Peripheral Nervous System Flashcards
3 Components of PNS
- Cranial Nerves
- Spinal Nerves
- Ganglia
Where is gray matter in the PNS?
in the ganglia
(dorsal root and autonomic)
Where is white matter in the PNS?
in cranial and spinal nerves
What makes a nerve an organ?
it contains different types of tissue
nervous tissue wrapped in layers of of connective tissue and containing blood vessels lined with epithelial tissue
Schwann cells
- cells that surround PNS axons and myelinate them
mixed nerves
nerves containing both sensory and motor axons
nerve fiber
a long axon
nerve
a collection of nerve fibers (axons) bundled into fascicles, all surrounded by epineurium (tough fibrous CT sheath)
Cranial Nerves
- 12 nerves numbered I-XII (rostral to caudal)
- attach to brain, pass through foramina of skull and innervate head and neck structures (except vagus)
- contain both sensory and motor nerve fibers
Which cranial nerves attach to the forebrain?
I (Olfactory) and II (Optic)
Which cranial nerves attach to the brain stem?
III-XII (all but optic and olfactory)
Sensory Neurons of Cranial Nerves
- cell bodies within receptor organs (nose, eye, tongue)
- cranial sensory ganglia along some cranial nerves external to brain
Motor Neurons of Cranial Nerves
- cell bodies in nuclei of brain stem
cranial nerve classification
- Sensory
- Motor
- Mixed
Cranial Nerve I
Olfactory Nerve
- Sensory nerve of smell
structures on inferior side of frontal lobes supported by cribriform plate of ethmoid bone which leads to nerve filaments that sense smell
bundles of axons connecting olfactory bulbs to brain
olfactory tracts
Cranial Nerve II
Optic Nerve
- sensory nerve of vision
crossing of highlighted structures
optic chiasm
- crossing of optic nerves directly inferior to the hypothalamus
2
optic tract
- continuation of optic nerve from optic chiasm to the thalamus
Cranial Nerve III
Oculomotor Nerve
- motor neurons
- innervates 4 extrinsic eye muscles
Cranial Nerve IV
Trochlear Nerve
- motor nerve
- innervates one extrinsic eye muscle (superior oblique)
Cranial Nerve V
Trigeminal Nerve
- mixed nerve
- sensory innervation to face, chewing muscles
Cranial Nerve VI
Abducens Nerve
- motor nerve
- abducts the eyeball (via lateral rectus muscle)
Cranial Nerve VII
Facial Nerve
- mixed nerve
- innervates facial muscles for expression
- sensory innervation for taste
Cranial Nerve VIII
Vestibulocochlear Nerve
- sensory nerve for hearing and balance
Cranial Nerve IX
Glossopharyngeal Nerve
- mixed nerve
- sensory innervation to tongue
- motor innervation to pharynx
Cranial Nerve X
Vagus Nerve
- mixed nerve
- sensory and motor innervation for pharynx, larynx and viscera
Cranial Nerve XI
Accessory Nerve
- motor nerve
- accessory part of Vagus nerve
- motor innervation to neck and upper back
Cranial Nerve XII
Hypoglossal Nerve
- motor nerve
- runs inferior to tongue, innervating its muscles
Cranial Nerve Names and #s Mnemonic
Oh, Oh, Oh, To Touch And Feel Very Good Velvet, HA!
- Olfactory
- Optic
- Oculomotor
- Trochlear
- Trigeminal
- Abducens
- Facial
- Vestibulocochlear
- Glossopharyngeal
- Vagus
- Accessory
- Hypoglossal
Mnemonic for Nerve Types of Cranial Nerves I-XII
(Sensory, Motor or Both)
Some Say Marry Money But My Brother Says Big Brains Matter More
Spinal Nerves
31 pairs attaching to SC through dorsal and ventral roots:
8 Cervical (one from above atlas vertebrae)
12 Thoracic
5 Lumbar
5 Sacral
1 Coccygeal
which set of spinal nerves?
Cervical Nerves
- 1st pair superior to atlas
- last pair inferior to C7
which set of spinal nerves?
thoracic nerves
- 12 pairs T1-12
- exit below vertebra of same number
which set spinal nerves?
lumbar nerves
- L1-5
- exit below vertebra of same number
which set of spinal nerves?
sacral nerves
- S1-5
- exit below vertebra of same number
name of most inferior set of nerves pictured
coccygeal nerves
- 1 pair named Co1
Nerve Plexus
- networks of intersecting nerves
- originate from anterior rami of all spinal nerves but T2-T12
cervical plexus
- anterior rami of C1-4
- innervate skin/muscles of neck and diaphragm
- Phrenic Nerve
brachial plexus
- C5 through T1
- innervates skin and muscles of arms
- Axillary, Radial, Median and Ulnar Nerves
lumbar plexus
- L1 - L4
- innervates anterior/medial thigh and skin of medial leg
Femoral and Obturator Nerves
the grouping of nerves shown here
sacral plexus
- L4, L5 and S1-S4
- innervates most of lower limbs
- Sciatic Nerve
the small yellow nodules lined up parallel to the spine here
paravertebral ganglia
- AKA sympathetic trunk/chain
- on both sides of vertebral column from neck to pelvis
- joined to ventral rami of spinal nerves by rami communicantes
- bundles of neuron bodies of the sympathetic nervous system
