CNS Flashcards
(88 cards)
What gives rise to higher complexity and higher computing functions
The number of folds, not the size of the brain
The number of neurons in the cortex
Morphology is strictly correlated with function.
Describe the communication of the CNS with the outside world
somatic and special senses
Describe the communication of the CNS within the organism
visceral sensation,
involuntary movement,
somatic movement,
higher cognitive functions
What is meant by an effector
Effectors are target organs whose response change according to neural commands.
What is meant by a receptor
Sensory structures that detect changes in the internal and external environment.
What does dorsal and ventral mean in the brain
Dorsal- superior
Ventral- inferior
What does rostral and caudal mean in the brain
Rostral- towards frontal lobe
Caudal- towards the spinal cord.
What is the spinal cord enclosed in
The spinal cord is enclosed and protected by the vertebral column.
What does the vertebral column permit
Movement
Describe the location of the spinal cord
The spinal cord occupies the vertebral canal within the vertebral column and is continuous rostrally with the medulla oblongata. The cord is approximately cylindrical and arranges segmentally with a central cellular area (grey mater) surrounded by nerve-fibre tracts (white mater). The tracts carry information between different levels of the spinal cord (thereby permitting reflex reactions) and also to and from supraspinal structures.
Where are the horns found
Within the grey mater
Describe the structure of the spinal cord
▪ The spinal cord is a column of neural tissue which is segmental.
▪ Each segment has a pair of spinal nerves attached to it.
▪ The core consists of grey matter (mainly neuronal soma).
▪ There is a wrapping around of the white matter (contains axons).
▪ The grey matter is then divided into sensory and motor areas.
Where do the dorsal and ventral roots join to form spinal nerves
Near to the intervertebral foramen where spinal nerves exit the vertebral canal.
Describe the intervertebral foramina
Along the sides of the vertebral column, you have a series of holes called intervertebral foramina (with each of these foramina having a spinal nerve coming from them).
Where does the spinal cord end
▪ The spinal cord is MUCH SHORTER than the vertebral column. o This is because the spinal cord finishes growing earlier in development compared to the vertebral column.
The spinal cord terminates at the level of the intervertebral disc between L1/L2 in adults
What is the consequence of the spinal cord being shorter than the vertebral column
A lumbar puncture can be inserted into the subarachnoid space below this level to take a sample of the CSF without damaging the spinal cord.
o LPs are usually taken between L3 and L4.
The area with no spinal cord is called the lumbar cistern.
What exists below the termination of the spinal cord
The area with no spinal cord but a flurry of nerves is also called the Cauda Equina.
The Cauda Equina are descendents of the lumbar and sacral nerve roots.
What are the different levels of the vertebral column
▪ Cervical – C1-C7 → 7 vertebrae.
▪ Thoracic – T1-T12 → 12 vertebrae.
▪ Lumbar – L1-L5 → 5 vertebrae.
▪ Sacral – S1-S5 → 5 vertebrae (varies)
What does each spinal cord segment innervate
A particular skin area (dermatome) and muscle area (myotome)
Why does white mater appear white
Due to the myelination of the axons
Where are the two enlargements of the spinal cord found
The diameter of the spinal cord is not the same along its length.
The spinal cord has two enlargements- the cervical (C3-T1) and lumbar (L1-S3)- which provide innervation to the upper and lower limbs respectively
Describe the structure of the grey mater of the spinal cord
Cells in the central grey mater can be divided into a series of layers in the dorsal horn and as a series of columns in the ventral horn. These layers and columns are known as Rexed’s laminae (numbered I-X) and are based on groupings of similarly shaped bodies
Dorsal Horn
Ventral Horn
Intermediolateral column
Describe the dorsal horn of the grey mater
The dorsal horn layers are involved in sensory pathways and are the target sites for some sensory afferent nerves, particularly for pain, temperature and crude touch.
Describe the ventral horn of the grey mater
The ventral horn columns are made up of pools of motor neuron innervating skeletal muscle. Medial motor neurons supply proximal muscles, and lateral motor neurons supply distal muscles.