Spinal cord function and dysfunction Flashcards
How many spinal nerves in each segment?
8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
What is section enlargement?
Cervical Enlargement C3 to T1
Has extra motor neurones that go to the muscles of the upper limb
Lumbosacral Enlargement L1 to S3
Has extra motor neurones that go to the muscles of the lower limb
How many layers in the meninges and how many spaces?
3 layers and 2 spaces.
Subarachnoid space- filled with CSF, continuous with subarachnoid space in brain.
Epidural space- between outside of the dura and the bone and full of venous plexuses and fatty tissue
What is the difference between where a spinal nerve block is administered and an epidural nerve block?
Spinal nerve blocks are administered into the subarachnoid space. Epidural nerve blocks are administered into the epidural space.
What is the difference between white and grey matter?
Grey matter consists of neuronal cell bodies and white matter consists of neuronal tracts.
What is the difference between a dermatome and myotome?
Dermatome- area of skin innervated by one spinal nerve or segment.
Myotome-muscles innervated by one spinal nerve or segment.
What are the 4 sulci in the cross section of the spinal cord?
Posterior median sulcus- divides the posterior half of the spinal cord into 2 halves.
Posterolateral sulcus- entry point of the sensory root.
Anterolateral sulcus- exit point for the motor root.
Anterior median fissure- divides the anterior surface of the spinal cord into two halves.
What is the substantia gelitanosa?
First point of modulation of pain and temperature.
What is the difference between the fasciculus gracilis and fasciculus cuneatus?
Both form part of the dorsal column. Carry sensory information about fine touch, vibration and proprioception. Gracilis is sensory from ipsilateral lower limb and cunneatus is sensory from ipsilateral upper limb.
What are the 2 motor tracts in the spinal cord?
Lateral corticospinal tract- motor to ipsilateral anterior horn and supplies limb musculature.
Anterior corticospinal tract- Motor to ipsilateral and contralateral anterior horn. Supplies mainly axial musculature.
Describe the decussation of motor fibres?
One single tract descends from the cortex which splits to form the anterior and lateral corticospinal tract at the decussation of the pyrmaids. The anterior corticospinal tract decusses itself at the level of the spinal cord to supple both halves of the spinal cord allowing it to have ipsi- and contralateral connections.
Describe the pathway of the dorsal columns?
Dorsal columns carry information on driscrimnative touch, vibration and proprioception. Sensory fibres enter the spinal cord and don’t synapse in the posterior horn. They travel up and synapse with the nucleus gracilis or cunneatus at the level of medulla after which they cross the contralateral side. They travel in the medial lemniscus tract and synapse in the ventral posterolateral nucleus in the thalamus. A third neurone then projects from the thalamus to the cortex.
Describe the pathway of the spinothalmic tract?
Fibres enter the dorsal horn and travel 1 or 2 segments in Leiusseur’s tact. Then they synapse in the nucleus proprious and cross the midline at the level of the spinal cord. Fibres then travel in the spinothalmic tract and synapse in the ventral posterolateral nucleus in the thalamus. A third neurone then projects from the thalamus to the cortex.
Describe a extensor reflex pathway?
1a fibre from muscle spindles sense stretching of the muscle and travels to spinal cord where it synapses with alpha motor neurone in spinal cord which then supplies extensor.
1a fibre also synapses with inhibitory neurone which inhibits flexor muscle
Describe a reflex to a noxious stimulus?
A delta and C fibres detect noxious stimulus and travel to spinal cord where they synapses with alpha motor neurone in spinal cord which then supplies the flexor.
1a fibre also synapses with inhibitory neurone which inhibits extensor muscle
