Basic Neuroanatomy 11 Flashcards
Where are afferent sensory fibres from skin and muscle present in the somatomotor pathway ?
- Cell bodies in dorsal root ganglia
- Enter SC via dorsal roots
- Terminate in grey matter of dorsal horn
Where are the efferent ( motor ) fibres present in the somatomotor pathway ?
- Cell body in grey matter of ventral horn
- Exit via ventral root
- Terminate in skeletal muscle
where are the afferent (sensory ) fibres from internal organs in the visceromtor pathway ?
- Cell bodies in dorsal root ganglia
- Enter SC via dorsal roots
- Terminate in grey matter of dorsal ( posterior ) horn ( deeper)
Where are the efferent (motor) fibres in the visceromotor pathway ?
- Preganglionic cell body in grey matter of lateral horn
- Exit via ventral root
- Terminate in autonomic ganglion
What forms a spinal nerve ?
Dorsal and ventral roots merge laterally to form spinal nerves
What are spinal nerves composed of ?
Majority are mixed nerves - composed of sensory and motor fibres
How many pairs total are there of nerves in the spinal cord ?
31 Pairs of nerves total
What are the different 31 pairs of nerves In the spinal cord ?
cervical - 8 pairs
Thoracic - 12 pairs
lumbar - 5 pairs
Sacral - 5 pairs
One pair of coccygeal nerves
Where do nerves exit in spinal cord ? what nerve is an exception ?
Nerves exit from below corresponding vertebra except for cervical nerves
How many cervical vertebrae are there ?
Only 7
Whats it called when the segments of the brain stem are further away from the brain ?
Caudal
What it called when the segments of the brain stem are closer to the brain ?
Rostal is closer
What are the 3 connective tissue layers around axons ?
ENDONEURIUM =
- Around individual axons
- Loose, delicate layer
PERINEURIUM =
- Encloses bundle for axons
EPINEURIUM =
- Dense tissue layer enclosing a number of bundles
What are the 4 layers of protection of the CNS ?
Bony outer casing = skull/spinal vertebral column.
Membranes = meninges
Hydraulic buffer = cerebrospinal fluid (CSF)
Foreign agents = Blood-brain barrier (BBB)
Where do nerves enter and exit the CNS ?
via foramen in the skull or between spinal vertebrae
In human where doesn’t the spinal cord segments and the vertebrae align ?
Does not align at lower thoracic and more caudal regions
What is the cauda equina ?
in the lumbar and the sacral end the spinal nerves themselves has to project in a caudal direction before they actually exit out between the vertebrae, this generates the cauda esquina
Whats the name of the three membranes that cover the CNS ?
OUTMOST LAYER - Dura mater
MIDDLE LAYER - Arachnoid mater
INNERMOST LAYER - Pia mater
What are the properties of the DURA MATER ?
- PROTECTIVE - strong, inelastic, prevent abrasion
- Highly vascularised and innervated.
Whats the properties of the DURA MATER in the head and spinal cord - how are they different ?
IN HEAD -
- Double layer
- Attaches to inside of skull
- Normally no epidural space between dura and skull
IN SPINAL CORD -
- Single NOT double layer
- epidural space above containing venous plexuses
Whats the subdural space ?
Very thin and contains interstitial fluid
What are the properties of the arachnoid mater and where is it found ?
- Below dura mater , above Pia mater
- loose fit
- Avascular
- Delicate, looks like a spiders web - strands connect to Pia mater - help support CNS
What is the subarachnoid space and what does it contain ?
Its between the arachnoid and the Pia mater and contains cerebrospinal fluid
What is the functions of the cerebrospinal fluid ?
- Shock absorber
- Suspension system for cns
Whats the Pia Mater and functions ?
- Thin layer of connective tissue (thicker in SC) - clings tightly to CNS
- Contains small plexuses of blood vessels - supply oxygen and nutrients to CNS
Whats meningitis ?
Bacterial/viral infection causing inflammation of meninges
Where is 70 percent of cerebrospinal fluid produced ?
Produced by choroid plexuses in walls and roofs of ventricles.
What produces the blood- CSF barrier ?
Capillaries covered by ependymal with tight junctions - filter blood plasma then secrete CSF
What is CSF composed of ?
Composed of glucose and various ions
Where is the cerebrospinal fluid present In the brain ?
- Inside ventricles and surrounding subarachnoid space and CNS
Whats the function of the microtubules In brain ?
produces a pulsatile movement of CSF
Whats the 2 functions of the cerebrospinal fluid ?
- gives the brain buoyancy
- Provides nutrition and removes waste products
Whats the pathway of the CSF fluid in the brain ?
Ventricles – Cisterna magna – arachnoud villi — venous sinuses
Whats is arachnid villi and where is it present ?
Projections of arachnoid mater through the dura mater and into venous sinuses
Explain why the arachnoid villi is one way valve ?
Due to imbalance of pressure and so can only go out of the arachnoid villi and into the venous sinuses
what occurs in the venous sinuses ?
Valveless channels supplied by brains venous system - ultimately drain into internal jugular veins
What is hydrocephalus ?
Is where there is excessive CSF due to overproduction, block of flow between ventricles - obstructed drainage into circulatory system
What does hydrocephalus cause to the Brain ?
Causes increased intracranial pressure within CNS ( dilation of ventricles ) which can cause permanent damage
