Nervous system structure Flashcards
What brain axes is in the direction of the nose?
Rostral
What brain axes is pointing to the top of the head?
Dorsal
What brain axes is pointing to the back of the neck in the brain stem?
dorsal
What are the middle and sides of the brain called?
Medial and lateral
How man cranial nerves are there?
12
What is the PNS?
The 12 cranial and 31 spinal nerves that come out at each vertebrae
How do the dorsal and ventral parts of the spinal cord differ in the information they carry?
Dorsal is afferent
Ventral is efferent
What are the two tracts of the afferent PNS and how do they differ?
Spinothalamic and dorsal column
The spinothalamic tract carries pin prick, temperature, and light touch sensations
The dorsal column tract carries two-point sensitivity, vibration, and propioception
What are the two parts of the autonomic nervous system and how do they differ?
Sympathetic and parasympathetic
Sympathetic have nerves coming all over the spinal cord and ganglia are near vertabrae
Parasympathetic = all nerves come from either the top (brain stem) or the bottom (S2-4) and ganglia are found near target organ
How does the CNS develop?
From a neural tube it expands and folds to form the brain.
What is the grey matter in the brain stem?
cell bodies
What is the white matter in the brain stem?
Myelinated axons
Where is the dorsal column tract in the spinal cord and what parts is it made up of?
It is in the dorsal, medial part of the spinal cord and is made up of the Cuneate and Gracile
Where is the spinothalamic tract in the spinal cord?
It is in the front (ventral) half of the spinal cord.
Where do the two afferent PNS tracts cross?
The dorsal column tract crosses at the brain stem while the spinothalamic tract crosses immediately after entering through the dorsal horn and stays on the other side until reaching the brain.
In general nerves in the back tends to cross higher in the brainstem
What is the PNS tract containing the motor neurons called?
Corticospinal tract
Where is the corticospinal tract and where does it cross?
95% of the motor fibers travel in the lateral spinal tract.
They cross in the brain stem and travel out through the ventral root after passing through the spinal column.
The other 5% are in the anterior corticospinal tract and these are in the ventral side and cross over in the spinal cord
What is the purpose of the anterior corticospinal tract?
It acts as a safety net to retain some amount of movement in case of damage to the lateral corticospinal tract
What happens if I stab someone in the right side of the spinal cord?
The right Gracile and Cunaete are damaged, so they feel no two-point sensitivity, vibrations, or propioception in the right side of the body.
The right spinothalamic tract is affected so they feel no pinprick pain or temperature (light touch is a bit mixed) on the left side of their body
Also the lateral corticospinal tract on the right is damaged so movement on the right side of the body is impaired (but not totally because of the anterior corticospinal tract on the left)
What are the 3 sections of the brainstem?
Midbrain
Pons
Medulla
What are the 3 things contained by the brainstem?
Grey matter is organised as 12 nuclei (one for each nerve)
White matter has the same tracts in the spinal cord going up and down
The reticular formation