Spinal Cord 2 Flashcards
Where do cervical spinal nerves exit?
Above their vertebra
How many spiral nerves are there? Be specific.
31 pairs
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
Where do thoracic and lower spinal nerves exit?
Below their vertebrae
What are the 2 spinal cord enlargements and where are they?
Why are these areas enlarged?
- Cervical: C4-T1
- Lumbar: L2-S3
Increased neuronal density create the enlargements. They supply the upper and lower limbs/perineum via the brachial and lumbosacral plexuses.
Where does the spinal cord bluntly terminate and what is this structure called?
It terminates at L2 and its called the conus medullaris
What is the area of the spinal cord below the conus medullaris? And what is the structure that descends with it? Where does it anchor?
Cauda equina
The filum terminale (thin filament of pia mater off the surface of the spinal cord) descends with the CE. It anchors to the coccyx.
What are the 3 layers that surround the brain and spinal cord?
3 meninges: dura mater, arachnoid and pia mater
Where is the epidural space and what does it contain?
It is superficial to the dura mater. It contains fat and venous anastomoses.
What is the arachnoid space filled with? What else lies in this layer?
CSF
Also, superficial arteries and veins of the spinal cord.
What forms the denticulate ligament? What is its function?
The pia mater extends off of the lateral edges of the spinal cord and attaches to the dura.
It functions to fix the spinal cord in place.
What ligaments run vertically along the tips of the spinous processes and which ones run in between the bases?
Supraspinous ligaments
Interspinous ligaments
Which ligaments run between the transverse processes? Which ones extend between lamina (on a cross section)?
Intertransverse ligaments
Ligamentum flava
Where do the rootlets emanate from?
Lateral sulci
Which root is considered the inflow pathway to the CNS? Outflow pathway?
Afferent stimuli is carried to the CNS via the posterior/dorsal root and the sensory ganglion. Efferent stimuli is carried from the CNS via the anterior/ventral root.
How do you define the true spinal nerve?
When the dorsal and ventral roots combine and exit thru the intervertebral foramen and before it splits into post/ant rami.
The __________ rami remains segmented throughout the length of the spinal cord. It innervates _____________.
Posterior
The skin, muscles and vasculature of the back
The __________ rami may either be segmental or anastomose throughout the length of the spinal cord. It innervates ______________.
Anterior
Muscles and blood vessels of lateral and anterior body wall of the abdomen
The ____________ rami is capable of forming plexuses.
Anterior
Describe the vasculature of the spinal cord. How many arteries? Where? Where do they arise from? What do they supply?
On the posterior side, there are two posterior spinal arteries that lie over the posterior intermediate sulci. These arteries arise from the posterior inferior cerebellum arteries (off the vertebral a.). They supply the posterior 1/3 of the spinal cord.
On the anterior side,nthe anterior spinal artery lies over the anterior median fissure. It arises from the vertebral artery. It supplies the anterior 2/3.
What does the anterior/ventral ramus innervate?
It innervates the blood vessels and muscles of the anterior and lateral abdominal wall.
What does the posterior ramus innervate?
The blood vessels, skin and muscles of the back.
Which branches off the post./ant. rami are responsible for distributing the cutaneous innervation?
The lateral and anterior cutaneous branches from the anterior ramus, coupled with the branches of the dorsal rami, innervate a dermatome.
What is a dermatome?
A band of skin/muscles and blood vessels of the body wall.
Where is the first point where a nerve becomes mixed?
At the true spinal nerve when the dorsal and ventral roots combine.
What vertebral levels exhibit typical (segmental) spinal nerve?
T2-T12
Describe a typical spinal nerve.
One whose ventral rami do not form a plexus and remained segmental
For complete cutaneous sensory loss, how many spinal nerves would have to be lesioned? Why?
3 because there is some overlap (collateral branches) from each spinal nerve into the dermatome above and below it.
Describe the modality of the ventral and dorsal roots.
Dorsal-sensory and postganglionic
Ventral- motor and preganglionic
How does the structural organization between the motor/sensory and ANS differ?
Motor/sensory: utilize single neuron to link CNS and effector organ in PNS
ANS: utilizes 2 neurons
What does the PNS contain to facilitate the difference between somatic and ANS systems?
The PNS contains ANS ganglia as a site of synapse between the two neurons.
