Spinal Chord and Reflexes Flashcards
Basic structure of spinal chord
Label this diagram
How is the white matter of the spinal cord subdivided into areas ina cross section ?
What are the funiculi
They are the vertical columns of the white matter of the spinal chord
they transmit information up and down
Function of ventral regions
Produce motor output from the efferent nerves inside
How is the grey matter of the spinal chord organised into regions?
Intermediolateral cell column only present between T1 (first thoracic vertebra) and L2 (second lumbar vertebra)
Function of dorsal regions
How can it be identified ?
To receive sensory input
dorsal root will have swelling from the cell bodies of the sensory neurones
Label the structure of a spinal segment from the posterior view
What are the meninges and what is their function
3 thin layers of tissue that cover the brain and spinal chord
They provide tight anchoring of CNS to the surrounding bones to prevent side-side movement
allow passage of CSF
Label :
A spinal segment
an artery
the meninges
the lumbar/cervical enlargements
Afferent information enters via the ___ root
Dorsal
Efferent information leaves via the ____ region
Ventral
The vertebral column structure
where is the cauda equina found in newborns?
L3 - L4
where is the cauda equina located in adults ?
L1-L2
what is the cauda equina
bundle of nerve roots at the bottom of the spine just below the spinal chord nerves responsible for movement of the legs and bladder
label the diagram of a vertebrae cross section
Where is local anaesthetic delivered during pregnancy ?
Epidural space
Name the ascending funiculi ?
2 for each region of spinal chord ; as they are ascending they are responsible for providing touch, pain, sensation of temperature and proprioception
What are the dorsal ascending funiculi present in the cervical region of the spinal chord ?
Gracile(hindlimb)
and cuneate (forelimb)
Which ascending dorsal funiculi are present in the lumbar region of the spinal chord ?
Gracile (hindlimb) only
What is decussation ?
When fibres cross from one side of a structure to another e.g when a sensory neurone passes through a funiculi that enters through the opposite side of the spinal chord
sometimes dessucation occurs in the brain
Label the descending funiculi
Replicated on both sides of spinal chord
7 in total
What does corticospinal mean ?
Controls voluntary movement of muscles of limbs
function of the reticulospinal funiculi
Regulation of voluntary movements and muscle tone; medial stimulates movement, lateral inhibits movements
function of vestibulospinal funiculi
Posture and balance via inneravtion of the anti-gravity muscles (flexors of arm, and extensors of leg)
Role of rubrospinal
Promotion of flexor and inhibition of extensor muscle activity
Role of tectospinal
Head and eye movement via visual stimuli
Define lower motor neurone
Spinal motor neurone
Where are upper motor neurones found
In the brain
Upper motor neurones innervate …
Spinal motor neurone
Alpha spinal motor neurones act on
Extramural muscle fibres that are responsible for contraction
Gamma spinal motor neurones innervate ….
Intrafusal muscle fibres in muscle spindles
Define humunculus
Spatial orientation of neural tissue relative to location of associated muscles
proximal muscles are linked to medial cell bodies
distal muscles are linked to lateral cell bodies
Types of reflexes
Superficial , deep (myotactic) and visceral (autonomic)
Superficial reflexes
Corneal
Sneezing (nasal )
plantar (Toes curl down in adults)
Myotactic reflexes
Patellar (knee jerk)
Visceral reflexes
Pupillary
micturition (peeing)
Babinskis reflex
Toes curl up and fan out
seen in healthy babies
sign of upper motor neurone lesion in adults
Abnormal babinski reflex is indicative of …
Upper motor neurone damage
Describe central modulation of spinal reflexes
Sensory neurones deliver info to spinal chord and its passed onto the brain via ascending motor neurones
inhibition of reflexes is achieved by transmission of an AP down a descending motor neurone within the spinal chord
Explain reciprocal inhibition
When a muscle contracts, it’s important that its antagonistic muscle remains relaxed
Inhibitory interneurone activated when a AP arrives from an muscle ; it synapses with efferent motor neurone causing inhibition of contraction in antagonist muscle
What are upper and lower motor neurones
Upper motor neurones travel between brain and spinal chord
Lower motor neurones travel from spinal chord to muscle
Function of interneurones
To connect spinal motor neurones and sensory neurones
Crossed extensor reflex
Afferent sensory neurone
interneurone synapses with 2 antagonistic pair one on either side of body ; opposite effect in either side
