Spinal Information - Glossary

Source: Christopher J. Centeno MD: "The Spine Dictionary" Hanley & Belfus, Inc., Philadelphia, 2001.


Annular fibers
The structure of the spinal disc resembles a jelly filled doughnut. The inner aspect of the disc contains a gel-like substance called the nucleus pulposus. Surrounding the nucleus are tough fibrocartilagenous fibers called the annulus fibrosis. These annular fibers contain the inner nuclear material similar to a basketball skin containing the air within.

Located in the front - the opposite of posterior.

Axial compression
Compression along the axis in the case of the back, an application of a vertical, downward pressure of the spine, between head and feet. Can be performed with DynaWell L-Spine.

Axial Compression in Extension (ACE)
Axial compression maintaining the lordosis, for instance with a pillow under the lumbar spine.

On two sides.

CerebroSpinal Fluid (CSF)
The fluid which bathes the brain and the spinal cord.

Of or referring to the neck. The cervical spine has 7 vertebrae, which allow head movement.

Cervical curve
A term that refers to a scoliosis in the cervical spine. The apex of the curve is between C1 and C6.

Computer Tomography (CT)
The use of x-rays at different angles and processed through a Computer to produce a cross-sectional image.

Wear and tear of the intervertebral disc, which may represent normal Disc Disease (DDD) aging or may be due to long-standing trauma. This involves small tears in the annulus (outer covering of the disc), and lack of water content of the nucleus (the gel-like center of the disc). This degenerative cascade can lead to disc bulging, bone spurs, and loss of disc height, which can affect the nerve roots.

Disc herniation/Disc protrusion
When the nucleus of the disc ruptures through the inner annular fibers, but does not rupture through a majority of those fibers.

Of or pertaining to the back or posterior aspect of the body. Opposite of ventral.

Dura/Dura mater
The outer-most covering of the spinal cord. This is a thick connective tissue covering, and provides protection and support to the spinal cord. This is a pain-sensitive structure, which envelops the spinal roots and ganglia as they pass through the intervertebral foramina.

Dural leak/Dural tear
The leakage of CSF from the dural sac. Dural leaks can be caused by spinal injections, or occasionally by spinal surgeries.

Dural sac/Dural tube
The inner part of the vertebral canal containing the nerves. The dura is actually a tube or sac-like covering, and pain is often associated with the dura in many treatment paradigms. The area diminishes under axial compression.

Dural sac impingement
Pressure on the dura caused by a bulging disc, HNP, or osteophyte.

The space through which the nerve root and nerve root sheath must pass to exit the spinal canal. There are two foramens per level, which are composed of arches in the vertebrae above and below. They are the "windows" through which the nerve roots pass. The size of the foramen can be decreased for instance, with DDD, disc herniation or spondylosis.

Foraminal stenosis
A decrease in the overall size of the intervertebral foramen (the bony window through which the nerve roots pass) caused by enlargement of the superior facet or a degenerative disc. The nerve root passing through the foramen can become irritated or compressed. Severe foraminal stenosis can cause radiculopathy (sciatica). Conservative management tends to be less effective. Surgical management can include enlarging the foramen by removing bone, a decompressive laminectomy, and/or fusion to reduce facet joint degeneration.

Herniated Nucleus Pulposus (HPN)
Commonly called "slipped disc". An extrusion of the nucleus pulposus through the anterior annular fibers.

Herniated Disc
A "slipped disc". The term "slipped disc" is actually not correct, since there is nothing to slip out of place. Instead, the disc is a like gel-filled, tough fibrous sack that gets a hole in it, causing the toothpaste-like gel to squirt out or herniate. This can cause pressure on the exiting nerve root and/or cause a significant inflammatory reaction that can lead to radiculopathy (sciatica, a dysfunction of the nerve root that can cause weakness, numbness, and/or tingling in one extremity). This term mean anything along a spectrum of disc injuries, including disc bulge, a disc protrusion, an extruded disc, or a sequestered disc.

An x-ray that is taken from the side.

The normal curve of the lumbar spine, which is maintained to balance the thoracic kyphosis. The shape of the lumbar lordosis can be changed by tilting the pelvis forward or backwards. The apex of the curve points anteriorly.

Lumbar curve
A scoliosis with its apex between L1 and L4.

Lumbar spine
The lower part of the spine, consisting of five vertebrae, L1 - L5, stacked on the top of the sacrum. Most movement in this region occurs at L5-S1 and L4-L5.

Magnetic Resonance Imaging (MRI)
An imaging technique, which uses magnetic fields to obtain pictures of both soft tissue and bony anatomy. MRI can be very effective in diagnosing HNP, tumors, vascular abnormalities, and lately, a host of diagnoses caused by bony encroachment. It can be enhanced by the use of Gadolinium, which helps visualize vascularized scar tissue more clearly. Most lumbar MRIs include T1 weighted sagittal cuts (fat is bright), T2 weighted sagittal cuts (water is bright), and proton density weighted sagittal cuts (better for anatomy). Axial images are often included.

Nerve root compression
The nerve roots are compressed, and usually causing symptoms.

Neurogenic claudication
A clinical symptom complex associated with lumbar central canal stenosis. The patient reports that walking causes lower extremity pain, and that walking in a flexed posture ("shopping cart posture") is more comfortable. This is differentiated from vascular claudication because the patient can exercise with lower extremities in a flexed position often without difficulty (such as riding a bicycle). With vascular claudication this would be expected to cause symptoms.

A surgeon specialized in surgery of the brain and the nerve system.

The bony ring that surrounds the sacrum. The sacrum can be considered the keystone of the bony arch that provides support for the spine. The pelvic ring is mobile through the S1 joints and pubic symphysis.

Of or pertaining to the back or dorsum of the body. Opposite to anterior.

Prolapsed disc
When the nucleus pulposus ruptures through most of the fibers of the annulus and is contained only by a few of the outermost fibers. The posterior longitudinal ligament is intact. This is synonymous with a large disc bulge.

Proton density image
An MRI imaging technique, which is obtained in the early part of a T2, weighted sequence. This imaging sequence shows anatomic detail of the lumbar spine well without the noise problems usually seen with a T2 weighted image. This is particularly good image sequence for showing the outermost annulus of the intervertebral disc.

Closest to the center.

Psoas-Relaxed Position (PRP)
The muscles of the back are relaxed, when lying down.

See sciatica.

A nurse specialized in radiology. It is the radiograph that uses DynaWell L-Spine in practice.

Physician specialized in radiology (roentgen/x-rays).

S1 nerve root
The first sacral nerve root that exists between L5 and S1. It supplies numerous muscles including the gastrocnemius, gluteus maximus, and semimembranosus. It supplies sensation to the lateral foot (the part with the little toe).

The base support for the spine. This bone is made up of the S1 through S5 vertebrae, which are fused to form a triangular bone. The sacrum articulates with the L5 vertebra through the L5-S1 intervertebral disc superiorly. Inferiorly, it articulates with the ilium on either side.

Sagittal curve
One of the three normal curves present in the adult spine. These are the cervical lordosis, lumbar lordosis, and thoracic kyphosis. Since this occurs in the sagittal plane (front/back plane), this is called sagittal curve. This is the view seen on a lateral x-ray.

Sagittal diameter
A common measurement in cervical stenosis. This is the anterior/posterior diameter of the cervical spinal canal. This is usually measured on lateral radiographs, CT scan, or MRI. The dural sac is the central part of such an image.

A general term, which is more accurately and specifically described by the term radiculopathy (pinched nerve in the spine). This is a clinical syndrome associated with an HNP (herniated disc) causing nerve root irritation and neurologic findings such as motor weakness or decreased sensation in a dermatomal distribution. (Numbness or tingling in specific areas of the skin that corresponds to nerve roots. For instance, if the big toe is numb, this is usually associated with the L5 nerve root.)

An abnormal curvature and/or rotation of the spine. Most often scoliosis seen clinically is idiopathic (an unknown cause), but can also be caused by neuromuscular diseases such as muscular dystrophy.

Spinal diseases
All pathologies involving the spine.

Spinal surgeon/Orthopedist
Physician specialized in surgery of the back.

Shift (or displacement) of the vertebra.

Spinal Stenosis
Narrowing of the spaces in the spine, resulting in compression of the nerve roots or spinal cord by bony spurs or soft tissues, such as disks, in the spinal canal. < 100 mm2 = relative spinal stenosis < 75 mm2 = absolute spinal stenosis.

Referring to any disease or condition of the vertebrae.

A degenerative disease of the spine, which is usually equated with the normal aging process. Bone spurs are seen on x-ray (osteophytes). On MRI, there is decreased disc height, as well as decreased hydration (loss of water) of the intervertebral discs. It is thought that disc degeneration with microtrauma occurring to the intervertebral disc also occurs.

Supine position
Lying on ones back. This is the position during axial compression.

Synovial cyst
A benign tumor protruding from a joint.

T1 weighted image
An MRI sequence, which is designed to show fat as a bright signal. This is particularly helpful in the lumbar spine, as many of the structures are outlined by fatty tissue and show up dark against the bright fat signal. This is part of the standard MRI sequence in the lumbar spine, which also includes a proton density sequence and a T2 weighted sequence. A T1 weighted sequence has a short TR (repetition time) and a short TE (echo time).

T2 weighted image
An MRI sequence that is designed to show water or fluid as bright. This is particularly helpful in the spine, because young healthy discs contain a significant amount of water. Thus, the nucleus pulposus of the discs shows up as bright on a T2 weighted sequence. Degenerated discs show up as darker because they contain less water. A T2 weighted image has a long TR (repetition time) and a long TE (echo time). It is one of the standard lumbar sequences for MRI which also includes T1 weighted images and proton density images.

Echo time in an MR image. The time at which data is required.

Repetition time in an MR image. This is the time between subsequent radio frequency pulses and is a crucial factor for image contrast.

Ventral ostheophyte
A bone spur which occurs on the anterior surface of the spine. Large cervical ventral osteophytes can compress the esophagus and cause dysphagia (difficulties in swallowing).

One of the 24 bones that make up the spine. There are three types: cervical, thoracic, and lumbar. The plural of vertebra is vertebrae.


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