Spinal Cord/Spinal Nerves Flashcards
Most common nerve compressed in herniated IV disc?
L5
Inferior extend of dura-arachnoid sac
SV2
Inferior extent of spinal cord
LV2
Location of internal vertebral plexus
Epidural space
Epidural anesthesia
Injection of anesthetic agent into epidural space, between lamina of L3-L4 or at sacral hiatus
Spinal anesthesia
Injection of anesthesia into the subarachnoid space; done via lumbar puncture
Lumbar puncture
insertion of a needle into the subarachnoid space of the lumbar cistern to remove CSF or deposit anesthesia; the needle should be inserted above or below the spinous process of LV4, the needle will pierce a number of structures, but should “pop” through the ligamentum flavum and enter the subarachnoid space by piercing the DURA and ARACHNOID mater
Order for lumbar puncture
skin, subcutaneous tissue, supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space containing the internal vertebral venous plexus, dura, arachnoid, and finally the subarachnoid space
Spinal cord consists of how many pairs of nerves?
31
How many cervical nerve pairs
8
What is composed of cervical nerve pairs
Brachial plexus
C3, C4, C5
Keeps the diaphragm alive -> phrenic nerve
How many thoracic nerve pairs?
12
How many lumbar nerve pairs?
5
How many sacral nerve pairs?
5
How many coccygeal nerve pairs?
1
When does spinal cord end?
L1-L2
Conus medullaris indicates
Tapering of spinal cord
Lumbar and sacral nerves descend in…
Dural sac
What are the lumbar and sacral nerves bathed in
CSF
What are the spinal meninges
Dura, arachnoid, pia mater
Dura mater is known as
Tough mother
Why did they name arachnoid space “arachnoid”
Looks like a spider web, middle layer
What are specialized pia mater called?
Filum terminale and denticulate ligaments
When can you not do an epidural?
When someone has a fresh back tattoo
Potential spaces
Epidural and subdural -> fills with BLOOD, AIR, etc
What mater contains CSF, blood vessels, and connective tissue?
Arachnoid mater
If mistake is made during lumbar puncture, what can happen?
Herniation of brain! Increased pressure
Blood supply of spinal cord
Vertebral artery, segmental spinal arteries
Venous drainage of spinal cord
Intervertebral veins, spinal veins, BATSON’S PLEXUS
Valveless, intercommunicates
What cancer is most commonly spread to vertebrae?
Prostate cancer
SAME DAVE
Sensory afferent, motor efferent
Dorsal afferent, ventral efferent
Facet joint disease
Dorsal rami destruction, ablation will cause dorsal rami to emit numbness, but NO PAIN
Compromise of segmental arteries can result in
Spinal cord infarcts
Prolonged or forceful turning of head can result in
Bow Hunter Syndrome -> compromise blood flow through the vertebral artery, resulting in dizziness, fainting or brainstem hypoperfusion syndromes
If we cut posterior root…
sensory loss, reflex loss
If we cut anterior root…
motor loss, reflex loss
Spinal nerve cut
ALL OF THEM
Posterior ramus cut…
Deep back muscles
Anterior ramus cut…
Shoulder/arm dermatome
Cutaneous nerve cut…
Sensory loss
GSA gives rise to
Muscle spindles and Golgi tendon organs
Herpes zoster
Viral infection of posterior root (or cranial nerve ganglia): characterized by vesicular outbreaks in a dermatomal pattern, corresponding to the territory of the infected ganglion
C5 Nerve Testing
Strength -> deltoid, biceps brachii
MSR - biceps brachii
Key sensory area - lateral shoulder and lateral arm
C6 Nerve Root Testing
Strength - biceps brachii, wrist extension
MSR - brachioradialis
Key sensory area - lateral foramen, lateral palm including first digit and possibly secondary digit
C7 Nerve Root Testing
Strength - triceps brachii, wrist flexion, and finger extension
MSR - triceps brachii
Key sensory area - middle finger
C8 Nerve Root testing
Strength - finger flexion
MSR - triceps brachii
Key sensory area - fifth digit and medial forearm
T1 Nerve Root Testing
Strength - finger adduction/abduction
MSR - none
Key sensory area - medial arm
L4 Nerve Root Testing
Strength - tibialis anterior, quadriceps
MSR - patellar tendon
Key sensory area - medial leg, medial aspect of foot including medial malleolus
L5 Nerve Root Testing
Strength - extensor hallicus longus, extensor digitorum longus, walk on heels
MSR - tibilias posterior
Key sensory area - dorsum of foot
S1 Nerve Root Testing
Strength - fibularis longus; walk on toes
MSR - calcaneal (Achilles) tendon
Key sensory area - lateral aspect of foot
Radiculopathy
Injury/compression of single spinal cord level
Common causes of radiculopathy
Disc herniations, spinal stenosis, osteophyte formation and tumors (Schwannoma, metastasis)
Sensory loss restricted to
Dermatomes
Motor loss (weakness, decreased reflexes)
Myotomes
When injury to distal nerve root occurs…
Distributed to the nerve root, NOT THE DERMATOMES or MYOTOMES
What is more common: sensory loss first or motor loss first?
Sensory loss
Reflex Man
Biceps, brachioradialis, triceps, patellar, Achilles/calcaneal
Cauda equina syndrome
Impairment of multiple spinal nerve roots below L1 or L2, typically unilateral
Common causes: disc herniations, tumor, abscesses
Signs/symptoms of cauda equina syndrome
Sensory loss in dermatomal pattern (saddle anesthesia), myotomal weakness, incontinence and erectile dysfunction