clinical significance

Because these ligaments lie in the posterior part of the

, their hypertrophy can cause spinal stenosis, particularly in patients with diffuse idiopathic skeletal hyperostosis. The ligamenta flava may also become fatty or calcify during ageing. These cause degeneration of

. Some studies indicate that the hypertrophy of these ligaments may be linked to a fibrotic process associated with increased collagen VI, which could represent an adaptive and reparative process in response to the rupture of elastic fibers.

Epidural

During an epidural, the needle has to be inserted into the spinal space through a ligamentum flavum. Once it passes through, this is felt as a decrease in the pressure requited to further advance the needle. This makes the ligamentum flavum an important landmark to overcome to ensure proper needle placement.

Removal

During a

microdiscectomy A discectomy (also called open discectomy, if done through a 1/2 inch or larger skin opening) is the surgical removal of abnormal disc material that presses on a nerve root or the spinal cord. The procedure involves removing a portion of an int ...

, a procedure to remove part of an

intervertebral disc An intervertebral disc (or intervertebral fibrocartilage) lies between adjacent vertebrae in the vertebral column. Each disc forms a fibrocartilaginous joint (a symphysis), to allow slight movement of the vertebrae, to act as a ligament to h ...

that is pressing on the spinal nerves, the ligamenta flava may need to be removed or reshaped. A hook can be placed underneath a ligamentum flavum to ensure it is separated from the dura mater.

References

External links

* {{Authority control Ligaments of the torso Bones of the vertebral column