Spine Dissection

Lab Summary

Spine and spinal cord anatomy from foramen magnum to sacrum are taught in this lab. Additionally, this lab includes the posterior dural venous sinuses of the brain, inferior IV ventricle, cervical vertebral artery, cervical, brachial and lumbosacral plexuses.

Lab Objectives

Describe the vertebral levels of the inferior angle of the scapula and the iliac crest.
Describe the features of the cervical, thoracic and lumbar vertebrae and the sacrum.
Describe the vertebral level of the conus medullaris as well as its spinal level.
Describe the blood supply of the spinal cord.
Describe the best site to perform a lumbar puncture.
Describe the formation of a spinal nerve.
Describe the significance of the cervical enlargement of the spinal cord.
Name the spinal levels of the cervical plexus, brachial plexus and lumbar plexus.
Describe the course of the vertebral arteries and their contribution to the brain and spinal cord circulation.

Lecture List

Spinal Column Part I & II, Exposure of the Posterior Spine and Spinal Canal, Dorsal Brain and Spinal Cord, Expose Ventral Spinal Cord, Ventral Spinal Cord, Removed Spinal Cord

Spinal Column Part I

Vertebral Column

Examine an articulated skeleton.

1.1a) Total spine
1.1b) Regions of spine
1.1c) Oblique view of spine
1.1d) Chest view of spine
1.1e) Rib articulations
1.1f) Lateral view of spine
1.1g) Lateral view of cervical spine
1.1h) Anterior view of cervical spine
1.1i) Vertebral bodies

Spinal Column Part II

Vertebrae

Examine an articulated skeleton.

2.1a) Spine segments
2.1b) Superior view of atlas (C1)
2.1c) Inferior view of atlas (C1)
2.1d) Superior view of axis (C2)
2.1e) Posterior view of C1 and C2
2.1f) Superior view of C1 and C2
2.1g) Cervical vertebrae
2.1h) Oblique view of thoracic vertebra
2.1i) Inferior view of thoracic vertebra
2.1j) Posterior view of thoracic vertebrae
2.1k) Lateral view of thoracic vertebrae
2.1l) Inferior view of lumbar vertebra
2.1m) Dorsal view of sacrum
2.1n) Anterior view of sacrum (pelvic surface)
2.1o) Sacral spinal canal

Expose Spine

Opening the Spine

Remove the skin and superficial fascia covering the back and neck.

Identify spinal landmarks: C7 (vertebra prominens), T7 at inferior angle of the scapula, and L4 at the iliac crest.

Reflect the erector spinae, deep intrinsic back and suboccipital muscles laterally.

Use an oscillating saw and chisel to divide the laminae on each side. Remove the laminae and spinous processes as a unit to expose the dura mater covering the spinal cord and cauda equina.

3.1a) Paraspinal muscles
3.1b) Exposing laminal arches
3.1c) Dividing laminal arches
3.1d) Spinal canal

Dorsal Brain and Spinal Cord

Exposing Cervical Spinal Cord and Posterior Brain

Complete removal of paraspinal muscles and suboccipital muscles. Perform a cervical laminectomy to expose the cervical spinal canal.

Remove the occipital bone with the oscillating saw to reveal the dura covering the occipital lobes and cerebellum. Be sure to include the foramen magnum.

Identify cervical spinal nerves and the adjacent vertebral artery. Locate the foramen magnum and cerebral dural venous sinuses. Identify the superior sagittal and transverse dural venous sinuses.

4.1a) Paraspinal and suboocipital muscles removed
4.1b) Craniocervical junction
4.1c) Vertebral artery

Craniovertebral Junction

Open and reflect the dura mater from the dorsal spinal cord and posterior brain. Remove the arachnoid mater to identify: dorsal rootlets, denticulate ligaments, ventral rootlets and posterior spinal vasculature.

Open the cisterna magna at the foramen magnum. Separate cerebellar tonsils to identify IV ventricle and obex (caudal extent of IV ventricle).

4.2a) Arachnoid mater
4.2b) Dorsal rootlets and denticulate ligaments
4.2c) IV ventricle

Spinal Cord Regions

Examine size differences between the cervical and thoracic spinal cord.

Note the differences in size, number and orientation of the spinal rootlets.

Follow the spinal cord inferiorly and identify the lumbar enlargement, conus medullaris and filum terminale.

Examine the exit of spinal nerves in the cauda equina into neural foramina (intervertebral foramina) between pedicles.

4.3a) Cervical and thoracic spinal cord
4.3b) Lumber spinal cord and conus medullaris
4.3c) Filum terminale

Lumbar Puncture

Expose the sacral portion of the vertebral canal. Note the dural sac and arachnoid end at approximately S2.

Identify the sacral spinal roots.

Lumbar punctures are ordinarily carried out at L4 but need to be below L2 and above S2 to avoid the spinal cord and to remain within a subarachnoid location.

Labels: Iliac crest, L4 — 4.4a) Lumbar punctures at L4

Expose Ventral Spinal Cord

Vertebral Body In Situ

Make midsagittal and coronal cuts through the vertebral bodies from the level of the carina to just superior to the diaphragm.

Identify vertebral bodies and intervertebral discs.

5.1a) Initial vertebral body cuts
5.1b) Vertebral bodies, intervertebral discs, surrounding structures

Anterior Thoracic Spinal Cord

Continue the removal of the vertebral bodies to expose the vertebral canal and the dura mater covering the spinal cord and the spinal nerves.

Identify a dorsal root ganglion at an intervertebral foramen.

Incise the dura mater and reflect it to examine the ventral spinal cord, anterior spinal artery, dorsal and ventral roots and denticulate ligaments.

5.2a) Final vertebral body cuts
5.2b) Ventral dura and spinal nerve
5.2c) Dorsal root ganglion
5.2d) Ventral spinal cord

Ventral Spinal Cord

Anterior Spinal Cord

View but do not perform this technically difficult and destructive tissue dissection from skull base to sacral canal. It demonstrates the ventral spinal cord, cervical, brachial and lumbosacral plexuses.