neuroanatomy 2 Flashcards
how many spinal nerves do we have
31 pairs
root of the nerve from spinal cord
rootlets emerge from dorsal or ventral aspect, roots then pass through the subarachnoid space until they reach intervertebral formina. the posterior root is enlarged by the posterior root ganglion. the roots fuse to form the mixed spinal nerve which produces anterior and posterior rami
are posterior roots sensory or motor
sensory
are anterior roots sensory or motor
motor
what is the tapered cone like shape called where the spinal cord terminates
conus medullaris which continues as a thin connective tissue cord called the filum terminal
what level does the spinal cord end
L1/L2
how is the spinal cord suspended in the canal
by a ribbon of tissue called denticulate ligament. it is formed of pia and arachnoid tissue and attatches to the dura at points
how do you know which are the posterior horns and anterior horns in teh SC
posterior horns extend to the edge, anterior horns do not
where can a lateral horn be seen
T1-L2. it contains preganglionic symp neurons
arterial supply of teh SC
three major longitudinal arteries (originate from vertebral arteries), segmental arteries (dervied from vertebral, intercostal and lumbar arteries), radicular arteries (travel along dorsal and ventral roots)
in teh SC why is there an epidural space
there is space between teh dura and the bone which doesnt occur in the cranial cavity. it contains adipose tissue and anterior and posterior epidural venous plexuses.
venous drainage
longitudinal and segmental
in sesnory sensations where is a sense from the left sode of teh body percieved
represented on the right cortex
how does the amount of grey matter change as we go down the cord
gets smaller as we loose motor fibres so the cord also gets smaller
is the sensory tract descending or ascending
ascending
what does the dorsal colums/medial lemniscus column percieve and where do fibres cross
fine touch, and conscious proprioception
cross in the medulla
what does teh spinothalamic tract percieve
pain, temp, deep pressure. fibres cross segmentally
where is teh primary motor cortex
anterior to the central sulcus
what does teh corticospinal tract percieve
fine, precise movement particularly of distal limbs muscles
tracts form visible ridges referred to as the pyramids on the anterior surface of teh medulla - so also called the pyramidal tract
wheer do the fibres cross from the corticospinal tract
85% cross in the caudal medulla as the decussation of teh pyramids. crossed fibres form the lateral CST. Uncrossed fibres form the ventral CST, which cross segmentally
what can a CVA in the internal capsule cause
lack of descending control of teh corticospinal trcat. this results in spastic paralysis with hyperflexion of the upper limbs. sometimes referred to as decorticate posturing
what are the motor systems outsode the pyramidal tract called
extrapyramidal synstem
what does teh tectospinal tract do
input i smostly to cervical segments. It is thought to mediate reflex head and neck movements due to visual stimuli
what does the reticulospinal tract do
reticular formation forms the central core of the brainstem. Fibres orogionate in areas of the reticular formation in pons and medulla. In general finbres origionating from pons facilitate extensor movements and inhibit flexor movements, while those origionating in medulla do the opposite
