Chapter 13 and Lab 9: Spinal Cord and Spinal Nerves Flashcards

Question

What are the functions of the ascending spinal tracts?

Answer 1

* Carry sensory signals up to spinal cord * Uses 3 neurons from origin (receptors) to destintation (sensory area in brain) * First order: detect stimulus and transmit signal to spinal cord or brain stem * Second order: continues to the thalamus at the upper end of the brainstem * Third order: carries the signal the rest of the way to the sensory region of the cerebral cortex

Answer 2

* Carry motor signals down brainstem and spinal cord * Involve 2 motor neurons * Upper motor neuron * originates in cerebral cortex or brainstem and terminates on a lower motor neuron * Lower motor neuron * soma is in brainstem or spinal cord * axon leads to muscle or other target organ

Answer 3

* Spinal cord communicates with the rest of the body by way of nerves * Nerve: cordlike organ composed of numerous nerve fibers (axons) bound together by connective tissue * Mixed nerves contain both afferent (sensory) and efferent (motor) fibers

Answer 4

* Nerve fibers of the PNS surrounded by Schwann cells forming neurilemma/myelin sheath around axon * Endoneurium: wrapping external to neurilemma * PErineurium: surrounds each fasicle * Epineurium: covering of entire nerve * ^{Blood vessels penetrate connective tissue coverings}

Answer 5

* Poliomyelitis * caused by poliovirus (fecal contamination of water) * destroys motor neurons in brainstem and anterior horn of spinal cord * paralysis, muscular dystrophy, and respiratory arrest * ALS (Amyotrophic lateral sclerosis or Lou Gehrig's disease) * destruction of motor neurons and muscular atrophy * sclerosis (scarring) of lateral regions of spinal cord * early signs: muscular weakness, difficulty speaking, swallowing, and using hands * sensory/intellectual functions remain unaffected

Answer 6

* Ganglion: cluster of neurosomas outside the CNS * enveloped in endoneurium * Posterior root ganglion * Sympathetic trunk ganglion

Answer 7

* 8 cervical (C1-C8) * first cervical nerve exits between skull and atlas (only 7 vertebrae) * others exit at intervertebral foramina * 12 thoracic (T1-T12) * 5 Lumbar (L1-L5) * 5 Sacral (S1-S5) * 1 Coccygeal (Co1)

Answer 8

* Each spinal nerve is formed from two roots * posterior (dorsal) root-sensory * posterior (dorsal) root ganglion * contains the somas of sensory neurons * enters posterior horn of cord * Anterior (ventral) root: motor * Cauda equina * formed from roots arising from L2 to Co1 * dorsal and ventral roots of lowest spinal nerves

Answer 9

* Outside vertebra, nerve divides into rami (distal branches) * Anterior ramus * in thoracic region gives rise to intercostal nerve * In other regions forms plexuses * Posterior ramus * innervates the muscles and joints in that region of the spine and the skin of the back * Rami communicantes * only in thoracic region * autonomic nerve fibers (sympathetic) * Meningeal branch * reenters the vertebral canals * to where the meninges are

Answer 10

* It goes into the intercostals and helps with breathing

Answer 11

* Somatosensory * carry sensory signals from bones, joints, muscles, and skin * proprioception: information about body position and movements from muscles, tendons, and joints * Motor * primarily to stimulate muscle contraction

Answer 12

* "Herpes Zoster" * painful trail of skin discoloration and fluid-filled vesicles along path of nerve * Chickenpox/caused by the varicella-zoster virus * Virus remains for life in the posterior root ganglia * kept in check by immune system * can pop out in elderly * Immune system is compromised: virus travels down sensory nerve

Answer 13

You can't breathe on your own (can with break below C3)

Answer 14

Causes hiccups

Answer 15

* Radial * passes through axilla * crutch paralysis: crutches too high, pressure on nerve, lose function * wrist drop: cast/wrap too tight * Sciatic * Sciatica: sharp pain that travels from gluteal region along the posterior side of the thigh and leg to ankle * usually caused by herniated intervertebral disc or osteoperosis of lower spine

Answer 16

* A specific area of skin that conveys sensory input to a spinal nerve * Dermatome map: a diagram of the cutaneous regions innervated by each spinal nerve * Dermatomes overlap their edges as much as 50%

Answer 17

* Require stimulation * Quick * Involuntary * Stereotyped * the same for everyone * Inclue glandular secretion and contraction for all 3 types of muscle * Somatic reflexes inolve the somatic nervous system innervating skeletal muscle

Answer 18

* Somatic receptors: in skin, muscles, or tendons * Afferent (sensory) nerve fibers * Integrating center * Efferent (motor) nerve fibers * Effectors: skeletal muscle * Example: patellar reflex

Answer 19

* Stretch receptors embedded in skeletal muscles * Muscle spindles inform the brain of muscle length and body movement * Enables brain to send motor commands back to the muscles that control coordinated movement, corrective reflexes, muscle tone, and posture * e.g. helps you stand upright while on a boat

Answer 20

* Stretch (myotactic) reflex: when a muscle is stretched, it "fights back" and contracts * Helps maintain equilibrium and posture * Mediated primarily by brain, sometimes spine is involved * Stabilizes joints by balancing tension between flexion/extension, etc. * Testing these helps diagnosis many diseases

Answer 21

* reflex phenomenon that prevents muscles from working against each other by inhibiting antagonist when agonist is excietd

Answer 22

* patellar tendon * flexor (withdrawal) * e.g. man stepping on a nail * ipsilateral * crossed extension reflex * e.g. man that stepped on nail maintains balance on other leg * contralateral

Answer 23

* 10,000 to 12,000 people paralyzed each year by spinal cord trauma * ^{USually vertebral fractures} * ^{Usually males 16 to 30} * ^{55% in automobile or motorcycle accidents} * Complete transection: complete severence of cord * immediate loss of motor control below level of injury * Above C4 threat of respiratory failure * Paralysis * paraplegia (lower limbs) * quadraplegic (all 4 limbs) * Hemiplegia (one side of body, strokes) * Paresis (partial paralysis or weakness of limbs)