Anaesthesia Practice

Topics: Spinal cord, Epidural, Anesthesia Pages: 16 (5229 words) Published: June 20, 2013
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ANAESTHESIA PRACTICE

Issue 22

SPINAL ANAESTHESIA
SPINAL CORD ANATOMY VERTEBRAE Vertebral column is central bony pillar of the body. It is composed of 33 vertebrae; 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and 4 coccygeal. Sacral hiatus is th th formed because of incomplete 5 and sometime 4 sacral laminae. A typical vertebra consists of a rounded body anteriorly and a vertebral arch posteriorly (arch consists of two pedicles and two laminae). The vertebral arch encloses the vertebral canal through which the spinal cord is running. Seven processes arise from the arch: one spinous, two transverse and four articular. The gap between two pedicles forms the intervertebral foramen which transmits the spinal nerves and blood vessels(Fig). LIGAMENTS  Anterior and posterior longitudinal ligament: Both these ligaments start from the skull to sacrum and are attached on the anterior and posterior surface of the vertebral bodies and intervertebral disks.  Ligamentum flavum:It connects the laminae of two adjacent vertebrae and is pierced during spinal anesthesia or lumber puncture.  Interspinous & supraspinous ligament (ligament nuchae):It connects the supraspinous and intraspinous processes. SPINAL CORD Spinal cord is an elongated, cylindrical and greyish white structure of central nervous system. It hangs in the vertebral canal, surrounded by meninges and cerebrospinal fluid. It is continuous above with medulla oblongata and terminates inferiorly in adults at lower border of first lumber vertebra. In children; it ends at upper border of third lumber vertebra. Its length is approximately 45 cm in adults. Blood supply is from anterior spinal artery, two posterior spinal arteries and from the branches of cervical, intercostal and lumber arteries. The artery of Adamkiewicz arises from the left side at lower thoracic or upper lumber level and supplies the lower two thirds of spinal cord.  There are thirty one pairs of spinal nerves (8 cervical, 12 thoracic, 5 lumber, 5 sacral and 1 coccygeal).  Each spinal nerve is formed by dorsal “afferent” (posterior or sensory) and ventral “efferent” (anterior or motor) nerve root when they unite in the intervertebral foramen (between pedicles) with their dural sleeves.  Sympathetic nerve fibers arise from intermediolateral (lateral horn) cells of the spinal cord at the of thoracolumbar level (T1 to L2).  Parasympathetic nerve fibers arise from intermediolateral (lateral horn) cells of the spinal cord at the level of sacral region (S2-S4).  Cauda equina is the bundle of spinal nerves in the subarachnoid space below the termination of spinal cord.

CONTENTS


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Spinal cord anatomy
Spinal Needles Drugs used for spinal anaesthesia Common complications of spinal anaesthesia Causes of failed spinal anaesthesia



Spinal anaesthesia in paediatric practice

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AP

Anaesthesia Practice – Issue 22

 Conus meddulearis is inferior end of spinal cord, has conical shape and tapers into medullary cone.  Filum Terminale is the thread like prolongation of spinal cord, it starts from conus meddulearis and is attached to the back of coccyx to anchor the spinal cord.  Spinal cord grey matter is divided into dorsal horn (sensory roots and ganglion), lateral horn (autonomic nerve roots) and ventral horn (motor roots). The white matter is divided into the three columns, posterior, lateral and anterior. The columns are in three different directions; ascending, descending and transverse. Sensory system is regulated by ascending fibers, the motor system is regulated by descending fibers and the transverse (commissural) fibers connect the opposite sides of spinal cord.  The sensory system works by relaying at three sites, 1st order neuron: carries the impulse/information from site of insult to the 2nd order neurons, which are in the dorsal horn of spinal cord. They synapse with 3rd order neuron in thalamus. The 3rd order neurons: carry the impulse from thalamus...
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