Neuro Lecture (006) The Spinal Cord PDF - A.Y. 2020-2021

(006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 OUTLINE THESPINAL CORD I. INTRODUCTION II. THE SPINAL CORD III. COVERING AND SPACES IV. INTERNAL STRUCTURE...

(006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 OUTLINE THESPINAL CORD I. INTRODUCTION II. THE SPINAL CORD III. COVERING AND SPACES IV. INTERNAL STRUCTURE V. SPINAL PATHWAYS VI. 5 BASIC MODALITIES OF SENSATION VII. SENSORY RECEPTOR VIII. SENSORY AREAS IX. TYPES OF SPINAL CORD INJURY I. INTRODUCTION FORAMEN MAGNUM Only true effective opening in the intact skull Marks the opening or start of the spinal cord Herniation syndrome- occurs when a tumor or hematoma inside the skull produces pressure that moves brain tissue II. SPINAL CORD DEVELOPMENT SPINAL CORD DEVELOPMENT FETAL: 3rd month ends at coccyx BIRTH: ends at L3 ADULT: between L1-L2 during childhood lags in length; shortening as spine lengthens PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 III. THE SPINAL CORD Conus medullaris: end of spinal cord This tapers into Filum Terminale of connective tissue, tethered to coccyx Cauda Equina: arise from the lumbar enlargement and conus medularis - “horse tail” - L2-L5 nerve pairs - S1-S5 nerve pairs - coccygeal nerve DENTICULATE LIGAMENTS Lateral shelves of pia mater anchoring to dura PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 Foramen Magnum to Conus medullaris 2 enlargement/ bulges due to greater number of fibers/ axons CERVICAL- upper extremity innervation ▪ C4- T1 ▪ Corresponds to brachial plexus LUMBAR- lower extremity innervation ▪ L1- S3 ▪ Corresponds to lumbar plexus SPINAL CORD Foramen magnum to Lumbar level L1L2 (Conus Medullaris) Runs through the vertebral canal of the vertebral/ spinal column (protects the spinal cord) PLEXUSES -collection of spinal nerves Neck/ shoulder/ upper limbs innervation 1. Cervical 2. Brachial Lower limb innervation 1. Lumbar 2. Sacral Note: NO thoracic plexus The cord possesses a deep longitudinal fissure called the anterior median fissure, in the midline anteriorly and a shallow furrow called the posterior median sulcus on the posterior surface. FUNCTIONS Two-way conduction (motor and sensory) pathway between the body and the brain Motor and sensory fibers run through different tracts ▪ Ascending tracts (sensory) ▪ Descending tracts (motor) Sensory and motor innervation of entire body inferior to the head through the spinal nerves arising from the different segments of the spinal cord PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 Both motor and sensory fibers run through the same spinal/ peripheral nerve but on different axons/ different fibers Major center for reflexes: reflex is an unconscious information that reaches the spinal cord and does not ascend to higher centers Eg: Patellar reflex, biceps reflex, abdominal reflex, cremasteric reflex. Bulbocavernosus reflex etc. 31 Spinal Segments: 8 cervical 12 throracic 5 lumbar 5 sacral 1 coccygeal Intervertibral foramen- where spinal nerves go out from the spinal cord Spinal nerve: 1. Ventral ramus- thicker; posterior muscle 2. Dorsal ramus- anterior muscles SAME- Sensory: Afferent; Motor: Efferent DAVE- Dorsal: Afferent; Ventral: Efferent IV. COVERINGS AND SPACES Dura mater- thickest; connective tissue POTENTIAL SPACES Epidural- between spine (bone) and dura mater Arachnoid mater - contains CSF and blood vessel Subdural- between dura and arachnoid mater Subarachnoid- between arachnoid and pia mater Pia mater - adherent to spinal cord Intraparenchymal- within the spinal cord Note: the subdural space is not naturally occurring but may develop due to trauma/ pathologic events -These meninges are a continuation of the meninges of the brain (Same structural composition) LP (LUMBAR PUNCTURE) = SPINAL TAP *Dorsal root ganglion- pseudounipolar neuron Needle introduced into subarachnoid space to collect CSF Lumbar spine needs to be flexed so can go between spinous processes Epidural space is external to dura. L3-L4; L4-L5--- to avoid hitting the conus modullaris - Anesthetics are often injected into epidural space injection into correct space is vital; mistakes can be lethal PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 SAGITTAL SECTION THROUGH SPINAL CORD 1. Intervertebral disc 2. Vertebral body 3. Dura mater 4. Extradural or epidural space 5. Spinal cord 6. Subdural space 7. Spinous process INTERNAL SPINAL CORD ANATOMY (TRANSVERSE AXIAL) V. INTERNAL STRUCTURE GREY AND WHITE MATTER OF THE SPINAL CORD Hollow central cavity (“central canal”) that contains CSF) The central canal is surrounded by central gray commissure Grey matter surrounds central canal: made up of nerve cell bodies and their dendrites White matter surrounds grey matter: made up of ascending and descending tracts of axons White matter is also made up of funiculus: posterior funiculus, anterior funiculus and lateral funiculus Grey matter is “H” shaped on cross section Dorsal horn of “H”: cell bodies of sensory neurons/ interneurons Ventral horn of “H”: cell bodies of motor neurons Note: Spinal cord has NO cortex The amount of gray matter present at any given level of the spinal cord is related to the amount of muscle innervated at that level. Thus, its size is greatest within the cervical and lumbosacral enlargements of the cord, which innervate the muscles of the upper and lower limbs. PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 ANTERIOR GRAY COLUMN NERVE CELL GROUPS. The MEDIAL GROUP is present in most segments of the spinal cord and is responsible for innervating the skeletal muscles of the neck and trunk, including the intercostal and abdominal musculature. The CENTRAL GROUP is the smallest and is present in some cervical and lumbosacral segments. In the upper five or six cervical segments, some of the nerve cells innervate the sternocleidomastoid and trapezius muscles and are referred to as the accessory nucleus. The lumbosacral nucleus present in the second lumbar down to the first sacral segment of the cord is made up of nerve cells whose axons have an unknown distribution. The LATERAL GROUP is present in the cervical and lumbosacral segments of the cord and is responsible for innervating the skeletal muscles of the limbs. POSTERIOR GRAY COLUMN NERVE CELL GROUPS. Two of the four nerve cell groups of the posterior gray column extend throughout the length of the cord; the other two are restricted to the thoracic and lumbar segments. LATERAL GRAY COLUMN NERVE CELL GROUPS The intermediolateral group of cells form the small lateral gray column, which extends from the first thoracic to the second or third lumbar segment of the spinal cord, WHITE MATTER is divided into anterior (lies on each side lies between the midline and the point of emergence of the anterior nerve roots), lateral (lies between the emergence of the anterior nerve roots and the entry of the posterior nerve roots), and posterior white columns or funiculi (lies between the entry of the posterior nerve roots and the midline.) Grey commissure surrounds the central canal - Connects the 2 halves of the spinal cord Columns of grey matter running the length of the spinal cord - Posterior (dorsal) horns (interneurons/ cell bodies of sensory neurons - Anterior (ventral) horns (cells bodies of motor neurons/ somatic motor neuron cells)- for skeletal muscle contraction - Lateral horns in thoracic and superior lumbar cord (T1-L2)- contains autonomic (sympathetic) preganglionic motor neuron cells that innervate the visceral organs (heart, lungs, stomach, intestines etc) - Horner’s syndrome Damage to the lateral horns Triad of ptosis (dropping of the eye), anhidrosis (failure to sweat) and miosis (pupils constricted) PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 VI. SPINAL PATHWAYS REMEMBER!!! BACK/ DORSAL/ POSTERIOR (HORN/COLUMN/ ROOT): sensory afferent information FRONT/ VENTRAL/ ANTERIOR (HORN/ COLUMN/ ROOT): pathway for motor efferent information PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 Ascending pathways: sensory information by multi-neuron chains from body (from each segmental spinal cord level) up to more rostral regions of the CNS.-carries afferent sensory information Dorsal column medial lemniscus tract. / Dorsal column medial lemniscus pathway or DMLS - carries information -The fasciculus gracilis carries information from the lower half of the body -The fasciculus cuneatus carries information from the upper- half of the body Spinothalamic tract (Anterolateral tract) - carries the information from the spinal cord to the thalamus, that’s why its ascending. -Lateral Spinothalamic Tract-carries information on pain and temperature -Anterior Spinothalamic Tract- carries information about crude touch or light touch Spinocerebellar tract – carries information about proprioception The information is coming from the spine up to the cerebellum, so it is ascending. -Posterior Spinocerebellar Tract -Anterior Spinocerebellar Tract Remember: the Dorsal column medial lemniscus system and the anterolateral system will reach the Somatosensory Cortex so the information that they are relaying are conscious information. On the other hand, the Spinocerebellar Tract carry the information only up to the Cerebellum, that means they relay unconscious information. Descending pathways: motor instructions from brain to more caudal regions. -Carries efferent motor information Pyramidal system: pass thru the pyramids of the medulla. Corticobulbar- emerge as cranial nerves. -carries information for the cranial nerves Pyramidal (Corticospinal) – emerge as spinal nerves. All others are (“extrapyramidal”) -tracts that do not traverse the pyramids of the medulla Most pathways cross (decussate) at some point Note: there are more tracts that are in the Nervous System, but we focus on important ones. Still take note the Ascending Fiber Sensory Function and Descending Fiber Motor Function PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 Note: MAJOR FIBER TRACTS IN THE WHITE MATER OF THE SPINAL DCML – discriminative sensation through large fiber tracts. CORD Spinothalamic tract (anterolateral) – non-discriminative through small fiber tracts. - Damage to motor tracts: Paralysis/Paresis (depending on the extent of the damage) VII. SENSORY RECEPTORS - Damage to sensory tracts: Anesthesia/Paresthesia’s. Ascending pathways/Tracts for the somatic senses: (made up of By location: thousands of nerve fibers in each) - Exteroceptors: sensitive to stimuli arising from outside Spinocerebellar tract: subconscious proprioception sense from body. Conscious sensation. skeletal muscles to cerebellum of some side (don’t cross/decussate) - Interoceptors: or visceroreceptors, from internal viscera. IPSILATERAL. - Proprioceptors: Monitor degree of stretch in skeletal If there is a damage in the cerebellum, the presentation is always muscles, tendons joints and ligaments. ipsilateral. SENSORY EXTERORECEPTORS Posterior/Dorsal column: discriminative or fine touch/conscious joint Unencapsulated: position(proprioception) and vibration sensation through thalamus to somatosensory cortex (cross/decussate in the medulla). Free nerve endings – pain (nociceptor) and temperature (thermoreceptor). The pain impulses are transmitted to the spinal Lateral spinothalamic tract: carries non-discriminative sensations cord in fast-conducting δ A-type fibers and slow-conducting C- (paint, temperature, pressure, light crude touch) thru the thalamus to type fibers. the primary somatosensory cortex (cross/decussate in the spinal cord before ascending. Merkel disc/cell – Fine touch Root hair plexuses – hair follicle receptors, fine touch OTHER TRACTS: CUNEOCEREBELLAR TRACT originate in the Encapsulated: nucleus cuneatus and enter the cerebellum through the inferior cerebellar peduncle of the same side. They are known as the posterior Meissner’s corpuscles: Fine touch in hairless skin. external arcuate fibers, and their function is to convey Information of muscle joint sense to the cerebellum. SPINOTECTAL TRACT Ruffini’s corpuscles: deep pressure and stretch. provides afferent information for spino-visual reflexes and brings about Pacinian corpuscles: deep pressure, vibration. Visceral: pain, movements of the eyes and head toward the source of the stimulation. nausea, hunger, fulness. The SPINORETICULAR TRACT provides an afferent pathway for the Neuromuscular, and neurotendinous spindles. reticular formation, which plays an important role in influencing levels of consciousness. The SPINO-OLIVARY TRACT conveys information to the cerebellum from cutaneous and proprioceptive organs. VI. 5 BASIC MODALITIES OF SENSATION Touch: Fine (discriminative) and light (crude/non- discriminative) Vibration Joint position sense (proprioception): Conscious (through the dorsal column medial lemniscus pathway) and subconscious (through the spinocerebellar tract) Pain (prick) Influenced by the emotional state and past experiences of the individual. Pain is a sensation that warns of potential injury and alerts the person to avoid or treat it. Pain can be divided into two main types: fast pain (within about 0.1 second after the pain stimulus is applied; sharp pain, acute pain, or pricking pain and is the type of pain felt after pricking the finger with a needle) and slow pain (felt 1.0 second or later after the stimulation; almost confined to the skin.) Temperature PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 Peripheral nerve The first order neuron, has its cell body in the posterior root ganglion of the spinal nerve. The second-order neuron gives rise to an axon that decussates (crosses to the opposite side) and ascends to a higher level of the CNS, where it synapses with the third-order neuron. Note: The Dorsal(posterior) column medial lemniscus tract remains ipsilateral up to medulla where it crosses/decussates over through the second order neuron which are found in the nucleus gracilis and nucleus cuneatus Joint position, vibration sense, fine touch (posterior column): ipsilateral during spinal cord course and then decussates at Nucleus gracilis and Nucleus cuneatus (2nd order neuron) in the medulla via medial lemniscus. Vibration, joint position and temperature senses are often lost without prominent symptoms. Loss of fine(discriminative) is usually symptomatic. The spinothalamic tract (anterior column/anterolateral tract) crosses mostly within one or two segments of entry into the posterior column through the substancia gelatinosa and ascends the spinal cord on the The peripheral nerve receives the information from the receptors and contra-lateral side then send it towards the spinal cord Pain, course touch and temperature sense (anterior column) DCML: Posterior columns – Position, Vibration, Fine touch. decussate at (2nd order neuron – substantia gelatinosa) almost (discriminative touch) immediately as it enters the spinal cord. Pinprick (pain) loss are usually symptomatic. Anterolateral system: Lateral spinothalamic tract – Pain, Temperature, Crude and light touch. (non-discriminative touch)/ NOTE: Fine touch – Discriminative touch ex. Two-point discrimination (atleast 5mm distance). A sensory modality that allows a subject to sense and localize touch. Crude/Light touch – Non-discriminative. Sensory modality that allows the subject to sense that something has touched them, without being able to localize where they were being touched. VIII. SENSORY AREAS Posterior to central sulcus Primary somatosensory cortex: Postcentral gyrus of parietal lobe (allows conscious awareness of sensation and the ability to localize it: where the sensation is from): broadmann area 3,2,1 PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 Somatosensory association area: Behind it (understanding of what SOMATOSENSORY PATHWAY is being felt: the meaning of it) broadmann area 5, 7. Homunculus – “Little man” 3 long neurons: Primary, Secondary or Tertiary (or first, second, and third). The first neuron always has its cell body in the dorsal root ganglion, of the spinal nerve. (if sensation is in parts of the head or neck not covered by the cervical nerves, it will be the trigeminal nerve ganglia or the ganglia of other sensory cranial nerves). The second neuron has its cell body either in the spinal cord or in the brainstem. This neuron’s ascending axons will cross/decussate to the opposite side either in the spinal cord or in the brainstem. In the case of touch or certain types pain, the 3rd neuron has its cell body in the VPN of the thalamus and ends in the post central Executive functioning occurs in the cerebral cortex (2-4 mm thick Mantle) Cortex: 90% Neocortex (6 layers) 10% Allocortex 14-16 Billion Neurons Remember that in lower extremity, the sensory information reaches through the medial side of the cortex or somatosensory cortex. Note: 2nd Order neuron: - point of decussation or crossing over of fibers. - Conscious sensations reach the somatosensory cortex. - Unconscious (reflex) reach only the spinal cord or the cerebellum. PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 gyrus of the parietal lobe. (somatosensory cortex). PROPIOCEPTION (POSITION SENSE) From latin “Proprius” – “one’s own”, “individual” “Capio” – “to take a grasp” “sixth sense” The sense of the relative position of neighboring parts of the body and strength of effort being employed in movement Kinesthesia or kinaesnthesia (kinesthetic sense) strictly means movement sense Sense of overall body position during movement and acceleration Kinesthetic sense Sensors: Muscle spindles Golgi tendon Joint kinesthetic MUSCLE SPINDLES - Type 1a neurons-encodes limb velocity and movement (muscle length and the rate of change) - Group II neurons- encode static muscle length GOLGI TENDON ORGANS - Type IIb afferent neurons - Determine the load of a limb JOINT KINESTHETIC RECEPTORS - Ruffini and Pacinian corpuscles - Activated when the joint is at a threshold, usually at the extremes of joint position DORSAL (POSTERIOR) COLUMN MLP: reaches the consciousness (somatosensory cortex) it also carries proprioception asidefromfine touch and vibration Somatosensory cortex send back the information to the cerebellum for control/ modulation of movement PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 CONSCIOUS VS NON-CONSCIOUS PROPIOCEPTION Dorsal Column- Medial lemniscus pathway -reaches the somatosensory cortex (conscious) -aware of body position Spinocerebellar (dorsal and ventral) -reaches up to cerebellum only (non-conscious) -eg. Righting reflex -cerebellum is the main control for balance and coordination The posterior spinocerebellar fibers receive muscle joint information from the muscle spindles, tendon organs, and joint receptors of the trunk and lower limbs. This Information concerning tension of muscle tendons and the movements of muscles and joints is used by the cerebellum in the coordination of limb movements and the maintenance of posture. The anterior spinocerebellar tract conveys muscle joint information from the muscle spindles, tendon organs, and joint receptors of the trunk and the upper and lower limbs. Spinal reflex arc -reaches up to the spinal cord only (non-conscious) -eg. Patellar reflex Posterior White Column: Fasciculus gracilis (present throughout the length of the spinal cord and contains the long ascending fibers from the sacral, lumbar, and lower six thoracic spinal nerves) and Fasciculus cuneatus (situated laterally in the upper thoracic and cervical segments of the spinal cord and is separated from the fasciculus gracilis by a septum; contains the long ascending fibers from the upper six thoracic and all the cervical spinal nerves.) PROPIOCEPTION INPUTS Skeletal muscles, joints, tendons, ligaments o Via proprioceptors (muscle spindle/ golgi tendon organ/ joint kinesthetic receptors) – information travels thru the ▪ Dorsal column (conscious) ▪ Spinocerebellar tracts (non-conscious) ▪ Spinal reflex arc of the spinal cord (non- conscious) Vision Vestibular system PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 Note: all information input goes to and is integrated into the cerebellum (known as little brain) CRANIAL NERVE VII: VESTIBULOCOCHLEAR NERVE Purely sensory nerve (send afferent information to the cerebellum) Transmits sound and equilibrium (balance) information from the inner ear to the brain Nuclei in the pontomedullary junction consist mostly of bipolar neurons 2 divisions: 1. Vestibular nerve (equilibrium/ balance) 2. Cochlear nerve (hearing) VESTIBULAR NERVE Vestibular ganglia - Nuclei: cell bodies of bipolar neurons Five sensory organs: hair cells - 3 cristae in the ampullae of the semicircular canals- afferent receptor in response to rotational acceleration - Maculae in the saccule- vertical acceleration - Maculae in the utricle- linear acceleration BRAINSTEM TOWARDS THE CEREBELLUM via the cerebellar peduncles Proprioception- DCML and Spinocerebellar tracts Vision- super colliculi Vestibular- inferior colliculi PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 PYRAMIDAL SYSTEM - Involved in control of motor functions of the body. - Voluntary, conscious (information comes from the motor cortex) PYRAMIDAL PATHWAYS ▪ Corticobulbar tract (brain stem-Cranial nerves) o Movement of muscle in head and face: facial expression, mastication, tongue etc. o Cortex-medulla oblongata ▪ Corticospinal tract (spinal cord-spinal nerves) o Tracts of the motor cortex that reach their targets travelling to the spinal cord thru the pyramids of the medulla, where they decussate. o Movement of muscles below the head with control from the opposite side of the brain. o The pathways concerned with voluntary, discrete, skilled movements, especially those of the distal parts of the limbs. THE DESCENDING MOTOR PATHWAY CORTICOBULBAR TRACTS – descending nerves for cranial nerves. Lower motor neurons are constantly bombarded by CN V3 Pons nervous impulses that descend from the medulla, pons, midbrain, and cerebral cortex as well as those that enter along sensory fibers from CN IX, X,XII Medulla the posterior roots. Nerve fibers that descend in the white matter from different supraspinal nerve centers are segregated into nerve bundles 50% decussate at the pyramids. called the descending tracts. These supraspinal neurons and their tracts are referred to as the upper motor neurons, and they provide Nerve cell bodies (Nucleis) numerous separate pathways that can influence motor activity. The descending pathway from the cerebral cortex ls often made up of - Trigeminal motor nucleus – innervate the muscles of three neurons. The first neuron, the first-order neuron, has Its cell mastication (CN V3). body in the cerebral cortex. Its axon descends to synapse on the - Facial motor nucleus – innervates the muscle of facial second-order neuron, an internuncial neuron, situated in the anterior expression (CN VII) gray column of the spinal cord. The axon of the third-order neuron - Nucleus ambiguous – innervate the soft palate, pharynx and innervates the skeletal muscle through the anterior root and spinal nerve. larynx (speech and swallowing) (CN IX, X) Sensory neuron (afferent) - Receive sensory input. And conducts impulses towards the CNS. Interneurons - Interconnectors, Establish neuronal circuit between sensory and motor neurons. Motor neuron (efferent) - Conduct impulses from the CNS to the muscle and glands. PRIMARY MOTOR AREA Precentral gyrus of frontal lobe. Precise, conscious voluntary movement of skeletal muscles. Large neurons called pyramidal cells (Betz cells) Their axons form massive pyramidal or corticospinal tracts. o Descend thru brain stem and spinal cord o Cross to contralateral side in medulla (Right side of the brain controls the left side of the body, and left side of the brain controls the right side of the body) PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 DESCENDING SPINAL PATHWAYS Corticobulbar tracts innervate cranial motor nuclei of the CNS Synapse with ventral (anterior) horn interneurons. bilaterally except: Innervation from contralateral cortex. Pyramidal tracts: Lateral corticospinal – cross in pyramids of ▪ Lower facial nuclei medulla; voluntary motor to limb (extremity) muscles. ▪ Genioglossus Ventral corticospinal – crosses at spinal cord; voluntary to axial/trunk muscles. Extrapyramidal tracts: Rubrospinal tract, tectospinal tract, vestibulospinal tract, reticulospinal tract. Sensory information passes thru the THALAMUS. Motor information passes thru the INTERNAL CAPSULE OF THE MEDULLA. Decussation occurs in the SPINOMEDULLARY JUNCTION. HOMONCULUS OF LITTLE MAN. PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 EXTRAPYRAMIDAL SYSTEM – DO NOT PASS THRU THE PYRAMIDS OF THE MEDULLA. AND DO NOT ORIGINATE FROM THE MOTOR CORTEX. ▪ Part of motor system involving involuntary actions. o Reflexes, locomotion, complex movements, postural control. ▪ Modulation and regulation (indirect control) of anterior horn cell of the spinal cord (without directly innervating the motor neurons). ▪ Chiefly found in reticular formation of the medulla targeting lower motor neurons in the spinal cord. ▪ Further modulations in the CNS: o Nigrostintial pathway/ Corpus striatum/ substantia nigra o Subthalamic nucleus/ Red nucleus o Basal Ganglia o Cerebellum o Vestibular nuclei o Sensory areas of the cortex Extrapyramidal tracts – involuntary movements (does not originate from the motor cortex) ▪ Rubrospinal tracts ▪ Pontine reticulospinal tract ▪ Medullary reticulospinal tract ▪ Lateral vestibulospinal tract ▪ Tectospinal tract ▪ Olivospinal tract ▪ Resticulospinal tract o may facilitate or inhibit the activity of the a and γ motor neurons in the anterior gray columns and may, therefore, facilitate or inhibit voluntary movement or reflex activity. Extrapyramidal symptoms ▪ Disorders: parkinsons disease, chorea, hemiballismus, athetosis, tics. LOOK FOR A SPECIFIC DAMAGE TO A PART OF THE EPS. ▪ Symptoms o Dystonia – continous spasms and muscle contraction o Akathisia – motor restlesness o Parkinsonism – rigidity, stooped posture. COMPLETE SPINAL CORD INJURY o Bradykinesia – slowness of movement o Tardive dyskinesia – involuntary muscle movements of lower face and distal extremities. ▪ IX. TYPES OF SPINAL CORD INJURY Spinal cord injuries are common and can occur as a result of automobile and motorcycle accidents, falls, sports injuries, and gunshot wounds. Spinal cord and spinal nerve damage may also be associated with vertebral fractures; vertebral infections; vertebral tumors, both primary and secondary; and herniated. Intervertebral discs. The assessment of neurologic damage requires not only an understanding of the main nervous pathways within the spinal cord but an ability to correlate radiologic evidence of bone injury with segmental levels of the spinal cord. PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 Example no.1 COMPLETE: QUADRIPLEGIA/ TETRAPLEGIA Example no. 1 ANTERIOR CORD SYNDROME Example no.2 COMPLETE: PARAPLEGIA Below the level of injury: Motor paralysis/ paresis bilaterally Loss of pain and temperature bilaterally Preserved: DCML; fine touch, vibration, and proprioception (position) sense Bilateral lower motor neuron paralysis ln the segment of the lesion and muscular atrophy ls caused by damage to the neurons in the anterior gray columns Bilateral loss of pain, temperature, and light touch sensations below the level of the leslon are caused by interruption of the anterior and lateral spinothalamlc tracts on both sides. Tactile discrimination and vibratory and proprioceptive sensations are preserved because the posterior white columns on both sides are undamaged. INCOMPLETE SPINAL CORD INJURIES: THE SPINAL CORD SYNDROMES PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 CORTICOSPINAL TRACT: motor information POSTERIOR/ DORSAL COLUMN SPINOTHALAMIC TRACT: sensory information Below the level of injury Motor weakness or paralysis on ipsilateral side (hemiparaplegia/ paresis) Loss of all sensory modalities on ipsilateral (same) side Loss of pain and temperature from the contralateral/ opposite side (hemianaesthesia) lpsilateral lower motor neuron paralysis in the segment of the lesion and muscular atrophy are caused by damage to the neurons on the anterior gray column and possibly by damage to the nerve roots of the same segment. lpsilateral loss of tactile discrimination and of vibratory and proprioceptive sensations below the level of the lesion are caused by destruction of the ascending tracts In the posterior white column on the same side of the lesion. Contralateral loss of pain and temperature sensations below the level of the lesion is due to destruction of the crossed lateral spinothalamic tracts on the same side of the lesion. Because the tracts cross obliquely, the sensory loss occurs two or three segments below the lesion distally. Contralateral but not complete loss of tactile sensation below the level of the lesion condition Is caused by destruction of the crossed anterior spinothalam.ic tracts on the side of the lesion Because the tracts cross obliquely, the sensory impairment occurs two or three segments below the level of the lesion distally. The contralateral loss of tactile sense Is incomplete because discriminative touch traveling in the ascending tracts In the contralateral posterior white column remains intact Example no. 2 BROWN-SEQUARD SYNDROME/ LATERAL HEMISECTION PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 Example no. 3 Example no. 5 POSTERIOR CORD SYNDROME CENTRAL CORD (SMALL LESIONS) Below the level of injury Motor function preserved Loss of DCML functions bilaterally; fine touch, vibration, and proprioception (position) sense Preserved pain and temperature bilaterally Example no. 4 CENTRAL CORD SYNDROME Small lesions as in syringomyelia (collection of fluid filled cyst in the central cord) Loss of pain and temperature at the level of the lesion bilaterally (note: spinothalamic tract cross the midline) with preserved fine touch, joint position and vibration sense- dissociated sensory loss Usually seen in cervical spinal injuries: Motor impairment o Upper extremity > lower extremity Variable sensory loss Bilateral lower motor neuron paralysis In the segment of the lesion and muscular atrophy is caused by damage to the neurons Jn the anterior gray columns (I.e., lower motor neuron) and possibly by damage to the nerve roots of the same segment In bilateral loss of pain, temperature. light touch, and pressure sensations below the level of the lesion with chararteristic sacral "sparing," because the ascending fibers in the lateral and anterior splnothalamlc tracts are also laminated, with the upper limb fibers located medially and the lower limb fibers located laterally, the upper limb fibers are more susceptible to damage than the lower limb fibers PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 PREPARED AND EDITED BY: TRANS GROUP 2  (006) THE SPINAL CORD DR. ALLAN VIADO | 10/28/2020 PREPARED AND EDITED BY: TRANS GROUP 2