Neural Devel.
Starting with Pro, Mes, and Rhomb name the general structures they develop into
Pro = Tel and Die
Mes = mesencephalon
Rhomb = metencephalon and myelencephalon
Using the Lloyd Hunt Classification, name the sensory fiber types, and their main function
Bonus: List them from fastest to slowest
Type I: fastest; Proprioception
Type II: fast; discriminatory touch
Type III and IV: Slower; pain + temp
Describe the gate theory and matrix theory (Lydia needs help - I don't understand)
Gate theory: non-painful signals (carried by large fibers type II) override the painful signals (carried by small fibers type III & IV) and "close the gate" so painful signal is not transmitted to the brain
Neuromatrix theory: pain experience can be "generated" by neurons in the brain. Pain experience is influenced by genetics, past experiences, emotions, etc
Describe the difference between an UMN and a LMN and how injuries would present
UMN: comes from higher brain centers and synapses on a LMN. Symptoms of Injury: disuse atrophy, hypertonicity, hyperreflexia, spasticity, clonus, spastic paralysis
LMN: Leaves CNS to synapse on muscle (alpha motor neuron) Injury: atrophy, arreflexia, and atonia
If the midbrain is damaged above the red nucleus what posture would you see and how does it present?
Decorticate: Flexed arms, fists, arms bent inwards. Legs extended and feet plantar flexed
What day does neuralation occur on and what structures does it form
Day 19
Neural crest, neural tube, outer/surface ectoderm
Using the Erlanger-Gasser system name the motor fiber types and the structure they're associated with
A-alpha: (fastest). extrafusal muscle spindles
A-gamma: (fast): Intrafusal muscle spindles
B and C: (slower): Preganglionic (B) and Postganglionic (C)
Describe the Dorsal column (medial Leminiscus) pathway and name the function
Dorsal Rook ganglion
Ascends ipsilaterally through the fasciculus gracilis or cuneatus
Goes to nucleus gracilis or nucleus cuneatus
Travels to medulla and crosses
After crossing it is the Medial Leminiscus
Travels to the VPL of the thalamus
Goes to primary somatosensory cortex
Pyramidal vs Extrapyramidal
Pyramidal: directly innervates motor neurons of the spinal cord or brainstem (ventral horn cells or certain cranial nerve nuclei) for voluntary movement. primary excitation units of the mammalian prefrontal cortex and the corticospinal tract
Extrapyramidal: centers on the modulation and regulation (indirect control) of anterior (ventral) horn cells. Primarily involved in involuntary and automatic control of muscles such as posture, balance, and locomotion. Originate from brainstem nuclei and influence motor neurons via interneurons in the spinal cord
What reflex is associated with GTOs?
Autogenic inhibition: Occurs when a muscle experiences high tension, triggering golgi tendon organs to send inhibitory signals to the spinal cord. These signals inhibit the alpha motor neuron that activate the same muscle, causing it to relax
Name the 2 divisions of rami and what part of the body it provides motor & sensory to
Epaxial (dorsal rami) - innervation of the posterior/back skin; develops into the spinal extensors
Hypaxial (ventral rami)- innervation of the anterolateral trunk; develops into spinal flexor, shoulder, trunk, hip, and limb musculature
What is the difference between receptor classification and qualities
THEN, name the 5 classifications and the 4 Qualities (can give definitions if your heart desires for learning purposes)
Classification: based on modality of stimulation: mechanoreceptors, thermoreceptors, photoreceptors, chemoreceptors, and pain receptors
Qualities: Modality, Intensity, Location Duration (MILD)
Describe the pathway of the Spinothalamic Pathway and its function
Pain & Temp
Dorsal Root Ganglion
Can go up or down 1-2 segments in Lissauer's tract
Synapses in dorsal horn
Crosses through anterior white commissure
Ascends to the VPL of the thalamus
Primary somatosensory cortex
In the lateral corticospinal tract, if there was an injury to the R medullary pyramids (after crossing) where would we see deficits?
Lose voluntary motor control Ipsilaterally (R side of body) at that level and below
Describe the differences between short and long propriospinal interneurons
Short: Span 1-2 segements and connect adjacent spinal segements. Short fibers are located closer to the gray. Coordinate local reflexes and segmental motor control. Support withdrawal reflexes and fine-tuned segmental activity.
Long: Axons span multiple segments (e.g. cervical to lumbar). Connect distant spinal segments. Coordinate interlimb movement, posture, and locomotion. Support whole-body coordination like walking or joint reaching. Lesions may disrupt gait, balance, and multi-joint movement
Name the 2 major placodes and what they develop into
For Fun: what do the somites differentiate into?
Adenohypophyseal: anterior lobe pituitary
Otic: cochlea, vestibular and auditory ganglion, vestibular system (saccule; utricle; semicircular canal)
For fun answer: dermis, skeletal muscle, cartilage, tendon, ribs, and vertebrae
First Classification: General or Special
Second Classification: Visceral or Somatic
Third Classification: Afferent or Efferent
Describe the pathway of the Spinocerebellar Tract and its function
Bonus: which spinocerebellar tract crosses twice?
Bonus Bonus: describe the tract after it reaches the cerebellum that Chris won't give us the name to
Unconscious proprioception
Dorsal Root Ganglion
Clarke's nucleus
Ascends ipsilaterally
Inferior cerebellar peduncle to cerebellum
Mystery Chris pathway: leaves cerebellum, crosses via superior cerebellar peduncle, goes to the thalamus, goes to motor cortex
The ventral tract crosses twice
Describe the pathway of the lateral Corticospinal tract and its function
Bonus: briefly describe anterior corticospinal tract
Precentral gyrus (motor cortex)
Posterior limb of internal capsule
Cerebral peduncle (midbrain)
Pyramids of pons and medulla
Crosses in lower closed medulla
lateral funiculus in spinal cord
Ventral horn -> LMN -> muscle
Anterior tract: follows the same path except it stays ipsilateral (doesn't cross). Most synapse on interneurons
Describe the 5 components of the Spinal Reflex Arc
Receptor: receive noxious stimulus (Hot)
Afferent signal: sensory neuron
Integration center: interneuron
Efferent signal: alpha motor neuron
Effectors: move fingers away from noxious stimulus
Pre-otic: associated with CNs 3, 4, 6 & contributes to dev of eye musculature
Post-otic: associated with CNs 11, 12 & contirbutes to dev of axial muscles in neck & laryngoglossal muscles (tongue, mouth, larynx)
Mesenchymal- associated with the spinal cord & develops into dermatomes, myotomes, & sclerotomes
Name the 3 different muscle spindles and then state their function and primary sensory and motor fiber type :)
Dynamic Bag: respond to rapid change. Sensory fibers: Ia and some II. Motor Fibers: dynamic gamma motorneurons
Static Bag: Respond to slow, steady changes in length; can increase the sensitivity (gain) of stretch reflex. Sensory fibers: Ia and some II. Motor fibers: static gamma motorneurons and A-beta motorneurons
Chain: Respond to slow, steady changes in length; can increase the sensitivity (gain) of stretch reflex. Sensory Fibers: significant group II, some Ia. Motor fibers: static gamma motorneurons
Spinotectal: coordinates reflexive responses to painful stimuli (turning head to source of pain)
Spinomesencephalic: modulates pain perception via activating descending pain inhibition pathways. (periaquaductal gray area :) )
Spinoreticular: Modulates arousal, attention, and emotional aspects of pain
Anterior spinothalamic: Crude touch and firm pressure
Besides the corticospinal tract, name the 3 other pathways and state their basic function
Rubrospinal: (in red nucleus) facilitates flexor tone and inhibits extensor tone in upper limbs
Vestibulospinal: medial stabilized head and neck during movement. Lateral facilitates extensor muscles for balance
Reticulospinal: Medial (pontine): facilitates extensor tone and posture and provides anticipatory postural adjustments. Lateral (medullary): inhibits extensor muscle tone and modulates spinal reflex excitability
Describe Recurrent Inhibition
A feedback mechanism where a motor neuron activates an inhibitory interneuron (Renshaw cell), which then inhibits the same motor neuron and its neighbor
Creates a negative feedback loop that helps to regulate motor neuron activity, prevents over excitation, refines motor output, and maintains motor control precision