General
This form of anaesthesia involves the introduction of an anaesthetic (substance that causes the region in question to become numb) into the area between the spinal bones and the spinal cord. This area is known as the liquor space or spinal canal. This type of anesthesia is used when performing a major surgery and in procedures where local anesthesia is insufficient or impossible. Examples of this can be: operations in the hip region, in the groin region, in the lower abdominal region (for example caesarean section) and patients with lung problems to bypass the anaesthesia. A spinal anaesthesia must not be performed in case of diseases in the spinal cord, severe malposition of the spinal column, inflammation in the spinal area or surrounding tissue, allergies to the anaesthetic, uncooperative patients or if the patient has not given his/her consent for this form of surgery.
Anatomy
The spinal cord is surrounded by the spinal column. The spinal column itself consists of 24 individual bones. A single vertebra consists of the vertebral body, the spinous processes and the vertebral arches, which together with the vertebral body form a round opening through which the spinal cord runs.
The spinal cord is surrounded by several meninges. The first skin, which can be imagined as a kind of wrapping around the spinal cord, is the soft meninges, also called pia mater. This is followed by the spider skin (= arachnoidea) and as the outermost skin, which in turn lies against the inside of the arch-shaped, round opening of the vertebra bone, the hard meninges, also called dura mater.
Between the soft meninges and the spider skin is a cavity filled with fluid, which is called the cerebrospinal fluid space or subarachnoid space. The cerebrospinal fluid circulates in this space. The anesthetic is injected into this area to numb the nerves and thus acts directly on the spinal cord and its adjacent spinal nerves. The advantage of this method is the limited suppression of any feelings in a certain area without having to burden the entire organism with a general anaesthetic.
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