The Central Nervous System (CNS)(CNS)2- The spinal cord2- The spinal cord

Physiology -IIPhysiology -II PHL 226PHL 226

Dr. Abdulaziz bin saeedanDr. Abdulaziz bin saeedan

Pharmacy CollegePharmacy College

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Spinal CordSpinal Cord

The spinal cord is a long bundle of neurons and support cells.

It extends from the bottom of the brain down to the space between the first and second lumbar vertebrae.

It is protected by the bony vertebral column. The length of the spinal cord is much shorter than the

length of the vertebral column, extending about 45 cm. The spinal cord is protected by: o Bone “vertebrae ”. o Spinal meninges. o CSF.

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Similar to the brain, the spinal meninges are made up of 3 layers of tissues:

1- The dura mater is the outermost layer, and it forms a tough protective coating.

Between the dura mater and the surrounding bone of the vertebrae is a space called the epidural space, which is filled with fatty tissue and a network of blood vessels.

2- The arachnoid mater is the middle protective layer.

3- The pia mater is the innermost protective layer.

The space between the arachnoid and the underlying pia mater is called the subarachnoid space which contains CSF.

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Function: It transmits signals from peripheral organs to the brain (ascending pathways) (ascending pathways)

and from the brain to the peripheral organs (descending pathways)(descending pathways).

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Spinal nervesSpinal nerves

They are 31 pair of nerves. They have no special names.

There are: There are: o 8 cervical. o 12 thoracic .o 5 lumbar.o 5 sacral.o 1 coccygeal.

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