Spinal Cord L2 Flashcards
What are the 5 groups of vertebrae/nerves in the spinal cord and how many of each?
Cervical- 8
Thoracic- 12
Lumbar- 5
Sarcal- 5
Coccygeal- 1
Where does the spinal cord itself end?
Lumbar region at L1-L2 at the conus medullaris (lower end of the spinal cord)
What is the basic setup of the spinal cord?
Two roots coming in either side: Dorsal (with a ganglion) and ventral.
Circular, with an anterior median fissure on the front and a posterior median sulcus on the back.
Gray matter is ‘butterfly shaped’, and separated into 3 horns: anterior, posterior and lateral
Central canal is located in the middle of the gray commisure
The white on either side of the gray commisure are called the anterior and posterior white commisure.
Posteriorly, there are 2 pairs of white columns.
The outer pairs are the cuneate fasciculii (Present C1-T8)
The inner pairs are the gracile fasciculii
There are also two anterior spinothalamic tracts and two lateral corticospinal tracts
What is a dermatome?
An area of skin supplied by a single spinal nerve
What are the different types of receptors?
Encapsulated or free nerve ending receptors
What are the types of encapsulated nerve endings and what do they do?
Meissner corpuscles: detect touch sensation
Pacinian corpuscles: detect pressure sensation
What do the free nerve endings detect?
Pain and temperature sensations
Which nerves out of encapsulated or free are myelinated?
The encapsulated ones are myelinated. They conduct their signals at approx. 50m/s-1 while free endings conduct at approx. 1m/s-1
What type of neuron is myelinated in the spinal cord?
Pseudounipolar neurons
What is discriminative vs non-discriminative sensation?
Discriminative means you can accurately determine where two different points of contact are. eg. touch and pressure (encapsulated nerve endings)
Non- discriminative means you can’t- you know a sensation is in an area, rather than a specific location. Eg. temperature. (free)
Meninges
Three membrane layers that cover and protect your brain and spinal cord
Pia Mater
The innermost layer of the meninges. The pial cellular layer firmly adheres to the surface of the spinal cord.
Dura Mater
Dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system.
Cauda Equina
The collection of nerves at the end of the spinal cord.
Where is motor and sensory information carried?
Motor carried forward through ventral root
Sensory carried towards the back through the dorsal root
Cervical enlargement
Area where the information goes to and from the arms
Lumbar enlargement
Area of the spine where the information goes to and from the legs
How does information about touch/pressure reach the spinal cord?
Stimulus applied to skin –> Encapsulated nerve ending receives it –> Forms a generator potential –> Conducted along myelinated axon –> Posterior root –> Cell body in posterior root ganglion –> (Posterior column) posterior gray horn (depending on whether it’s a spinal reflex)
How does information about temperature/pain reach the spinal cord?
Stimulus –> free nerve ending receives it –> generator potential formed –> conducted along unmyelinated axon –> Posterior root –> Posterior root ganglion –> posterior gray horn
Dorsal root ganglion
Bundle of cells bodies in dorsal root
How does the sensory pseudounipolar neuron split?
One end goes to grey matter (synapses with other neurons) and the other to white matter (straight to the brain)
What is convergence and what is its function?
1 sensory neuron picks up information from other neurons and then carries it to the brain. This reduces the spinal cord’s volume as fewer neurons enter the brain.
Where is motor and sensory information carried?
Motor carried forward through the ventral root
Sensory carried towards the back through the dorsal root
Where is white and grey matter located in the spinal cord?
White on the outside, grey on the inside.
Where are opioid receptors located?
Dorsal gray root
Where are cell bodies for upper motor neurons located?
Precentral gyri of the cerebral cortex
Where are cell bodies of lower motor neurons located?
Anterior gray horns of the spinal cord
Touch and pressure (and proprioception) information is sensed in the periphery by a ________, which
__ encapsulated. Information is then carried along a nerve, which __ covered in myelin, with a comparatively ____ conduction velocity of approximately __ m/s. The nerve fibre passes through the _______ root of the spinal nerve and into the spinal cord.
Touch and pressure (and proprioception) information is sensed in the periphery by a
receptor, which is encapsulated. Information is then carried along a nerve, which
is covered in myelin, with a comparatively
fast conduction velocity of approximately
50 m/s. The nerve fibre passes through the
dorsal root of the spinal nerve and into the spinal cord.
Pain and temperature information is sensed in the periphery _____ , which ____ encapsulated. Information is then carried along a nerve, which ___
overed in myelin, with a comparatively ____ conduction velocity of approximately ___ m/s. The nerve fibre passes through the ___ root of the spinal nerve and into the spinal cord.
Pain and temperature information is sensed in the periphery by a free-nerve receptor/free nerve ending, which is not encapsulated. Information is then carried along a nerve, which is not covered in myelin, with a comparatively slow conduction velocity of approximately 1/one m/s. The nerve fibre passes through the dorsal root of the spinal nerve and into the spinal cord.
