Материал: Kaplan USMLE-1 (2013) - Anatomy

Relationship ofExit ofSpinal Nerves and Vertebral Levels

The spinal nerves exit the vertebral columnby a specific relationship to the verte­ brae as described.

1. The cervical nerves Cl-C7 exit the intervertebral foramina superior to the pedicles ofthe same-numbered vertebrae.

2.The C8 nerve exits the intervertebral foramen inferior to the C7 pedicle. This is the transition point.

3.Allnerves beginning with Tl and below willexit the intervertebral foramina inferior to the pedide ofthe same-numbered vertebrae.

Lumbar Puncture

A lumbarpuncture is used to inject anesthetic material in the epidural space or to withdraw CSF from the subarachnoid space.

•A spinal tap is typically performed at the IA-LS interspace.

•A horizontal line drawn at the top ofthe iliac crestmarks the level of the L4 vertebra.

•When a lumbar puncture is performed in the midline, the needle passes through the interlaminarspace of the vertebral column found between the laminae of the lumbar vertebrae (Figure IIl-1-8).

•The interlaminar spaces are covered by the highly elastic ligamentum

flava.

Figure 111-1-8. lnterlaminar Spaces

Clinical Correlate

During a lumbar puncture a needle is passed through the interlaminar space while the vertebral column is

flexed. The needle passes through the following layers:

•Skin

•Superficial fascia

•Deep fascia

•Supraspinous ligament

•lnterspinous ligament

•lnterlaminar space

•Epidural space

•Dura

•Arachnoid

•Subarachnoid space