What does the spinal cord do?
- conducts or transmits sensory impulses from the body to the brain
- conducts motor impulses from the brain to the body
- controls reflex action
What is the epidural space?
fairly large space filled with adipose tissue that acts as a buffer around the spinal cord
What are meninges?
membranes that surround the brain and spinal cord
What protects the spinal cord?
spinal vertebrae, meninges, and epidural space
What are the 3 types of meninges?
- Dura mater- subdural SPACE filled with INTERSTITIAL fluid that anchors and protects
- Archnoid mater- subarchnoid SPACE filled with CSF
- Pia mater- thin MEMBRANE that follows the contour of the brain and spinal cord
Whats the Dura Mater?
subdural SPACE filled with INTERSTITIAL fluid that anchors and protects
What is the Archnoid mater?
subarchnoid SPACE filled with CSF
What is the Pia mater?
thin MEMBRANE that follows the contour of the brain and spinal cord
Pia mater is the most _______ of the meninges.
central or deep
The arachnoid mater is ______ to the pia mater.
superficial
THe dura mater is the most _______ meninges on the spinal cord.
superficial
How long is the typical spinal cord?
42-45 cm long
What is the foreman magnum?
the hole where the spinal cord attaches to the brain
Which vertebrae does the spinal cord reach to as an infant and as an adult?
infant- L4
adult - L1
When does the growth of the spinal cord stop?
age 5
What makes the cervical enlargement and the lumber enlargement, enlarged?
there is an increase of nerve tissue
Define conus medullaris
cone shaped end of spinal cord
Define cauda equina
the dorsal ventral roots of lowest spinal nerves
Define filum terminale
thread-like extension of the pia mater that stabalizes spinal cord in spinal canal
What is a sulcus?
shallow groove
Is the sulcus of the spinal cord on the ventral or dorsal side?
sulcus is on the dorsal side
Is the Fissure of the spinal cord on the ventral of dorsal side?
fissure is on the ventral side
What are the 2 spinal nerve roots that emerge from the spinal cord?
- dorsal root (sensory)
- ventral root (motor)
What kind of fibres does the dorsal root have?
sensory fibres in the dorsal root
What kind of fibres does the ventral root have?
motor fibres in the ventral root
What is the dorsal root ganglion?
contains cell bodies of sensory neurons
What neuroglial cells protect by wrapping themselves around the dorsal root ganglion?
satellite cells
What is the motor tract?
- descending tract
- has pyramidal (direct) and
- has extrapyramidal tracts (indirect)
What are sensory tracts
- ascending tracts
- dorsal columns
- spinothalamic
- spinocerebellar
What are the 3 sensory tracts?
- dorsal columns
- spinothalamic
- spinocerebellar
What is the function of the dorsal (posterior) column (sensory tract)?
responsible for…
- proprioception (know where your body parts are at any given time)
- discriminative touch
- two-point discrimination (deciphering whether there are 2 points or one when they are separating),
- pressure
- vibration
What is the function of the spinothalamic (sensory tract)?
responsible for..
- pain
- deep pressure
- crude touch (rough, textured)
What is the spinocerebellar tract (sensory tract) responsible for?
responsible for…
- unconscious proprioception (balance)
What are the 2 types of motor tracts and their function?
- DIRECT pathways (pyramidal tracts); precise VOLUNTARY movement, happen right away
- INDIRECT pathways (extrapyramidal tract); programmed or AUTOMATIC movement; coordinate gross movement and visual reflexes
What is the function of direct pathways (pyramidal tracts)?
- precise
- voluntary movement
- happen right away
What is the function of indirect pathways (aka extrapyramidal tracts)?
- automatic movements
- coordinate gross function and visual reflexes
What are reflexes?
- fast, predictable, automatic responses to environment change
What are integration centres?
- regions in the CNS that relay impulses from sensory to motor neurons directly (eg reflexes)
Name the 4 important somatic spinal reflexes.
- stretch reflex
- tendon reflex
- flexor (withdrawal reflex)
- cross extensor reflex
What are the nerve membranes/coverings?
- epineurium
- perineurium
- endoneurium
What is the stretch reflex?
aka patellar reflex
- monosynaptic reflex (no interneuron)
- prevents over stretching and injury
What is activated when the tendon stretches in a tendon reflex?
Golgi tendon organ causes muscle to relax antagonistic muscle contracts
What is the flexor cross extensor reflex?
a polysynaptic reflex involving several spinal segments
- flexor reflex draws leg back
- cross extensor reflex extends contralateral limb to maintain balance
What is the physiological role of reflexes?
- protection- minimizes duration of exposure to noxious stimuli
- maintains posture and balance
What are plexuses?
complex networks of nerves
What part of the spine does not form plexuses?
spinal nerve T2- T12 don’t form plexuses
What does the CERVICAL plexus innervate ?
C1-C5 innervates skin, muscle of head and neck, and superior shoulders and chest
What does the BRACHIAL plexus innervate?
C5-T1 innervate shoulder and upper limb
What does the LUMBAR plexus innervate?
L1-L4 innervates abdominal wall, external genitals and anterior medial thigh
What does the SACRAL plexus innervate?
L4-S4 innervates buttock perineum and part of the lower limb
What is dermatome?
areas of the skin supplied by one spinal nerve
- overlap of dermatomes prevents loss of sensation if one spinal nerve gets damaged