Topic 4: PNS "Road Maps" Flashcards
The SC is the nervous tissue link between the ________
The brain and the rest of the body
It has 31 segments: __ cervical, ___ thoracic, ___ lumbar, ___, ___ sacral segments and __ coccygeal
8 cervial, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
How many roots does each segment of the spinal cord connect to?
4.
Ventral root and Dorsal root (a pair on each half)
What is each root made up of?
1-8 rootlets, which consist of bundle of nerve fibres
What is another aka for mixed nerves?
Spinal nerves
T/F: Ventral (anterior) root contains axons that carry afferent signals from the spinal cord to effectors (muscles and viscera)
False. They carry efferent signals
What lies in the dorsal root, close to the junction of the ventral root?
A dorsal root ganglion (spinal ganglion), a swelling that contains the cell bodies of 1st order neurons aka unipolar aka primary afferent (these attach to receptors)
The spinal nerve splits into two primary divisions:
- The Dorsal rami: supply the posterior body trunk & back of the head
- The Ventral rami: supply the lateral and anterior trunk and the upper and lower extremities
T/F: The dorsal and ventral rami are mixed nerves because they are branches of the spinal root
False.
The dorsal and ventral rami are mixed nerves because they are branches of the spinal NERVE
T/F: The dorsal rami supply the posterior body trunk & back of the head including the intrinsic back muscles - sacrospinalis, deep paraspinals aka transversospinalis, splenius capitis and crevices, & the sub occipital muscle
True
T/F: All dorsal primary rami travel anteriorly b/w the TVPs and most are mixed nerves.
False.
Dorsal primary rami travel posteriorly
Remember: Dorsal = posterior
The sensory distribution of dorsal primary rami appear in regular segmental bands except for …
when they become clunial nerves of the buttocks (small nerves in the butt)
T/F: The intercostal nerves and the ventral rami are different structures
False. They are the same structures
Nerve plexuses are formed when
The axons in the ventral rami that serve the upper and lower extremities mix and mingle with each other to form nerve networks called plexuses
Post plexus is an aka for ___
Peripheral nerves i.e those serving the upper and lower extremities, usually contain fibres from more than one spinal nerve
A muscle getting innervation from multiple spinal nerves can retain some function if one spinal nerve is damaged at the spinal cord location. What does this mean?
If you have damage in one section of the brain, you may not lose function in the other
T/F: Only ventral rami form plexuses
True.
In the lower cervical and upper thoracic region, ventral rami form _______
Brachial plexuses
In the lumbar and sacral regions, ventral rami form _____
Lumbosacral plexuses
T/F: The level SC injury is indicated by the highest level that remains intact.
True
What does a C3 lesion (complete or incomplete) mean?
It means that the dermatomes and myotomes associated with C1 to C3 are fully functioning. All those below C3 are affected
What does a L4 lesion mean?
It means that all dermatomes and myotomes located at L4 and above are intact and those below L4 are not.
What makes up the brachial plexus?
The brachial plexus is formed by ventral rami C5-T1 and it supplies the upper limb and the supporting musculature of the scapula
Name the regions of the plexus.
Roots, trunks, divisions and cords
What gives rise to terminal branches aka nerves aka peripheral nerves aka post-plexus nerves.
Cords
Roots of spinal nerves connect to _____
Spinal cord.
4 roots for every segment
The ventral rami of spinal nerves C5-T1 are referred to as _____ of the brachial plexus
Roots
* NOT the same as roots that form the spinal nerves
Roots that form the spinal nerve (mixed) are
Ventral root (efferent) and Dorsal root (afferent) which bifurcate into dorsal and ventral rami(mixed), those from C5-T1 are “roots” of brachial plexus.
The trunks of the brachial plexus pass b/w the _____ and ______ muscles
Anterior and middle scalene.
Trunks go to the tightest muscles because the breathing sucks
T/F: Roots and terminal branches are not a network
True
Name the 5 types of nerves
1) Musculocutaneous nerve
2) Ulnar nerve
3) Median nerve
4) Axillary nerve
5) Radial nerve
Which nerve innervates most of the flexor muscles in the forearm and thenar muscles
Median nerve.
Fluid in thenar muscles indicate (pregnant)
Which nerve is related to motor innervation to deltoid and teres minor?
Axillary nerve
Which nerve innervates the extensor muscles of the elbow, write and fingers & anatomical snuffbox?
Radial nerve. It is also the biggest nerve
Which nerve innervates most of the intrinsic muscles of the hand - a notable exception is the thenar eminence?
Ulnar nerve
Which nerve innervates the muscles in the flexor compartment of the upper arm such as the biceps brachia, coracobrachialis?
Musculocutaneous nerve
Dorsal scapular nerve innervates ____
Rhomboids & levator scap
Long thoracic nerve innervates ____
Serratus anterior
Thorocodorsal nerve innervates ______
Latissimus dorsi (if this is taken out, you could lose an important muscle)
A dermatome is an area of the skin supplied by sensory nerve fibres that originate from _______
A single dorsal nerve root of a single spinal nerve
What is a receptive field?
Responsible of one unipolar neurone, for touch or for pain. Makes dermatome combine receptive field
Dermatomes are not named according to the spinal nerve which supplies them
False. They are
There is no C1 dermatome
True
There is a reduction in sensitivity with loss of afferent nerve function by one spinal nerve.
True
Radioculopathy is suspected when there is loss of sensation in a myotome
False. Its in the dermatome
Radioculopathy aka
nerve root damage
____ is derived from the latin and french words for girdle
Shingles
This is a common name for a disease caused by the virus Herpes zoster, same virus that produces Chicken pox
Shingles
Shingles is most common in what age?
50 and older
What are the s/s of shingles?
Burning, tingling, sensitive skin.
Rash of raised dots develops into painful blisters that last about 2 weeks
Where does shingles occur?
Trunk and buttocks, but can appear anywhere.
Cutaneous nerves are _____ nerves that are response for providing sensory innervation of the skin.
Peripheral nerves
How are cutaneous and spinal nerves different?
Cutaneous nerves can be derived from multiple mingled spinal nerves whereas, dermatomes only specify the area served by the dorsal root of 1 spinal nerve
