| Term | Definition |
| Neuraxial | Brain and Spinal Cord |
| Six Neuraxial* Levels of Motor system | 1. Spinal Cord
2. Brainstem
3. Cerebellum
4. Diencephalon
5. Basal Ganglia
6. Cerebral Cortex |
| Functional Levels of spinal cord (lower level of the Neuraxial | -Simple
-Reflexes
-Regulation of Higher Skilled or Patterned Movements |
| Functional Levels of the upper level of the Neuraxial | -Initiation (deciding to standup), Inhibition (stopping muscles from working) or Facilitation (When running) of Motor Functions that are within your control
-Voluntary Motor Movements |
| Size of the spinal cord | 43.5 cm long (fluctuates with height of person), 1cm in diameter (Average) |
| Five Spinal Segments and nerves | -Cervical (8)
-Thoracic (12)
-Lumbar (5)
-Sacral (5)
-Coccygeal (1-3 b/c some have fused together some have not) |
| Conus Medullaris | -End of Spinal Cord at L2
-Vertebral Column Longer Than Spinal Cord. Spine itself does not travel the length of the vertebral column. |
| Cauda Equina (Horse’s Tail) | -Stretched nerve root fibers from L3 to S5
-After spinal cord nerves will continue through Vertebral Column |
| Filum Terminale | Where Stretched Spinal Cord ends and remnant is attached to Coccyx |
| Lumbosacral Cistern | -Fluid Filled Space for Spinal Puncture (where they do spinal taps and give epidurals) |
| Function of spinal nerves | Carry info from CNS TO PNS
-Is part of the PNS |
| Meninges of the spinal column | Pia mater-Arachnoid mater -Duramater |
| Dentate Ligaments | -Group of Ligaments That Connect Arachnoid and Pia Mater Layers |
| Internal Structure of spinal cord | -White Matter – outer parts of the cord
-Gray Matter Horns and Commissures – the internal sections
-Varies in Shape With Level of Spinal Segment
Dorsal Root and Ventral Root |
| Intervertebral Foramina | Holes on side of vertebrae where nerves exit |
| Make up of Spinal | Made of:
-Dorsal Roots - Sensory Information
-Ventral Roots- Motor Information
-Dorsal and Ventral Rami fuse to make up the Spinal Nerve |
| Dorsal Root Ganglia | House cell bodies for sensory nerves |
| Plexi | -Neural nets in motor pathways that innervate multiple muscles to be excited
-NOT found in T-2 and T-11 |
| Brachial Plexus | -From C5 to T1
-Plexi (Net of nereves) that innervate the shoulder and arm |
| Brachial Plexus palsy | -Usually occurs in children at birth if some kind of complication and child is pulled out of birth canal with force causing this to tear. |
| Lower Motor Neuron | -Path for Efferent Impulses (away from CNS) and start of PNS
-Final common pathway to muscles
-Exit spinal column to activate muscles. |
| Four Components of the Motor Unit | 1)Motor Cell body (in spinal column)
2)Efferent Fiber (exits spinal column)
3)Myoneural-Neuromuscular Junction (where nerve innervates the muscle)
4)Muscle Fibers Innervated by Axon |
| Three Major Bundles in the spinal cord | -Dorsal Column
-Lateral Column
-Ventral Column |
| Dorsal Column | -Ascending (sensory) fibers
-located in back of spinal cord |
| Lateral Column | -Ascending (sensory) and Descending (motor) Fibers
-located on the sides of the spinal cord |
| Ventral Column | -Ascending (sensory) and Descending (motor) Fibers
-Located on the front of the spinal cord |
| Pyramidal system | -aka upper motor neuron
-made up of Anterior cortical spinal tract and lateral cortical spinal tract
- Goes straigt from cortex to spinal column |
| Extrapyramidal system | Consist of:
1)Rubrospinal tract
2)Madulary reticulospinal tract
3)vestibular spinal tract
4)Tectospinal tract
5)Pontine recticulospinal tract
Goes from cortex to other stations where info is modified before going to the spinal column. |
| Pyramedial decussation | 90% Occurs at level of Medulla
10% decussate in the spinal collumn |
| Path of the Pyramidal system | -Starts at precentral gyrus of the motor cortex
-Through Internal Capsule and Pes Pedunculi
-Into the Pontine Nuclei
-Pyramidal Decussation (medulla)
90% decussate
-Spinal Cord |
| Path of the Extrapyramidal system | -Not directly from motor or premotor cortex. Come from areas like cerebellum and basil ganglia. Come from areas that have done some modification of movements. |
| Autonomic Pathways | -Pathways from thalamus to spinal cord and brainstem – regulates motor functions of the sympathetic and parasympathetic systems (breathing, vomiting, and coughing reflexes) |
| Lateral Corticospinal Tract | -Pyramedial Tract
Control of Skeletal Muscle (Fingers, Toes, Forearm)
-Skilled Manipulations I.e. writing, tie shoes, brushing teeth)
-90% Decussate at medulla and Form Alpha Fibers in Ventral Horn |
| Alpha nerves | Important for skilled movement |
| Anterior Corticospinal Tract | -8-10% Fibers That Did Not Cross Midline (in Medulla)
-Decussates at Spinal Horn
Control Axial and Girdle Muscles
–responsible for axial movement of head and trunk |
| Tectospinal Tract | -Extrapyramidal Tract
-Response to Visual Stimulation
- Goes from Superior Colliculus to Cervical Spinal Cord |
| Rubrospinal Tract | -Extrapyramidal Tract
-Starts in Midbrain at the Red Nucleous
-Regulation of Muscle Tone Against Gravity
-Goes from Red N. To Motor Nerve Cells in Ventral Horn |
| Vestibulospinal Tract | -Reflexive Adjustment of Body and Limbs
-Goes fromVestibular N. at the brainstem To Spinal Cord |
| Reticular Descending Tract | Alteration of Muscle Tone |
| Anterior Motor Neurons | – exit at the ventral horns
-Alpha and Y (Gamma) Motor Nerve Cells
-Lower Motor Neurons (Below 2nd Level in Neuronal Pathway) |
| Interneurons | -Association Cells Connecting Sensory and Motor Neuron Pools
-Often Part of Reflexive Action
-30 Times More Than Motor Neurons
-Filter of Sensory and Motor Function |
| Alpha Neurons | -Major Motor Neurons
-Responsible for Voluntary and Reflexive Movements of Head, Trunk and Extremities
-One Fiber Can Innervate 200 Muscles FIBERS |
| Y(Gamma)-Motor Neurons | -Smaller and Fewer
-Controlled by Reticular and Vestibular Systems
-Automatic functions |
| Two Types of Muscle Receptors | 1)Muscle Spindle
2)Golgi Tendon Organs |
| Muscle Spindle | -Detects and Maintains Muscle Tension (how much it contracts and stretches) |
| Golgi Tendon Organs | -Monitors Degree of Muscle Tension During Contraction
-Stretch to Prevent Too Much Tension |
| Stretch Reflex i.e. knee reflex | -Tap Patella causing tendon change (y motor neuron)
-Muscle spindles stimulate alpha motor neuron response, and muscle contracts
-Occurs at the L3 level |
| Withdrawal (Flexor) Reflex i.e. Touching Hot Stimulus | -Protective Response to pain
-Flexion of leg or arm |
| Crossed (Intersegmental) Extensor Reflex | -Protective response
-Involves both sides of the body
-As one arm is withdrawn, the other arm is extended
-Multisynaptic because it involves opposite body parts |
| Neuro-Transmitters of motor system CNS | -Epinephrine
-orepinephrine
-Serotonin |
| Neuro-Transmitters of motor system PNS | Acetylcholine |
| Symptom of Upper Motor Neuron Problem | -Hyper Quality of Movement (Spastic movement) |
| Symptom of Spinal or Spinal Nerve Level - Lower Motor Neuron problem | -Hypo Quality of Movement
-Flaccid Paralysis- limp limbs |
| What does absent of reflexes indicate | Atrophy or Muscle Wasting |
| Complete Spinal Transection (cutting of spinal column) | -Dislocations, tumor, myelitis (inflimation of the spinal column)
-Function lost below the lesion
-After a period of time, reflexes may become spastic in nature |
| Brown-Sequard Syndrome- | -Lesion on ipsilateral half of body, ipsilateral sensory loss, contralateral pain and temperature sensation loss depending on where the lesion is |
| Syringomyelia | -Rare developmental condition: cyst formation within spinal cord with loss of sensation and muscle control â usually starts between ages 25-40 |
