Pain Exam 2-S4 Flashcards
How many vertebrae in the human spine?
33
How many Cervical vertebrae?
7 cervical
How many Thoracic vertebrae?
12 thoracic
How many Lumbar vertebrae?
5 lumbar
How many Sacral vertebrae?
5 fused sacral
How many coccygeal vertebrae?
4 fused coccygeal
Which vertebrae are fused?
Sacral and Coccygeal
Where is the end of the spinal cord?
What is it called?
L1- end of spinal cord
Conus medullaris
Afferent nerves are located _____ and function as what?
Dorsal
Somatosensory
Efferent nerves are located ____ and function as what?
Ventral
Motor
What are the layers of the spinal cord for an epidural?
Skin
Subcutaneous
Supraspinous
Interspinous
Ligamentum Flavum
Epidural space
Meningeal layer order?
1
2
3
Outer- Dura mater
Middle- Arachnoid mater
Inner- Pia mater
CSF is contained between what 2?
Arachnoid and Pia mater
Subdural space is between what 2?
Dura and Arachnoid mater
The single Anterior Artery, which is the sole source of blood supply to the anterior cord lies where?
Pia mater
The 2 posterior spinal arteries originate from what?
Cerebellar arteries
Located at Sides of spinal cord
The Artery of Adamkiewicz which supplies the lower 2/3rd of the spinal cord originates from ____ and is usually on ____ side?
Aorta
Left side
C8 dermatome?
Little finger
T4 dermatome?
Nipple
T6 dermatome?
Xiphoid process
T10 dermatome?
Umbilicus
S2-S4 dermatome?
Sacral
L2-L3 dermatome?
Knee
A-alpha fibers are for what?
Motor and Proprioception
A-beta fibers are for what?
Touch, pressure, small motor
A-gamma fibers are for what?
Touch and pressure
A-delta fibers are for what?
Sharp pain, heat and cold
These fibers are myelinated
- autonomic fibers
- Preganglionic SNS
- Small
- Easiest to block with locals
B-fibers
These fibers are unmyelinated
- Postganglionic sympathetic fibers
- small, slow
- Dull pain, temperature, touch
C-fibers
What is the site of action for neuraxial blockade?
Bathing the nerve root
What is the order of nerve fiber blockade?
B-fiber (autonomic)- 1st
C-fiber (slow pain)
A-delta (pin prick/cold sensation)
A-beta (touch)
A-alpha (motor)- Most resistant
Which nerve fibers are blocked first?
B-fibers
autonomic
Which nerve fibers are blocked last?
A-alpha
large myelinated, motor
This system
- Thoracolumbar
- Controls vascular tone
- Exits spinal cord T1-L2
- Blockade of cardiac accelerator fibers cause vagal response
- level of block is 2-3 dermatomes above sensory level?
Sympathetic nervous system
(SNS)
This system
- Craniosacral
- Exits cranium
- Postganglionic fibers found in target organs
- Nerve fibers located outside of the subarachnoid space.
- Rarely affected by spinal or epidural block
Parasympathetic nervous system
(PNS)
The physiologic response to neuraxial blockade result from what 2 things?
Decreased sympathetic tone
Unopposed parasympathetic tone
This blockade results in sympathetic blockade that may be 2 segments higher than the sensory block which in turn is 2 segments higher than the motor blockade?
Differential blockade
This blockade involves thoracolumbar outflow at T1-L2, blockade decreases sympathetic tone and involves small, myelinated B fibers?
Autonomic blockade
Vasomotor tone is determined by sympathetic fibers arising from___ which innervate what?
T5-L1
Arterial and venous smooth muscle
A high sympathetic blocks the ______ that arise at T1-T4?
Cardiac accelerator fibers
Cardiac accelerator fibers arise from where?
T1-T4
SNS blockade at T5-L1 affects what?
Vasomotor tone
SNS blockade at T1-T4 affects what?
Cardiac accelerator fibers
The diaphragm is innervated by ___ nerve and located at ___?
Phrenic nerve
C3-C5
What are the 2 absolute contraindications to neuraxial anesthesia?
Patient refusal
Lack of consent