AN42.1-3 | Back Region — Glossary

Tapered terminal end of the spinal cord at the L1-L2 vertebral level in adults; injury causes lower motor neuron signs

Bundle of nerve roots (L2-S5) and the filum terminale below the conus medullaris; occupies the lumbar cistern from L2 to the sacral hiatus

CSF-filled subarachnoid space between L2 and S2 containing the cauda equina; the site for lumbar puncture

Space between the dura mater and the periosteum of the vertebral canal; contains epidural fat, internal vertebral venous plexus, and spinal arteries

Internal vertebral venous plexus in the epidural space; valveless, communicating with pelvic and cranial veins; route for metastatic spread to the vertebrae

Single artery supplying the anterior two-thirds of the spinal cord (motor pathways); occlusion causes paraplegia with loss of pain/temperature but preserved vibration

Major radicular artery reinforcing the anterior spinal artery; usually arises from T8-L2 on the left side; critical during aortic surgery

Needle insertion into the lumbar cistern at L3-L4 or L4-L5 to sample CSF; performed below the conus medullaris to avoid spinal cord injury

Line connecting the highest points of the iliac crests; passes through the L4 spinous process or L4-L5 interspace; landmark for lumbar puncture

Triangle bounded by rectus capitis posterior major, obliquus superior, and obliquus inferior; contains the vertebral artery (V3) and suboccipital nerve (C1)

Segment of the vertebral artery winding around the posterior arch of C1 in the suboccipital triangle before piercing the dura to enter the foramen magnum

Dorsal ramus of C2; pierces the semispinalis capitis and trapezius; supplies the posterior scalp; entrapment causes occipital neuralgia

Pain from entrapment of the greater occipital nerve radiating from the occiput over the vertex to the forehead; common in desk workers and post-whiplash

Deep back muscle (transversospinalis group) extending and rotating the head to the opposite side; the greater occipital nerve pierces through it

Superficial back muscle extending the head and rotating it to the same side; covers the deeper semispinalis capitis

Strand of pia mater extending from the conus medullaris to the coccyx; anchors the spinal cord inferiorly

Tubular extension of the dura mater enclosing the spinal cord and cauda equina; extends from the foramen magnum to the S2 vertebral level

Infarction of the anterior two-thirds of the spinal cord causing paraplegia and loss of pain/temperature with preserved vibration and proprioception (posterior columns spared)

Tuberculosis of the spine; most common cause of spinal cord compression in India; lumbar TB can cause psoas abscess presenting in the groin

Triangular fibrous membrane in the midline of the posterior neck from the external occipital protuberance to C7 spinous process; provides muscle attachment

Posterior branch of a spinal nerve supplying the deep back muscles and skin of the back; the suboccipital and greater occipital nerves are dorsal rami