Peripheral nervous system Flashcards
Do neurons replicate?
No
What is the center of integration?
The brain
What does the PNS consist of?
Nerves
Ganglia
What are ganglia?
Aggregated of neurons located along the pathway of the PNS
(cluster of cell bodies of neurons)
What are axons packed into nerves based on?
Topographical distribution (PNS)
Their function (CNS)
Are receptors innervated?
Yes as they change energy into a nerve signal
What are the nerves that bring the signal from the PNS to the CNS?
Afferent/sensitive
What are the nerves that bring the signal from the CNS to the PNS?
Efferent/effector
What kind of nerves are most of our nerves?
Mixed
What are mixed nerves?
Nerves that contain both sensitive and motor fibers (both afferent and efferent)
Can nerves have multiple branches?
Yes they can have many “exists” and therefor bring neurons to many points
In resting neuron what happens to sodium?
It is actively pumped out the cell by the sodium potassium pump
What gives the neuron the resting potential of -70?
The active pumping by the sodium potassium pump of the sodium from inside to outside the cell
Is the membrane of a neuron permeable to ions?
No
Are the sodium channels open or closed when the neuron is at rest?
Closed
What happens when a neuron is stimulated?
Sodium channels are opened and sodium rushes inside the neuron
What is the average of the max action potential/spike
+40mV
What happens when the action potential is propagated and reaches the terminal?
Calcium channels are opened and the signal is transmitted between neurons and neurons or effector cells by neurontransmitters being released into the synapses
How do vesicles know when they are at the presynaptic part of the membrane?
They roll along the membrane until they reach the pre-synaptic part which has internal receptors that signal to begin exocytosis
Is axonal trafficking regulated?
Yes highly
2 types of neurotransmitters
Excitatory
Inhibitory
2 types of nerves in the PNS (dependant on origin)
Spinal nerves
Cranial nerves
How many pairs of cranial nerves do we have?
12
How many pairs of spinal nerves do we have?
31
2 functional components of the PNS
Somatic nervous system
Autonomic (visceral) nervous system
Which part of the PNS can we control?
The somatic nervous system
Parts of the autonomic nervous system
Sympathetic
Parasympathetic
(Enteric)
Names of the 3 layers of the meninges
Dura
Arachoid
Pia
How many roots does each spinal nerve originate with?
2
Anterior
Posterior
Where does the fusing of the 2 root of the spinal nerve take place?
Right before the intervertebral foramen
How many of the spinal nerves are mixed?
All of them (no exceptions)
Why do the spinal nerves have 2 roots?
Because they are mixed nerves and the motor and sensory have different origins in the spinal chord
Which fibers belong to the posterior root?
Sensory
Which fibers belong to the anterior root?
Motor
How many pairs of cervical nerves?
8
How many pairs of thoracic nerves?
12
How many pairs of lumbar nerves?
5
How many pairs of sacral nerves?
5
How many pairs of coccigeal nerves?
1
How are the spinal nerve pairs named?
Like vertebrae ex: C1 or S5
Why are there 1 more cervical nerve pair than vertebrae?
Because the first originates above the first vertebrae
What is the collective name for the nerves travelling through the vertebral canal below the spinal chord?
Cauda equina
Where are the cell bodies of sensory neurons contained?
Not in spinal chord but in ganglion located along the dorsal roots of spinal nerves
Where are the ganglion located?
Along the dorsal (posterior) roots of the spinal nerves
Where does the cervical plexus go through?
C1-C5 (part)
Where does the brachial plexus go through?
C5(part)-T1(part)
Where does the Lumbar plexus go through?
L1-L4 (part)
Where does the cervical sacral/pudendal go through?
L4 (part) -S5
2 types of branches of the cervical plexus
Cutaneous and muscular
Name of the 4 cutaneous branches of the cervical plexus
Lesser occipital nerve
Greater auricular nerve
Transverse cervical nerve
Supraclavicular nerve
3 muscular nerves of the cervical plexus
Ansa cervicalis
Phrenic
Segmental branches
Where is the nasa cervicalis found in relation to the jugular vein?
External
Which kind of fibers does the phrenic nerve mainly consist of? (despite being mixed)
Motor nerves
Do intercostal nerve in the thorax form plexuses?
No
What does the sciatic nerve branch into?
Tibial nerve
Common fibular nerve
What does the lumbosacral trunk participate to the formation of?
The sciatic nerve
What kind of nerve is the obturator nerve mainly?
Motor
But sensory for small part of the inner thigh
What kind of nerve is the femoral nerve mainly?
Motor
What is the most important muscle the femoral nerve innervates?
Quadriceps femoris
Where does the inferior gluteal nerve run in relations to the piriform?
In 87% of people anteriorly
Do the 2 components of the sciatic nerve exchange fibres?
No
What do the sensory fibers of the pudendal nerve innervate?
The genitals
What do the motor fibers of the pudendal innervate?
Peritoneal muscles
Which is the major terminal branch of the sciatic nerve?
Tibial nerve
Why is the phrenic nerve important for breathing?
Because it provides exclusive motor vitriol of the diaphragm
What is the phrenic nerve supplied by?
C4 primarily
C3 and C5 contributes
Which plexus is the phrenic nerve a part of?
None but it receives contributions from nerve roots of the cervical and branchial plexus
Which nerves in the brachial plexus makes up the posterior cord?
WHThe Radial nerve and axillary nerve
Which is the biggest nerve of the brachial plexus?
Radial nerve (terminal branch of the posterior cord)
What nerve controls abduction one the arm?
Axillary nerve
Which nerve is an extensor of the upper limb?
The radial nerve
What movement does the muscle-cutaneous nerve contribute to?
Arm and forearm flexion
Where does the median nerve terminate?
In the hand
What movements does the median nerve contribute to?
Flexing and pronation
Which nerve passes in the carpal tunnel?
The median nerve
Which is the major terminal branch of the medial cord?
Ulnar nerve
What nerve controls flexion of the hand?
The ulnar nerve
Which nerve runs within the poses major muscle?
Genitofemoral nerve
Which nerve controls abduction of the lower limb?
Iliohypogastric and ilioinguinal nerves
Which nerve controls adduction of the lower limb?
Obturator nerve
Which nerve controls hip flexion and leg extention?
Femoral nerve
Which devision of the sciatic nerve is the fibular nerve formed by?
The posterior
Which devision of the sciatic nerve is the tibial nerve formed by?
The anterior
Where does the sciatic nerve cross?
The greater ischiadic foramen
What is the major terminal branch of the sacral plexus?
The sciatic nerve
Different name for fibular nerve
Common peroneal nerve (CPN)
Which is the major terminal branch of the sciatic nerve?
The tibial nerve
Which nerve controls abduction (walking) in the lower limb?
Superior gluteal
Which nerve controls extension (climbing stairs) in the lower limb?
Inferior gluteal
Which nerve controls hip extension and knee flexion in the lower limb?
Sciatic nerve
What movement does the tibial nerve control?
Flexion of foot and fingers (toes)
What movement does the fibular nerve control?
Superficial: External foot rotation (pronation)
Deep: extension of foot and fingers (toes)
