Anatomy: Nerves Flashcards
What is a group of nerve cell bodies in the CNS called?
A nucleus
What is a group of nerve cell bodies in the PNS called?
A ganglion
What is an axon?
A nerve fibre conveying action potentials
What are bundles of axons travelling together in a) the CNS and b) the PNS called?
a) A tract
b) A peripheral nerve
What is a myelin sheath?
A cover round the nerve which is an electrical insulator. A myelinated nerve conducts faster
What happens at a synapse?
one neurone communicates with another neurone in a ganglion in the PNS or in a nucleus in the CNS. electrical signal (AP) becomes a chemical signal (neurotransmitter) then an electrical signal again
What are the folds in the brain called?
Gyri (single gryus)
What are the spaces in between the gyri called?
Sulci (plural sulcus)
What is the cerebral neocortex/cortex?
the outermost layer of the cerebral hemispheres, consisting of all the gyri and sulci
How many lobes does each cerbral hemisphere consist of?
4
How are the 4 lobes of each cerebral hemisphere named?
approximately according to the bone of the cranial vault they lie deep to: Frontal lobe Parietal lobe Occipital lobe Temporal lobe
What fissure separates the two lobes of the brain sagitally?
The longutidinal fissure
Name the 12 cranial nerves
- CN I the olfactory nerve
- CN II the optic nerve
- CN III the oculomotor nerve
- CN IV the trochlear nerve
- CN V the trigeminal nerve
- CN VI the abducent nerve
- CN VII the facial nerve
- CN VIII the vestibulocochlear nerve
- CN IX the glossopharyngeal nerve
- CN X the vagus nerve
- CN XI the spinal accessory nerve
- CN XII the hypoglossal nerve
What are the indents in the floor of the cranium called?
The anterior, middle and posterior cranial fossae
Name the foraminae for the cranial nerves
Cribriform plate of the ethmoid bone Optic canal Superior orbital fissure Foramen rotundum Foramen ovale Internal acoustic meatus Jugular foramen Hypoglossal canal Foramen magnum
What type of matter is in the cerebral cortex of the brain?
Grey matter- contains cell bodies
What type of matter is deep to the grey matter?
What gives it this appearance?
White matter
It contains many axons which are myelinated
Myelin gives the whiter appearance
What is different about the structure in the spinal cord in terms of the matter?
The white matter is superficial and the grey matter is deep
How does the spinal cord connect with the brain?
It passes through the foramen magnum of the occipital bone
Where does the spinal cord lie?
In The vertebral canal
What are the 4 segments of the spinal cord?
cervical
thoracic
lumbar
sacral/coccygeal
What are the two enlargements (wider parts) of the spinal cord?
cervical enlargement due to all the upper limb nerves
lumbosacral enlargement due to all the lower limb nerves
How many pairs of spinal nerves does the spinal cord connect bilaterally with?
31
Where does the spinal cord end as a solid structure?
At the conus medullaris
At the level of L1/L2 intervertebral disc
What is the cauda equina?
lumbar and sacral spinal nerve ROOTS have to descend in the vertebral canal to their respective intervertebral foraminae
How many pairs of cervical spinal nerves are there?
8
How many pairs of thoracic spinal nerves are there?
12
How many pairs of lumbar spinal nerves are there?
5
How many pairs of sacral spinal nerves are there?
5
How many pairs of coccygeal spinal nerves are there?
1
What is the spinal nerve?
the part that is located within the intervertebral foramen BELOW* the vertebra of the same number (*except cervical region)
What connects the spinal cord to the spinal nerves?
The roots and rootlets
What connects the spinal nerve to the structures of the soma?
The rami
What is a dermatome of a spinal nerve?
the dermatome of the spinal nerve is the area of skin (strip) supplied by both the anterior and the posterior rami
What do the posterior rami supply?
the posterior paramedian strip of the dermatome
What do the anterior rami supply?
the larger anterior rami supply the remainder of the posterior part, the lateral and the anterior parts of the dermatome and ALL of the limb dermatomes (there are no posterior rami in limb dermatomes)