CNS Flashcards
What does the limbic lobe/system consist of?
→ amygdala,
→ hippocampus,
→ mamillary body,
→ cingulate gyrus
What is the limbic lobe concerned with?
Concerned with learning, memory, emotion, motivation and reward
Where is the insular cortex/lobe found?
Deep within the lateral fissure
What is the insular cortex/lobe?
Concerned with visceral sensations, autonomic control, and interoception, auditory processing, visual-vestibular integration
How many pairs of nerves originate from the spinal chord?
31
What are the 5 different classes of nerves in the spinal chord? Superior to inferior?
→ cervical → thoracic → lumbar → sacral → coccygeal
How many pairs of cervical nerves?
8
How many thoracic pairs of nerves?
12
How many lumbar pairs of nerves?
5
How many sacral pairs of nerves?
5
How many coccygeal pairs of nerves?
1
Where do these nerves emerge from?
intervertebral foramina
What nerves emerge from above the vertebrae?
C1-C7
What nerves emerge from below the vertebrae?
C8-Co1
Where down the spinal chord is there enlargement?
→ cervical enlargement from C3-T1
→ lumbar enlargement from L1 to S2
Why does the spinal chord have certain areas of enlargement?
innervation of the upper + lower limbs
What is the major descending pathway responsible for voluntary movement?
Corticospinal tract
What are the major ascending pathways for sensation?
Dorsal column pathway + spinothalamic tract
What is the corticospinal tract composed of?
→ upper motor neurones in primary motor cortex
→ lower motor neurones in brainstem (going to head + neck muscles) + spinal cord (going to muscles of trunk + limbs)
What kind of sensation is the dorsal column pathway responsible for?
fine touch, vibration, pressure and proprioception (position) from the skin and joints
What kind of sensation is the spinothalamic tract responsible for?
pain, temperature (and crude touch) from the skin
What is the main difference between the lateral and ventral spinothalamic tracts?
Lateral = paint + temperature Ventral = crude touch
How are the lateral + anterior/ventral corticospinal tracts formed?
→ Approx. 85% of fibres decussate in medulla to form the lateral corticospinal tract
→ rest of the 15% of fibres continue down + form anterior/ ventral corticospinal tract
What does the lateral corticospinal tract usually control?
Voluntary movement in limbs + digits.
What does the lateral corticospinal tract usually control?
Voluntary movement in trunk, shoulder + neck muscles
Where does the anterior corticospinal tract decussate?
Doesn’t, stays ipsilateral but decusrates at the level of the spinal nerve at which each pair exits.
What is the Corticobulbulbar tract?
Pathway from the Primary motor cortex to the muscles of the face.
What does the corticobulbar tract consist of?
upper motor neurons of the cranial nerves
What does the corticobulbar tract do?
→ controls muscles of face, head + neck, terminates on motor neurons within brainstem motor nuclei.
→ directly innervates the nuclei for cranial nerves V, VII, IX, and XII
Does the corticobulbar tract decussate?
50% of corticobulbar tract would decussate, above each relevant nuclei
Name 4 other brainstem motor tracts.
→ Vestibulospinal
→ Tectospinal
→ Reticulospinal
→ Rubrospinal
What does the vestibulospinal tract do?
provides information about head movement + position and mediates postural adjustments
What does the Tectospinal tract do?
orientation of the head neck during eye movements
What does the reticulospinal tract do?
controls breathingand emotional motor function
What does the rubrospinal tract do?
innervates lower motor neurones of the upper limb
How do nerve fibres enter the dorsal column pathway?
Via the dorsal horn
What 2 tracts can the dorsal column pathway be divided into?
→ gracile tract (most medial)
→ cuneate tract (more lateral)
What information is conveyed ipsilaterally through the gracile tract?
Info from lower limbs + body below T6
What information is conveyed ipsilaterally through the cuneate tract?
Info from upper limbs + body above T6
Where does the dorsal column pathway first synapse?
In the medulla
Where are the 2nd order axons of the dorsal column pathway? Do they decussate?
Through the medulla, decussate in the caudal medulla to form the contralateral medial lemniscus tract
What is the contralateral medial lemniscus tract?
Tract formed after the dorsal column pathway decussates in the caudal medulla
Where are the 2nd synapses of the dorsal column pathway?
In the thalamus
Where are the 3rd order axons of the dorsal column pathway?
Project from thalamus to somatosensory cortex
What is the size of each somatotopic area in the Somatosensory cortex proportional to?
Density of sensory receptors in that body region
Where are the 1st synapses of the spinothalamic tracts?
In the dorsal horn upon entering the spinal chord
Where do the spinothalamic tracts decussate?
2nd order neurones decussate immediately when entering the spinal chord to form the spinothalamic tract
Where are the 2nd synapses of the spinothalamic tracts?
in the thalamus
Where are the 3rd order axons of the spinothalamic tracts?
projects to the somatosensory cortex from the thalamus
