Intro To PNS Flashcards
What is the sympathetic division of the autonomic nervous system driven by?
The hypothalamus to regulate involuntary functions in the skin and viscera
What is Group A of the peripheral nerves?
I to III or alpha, beta, delta and gamma fibers
Largest and fastest. Up to 20 micrometers
Ex: motor nerves, fusimotor nerves, propioceptive, pressure, touch, temperature and pain fibers
What are Group B peripheral nerves?
Up to 3 micrometers in diameters
Ex: myelinated pre-ganglionic autonomic fibers
What are group C peripheral fibers?
Up to 2 micrometers
Ex: unmyelinted post-ganglionic autonomic, touch and pain fibers
What are the 12 cranial nerves?
- Olfactory
- Optic
- Oculomotor
- Trochlear
- Trigéminal
- Abducent/abducens
- Facial
- Vestibulocochlear/auditory
- Glossopharyngeal
- Vagus
- Spinal accessory
- Hypo gloss all
What are the cranial nerves covered in as they emerge from the foramina or fissures of the skull?
Tubular sheaths derived from the meninges
Where do most cranial nerves emerge from except for cn 4?
Ventral aspect of the brain
What is the sulcus límitans?
The part that turns into the central canal in the embryo
What is the precursor to white matter?
Outer marginal layer
What is the precursor for gray matter
Inner mantle layer
What do the outer and inner marginal zone develop into?
Outer turns into alar plate
Inner turns into basal plate
What does the basal lamina develop into?
Into somatic motor efferent cells (GSE)
What does the alar lamina contain?
Cells that will develop into somatic sensory afferent cells (GSA)
After the basal and alar lamina develop, a group of new cells starts to develop around the sulcus limitans. What will this new group turn into?
General visceral afferents (GVA)
General visceral efferent (GVE)
Another cell type develops between the somatic and GVE/GVA to serve the branchial/pharyngeal apparatus. What will this cell develop into?
Into special visceral afferents (SVA) and special visceral efferent (SVE)
What s the special group of cells that serves the eye and ear?
Special somatic afferent (SSA)
What functional nerve groups are specific to the cranial nerves?
Special somatic afferent (SSA)
Special visceral afferent (SVA)
Special visceral efferent (SVE)
GSA, GSE, GVA and GVE are nerve fibers in all the PNS. What are their functions?
GSA: transmit general sensation from the body to the CNS
GSE: transmite motor impulses from CNS to Body
GVA: transmit sensation from viscera to CNS
GVE (autonomic): transmite secreto motor impulses to smooth muscle, cardiac muscle and glands
What are the function of the nerves fibers only found in cranial nerves?
SSA: convert sensation of vision, hearing/balance to CNS
SVA: convey smell ad taste sensation to the CNS
SVE: transmit motor impulses to muscles of the head and neck
How can you tell if a nerve is traveling to the CNS or away from the CNS?
Afferent: Ascend to CNS
Efferent: Exit CNS
Each spinal nerve contains sensory fibers with cell bodies in what location?
Dorsal root ganglion (GSA and GVA)
Each spinal nerve contains motor fibers with cell bodies in which locations?
Lamina IX (GSE)
Lateral horn = Lamina VII (GVE)
How are c1 to c11 connected to the sympathetic chain via which kind of fibers?
White rammus commicans with pre-ganglionic fibers
After c1-c11 synapse in the spinal ganglion, what kind of fibers are carried and to what location?
Post ganglionic (unmyelinated) to vessels for vasoconstriction, to sweet glands (sudomotor) and to the erector pilorum muscle of hair follicle
What do the dorsal rami innervates?
The integumentum and intrinsic back muscles
What do ventral rami give rise to?
Limb plexuses
E.g. Brachial, sacral
What is the neurovascular plane?
The space between the internal and innermost intercostal muscles where the spinal nerve branches and vessels that supply them are located
What is a reflex and which is the simplest one?
An automatic response mediated by the nervous system
Spinal reflex
What kind of reflex is the spinal reflex?
Monosynaptic.( two nerves and one synapse)
What are some examples of monosynaptic reflexes?
Ankle, knee, biceps and triceps
What does diminution of a reflex indicate?
Disruption of the reflex arc or muscle defect (Lower motor neuron lesion, LMNL)
What does exaggeration of a reflex indicate?
Supra-spinal component is disturbed (UMNL)
What kind of effect does supra-spinal control have on stretch reflex?
Produces a calming influence on the stretch reflex via the anterior horn cells of the spinal cord (alpha motor neuron)
What are some examples of multi-synaptic reflexes?
Abdominal, plantar and anal reflexes
What is the Beevor’s sign?in
The absence of abdominal wall contraction when the skin over the abdomen is lightly stroked
Where can Beevor’s sign be seen?
In parlegics which indicates UMNL
When is the dermatome concept applicable?
A. Low SPINAL anesthesia
B. Herpes zoster
What are the dermatomes of the Cervical nerves?
C1: no skin (both terror and posterior rami supply muscles, e.g. The suboccipital nerve)
C4: from clavicle to angle of Louis
C7: middle finger (thumb is C6, and pinky by C8)
What are the dermatome levels of the Thoracic nerves?
T4: nipple
T7:epigastrium
T10:umbilicus
What are the dermatome levels of the Lumbar and Sacral nerves?
L1:groin/supra-pubic/penis/anterior scrotum - Labium majus/upper buttock
S1: ankle/lateral side of dorsi mark of foot
S3: sitting areas of buttock/posterior scrotum - labium majus
S4: perianal skin
What is the extensor of the arm innervated by?
C7 & c8
How do the moto neurons (ANS) run from their nuclei to muscle?
Rum from the motor nuclei of cranial nerves or anterior horn cells of the spinal cord uninterruptedly to the motor end plate of skeletal muscle
What system is involved in the fight/flight response and the freeze/dissociate response?
ANS