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Spinal Cord
Chapter 12 - A & P Lecture
| Question | Answer |
|---|---|
| what is the spinal cord? | a long, cylindrical structure of nervous tissue that is a comm. highway between the brain and body. |
| spinal cord key structural features? | - extends from the foramen magnum to the second lumbar vertebra (L2) - segmented (organized into repeating functional units) |
| segments of the spinal cord? | - Cervical - Thoracic - Lumbar - Sacral |
| Each segment gives rise to spinal nerves, resulting in: | 31 pairs of spinal nerves total |
| variations in spinal cord length? | yes, not uniform in diameter |
| what are enlargements? | regions where more neurons are present to serve the limbs: Cervical enlargement & Lumbar enlargement |
| what is Cervical enlargement? | Supplies the upper limbs |
| what is Lumbar enlargement? | Supplies the lower limbs |
| List the terminal structures? | Conus medullaris & Cauda equina |
| what is Conus medullaris? | - The tapered inferior end of the spinal cord |
| what is Cauda equina? | - bundle of spinal nerve roots extending downward from the conus medullaris - “horse’s tail” |
| what is the meninges composed of? | connective tissue membranes |
| what do the meninges do? | wrap around the spinal cord |
| list the layers of the spinal cord: | - dura mater - arachnoid mater - pia mater |
| what is Dura mater? | - Tough, outermost layer - called the thecal sac - Continuous with the epineurium of spinal nerves |
| what is Arachnoid mater? | - Thin, delicate, web-like membrane |
| what is Pia mater? | - Innermost layer, tightly bound to the spinal cord surface - Forms important stabilizing structures: filum terminale & denticulate ligaments |
| what is the filum terminale? | anchors spinal cord to coccyx |
| what is the denticulate ligaments? | stabilize cord laterally |
| list the spaces between the meninges: | epidural space, subdural space, subarachnoid space |
| what is Epidural space? | - Contains fat, blood vessels, and connective tissue - Site of epidural anesthesia |
| what is Subdural space? | - Contains a small amount of serous fluid |
| what is Subarachnoid space? | - Contains cerebrospinal fluid (CSF) and blood vessels - Critical for cushioning and nutrient transport |
| if you cut the spinal cord horizontally what 2 major regions? | Gray Matter (Inner Region) & |
| what is gray matter composed of? | - Neuron cell bodies - Dendrites - Unmyelinated axons |
| how is gray matter organized into horns? | 1) Posterior (dorsal) horns [Receive sensory input] 2) Anterior (ventral) horns [Contain somatic motor neurons] 3) Lateral horns [Contain autonomic neurons (part of the ANS)] |
| what is white matter composed of? | myelinated axons |
| how is white matter organized into columns(funiculi)? | - Dorsal (posterior) - Ventral (anterior) - Lateral |
| each column(funiculi) contains: | tracts (fasciculi)—bundles of axons that carry information |
| list the tracts(fasciculi) of white matter? | Ascending tracts & Descending tracts |
| what is Ascending tracts? | sensory information to the brain |
| what is Descending tracts? | motor commands from the brain |
| what are key landmarks of the spinal cord? | Anterior median fissure & Posterior median sulcus (divide the spinal cord into left and right halves) |
| what is Anterior median fissure? | Deep groove on the front |
| what is Posterior median sulcus? | Shallow groove on the back |
| what is commissures of the spinal cord? | Bands of tissue that connect the left and right sides |
| what is the function of commissures? | Allow communication across the spinal cord |
| where is the central canal of the spinal cord located? | center of the gray matter |
| what does the central canal of the spinal cord contain? | cerebrospinal fluid (CSF) |
| spinal nerves form through the merging of what 2 roots? | Dorsal Root (Sensory) & Ventral Root (Motor) |
| where does the dorsal root (sensory) carry signals? | sensory (afferent) information into the spinal cord |
| what does the dorsal root (sensory) contain? | dorsal root ganglion |
| where does the ventral root (motor) carry signals? | out of the spinal cord |
| how is the ventral root (motor) formed? | by axons of: - Somatic motor neurons (anterior horn) - Autonomic neurons (lateral horn) |
| The dorsal and ventral roots merge to form a _____ _____ | spinal nerve |
| what are the pathways? | Sensory Pathway & Motor Pathway |
| describe the Sensory Pathway? | Sensory receptors → dorsal root → dorsal horn |
| describe the Motor Pathway? | Motor neuron cell body (in anterior/lateral horn) → ventral root → muscles or glands |
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