1. Spinal Cord and Reflexes

2. Spinal Cord & Nerves

3. Spinal Cord Connects the PNS with the brain Produces spinal reflexes
Passes down the foramen magnum and descends to T12-L3
In children, spinal cord is as long as the spine
Two enlarged regions:
Cervical Enlargement: supplies nerves to upper limbs
Lumbar Enlargement: supplies nerves to lower limbs
Conus Medullaris: where the spinal cord ends
Cauda Equina (“horse’s tail”): group of spinal nerves that branch from the end of the conus medullaris

4. Introduction
The spinal cord is composed of white matter surrounding a gray matter core
The gray matter is arranged with a left and right dorsal horn and a left and right ventral horn.

7. Sectional Anatomy
Cord is divided by deep anterior median fissure and surface posterior median sulcus
White Matter: contains many myelinated axons
Divided into columns
Grey Matter: contains many glial cells and cell bodies
Divided into “horns”
Posterior Gray Horn: carry sensory neurons in spinal cords
Anterior Gray Horn: carry somatic motor neurons to skeletal muscle
Lateral Gray Horn: occur in T1=L2 and consists of visceral motor neurons
Axons can cross opposite side of spinal cord at the crossbars called “commissures”

9. Spinal Meninges Dura Mater – outer membrane, tough connective tissue
Epidural space – contains adipose tissue to pad the spinal cord
Arachnoid space
Subdural space – separates the dura mater from the arachnoid
Subarachnoid space – contains the CSF to protect and cushion the spinal cord
Pia Mater – thin, inner meningeal layer directly over spinal cord; hold the blood vessels in place

10. Spinal and Peripheral Nerves
12 pairs of cranial nerves
31 pairs of spinal nerves
8 cervical nerves –
12 thoracic nerves
5 lumbar nerves
1 coccygeal nerve

11. Spinal Nerve Plexus Plexus: groups of spinal nerves Four regions
Cervical
Brachial
Lumbar
Sacral
**Thoracic  NOT part of any plexus but make up the intercostal nerves that innervate the intercostal and abdominal muscles

12. Spinal Reflexes
Reflexes – automatic neural responses to certain stimuli
CNS has little involvement in these reflexes
Many type of reflexes
Reflex Arc – a stimulus does not to be recognized to elicit a response to it