The central nervous system Flashcards
What are the 3 parts of the brain?
Forebrain- composed of central hemispheres and diencephalon
Midbrain
Hindbrain- composed of medulla, pons and cerebellum
What does the limbic lobe contain?
Amagdyla
Hippocampus
Mamillary body
Cingulate cortex
What is the role of the limbic lobe?
Associated with learning, memory, emotion, motivation and reward
Where is the insular cortex located?
Deep within the lateral fissure
What is the insular cortex concerned with?
Visceral sensation
Autonomic control
Interoception
Auditory processing
Visual- vestibular integration
What is the cerebrum also known as?
The cerebral cortex
What is white matter?
Myelinated neuronal axons forming tracts
What is grey matter?
Cell bodies of neurones
What is lamina?
A layer of neurones
Label the following
What is brown sequard syndrome?
Caused by hemisection of spinal cord (damage to one half)
Leads to loss of function below injury
What are symptoms of brown sequard syndrome?
Spinothalamic tract on contraleteral side (opposite) interruped so loss of pain and temperature in that leg
Dorsal tract on ipsilateral side interupted so loss of proprioception, touch and vibration
Corticospinal tract on ipsilateral side interupted so paralysis below leison
How is the spinal cord arranged?
8 pairs cervical
12 pairs thoracic
5 pairs lumbar
5 pairs sacral
1 pair coccygeal
Nerves are in pairs: 1 left and 1 right
Where do spinal nerves emerge?
Emege through invertebral foramina
C1- C7 emerge above vertibrae
C8- Co1 emerge below vertibrae
No C8 vertibrae but C8 nerve
Where can enlargements be found along the spinal cord?
Enlargement in cervical due to increased innervation from upper limbs
Englargment in lumbar region due to increased innervation of lower limbs
What descending tracts are there?
Corticospinal tract
Corticobulbar tract
What is the corticospinal tract responsible for?
Voluntary movement
How is the corticospinal tract structured?
Motor corticospinal tract has 2 neurones:
Upper motor neurones- housed in primary motor cortex
Lower motor neurones- housed in brainstem (if going to head and neck) or spinal cord (if going to trunk or limbs)
Tract on lateral side of the spinal cord is called the lateral corticospinal tract
What journey does the lateral corticospinal tract take?
Fibres cross in the medulla from one motor cortex to opposite side of the cord- pyrimidal decussate
Theres tracts in both hemespheres- these form lateral corticospinal tracts which come from opposite hemispheres
How is the corticospinal tract divided?
Lateral corticospinal tract supplies limb muscles
Anterior corticospinal tract: supplies trunk muscles
What are the ascending tracts?
Dorsal column
Spinothalamic tract
What is the dorsal colum responsible for?
Fine touch, vibrations, propriception
What are the 2 types of fibres found in the dorsal column?
Gracile tract: carries fibres from lower limbs ipsilaterally- lateral part of dorsal column
Cuneate tract: carries fibres from upper limbs ipsilaterally- medial part of dorsal column
What journey do first order neurones in the dorsal column take?
Sensory neurones in the dorsal root ganglia send afferent fibres via gracile or cuneate pathway
Fibres enter the dorsal horn and enter the ascending dorsal column pathway
First synapse of gracile tract is gracile nucleus
First synapse of cuneate tract is cuneate nucleus
These synapses are located in the lower medulla and is where first order neurones meet second order neurones
What journey do second order neurones take in the dorsal colum tract?
Second order neurones cross in the caudal medulla to form the contralateral medial lemniscus tract
These synapse in the thalamus where they meet the third order neurone
What journey do third order neurones take in the dorsal colum tract?
These are found in the ventral nuclear group in the thalamus
Fibres ascend to primary somatosensory cortex
What is the spinothalamic tract responsible for?
Lateral spinothalamic tract: pain and temperature
Anterior spinothalamic tract: crude touch
What journey do first order neurones take in the spinothalamic?
Neurones origionate in dorsal root ganglia
They synapse onto second order neurones
What journey do second order neurones take in the spinothalamic tract?
These are found in the posterior horn
They decussate immediately in the spinal cord to form the contralateral spinothalamic tract
They terminate in the thalamus where they synapse at the ventroposteriorlateral nucleus
What journey do third order neurones take in the spinothalamic tract?
These project through the internal capsule to the somatosensory cortex
What is the responsibility of the corticobular tract?
Movement of extraoccular muscles, muscles of mastication, muscles of facial expression, muscles of tongue
What are the 2 fibres of the corticobular tract?
Upper motor neurones: in primary motor cortex
Lower motor neurones: in brainstem in nuclei of cranial nerve (CN 3, 4, 5, 6, 7, 12 )
What jouney does the corticobulbar tract take?
UMNs go from primary motor cortex to brainstem where thay can do the following:
- Terminate directly onto alpha motor neurones or interneurones and innervate neurones in the brainstem
- Can dessucate in the brainstem and synapse with LMNs to innervate contralateral motor CNs
- Can synapse with LMNs ad innervate ipsilateral CNs (not dessucate)
- Can innervate CNs via corticospinal tract
How are fibres organised as they descend?
Tracts that are descending are likely to be bundled together
As the tract descends it forms the internal capsule
What are examples of brainstem motor tracts?
Verstibulospinal: provides info. about head movement and position and mediates postural adjustments
Tectospinal: orientation of the head and neck during eye movements
Reticulospinal: control of breathing and emotional motor function
Rubrospinal: innervates LMNs of upper limb
