Bma Illustrated Medical Dictionary

spinal anaesthesiaInjection of an

anaesthetic into the cerebrospinal fluid

in the spinal canal to block pain sensa-

tions before they reach the central

nervous system. It is used mainly during

surgery on the lower abdomen and legs.

(See also epidural anaesthesia.)

spinal cordA cylinder of nervetissue

that runs from the brain, down the cen-

tral canal in the spineto the 1st lumbar

vertebra. Below that, the nerve roots con-

tinue within the canal as cauda equina.

Grey matter, the spinal cord’s core, con-

tains the cell bodies of nerve cells.

Areas of white matter (tracts of nerve

fibres running lengthwise) surround the

grey matter. Sprouting from the cord on

eachside at regular intervals are the sen-

sory and motor spinal nerve roots. The

small nodule (ganglion) in each sensory

root comprises nerve cell bodies. Nerve

rootscombine to form the spinal nerves

that link the spinal cord to all regions of

the trunk and limbs. The entire spinal

cord is bathed in cerebrospinal fluidand

surrounded by the meninges.

The nerve tracts in the white matter act

mainly as highways for sensory informa-

tion passing up to the brain or motor

signals passing down. However, the cord

processes some sensory information

itself and provides motor responses

without involving the brain. Many reflex

actions are controlled in this way.

The spinal cord may be injured by

trauma (see spinal injury); spinal-cord

infections such as poliomyelitisare rare

but can cause serious damage.

spinal fusionMajor surgery to join 2 or

more adjacent vertebrae. It is perfor-

med if abnormal movement between

adjacent vertebrae causes severe back

pain or may damage the spinal cord.

spinal injuryDamage to the spineand

sometimes to the spinal cord. Spinal

injury is most often the result of falling

from a height or of a road traffic accident.

Damage to the vertebraeand their liga-

mentsusually causes severe pain and

swelling of the affected area. Damage to

the spinal cord results in paralysis and/or

loss of sensation below the site of injury.

X-raysof the spine are carried out to

determine the extent of damage. If the

bones are dislocated, surgery is needed

to manipulate them back into position.

Treatment with the drug methylpred-

nisolonewithin a few hours of an injury

aids recovery from spinal-cord damage.

Surgery may be needed to remove any

pressure on the cord, but damaged nerve

tracts cannot be repaired. Physiotherapy

may stop joints locking and muscles

contracting as the result of paralysis.

If there is no spinal-cord damage,

recovery is usually complete. In cases of

spinal-cord damage, some improve-

ment may occur for up to 12 months.

spinal nervesA set of 31 pairs of nerves

that connect to the spinal cord. Spinal

nerves emerge in 2 rows from either side

of the spinal cord and leave the spine

through gaps between adjacent verte-

brae. The nerves then branch out to

supply all parts of the trunk, arms, and

legs with sensory and motor nerve fibres.

SPINAL ANAESTHESIA SPINAL NERVES

S SPINAL CORD

White matter

Grey matter

Motor

nerve

root

Sensory

nerve root

Meninges

LOCATION

Brain

Spinal

cord

Spinal

nerve

Ganglion

Spinal

nerve

Cauda

equina

STRUCTURE OF SPINAL CORD