Spinal cord Flashcards
(22 cards)
What are the functions of the spinal cord?
- Impulse conduction; connecting the body to the brain and then brain to the body.
- Reflex integration.
Facts about the spinal cord?
- 42 cm’s
- Extends to lumbar 1
- 2 way conduction pathway
- Protected by bone, CSF
- 31 pairs of spinal nerves
Describe the ventral and dorsal root?
- Ventral root contains axons of motor neurone.
- Dorsal root contains axons of sensory neurone.
Describe each spinal nerve?
- Each side of the spine contains dorsal and ventral roots to form a spinal nerve.
- Mixed nerves carry afferent and efferent fibres.
Describe the spinal meninges?
- Specialised membranes isolate spinal cord from surroundings.
- They protect spinal cord, carry blood supply, continuous with cranial meninges.
Name the 3 types of mater in spinal meninges?
- Dura mater; outer layer of spinal cord.
- Arachnoid mater; middle layer which contains sub arachnoid space with CSF.
- Pia mater; inner layer.
Describe the gray and white matter?
- White matter; outside layer, contains myelinated and unmyelinated axons.
- Gray matter; inside spinal cord and surrounds central canal of cord, contains neuron cell bodies, has projections called gray horns.
Describe the organisation of gray matter?
- Sensory nuclei; dorsal root of spinal nerves, receive info from peripheral sense organs.
- Motor nuclei; anterior horns of cord, connect to peripheral effectors.
Describe the white matter in the spinal cord?
- Posterior, anterior and lateral white columns.
- Comprise bundles of axons.
- Ascending = sensory to brain.
- Descending = motor from brain.
Describe the 5 nerves + how many?
- 8 cervical nerves
- 12 thoracic nerves
- 5 lumbar nerves
- 5 sacral nerves
- 1 coccygeal nerve
Name the 3 types of neurones?
- Motor neurone.
- Sensory neurone.
- Interneurone.
Describe the tracts / pathways?
- Motor pathways = descending from brain to spinal cord and then to muscle.
- Sensory pathways = ascending from sensory nerve endings in body to spinal cord to brain.
Describe the 2 types of descending pathways?
- Pyramidal tracts = originate mainly within primary motor cortex, control voluntary muscle activity.
- Indirect system = support and help smooth muscle activity which is involuntary, all motor pathways except corticospinal tracts.
Describe the corticospinal pathways?
- Function is control of skeletal muscle.
- Involves upper and lower motor neuron.
- Reflexes at spinal cord involve lower motor neurone.
Describe the ascending sensory pathways?
- Pain, temperature, coarse touch, discriminative touch and vibration.
- Impulses from periphery of body to sensory cortex.
- 2 pathways = proprioceptive info, skeletal muscle, from muscles, tendons and joints.
What happens when there is damage to the spinal cord?
- Can result in paralysis + sensory loss.
- No recovery from complete lesion.
- Incomplete lesion has potential for recovery.
Describe the nerve plexuses?
- They are interwoven networks of nerve fibres.
- Control skeletal muscles of neck and limbs
- Cervical plexus
- Brachial plexus
- Lumbar plexus
- Sacral plexus
Describe the cervical plexus?
- Includes spinal nerves C1 to C5.
- Innervates neck, thoracic cavity and diaphragm.
- Major nerve = phrenic.
Describe the brachial plexus?
- Includes spinal nerves C5 to T1.
- Innervates muscles of shoulder girdle and upper limbs.
Describe the nerves of the hand?
- Median nerve
- Ulnar nerve
- Radial nerve
Describe the lumbar plexus?
- Includes spinal nerves T12 to L4.
- Major nerves = genitofemoral, lateral femoral cutaneous, femoral nerve.
Describe the sacral plexus?
- Includes spinal nerves L4 to S4.
- Major nerves = pudendal and sciatic.
- Branches of sciatic are fibular and tibial.
