Lunate

The lunate bone  or semilunar bone is a carpal bone situated in the center of the proximal row of the carpus (wrist).  {See diagram below}

Lunate is situated between the lateral scaphoid bone and medial triquetral bone. .

The name derives from the Latin luna which means “moon”, the lunate bone looks semi-similar to a crescent moon.

The superior surface, convex and smooth, articulates with the radius.

The inferior surface is deeply concave and  articulates with the head of the capitate, and, by a long, narrow facet with the hamate.

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The dorsal and palmar surfaces are rough, for the attachment of ligaments.

The lateral surface articulates with the scaphoid.

The medial surface is marked by a smooth, quadrilateral facet, for articulation with the triangular bone (triquetral).

Intervertebral Disc

Intervertebral discs is fibrocartilage that lies  between  two adjacent vertebrae in the spine. Each disc forms a cartilaginous joint to allow slight movement of the vertebrae, and acts as a ligament to hold the vertebrae together.

Discs consist of an outer annulus fibrosus, which surrounds the inner nucleus pulposus.

There  are a total of twenty-three discs in the spine. They are identified by specifying the particular vertebrae they separate. For example, the disc between the fifth and sixth cervical vertabrae is designated as C5-6 disc.

Laminoplasty

Laminoplasty is a surgical procedure that involves the cutting of the lamina on one side and cutting a groove on the other side of the affected vertebrae and then “swinging” the freed flap of bone by hinging over the grooved part.

This procedure is done to relieve spinal stenosis of cervical spine.

The bone flap can either be fixed with implants or held with sutures, depending upon the technique and surgical preference.

Laminotomy

A laminotomy is a neurosurgical  procedure that removes part of a lamina of the vertebral arch in order to decompress the corresponding spinal cord and/or spinal nerve root.

Complete removal of lamina is called laminectomy.

Laminotomy is also often accompanied by facetectomy.

Intervertebral Foramen

Between every pair of vertebræ are two apertures, the intervertebral foramina.

The foramen allows for the passage of the spinal nerve root, dorsal root ganglion, the spinal artery of the segmental artery, communicating veins between the internal and external plexuses, recurrent meningeal  nerves, and transforaminal ligaments.

Their size is variable due to placement, pathology, spinal loading, and posture.

They can be occluded by arthritic degenerative changes and space-occupying lesions like tumors, metastases and spinal disc herniations.

Motion Segment

A motion segment consists of two adjacent vertebrae, including the intervertebral disk between them, and the ligaments that bind them together.

Concept of motion segment is important in planning the fusion of the vertebrae.