6- Spinal Cord and Tracts Flashcards
Afferent Info Streams
Local Reflexes
To cortex
To cerebellum
Info goes to all 3 streams simultaneously
Spinal Cord Ends At
Conus Medullaris at L1/L2
Cauda Equina
Collection of nerve terminals (L3-S5) caudal to the conus medullaris
Formed from lower spinal nerves descending before exiting spinal cord
Filum Terminale
Fibrous tissue connecting conus medullaris to coccyx
Made of pia mater- anchors spinal cord to vertebrae
Dermatomes
Mesoderm—-> somites
Somites retain connectivity with originating vertebral level
Somites differentiate
Result in different regions of the body connected to different parts of spinal cord
Lissauer’s Tract
Entry point of some DRG fibers
In PH
Intermediate Gray (IG)
Contains interneurons adn tract cells , some autonomic pre-ganglionic MN
Ventral Horn (VH)
Has motor neurons
Substantia Galatinosa
Superficial zone of DH
Has nerve terminal
In PH
Rexed Laminae
Defined by cellular structure
I-X
Rexed Laminae- DH
I-VI
Rexed Laminae- IG
VII
Rexed Laminae-VH
VIII-IX
Central Canal
X
Fibers of the Spinal Cord
Long ascending—> thalamus, cerebellum, brainstem
Long descending–> from cortex to spinal cord
Local propriospinal- shorter fibers that interconnect different parts of spinal cord
Spinal Tracts
Carries specific type of sensory/motor info
Most tracts consist of 2-3 neurons
Has a consistent location at all spinal cord level
Usually cross over at some point
Ascending Tracts
Dorsal Column Medial Lemniscal
Spinocerebellar
Anterolateral (spinothalamic)
Spinocerebellar Tract
Provide info from legs
Ipsilateral to cerebellum
Cuneocerebellar Tract
Info from arms
Ipsilateral to cerebellum
Reticulospinal Tract
Involved in locomotion and posture (need to be awake to move)
Includes pontine and medullary branches
Tectospinal Tract
Orientation of head towards source of visual or auditory stimuli
Descending
Vestibulospinal Tract
Centre of gravity/posture
Descending
Raphespinal Tract
Pain modulation
Descending
Symptoms of UMN Damage
Shock (paralysis and areflexia) followed by hyperreflexia
Symptoms of LMN Disease
Paral
ysis followed by areflexia and muscle atrophy
IG- Sympathetic Pre-Ganglionic
Thoracolumbar
IG- Parasympathetic Pre-Ganglionic
Sacral and cervical
Symptoms of Nerve Root Compression
Most common in lower cervical and lumbar regions
Pin in muscle
Paraesthesia (numbness)
Loss of cutaneous snesory info
Loss of spinal reflex