The Spinocerebellar Tracts
PROPRIOCEPTIVE INFORMATION IN THE BODY TRAVELS UP THE SPINAL
CORD VIA THREE TRACTS. BELOW L2, THE PROPRIOCEPTIVE INFORMATION
TRAVELS UP THE SPINAL CORD IN THE VENTRAL SPINOCEREBELLAR TRACT.
ALSO KNOWN AS THE ANTERIOR SPINOCEREBELLAR TRACT, SENSORY
RECEPTORS TAKE IN THE INFORMATION AND TRAVEL INTO THE SPINAL CORD.
THE CELL BODIES OF THESE PRIMARY NEURONS ARE LOCATED IN THE
DORSAL ROOT GANGLIA. IN THE SPINAL CORD, THE AXONS SYNAPSE AND THE
SECONDARY NEURONAL AXONS DECUSSATES AND THEN TRAVEL UP TO THE
SUPERIOR CEREBELLAR PEDUNCLE WHERE THEY DECUSSATE AGAIN. FROM
HERE, THE INFORMATION IS BROUGHT TO DEEP NUCLEI OF THE CEREBELLUM
INCLUDING THE FASTIGIAL AND INTERPOSED NUCLEI.
FROM THE LEVELS OF L2 TO T1,
PROPRIOCEPTIVE INFORMATION ENTERS
THE
SPINAL
CORD AND ASCENDS
IPSILATERALLY, WHERE IT SYNAPSES IN
CLARKE'S NUCLEUS. THE SECONDARY
NEURONAL
AXONS
CONTINUE
TO
ASCEND IPSILATERALLY AND THEN PASS
INTO
THE
CEREBELLUM
VIA
THE
INFERIOR CEREBELLAR PEDUNCLE. THIS
TRACT IS KNOWN AS THE POSTERIOR
SPINOCEREBELLAR TRACT.
FROM ABOVE T1, PROPRIOCEPTIVE
PRIMARY AXONS ENTER THE SPINAL
CORD AND ASCEND
IPSILATERALLY
UNTIL
REACHING
THE ACCESSORY
CUNEATE
NUCLEUS,
WHERE
THEY
SYNAPSE. THE SECONDARY AXONS PASS
INTO
THE
CEREBELLUM
VIA
THE
INFERIOR
CEREBELLAR
PEDUNCLE
WHERE AGAIN, THESE AXONS SYNAPSE
ON CEREBELLAR DEEP NUCLEI. THIS
TRACT
IS
KNOWN
AS
THE
CUNEOCEREBELLAR TRACT.
The Pyramidal (Corticospinal) Tract
THE
CORTICOSPINAL
TRACT
SERVES AS THE MOTOR PATHWAY
FOR UPPER MOTOR NEURONAL
SIGNALS
COMING
FROM
THE
CEREBRAL CORTEX AND FROM
PRIMITIVE
BRAINSTEM
MOTOR
NUCLEI.
CORTICAL
UPPER
MOTOR
NEURONS
ORIGINATE
FROM
BRODMANN AREAS 1, 2, 3, 4, AND 6
AND THEN
DESCEND
IN
THE
POSTERIOR LIMB OF THE INTERNAL
CAPSULE, THROUGH THE CRUS
CEREBRI, DOWN THROUGH THE
PONS, AND TO THE MEDULLARY
PYRAMIDS, WHERE ABOUT 90% OF
THE
AXONS
CROSS
TO
THE
CONTRALATERAL
SIDE AT
THE
DECUSSATION OF THE PYRAMIDS.
THEY THEN DESCEND AS THE
LATERAL
CORTICOSPINAL
TRACT. THESE AXONS SYNAPSE
WITH LOWER MOTOR NEURONS
IN THE VENTRAL HORNS OF ALL
LEVELS OF THE SPINAL CORD.
THE REMAINING 10% OF AXONS
DESCEND ON THE IPSILATERAL
SIDE
AS
THE
VENTRAL
CORTICOSPINAL TRACT. THESE
AXONS ALSO SYNAPSE WITH
LOWER MOTOR NEURONS IN THE
VENTRAL
HORNS.
MOST
OF
THEM WILL CROSS TO THE
CONTRALATERAL SIDE OF THE
CORD
(VIA
THE
ANTERIOR
WHITE
COMMISSURE)
RIGHT
BEFORE SYNAPSING.
The Extrapyramidal Tracts
THEY ARE CALLED SO BECAUSE THEY DON’T REACH THEIR TARGETS BY
TRAVELING THROUGH THE "PYRAMIDS OF MEDULLA". PYRAMIDAL
TRACTS GO THROUGH THE PYRAMIDS OF MEDULLA.
EXTRAPYRAMIDAL TRACTS INDIRECTLY CONTROL THE ANTERIOR HORN
CELLS (FOR MODULATION AND REGULATION).
EXTRAPYRAMIDAL SYSTEM IS RESPONSIBLE FOR GROSS, SYNERGIC
MOVEMENTS WHICH REQUIRE THE ACTIVITY OF LARGE GROUPS OF
MUSCLES
Clinical Symptomatology
RADICULOPATHY
NERVE
ROOT
IMPINGEMENT
WITH
TYPICAL PAIN RADIATION AND/OR MOTOR
OR SENSORY IMPAIRMENT LEADING TO
NERVE ROOT DYSFUNCTION.
TYPICAL FINDINGS: WEAKNESS OF THE
INDEX MUSCLE MAINLY INNERVATED BY
THAT NERVE, DIMINISHED REFLEXES OF
THE SAME MUSCLE AND DERMATOMAL
SENSORY DISTURBANCE.
THE MOST COMMON DISTRIBUTION OF
RADICULOPATHY IS THE LUMBAR SPINE
FOLLOWED BY THE CERVICAL SPINE.
RADICULOPATHY IS LESS COMMON IN THE
THORACIC SPINE.
PAIN
USUALLY EXACERBATED WITH
COUGHING,
SNEEZING
OR
DURING
DEFECATION.
MYELOPATHY
COMPRESSION OR STRETCHING OF
THE SPINAL CORD CAN CAUSE
MYELOPATHY, WHICH IS MORE COMMON
IN THE CERVICAL RATHER THAN THE
THORACIC SPINE.
HYPERREFLEXIA AND POSITIVE
BABINSKI SIGN ARE COMMON.
SENSORY DEFICITS INCLUDE IMPAIRED
SENSORY LEVEL, DERMATOMAL
SENSORY DISTURBANCE IN THE ARMS,
GLOVE-DISTRIBUTION SENSORY LOSS IN
THE HANDS AND POSTERIOR COLUMN
DYSFUNCTION.
MOTOR DEFICITS WITH ARM
WEAKNESS AND WASTING OF HAND
MUSCLES ARE ENCOUNTERED AND
PARAPARESIS CAN OCCUR . HOWEVER,
HEMI- OR TETRAPARESIS ARE LESS
FREQUENT. SPASTICITY AND SPHINCTER
DISTUBANCES OCCUR ALSO.
Transverse Myelitis
LOCALIZED DEMYELINATION OF
THE SPINAL CORD.
IS
CAUSED
BY AN
IMMUNE
PROCESS
RESULTING
IN
SMALL
VESSEL VASCULOPATHY, ISCHEMIA,
AND DEMYELINATION.
SYMPTOMS: CLINICAL PICTURE IS
IDENTICAL TO CORD TRANSECTION
OCCURRING OVER HOURS TO A FEW
DAYS.
MOST
COMMON
IN THE
THORACIC CORD. BAND-LIKE CHEST
PAIN
MIMICKING
ACUTE
MYOCARDIAL
INFARCTION
MAY
OCCUR BEFORE THE ONSET OF
FLACCID
PARALYSIS,
SENSORY
LEVEL, AND URINARY RETENTION.
PROGRESSIVE RISE IN THE SENSORY
LEVEL MAY OCCUR.
TREATMENT:
HIGH-DOSE
INTRAVENOUS STEROIDS
Lumbar Puncture
DEFINITION:
THE PROCEDURE OF TAKING CSF FROM THE
SPINE IN THE LOWER BACK THROUGH A HOLLOW NEEDLE,
USUALLY DONE FOR DIAGNOSTIC PURPOSES (E.G. MENINGITIS).
Technique of Lumbar Puncture
THE PATIENT SHOULD LIE
FLAT ON HIS SIDE WITH THE
BACK AT THE EDGE OF THE
BED.
FLEXION
OF
HIPS
AND
KNEES IS DONE.
INTRODUCTION OF 20- TO
22-GAUGE
NEEDLE
IN
BETWEEN
2
SPINOUS
PROCESSES
(EITHER
,COMMONLY L3-L4, OR L4-L5)
EXACTLY IN THE MIDLINE.
BY PUSHING THE NEEDLE
POINTING SLIGHTLY TOWARDS
THE
PATIENT’S
HEAD,
PIERCING
THE
DURA
IS
PERFORMED AT 5-6 CM.
COLLECT
THE
CSF
AND
SEND IT TO ANALYSIS.
Thank you