Basic Neuroanatomy 11

Question 1

Where are afferent sensory fibres from skin and muscle present in the somatomotor pathway ?

Answer 1

• Cell bodies in dorsal root ganglia
• Enter SC via dorsal roots
• Terminate in grey matter of dorsal horn

Question 2

Where are the efferent ( motor ) fibres present in the somatomotor pathway ?

Answer 2

• Cell body in grey matter of ventral horn
• Exit via ventral root
• Terminate in skeletal muscle

Question 3

where are the afferent (sensory ) fibres from internal organs in the visceromtor pathway ?

Answer 3

• Cell bodies in dorsal root ganglia
• Enter SC via dorsal roots
• Terminate in grey matter of dorsal ( posterior ) horn ( deeper)

Question 4

Where are the efferent (motor) fibres in the visceromotor pathway ?

Answer 4

• Preganglionic cell body in grey matter of lateral horn
• Exit via ventral root
• Terminate in autonomic ganglion

Question 5

What forms a spinal nerve ?

Answer 5

Dorsal and ventral roots merge laterally to form spinal nerves

Question 6

What are spinal nerves composed of ?

Answer 6

Majority are mixed nerves - composed of sensory and motor fibres

Question 7

How many pairs total are there of nerves in the spinal cord ?

Answer 7

31 Pairs of nerves total

Question 8

What are the different 31 pairs of nerves In the spinal cord ?

Answer 8

cervical - 8 pairs
Thoracic - 12 pairs
lumbar - 5 pairs
Sacral - 5 pairs
One pair of coccygeal nerves

Question 9

Where do nerves exit in spinal cord ? what nerve is an exception ?

Answer 9

Nerves exit from below corresponding vertebra except for cervical nerves

Question 10

How many cervical vertebrae are there ?

Answer 10

Only 7

Question 11

Whats it called when the segments of the brain stem are further away from the brain ?

Answer 11

Caudal

Question 12

What it called when the segments of the brain stem are closer to the brain ?

Answer 12

Rostal is closer

Question 13

What are the 3 connective tissue layers around axons ?

Answer 13

ENDONEURIUM =
- Around individual axons
- Loose, delicate layer

PERINEURIUM =
- Encloses bundle for axons

EPINEURIUM =
- Dense tissue layer enclosing a number of bundles

Question 14

What are the 4 layers of protection of the CNS ?

Answer 14

Bony outer casing = skull/spinal vertebral column.
Membranes = meninges
Hydraulic buffer = cerebrospinal fluid (CSF)
Foreign agents = Blood-brain barrier (BBB)

Question 15

Where do nerves enter and exit the CNS ?

Answer 15

via foramen in the skull or between spinal vertebrae

Question 16

In human where doesn’t the spinal cord segments and the vertebrae align ?

Answer 16

Does not align at lower thoracic and more caudal regions

Question 17

What is the cauda equina ?

Answer 17

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

Question 18

Whats the name of the three membranes that cover the CNS ?

Answer 18

OUTMOST LAYER - Dura mater
MIDDLE LAYER - Arachnoid mater
INNERMOST LAYER - Pia mater

Question 19

What are the properties of the DURA MATER ?

Answer 19

• PROTECTIVE - strong, inelastic, prevent abrasion
• Highly vascularised and innervated.

Question 20

Whats the properties of the DURA MATER in the head and spinal cord - how are they different ?

Answer 20

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

Question 21

Whats the subdural space ?

Answer 21

Very thin and contains interstitial fluid

Question 22

What are the properties of the arachnoid mater and where is it found ?

Answer 22

• Below dura mater , above Pia mater
• loose fit
• Avascular
• Delicate, looks like a spiders web - strands connect to Pia mater - help support CNS

Question 23

What is the subarachnoid space and what does it contain ?

Answer 23

Its between the arachnoid and the Pia mater and contains cerebrospinal fluid

Question 24

What is the functions of the cerebrospinal fluid ?

Answer 24

• Shock absorber
• Suspension system for cns

Question 25

Whats the Pia Mater and functions ?

Answer 25

• Thin layer of connective tissue (thicker in SC) - clings tightly to CNS
• Contains small plexuses of blood vessels - supply oxygen and nutrients to CNS

Question 26

Whats meningitis ?

Answer 26

Bacterial/viral infection causing inflammation of meninges

Question 27

Where is 70 percent of cerebrospinal fluid produced ?

Answer 27

Produced by choroid plexuses in walls and roofs of ventricles.

Question 28

What produces the blood- CSF barrier ?

Answer 28

Capillaries covered by ependymal with tight junctions - filter blood plasma then secrete CSF

Question 29

What is CSF composed of ?

Answer 29

Composed of glucose and various ions

Question 30

Where is the cerebrospinal fluid present In the brain ?

Answer 30

• Inside ventricles and surrounding subarachnoid space and CNS

Question 31

Whats the function of the microtubules In brain ?

Answer 31

produces a pulsatile movement of CSF

Question 32

Whats the 2 functions of the cerebrospinal fluid ?

Answer 32

• gives the brain buoyancy
• Provides nutrition and removes waste products

Question 33

Whats the pathway of the CSF fluid in the brain ?

Answer 33

Ventricles – Cisterna magna – arachnoud villi — venous sinuses

Question 34

Whats is arachnid villi and where is it present ?

Answer 34

Projections of arachnoid mater through the dura mater and into venous sinuses

Question 35

Explain why the arachnoid villi is one way valve ?

Answer 35

Due to imbalance of pressure and so can only go out of the arachnoid villi and into the venous sinuses

Question 36

what occurs in the venous sinuses ?

Answer 36

Valveless channels supplied by brains venous system - ultimately drain into internal jugular veins

Question 37

What is hydrocephalus ?

Answer 37

Is where there is excessive CSF due to overproduction, block of flow between ventricles - obstructed drainage into circulatory system

Question 38

What does hydrocephalus cause to the Brain ?

Answer 38

Causes increased intracranial pressure within CNS ( dilation of ventricles ) which can cause permanent damage