1. Spinal Cord Notes

2. ANATOMY OF SPINAL CORD Extends from medulla oblongata
Ends at second lumbar (L2) vertebra in adults
31 pairs of spinal nerves
Conus medularis – end of cord

4. Two enlargements:
Cervical enlargement - C4 – T1 – nerves to & from upper limbs
Lumbar enlargement – T9-T12 – nerves to & from lower limbs

5. Cauda equina = “horse’s tail”
After conus medullaris, spinal cord divides into nerves that leave at lower levels

7. CROSS SECTION ANATOMY Two grooves divide spinal cord:
Anterior median fissure (deeper)
Posterior median sulcus
Gray matter (unmyelinated) forms an “H” in center
Gray commissure where fibers cross from side to side

9. Central canal – center of gray commisure; continuous with fourth ventricle
Gray matter is divided into horns:
Anterior (ventral) gray horns - cell bodies of motor neurons to skeletal muscle

10. Posterior ( dorsal ) gray horns
Lateral gray horns – cell bodies of motor neurons to cardiac, and smooth muscle & glands
Part of autonomic nervous system

12. White matter (myelinated nerve fibers) is divided into columns
Anterior (ventral), posterior (dorsal), lateral white columns

13. Each column is divided into nerve tracts
Each tract carries one type of information (sensory or motor)
Ascending (sensory) tracts - impulses toward brain
Descending (motor) tracts – impulses from brain

15. Spinal cord has two functions:
White matter tracts serve as information highways to and from brain
Gray matter receives and integrates information, especially for spinal reflexes

16. Name of tract indicate position in cord, where it begins and ends, and direction of impulses

17. DEVELOPMENT OF NS Begins in third week of development
Ectoderm forms a neural tube
Neural tube defect due to low levels of a folic acid
Spina bifida – failure of laminae of spine to unite, caused by low levels of folic acid

18. Portions of neural tube form fluid-filled vesicles
Hypothalamus is one of last areas of brain to develop
No new neurons form after birth, only grow and maturation
Brain reaches maximum weight as a young adult