Week 2- Central Nervous System Flashcards
What is the CNS composed of?
The brain and spinal chord
What is the PNS composed of?
The nerves (cranial and spinal) and ganglia
What are the different parts of the brain and what do they comprise of?
Forebrain: Cerebral hemispheres and diencephalon
Midbrain
Hindbrain: Pons, medulla and cerebellum
What does the frontal lobe do?
Motor function, language, cognitive skills
What does the parietal lobe do?
Sensation, spatial orientation, self perception
What does the temporal lobe do?
Processing auditory information
What does the occipital lobe do?
Processing visual information
What does the limbic lobe contain?
Amygdala, hippocampus, mammillary body and cingulate gurus
What does the Limbic lobe do?
Learning, memory, emotion, motivation, reward
Where is the insular cortex?
Deep in the lateral fissure
What does the insular cortex do?
Visceral sensation, autonomic control, interception, auditory processing
What are the 3 layers of the meninges?
Dura, arachnoid and pia mater
Describe the dura mater
2 layers, periosteal, and meningeal
Describe the arachnoid mater
Thin, transparent, fibrous membrane
Describe the pia mater
Thin, translucent and mesh like
Where is the CSF produced?
The choroid plexus of lateral, 3rd and 4th ventricles
Where can CSF be found?
The ventricular system and sub arachnoid space
What reabsorbs the CSF?
Arachnoid villi (granulations) into superior sagittal sinus
What are the characteristics of CSF
Lower pH, less glucose, protein and potassium than plasma
What are the different types of nerves in the spinal chord?
Cervical (8 pairs), thoracic (12 pairs), lumbar nerves (5 pairs), sacral nerves ( 5 pairs), coccygeal nerve
How do the nerves emerge?
Through intervertebral foramina
Which nerves emerge above the vertebrae?
C1- C7
Eg C3 comes out between C2 and C3
Which nerves emerge below the vertebrae?
C8- Co1
What is cervical enlargement?
Large at C5 due to larger amount of info going out to upper limbs than coming in from upper limbs
What is lumbar enlargement
For innervation of lower limbs
What is the major pathway for voluntary movement?
The corticospinal tract, composed of upper motor neuron in primary motor cortex and lower motor neurons in brainstem and spinal chord
What are the pathways for sensation?
Dorsal column pathway and spinothalamic tract
What is the dorsal column pathway for?
Fine touch, vibration and proprioception from the skin and joints
What is the spinothalamic pathway for?
Pain, temperature from skin
How many descending tracts are there?
2, motor and sensory
What is decussation?
The crossing of fibres from one hemisphere to the other side of the body (85% of corticospinal tract)
What is the corticobulbar tract
A group of cranial nerves
What is somatotopy?
When a region of the body is represented by an area of the brain, occurs as fibres descend
Describe the dorsal column pathway (ascending)
- Fibres enter via the dorsal horn and enter ascending column pathways
- Info from lower limbs- travel ipsilaterally along gracile tract
Info from upper limbs- travel ipsilaterally along cuneate tract
- First synapse is the gracile nucleus or cuneate nucleus
- 2nd order axons decussate in the caudal medulla
- They form the contralateral medial lemniscus tract
- Synapse again in thalamus
- 3rd order neurons project to somatosensory cortex
Describe the spinothalamic (anterolateral) pathway [ascending]
Pain and temperature ascend along LATERAL spinothalamic tract, crude touch ascends within the ANTERIOR spinothalamic tract
Primary afferent axons terminate upon entering the pathway in dorsal horn
Secondary decussate immediately, forming the spinothalamic tract and terminate in the thalamus
Tertiary project from the thalamus to the somatosensory cortex
