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CLINICAL ANATOMY OF THE SPINE AND SPINAL CORD
Mirzaev Mirzokhid Vokhidovich
Abstract:
The spine and spinal cord are central structures in human anatomy, providing both
mechanical support and neural function. This article explores the clinical anatomy of the
vertebral column and spinal cord, highlighting their structural organization, functional
significance, and implications in clinical practice.
Kеywоrds:
spine, spinal cord, vertebral column, neuroanatomy.
INTRОDUСTIОN
As is known, the spinal column consists of 7 cervical, 12 thoracic and 5 lumbar vertebrae with
the adjacent sacrum and coccyx. It has several clinically significant curves. The characteristics of
individual vertebrae affect the technique, first of all, of epidural puncture. The spinous processes
depart at different angles at different levels of the spine.
MАTЕRIАLS АND MЕTHОDS
Access to the epidural (ED) and subarachnoid space (SA) is achieved between the plates
(interlaminar). The superior and inferior articular processes form facet joints, which play an
important role in the correct positioning of the patient before ED puncture. The correct
positioning of the patient before ED puncture is determined by the orientation of the facet joints.
Since the facet joints of the lumbar vertebrae are oriented in the sagittal plane and provide
forward and backward flexion, maximum flexion of the spine (fetal position) increases the
interlaminar spaces between the lumbar vertebrae.
RЕSULTS АND DISСUSSIОN
Identification of the required intervertebral space is the key to the success of epidural and spinal
anesthesia, as well as a prerequisite for patient safety.
In clinical settings, the choice of the puncture level is made by the anesthesiologist through
palpation in order to identify certain bone landmarks. It is known that the 7th cervical vertebra
has the most pronounced spinous process. At the same time, it should be taken into account that
in patients with scoliosis, the most prominent spinous process may be the 1st thoracic vertebra
(in about ⅓ of patients).
The line connecting the lower angles of the scapulae passes through the spinous process of the
7th thoracic vertebra, and the line connecting the iliac crests (Tuffier's line) passes through the
4th lumbar vertebra (L4) [1].
Identification of the required intervertebral space using bone landmarks is far from always
correct. The results of the study by Broadbent et al. (2000) are known, in which one of the
anesthesiologists marked a certain intervertebral space at the lumbar level with a marker and
tried to identify its level with the patient in a sitting position, the second made the same attempt
with the patient lying on his side. Then a contrast marker was attached above the mark and
magnetic resonance imaging was performed. Most often, the true level at which the mark was
made was located from one to four segments lower, compared to the values indicated
by the anesthesiologists participating in the study. It was possible to correctly identify the
intervertebral space in only 29% of cases. The accuracy of the determination did not depend on
the patient's position, but worsened in overweight patients. By the way, the spinal cord ended at
the L1 level in only 19% of patients (in the rest at the L2 level), which created a threat of damage
if a high puncture level was chosen incorrectly [2].
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volume 4, issue 4, 2025
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The anterior longitudinal ligament runs along the anterior surface of the vertebral bodies from
the skull to the sacrum, which is rigidly fixed to the intervertebral discs and the edges of the
vertebral bodies. The posterior longitudinal ligament connects the posterior surfaces of the
vertebral bodies and forms the anterior wall of the spinal canal.
The vertebral plates are connected by the yellow ligament, and the posterior spinous processes
are connected by the interspinous ligaments. The supraspinous ligament runs along the outer
surface of the spinous processes of C7–S1. The pedicles of the vertebrae are not connected by
ligaments, as a result of which intervertebral openings are formed, through which the spinal
nerves exit [3].
The yellow ligament consists of two leaves fused along the midline at an acute angle. In this
regard, it is stretched like an “awning”. In the cervical and thoracic spine, the ligamentum flavum
may not be fused in the midline, which causes problems in identifying the EP using the loss of
resistance test. The ligamentum flavum is thinner in the midline (2–3 mm) and thicker at the
edges (5–6 mm). In general, it is thickest and densest at the lumbar (5–6 mm) and thoracic (3–6
mm) levels, and thinnest in the cervical spine (1.5–3 mm). Together with the vertebral arches,
the ligamentum flavum forms the posterior wall of the spinal canal. When passing the needle
through the medial approach, it must pass through the supraspinous and interspinous ligaments,
and then through the ligamentum flavum. With the paramedian approach, the needle bypasses
the supraspinous and interspinous ligaments, immediately reaching the ligamentum flavum. The
yellow ligament is denser than the others (80% consists of elastic fibers), therefore, the increase
in resistance when the needle passes through it, followed by its loss, is known to be used to
identify EP. The distance between the yellow ligament and the dura mater in the lumbar region
does not exceed 5-6 mm and depends on factors such as arterial and venous pressure, pressure in
the spinal canal, pressure in the abdominal cavity (pregnancy, abdominal compartment syndrome,
etc.) and the chest cavity (arterial ventilation) [4].
The spinal canal has three connective tissue membranes that protect the spinal cord: the dura
mater, the arachnoid mater, and the pia mater. These membranes participate in the formation of
three spaces: epidural, subdural, and subarachnoid. The spinal cord (SC) itself and its roots are
covered by a well-vascularized pia mater, the subarachnoid space is limited by two adjacent
membranes - the arachnoid and dura mater. All three SC membranes continue in the lateral
direction, forming a connective tissue covering of the spinal roots and mixed spinal nerves
(endoneurium, perineurium, and epineurium). The subarachnoid space also extends for a short
distance along the roots and spinal nerves, ending at the level of the intervertebral foramina.
СОNСLUSIОN
Correct understanding of the anatomy of the spine and the structures of the spinal canal is
absolutely necessary in the daily practical work of an anesthesiologist-resuscitator. It is the key
to the success of performing neuraxial blocks, and also allows to reduce to a minimum the
number of complications of neuraxial anesthesia, which are sometimes life-threatening.
RЕFЕRЕNСЕS
1. Angst M., Ramaswamy B., Riley E., Stanski D. Lumbar epidural morpfline in flumans and
supraspinal analgesia to experimental fleat pain // Anestflesiology. 2020; 92: 312–324.
2. Bernards C., Hill H. Pflysical and cflemical properties of drug molecules governing tfleir
diffusion tflrougfl tfle spinal meninges. // Anestflesiology. 2012; 77: 750–756.
3. Hogan Q. Lumbar epidural anatomy. A new look for cryomi- crotome section. //
Anestflesiology. 2011; 75: 767–775.
4. Igarashi T., Hirabayashi Y., Shimizu R. The epidural structure of flanges during deep
breatfling // Can. J. Anaestfl. 2019; 46:850–855.
