Thoracolumbar Spine Anatomy and Pathology - Pedicles of L2, L3, L4

Coronal section through the pedicles of L2,L3, and L4


Coronal section through the pedicles of L2, L3, and L4. This section through the mid–pedicle level shows the serpentiginous course of the nerve roots in a thecal sac of normal width. The shallow (axillary) pouches of the root sleeves lie immediately below the pedicles where the roots snugly follow the pedicles. The cancellous and cortical bone and the cross–sectional shape of the pedicles vary within wide ranges. At L2–L3 large veins lie lateral to the dura, at L3–L4 the dura is bordered by fat interspersed with smaller veins. At L2–L3 the section is closer to the base of the pedicles and therefore shows the ventral internal venous plexus whereas at L3–L4 the posterior, less vascularized portion of the foramen is displayed. At two levels the entire course of the "roots" can be followed. This root–complex consists of the still intrathecal roots, the root sheath (or root sleeve), the dorsal root ganglion and the ventral root, and the postganglionic lumbar nerve. The long, cylindrical lumbar ganglia take a steep and obliquely–inferiorly directed course towards the upper lateral comer of the infrajacent pedicle. Lateral to the ganglion and close to the inferior–lateral margin of the pedicle the segmental arteries are located. The lumbar nerve curves around the lateral aspect of the pedicle below, firmly held by the deep portions of the iliopsoas muscle.

Updated on: 04/08/19

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