Microscopic organization of the ligamenta flava in Cercopithecinae.

The ligamenta flava have been investigated in Cercopithecus pygerythrus (vervet monkey) and C. mitis (blue monkey) at various levels of the vertebral column. It has been shown that in the cervical, thoracic and lumbar regions the topography of these ligaments differs. The cervical ligamenta flava do not extend over the intervertebral joints, while in the thoracic and lumbar regions they reinforce and fuse with the capsule. The ligamenta flava from T4 to S1 replace the interspinous ligaments by extending into the interspinous space. The ligamenta flava consist mostly of interwoven layers of elastic and collagen fibres. The area of attachment has four zones whose histological details are described. These findings are discussed in relation to the function of the vertebrbility of the column and mechanical adaptation to absorb sudden stresses.