Spinal Cord

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Spinal Cord by Mind Map: Spinal Cord

1. Functions

1.1. conduit of information to and from spinal cord

1.2. Initiates Spinal Reflexes

1.3. Controls body via spinal nerves

2. Anatomy

2.1. Boundaries

2.1.1. Foramen Magnum

2.1.2. Conus Medullaris L1/L2

2.1.3. Cauda Equina

2.2. The mature SC is about 45 cm long and 1cm in diameter

2.3. Segmental organization

2.3.1. 31pair of Spinal nerves

2.4. Enlargements

2.4.1. Cervial C5-T1

2.4.2. Lumbar L1-S3

2.5. White Matter

2.5.1. myelinated axons

2.5.2. Funiculi tracts ventral/anterior Lateral Dorsal/Posterior

2.6. Gray Matter

2.6.1. Cell bodies

2.6.2. unmyelinated axons

2.6.3. interneurons

2.6.4. Ventral Horn (2) LMNs Medial Ventral Horn Lateral Ventral Horn

2.6.5. Lateral Horn Preganglionic autonomic neuron cell bodies T1-L2 S2-S4

2.6.6. Dorsal horn (2) Sensory

2.6.7. Columns Rexed's Laminae Dorsal Horn Intermediate/Lateral Horn Ventral Horn

2.7. Meninges

2.7.1. Dura tough extends into IV foramina sensory nerve endings Dural sac to S2 level Subdural space potential space serous fluid for lubrication and moistening Epidural Space fat internal venous plexus

2.7.2. Arachnoid subarachnoid space

2.7.3. Pia denticulate ligaments adhered to SC filum terminale coccygeal ligament

2.7.4. Clinical Implications Lumbar Puncture lumbar cistern Spinal anesthesia spinal nerve block epidural nerve block

2.8. Blood Supply

2.8.1. Longitudinal arteries Anterior Spinal artery union of branches from vertebral artery blockage Posterior Spinal Ateries (2) vertebral artery or posterior inferior cerebellar arteries blockage

2.8.2. Radicular arteries

2.8.3. Segmental Medullary arteries vertebral and deep cervical supply the cervical region posterior intercostal arteries supply thoracic lumbar arteries=lumbar Artery of Adamkiewicz

2.8.4. Watershed Area T4-T8 area

2.9. structural Features

2.9.1. Cervical cord oval Dorsal columns Gracilis cuneatus Ventral horn larger C3-C8 Highest ratio of white matter to gray

2.9.2. Thoracic slim dorsal and ventral horns Lateral horn present here cord is smaller overall cuneatus gone at about T6 level

2.9.3. Lumbosacral round Lateral horn at L1 Thicker dorsal and ventral horns dec white to gray matter ratio

3. Tracts

3.1. Sensory

3.1.1. Dorsal Columns (medial Lemniscus) discriminative touch and conscious proprioception Gracilis Lower Limb medial Cuneatus Upper limb lateral

3.1.2. anterolateral system spinothalamic discriminative pain and temperature crude touch slow pain pathways somatotopy opposite of dorsal columns so proximal is more medial

3.1.3. spinocerebellar posterior unconscious proprioception from lower limb ventral feedback from interneurons

3.2. Motor

3.2.1. Ventromedial UMN posture balance head and neck movments

3.2.2. Lateral coricospinal tract voluntary movement distal musculature fine motor movments

4. Reflexes

4.1. Functions of spinal reflexes

4.1.1. Adjust for unexpected pertubations

4.1.2. allow for rapid protection from painful/damaging stimuli withdrawal

4.1.3. organize patterns of coordination

4.2. Types

4.2.1. Superficial skin and mucous membranes corneal cremasteric

4.2.2. Myotatic/Deep Tendon Stretch muscle spindle fibers biceps, achilles check nerve roots feedback mechanism for keeping appropriate muscle tone monosynaptic alpha motor neurons to muscle group Renshaw cells

4.2.3. reciprocal Inhibition decreases activity of antagonists when an agonist muscle is active occurs in response to myotatic reflex

4.2.4. Inverse Myotatic increased tension GTOs antagonist contracts

4.2.5. Flexor reflex Withdrawal Pain fibers activated Crossed extensor contralateral limb interneurons

4.2.6. Visceral accomodation carotid sinus

4.2.7. Pathological Babinski

5. Spinal Control of Motor Coordination

5.1. Central Pattern generator

5.1.1. rhythmic output

5.1.2. simplify signals

5.1.3. interneurons in SC and BS

5.1.4. subject to Conscious control

5.1.5. example of how it works

5.2. Sensory influence

5.2.1. modulates activity of the CPG/SPG

5.2.2. how it works

6. Lesions

6.1. Semental Lesion

6.1.1. "patchy loss"

6.1.2. autonomic hard to detect

6.1.3. dermatomal sensory loss

6.1.4. myotomal motor loss

6.2. Vertical Tract Lesion

6.2.1. autonomic loss of descending control of BP pelvic viscera thermoregulation

6.2.2. sensory abnormal or lost below level of lesion

6.2.3. Motor muscle paresis/paralysis UMN signs with LCST involvement from level of lesion down

6.3. example of segmental vs vertical tract

6.4. Causes of Lesions

6.4.1. Trauma crush penetrating

6.4.2. Tumors compression

6.4.3. Degenerative diseases Spondylolysis ALS

6.4.4. Demyelinating diseases MS

6.4.5. Infections Polio myelitis

6.4.6. Disorders of Blood Supply Hemorrhage infarcts

6.4.7. Developmental Spinal Bifida Cerebral Palsy

6.5. Deficits

6.5.1. Predictable DCML ipsilateral deficit level and below spinothalamic contralateral deficit 2 segments below corticospinal Motor deficit ipsilateral to damage

6.5.2. Spinal Shock Initial LMN signs flaccid paresis hypo/areflexia moderal dec in BP absent sphincteric reflexes and tone UMN Signs develop over weeks to months Spasticity hyperreflexia Babinski Some spincteric reflexes and erectile dysfunction may return but often without voluntary control

6.5.3. Chronic SC injury neurological deficit stable laste for years-decades

6.6. Syndromes

6.6.1. Definition

6.6.2. importance

6.6.3. Tranverse cord lesion spastic paralysis complete anesthesia Urinary and fecal incontinence Hyperreflexia Breathing paralysis if lesion is above C5 anhidrosis, loss of vasomotor tone causes trauma tumors MS transverse myelitis

6.6.4. Hemicord Lesion Brown-Sequard syndrome below level of lesion ipsilateral Contralateral at level of lesion ipsilateral causes penetrating injury MS tumors

6.6.5. Posterior Cord Syndrome Bilateral loss tactile discrimination vibration pressure proprioception causes trauma tumor MS neurosyphillis

6.6.6. Anterior Cord Syndrome Motor flaccid paralyis areflexia larger lesion Pain and temp B loss 1-2 segments below lesion causes trauma MS anterior spinal artery infarct

6.6.7. Central Cord syndrome small lesions Bilateral loss of pain and temp sensation in affected dermatomal areas cervical lesions causes Large lesions LMN effects UMN signs Dorsal Columns may be involved Anterolateral tracts causes

6.7. autonomic dysfunction with spinal cord injury

6.7.1. Know this table

6.7.2. worse the higher you go

6.8. Classification

6.8.1. Complete

6.8.2. incomplete better prognosis

6.8.3. neurologic level sensory and motor function most caudal level

6.8.4. American Spinal Cord Injury Association form

6.9. Prognosis

6.9.1. Barriers of regeneration in CNS inhibitory molecules Glial scars Dec Growth factors Mature vs embryonic neurons

6.9.2. Secondary changes following SC injury bleeding edema ischemia Pain inflammation

6.9.3. Research for Tx therapeutic hypothermia reduce secondary injury promote growth cell transplantation growth factors many neuroprotective and neuroregenerative compounds being studied

6.9.4. complications Second Year following SC injury UTI Spasticity Chills and Fever Decubiti Autonomic Dysreflexia Contractures Heterotropic ossification Pneumonia

6.9.5. Rehabilitation Strenghtening ROM mobility/ ADL training adaptive equipment Environmental modifications Body wt support gait training incomplete spinal cord injury