GRAY COLUMNS OF THE SPINAL CORD.
- The gray matter of the spinal cord is a butterfly-shaped structure made up of neuronal cell bodies, glial cells and neuropile (unmyelinated axons, dendrites & glial cell processes).
inside CNS → nucleus / outside CNS → ganglion
Division:
- The gray matter can be functionally divided into 3 main regions:
- Anterior horn: responsible for somatic motor function.
- skeletal muscles
- Intermediate horn: contain lateral horn (T1-L2) responsible for visceral motor function.
- heart...
- Posterior horn: responsible for sensory functions
- Somatic sensation: picking up sensations from the skin, skeletal muscles, joints, tendons & ligaments.
- Visceral Sensation from internal organs.
Lamina:
- The gray matter of the spinal cord can also be divided into layers (Rexed Lamina)
- They are 10 laminae in total.
I - VI → Posterior horn
III → Intermediate horn
VIII + IX → Anterior horn
X → Central zone.
There are specific nuclei that are present in each lamina & have specific functions.
- Marginal nucleus: (lamina I)
- Reciving pain /temp. sensation. (fast pain → “A-δ fibers”) via the spinothalamic tract
- Substantia gelatinosa of Ronald (II)
- Reciving pain / temp. sensations (slow pain) → “C-fibers” via spinothalmic tract.
- Nucleus proprius (III + IV):
- Pain / temp. → “A-δ + C fibers”
- touch / vibration → “A-β fibers”
- via propriception.
- Lamina (V):
→ Pain /temp. from the Viscera.
- lamin (VI)
→ limb reflexes
- Lamina VII
- Clarks column
- Interomediomedial nucleus (S2-S4)
- Interomediolateral nucleus (T1-L2)
→ Sympathetic and parasympathetic preganglion neurons (type of nerve cells that transmit signals from the CNS to ganglia of PNS) for the visceral organs sit in lamina VII.
- Lamina VIII:
→ hleps to modulate movement and muscle tone.
- lamina X: where axons cross over from one side to another
- Lamina IX:
- Phrenic (C3-C5)
- Diaphragm
- Accessory spinal (C1-C6)
- Sternocleidomastoid
- Trapezius
- Onufs nucleus (S2-S4)
- sphincter (external)