Spinal Cord and PNS Flashcards
4 Functions of the Spinal Cord
- Sensory from PNS to brain
- Motor from brain to PNS
- Reflexes
- Modifying ascend/descending information
Term: Connective tissue that connects end of cord to coccyx, places tension on the spinal cord in flexion
Filum terminale
Term: L2-S5 nerve roots
Cauda equina
Term: L1-L2 intervertebral space
End of Spinal Cord
Spinal Nerves (all in pairs)
- Total
- Cervical
- Thoracic
- Lumbar
- Sacral
- Coccygeal
- 31
- 8
- 12
- 5
- 5
- 1
Describe the location of spinal nerve in relation to vertebral bodies
C1-C7 exit ABOVE their corresponding vertebra
C8 exits BELOW C7 vertebra
All others exit BELOW their corresponding vertebra
Describe why the cord is thicker or enlarged at the C&L-spine
Due to nerve plexuses - need to fit in all the MU for innervation of the extremities
Defn: Dorsal root ganglia
Sensory neuron cell bodies
Term: Nerve roots extening from end of spinal cord
Cauda Equina
Location: Spinal nerves exit
Intervertebral space
Location: Dorsal rootlets enter
Posterolateral sulcus (form dorsal root)
Location: Ventral rootlets exit
Anterolateral sulcus (form ventral root)
Structure: Formed by dorsal and ventral root
Spinal Nerve
Type of Matter: in the spinal cord is arranged in horns
Gray matter
Type of Matter: In the spinal cord is arranged in columns
White matter
Term: Pathways to the brain
Tract cells
2 Types of LMN
- Alpha (primary) - innervate mm
- Gamma - innervate spindle fibers, detect quick stretch and maintain appropriate length
Type of Matter:
- Sensory
- Contains endings of sensory neurons
- Interneurons
- Cell bodies of tract cells
Gray matter - Dorsal horn
Type of Matter:
- From T1-L2
- Cell bodies of preganglionic sympathetic neurons
Gray matter - Lateral horn
Type of Matter:
- Motor
- Cell bodies of LMN
Gray matter - Ventral horn
Type of Matter:
- Sensory tracts
- Discrimative touch
- Conscious proprioception
White matter - Dorsal column
Type of Matter:
- Sensory tracts
- Motor tracts
White matter - Lateral column
Type of Matter:
- Motor tracts
- Postural regulation
White matter - Anterior column
2 Regions within the Dorsal Column
- Fasciculus Gracilis (LE)
- Fasciculus Cuneatus (UE)
Structure:
- Indicates that you are in the C-spine
- Separates Fasciculus Gracilis and Cuneatus
Posterior Intermediate Sulcus
5 Changes in the Spinal Cord as you DESCEND
- Decrease in white matter
- MORE sensory info as you move UP, motor info descends LESS pathways needed lower down - Overall size decreases
- No posterior intermediate sulcus below T2
- Lateral horn from T1-L2
- Anterior horn larger at C&L plexuses
Term: All structures enclosed in bone, brain and spinal cord
CNS
Term: All neural structures distal to spinal nerves, sensory axons, motor/autonomic neurons, cranial nerves
PNS
Term: Carries sensory information to spinal cord
Afferent Axon
Term: Carries sensory infromation from spinal cord
Efferent Axon
Term: Group of mm innervated by a single spinal nerve
Myotome
Term: Dermis innervated by a single spinal nerve
Dermatome
Signs and Symptoms of CNS Injury
Motor/Sensory/Autonomic deficits will be in a myotomal/dermatomal distribution
Will still receive some input/output from surrounding spinal levels
Signs and Symptoms of PNS Injury
Motor/sensory deficits will be in a peripheral nerve distribution
5 Periphery Deficit Signs
- Paresis or paralysis
- Sensory loss
- Abnormal sensation
- Muscle atrophy
- Reduced/absent DTR
Type of Neuron:
- Axons that descend from cerebral cortex or brain stem
- 1st pathway
- Completely within CNS
Upper Motor Neuron
Type of Neuron:
- Cell body in brain stem or ventral horn
- Axon leaves CNS
- Synapses in PNS (on mm)
- 2nd pathway
Lower Motor Neuron
4 Clinical Signs of UMN Injury
- Paresis (not complete loss or paralysis - mutliple levels coming down)
- Spasticity
- Hypertonia
- Hyperreflexia
5 UMN Diseases
- Stroke
- SCI
- PD
- TBI
- MS
4 Clinical Signs of LMN Injury
- Loss of reflexes or Hyporeflexia
- Atrophy
- Flaccid paralysis
- Fibrillations/Fasciculations
4 LMN Diseases
- Stroke
- Polio
- Peripheral nerve injury
- Guillian Barre Syndrome
Disease that affects both UMN and LMN
Amyotrophic Lateral Sclerosis (ALS)
Term: 10 histologic regions of spinal gray matter
Rexed’s Laminae
Function: Substantia Gelatinosa (LII)
Process pain information
Function: Nucleus Proprius (LIII&IV)
Processes conscious proprioception and discriminative touch
Function: Nucleus Dorsalis or Clark’s Column (LVII)
Relays unconscious proprioceptive information to cerebellum
Rexed Laminae: Processes pain information
Substantia Gelatinosa (LII)
Rexed Laminae: Processes conscious proprioception and discriminative touch
Nucleus Proprius (LIII&IV)
Rexed Laminae: Relays unconscious proprioceptive infromation to cerebellum
Nucleus Dorsalis or Clark’s Column (LVII)
Term: Involuntary sterotyped response to a sensory input
Reflex
Term: Reflex that does not involve interneurons
Stretch Reflex
2 parts of a Reflex Arc or Monosynaptic Reflex
- Quick stretch stimulates Ia afferent in mm spindle
- Ia afferent synapses in SC with alpha motor neuron located in dorsal horn
2 Ways the Reflex Arc is Modulated
- Interneurons
- UMN
Pathway Function: Dorsal Column Pathway (White)
F: Discriminative touch and conscious proprioception
2 Columns in White Matter that are Sensory Pathways
- Dorsal Column
- Lateral Column
Pathway Function and End Point: Spinothalamic Pathway (White)
F: Conscious pain and temperature
EP: Thalamus
Pathway Function and End Point: Spinoreticular Pathway (White)
F: Alerting/Arousal; Unconscious Pain
EP: Reticular Area
Pathway Function and End Point: Spinocerebellar Pathway (White)
F: Unconscious Proprioception
EP: Cerebellum
3 Lateral Column Sensory Pathways (White)
- Spinothalamic
- Spinoreticular
- Spinocerebellar
2 Columns in White Matter that are Motor Pathways
- Anterior Column
- Lateral Column
Pathway Function: Lateral Corticospinal Pathway (White)
Primary motor ouput: voluntary movement and fine motor control
MOST CROSS
Pathway Function: Medial Corticospinal Pathway (White)
Same function as Lateral Corticospinal pathway HOWEVER only makes up 10% of total corticospinal pathways
DO NOT CROSS
Pathway Function: Rubrospinal Pathway (White)
Gross motor movements under voluntary control
Location: Where rubrospinal pathway begins
Red Nucleus of Brainstem
Pathway Function: Reticulospinal Pathway (White)
Trunk movements and postural control
Pathway Function: Vestibulospinal Pathway (White)
Trunk movements and postural control
Pathway Function: Tectospinal Pathway (White)
Refelxive movement of head