1.5.3 Spinal Cord Lab Intro Flashcards
Where does decussation occur in the DC/ML system?
The axon of the DCN (2nd order neuron) decussates and enters the medial lemnisci
Decussation of medial lemnisci
Which sensory modalities are carried by the AL System? Type of fibers?
Pain and Temp; Small diameter myelinated and unmyelinated fibers
How many neurons are in the DC/ML pathway? What are their names and location?
3 neuron pathway
First order (DRG) neuron: found in the dorsal root ganglia
Second order (DCN) neuron: found in the dorsal column - either gracile or cuneate nuclei
Third order (VPL) neuron: found in the ventro-postero-lateral nucleus of thalamus
What are two neurons located in the arm and leg pathways of the spinocerebellar pathway?
Definition: bundle of axons in the CNS
Tract (also called a fasciculus)
What type of deficits will be seen if a lesion affects the corticospinal system? If the lesion occurs ROSTRAL to the decussation, where will these deficits be seen? If the lesion occurs CAUDAL to the decussation, where will the deficits be seen?
Weakness and paralysis of voluntary movements
Rostral to decussation: Contralateral deficits
Caudal to decussation: Ipsilateral deficits
What is role of the cerebellum regarding movement?
Coordination
What are the three major long tracts or long pathways that carry motor and sensory info?
Motor: Corticospinal system
Sensory: DC/ML (touch) System and AL (spinothalamic) System
What are the two main components of the dosal column?
What is the role of the dorsal spinocerebellar tract?
Carries unconscious proprioceptive (muscle spindle) info from body to the ispilateral cerebellum
What are the names of the corticospinal tract at these different levels of the CNS: forebrain, midbrain, pons, medulla, and spinal cord?
Forebrain: Part of posterior limb of internal capsule
Midbrain: Part of cerebral peduncle (cerebral crus)
Pons: Corticospinal fibers
Medulla: Pyramids
Spinal Cord: Lateral corticospinal tract
What type of deficits are seen with a lesion of the DC/ML system?
Touch, proprioception, vibration
Where does the axon of the DRG in the DC/ML system project to from the leg? Alternatively, where does the axon of the DRG in the DC/ML system project to from the arm?
Leg: Nucleus gracilis - located more medial
Arm: Nucleus cuneate - located more laterally
The gracilis and cuneate nuclei make up the DCN (dorsal column nuclei)
How many neurons are in the AL pathway? What are their names and locations?
3 neuron pathway
First order (DRG) neuron: cell body in dorsal root ganglion
Second order (dorsal horn- substantia gelatinosa) neuron: dorsal horn decusses in anterior white commisure
Third order (VPL) neuron: VPL of thalamus
Id their location within the spinal cord and features
What is the somatotopy of the AL system? Where are the dorsal horn cells, anterior white commisure, and anterolateral tract located?
Describe the anatomic/somatotopic organization of the corticospinal system
What are some terms used to describe where an axon synapses?
Project to; Terminate
Where does decussation occur in the corticospinal system?
In the pyramids near the junction b/t the cervical cord and medulla (Pyramidal decussation)
Which sensory modalites are carried by the DC/ML system? What type of fibers?
Vibration, proprioception (joint poistion and movement), discriminative touch
Large-diameter, myelinated fibers
Name the covered parts
Definition: cross from one side of the brain to the other
Decussate
What is the somatotropic organization of the DC/ML system at each level of the pathway?
How many neurons are in the corticospinal system? And, where are they located?
2 neuron pathway
Cortical motoneuron (upper motoneuron) - found in the motor cortex
Alpha motoneuron (lower motoneuron) - found in ventral horn of spinal cord
What is the anatomical/somatotopic distribution of the DC/ML system?
