1. Overview Sept. 4, 2008 Jennifer LaVail, Ph.D.(

2. Comparative Anatomy Terminology
Terms used for brain and entire body are consistent in rat.
However, the human brain has a flexure, so above midbrain the terms change.

3. The horizontal plane of the cerebral cortex is a longituinal plane in the spinal cord.

5. BIG PICTURE

6. The Spinal Cord is composed of repeating segments.8 12 5 5

7. Plan of the Spinal Cord
Each segment has the same elements.
Somatosensory afferents (fibers that come into the CNS)
Motoneuron axons or efferents (fibers that exit the CNS).
Interneurons (cells whose axons do not leave the CNS.

8. Repeating Plan of the Spinal Cord
Somatosensory afferents have their cell bodies in the dorsal root ganglion outside of the CNS.
The afferents enter the spinal cord and synapse on the same side of the cord.
The motor neurons that innervate muscles (smooth or striated) are located on the same side of the cord as are the muscles.
The interneurons have axons that synapse with other interneurons or with motor neuron cells.

9. Functional Segment

10. Protective Layers for Spinal Cord
Vertebra

11. Segmental Arrangement of the Spinal Column

12. Segmental Organization of the Spinal Cord

13. Segmental Differences in Internal Structures
ARM
Why is that?
LEGS

14. Segmental Differences
Why?

15. B CNS develops from a tube

16. Origins of Brain Divisions

17. Brain stem

18. Ventral brain

19. The Brainstem