78. Spinal cord. The white matter – ascending (sensory) and descending (motor) tracts. Intersegmental tracts.

Introduction

7. Lamina VIII:

• → hleps to modulate movement and muscle tone.

9. lamina X: where axons cross over from one side to another

8. Lamina IX:

• Posterior → Supplying flexors
• Anterior → " Extensors
• lateral — only in Enlargments — S: Distal limbs
• Central — S: Proximal limbs
• Medial — S: Axiall musculator " neck + head "
• Phrenic (C3-C5) → Diaphragm
• Accessory spinal (C1- C6) → Sternocledio mastoid → Trapezius
• Onufs nucleus (S2 -S4) ↳ sphincter (external)

WHITE SUBSTANCE

• White matter - Contains tracts of myelinated axons with supporting cells (myelinated ↓ contains white lipids.)
• Function: Enable communication between the spinal cord and higher levels of the CNS.

Forms a system of Ascending, Descending and Associative tracts

* tracts - Bundle of Axons In CNS.

Arrangment:

• White matter arranged into columns:

Each column contains spesific tracts (Ascending ↓ Sensory & Descending ↓ Motor) with specific functions.

Tracts:

→ Lateral column: → Somatotopic arrangment

1. Lateral Corticospinal tract. ↳ Responsible for voluntary motor control
2. Rubrospinal tract - responsible in motor coordination

Descending ↓ motor

3. Dorsal spinocerebral tract
4. Ventral spinocerebral tract
5. Lateral spinothalmic tract
6. Spinolivary tract

Ascending ↑

→ Posterior column: "transmit sensory info. from the Peripheral nerves to the brain"

1. Fasciculus Gracilis - Caries signals from the lower body.
2. Fasciculus Cuneatus - Caries signals from the upper body

Asc. ↑↑

→ Anterior column

1. Lateral reticulospinal track.
2. Medial " "
3. Vestibulo spinal tract.
4. Tectospinal "
5. Ant. corticospinal " (cortex)

Desc. ↓

6. Ant. Spinothalmic tract ] Ascending ↑ " sensory "

148 cont.