Spinal Cord Flashcards
At what vertebral level does the spinal cord end?
L1/L2
What is the denticulate ligament?
Connective tissue derived from pia and arachnoid mater that anchors the spinal cord at each vertebral level
What is the conus medullaris?
End of the spinal cord that becomes cauda equina
What is the name of thin tissue that anchors the spinal cord to the coccyx?
Filum terminale
What is the difference between the dura mater on the brain and on the spinal cord?
On the brain the Dura mater attaches directly to the bone like a periosteum but that does not occur in spinal cord
What lies between the vertebrae and the dura mater of the spinal cord?
Epidural fat (called the epidural space) (allows movement)
What are the respective names of the dips in the spinal cord anteriorly and posteriorly?
Anterior: ventral median fissure
Posterior: dorsal median sulcus and septum
Where does the central canal begin and end?
Begins from 4th ventricle of brain and is blind ending
From what arteries do the 3 major longitudinal arteries of the spine originate?
Vertebral arteries
Longitudinally, there are 2 anterior arteries and 1 posterior. True/false?
False. 1 anterior and 2 posterior
Called anterior and posterior spinal arteries
What 3 arteries do the segmental arteries arise from?
- vertebral
- intercostal
- lumbar
What is the name of the arteries that travel along the dorsal and ventral roots?
Radicular arteries
In which layer does the anterior and posterior internal vertebral venous plexus sit?
Epidural space
Where is the primary somatosensory cortex on the brain?
On the postcentral gyrus in the parietal lobe
The size of the somatosensory cortex is proportionate to the level of sensitivity of the body part and not to the size of the body part, i.e. arranged somatotopically. True/false?
True
What are the two areas of the body that’s somatosensory nerves don’t travel in the spinal cord?
- Face
- Scalp
Why is the spinal cord thickened at the cervical and lumbar region?
Because there is more grey matter to supply motor nerves to upper and lower limbs
What system carries most of the fine touch, pressure, conscious proprioception and vibration nerves?
Dorsal column (AKA funiculus)-medial lemniscus system
What is the difference between the nucleus gracilis and nucleus cuneatus in the medulla?
- nucleus gracilis receives presynaptic sensory fibres from lower portion of body
- nucleus cuneatus receives presynaptic sensory fibres from thoracic/upper limb portion of body
What is the medial lemniscus?
It’s a band of white matter in the brain
Where specifically do the 2nd order sensory fibres synapse to the 3rd order sensory fibres to bring info to cortex?
Ventral posterior lateral nucleus of the thalamus
What tract carries info relating to pain, temperature, itch, tickle and deep pressure?
Spinothalamic tract (or anterolateral tract)
Where do the fibres cross the spinal cord in the spinothalamic tract?
Fibres cross segmentally i.e. at the level of the vertebrae they enter
Outline the pathway of neurons in the spinothalamic tract.
First order neurons enter posterior roots and posterior horn, synapse in dorsal horn -> second order neurons, cross over spinal cord to other side to anterolateral portion, ascends spinal cord then synapses into third order neurons at thalamus which takes info to primary somatosensory cortex.
What is the name of the white matter within which the spinothalamic tract neurons travel?
Spinal Lemniscus
Where is the primary motor cortex located specifically in the brain?
On the precentral gyrus
What tract carries motor info on fine, precise movement?
Corticospinal tract
Outline the pathway of the corticospinal tract axons from the cerebral motor cortex.
Pass from motor cortex through internal capsule, then through basis pedunculi (white matter tract on anterior surface of midbrain), through pyramidal tract on medulla - here most fibres cross to other side AKA decussation & splits into lateral CST and ventral CST
What is the difference between lateral CST and ventral CST?
- Lateral CST fibres cross at medulla (decussation of the pyramids)
- Ventral CST fibres continue down same side until they cross segmentally at level at which they are carrying out action
What is decussation of the pyramids?
Where the axons in the corticospinal tract split into lateral CST and ventral CST. Most axons cross spinal cord into opposite (lateral CST) and rest stay and cross segmentally (ventral CST)