Term
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Definition
-Information highway between brain and body
-Extends through vertebral canal from foramen magnum
-Each pair of spinal nerves receives sensory information and relays motor signals to muscles and glands |
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Term
| Spinal cord is part of the... |
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Definition
| Central nervous system (CNS) |
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Term
| Spinal nerves are part of the... |
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Definition
| Peripheral nervous system (PNS) |
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Term
| Functions of the Spinal Cord |
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Definition
1.Conduction
bundles of fibers pass information up and down
2.Locomotion
repetitive, coordinated actions of several muscle groups central pattern generators are pools of neurons providing control of flexors and extensors ie. walking
3.Reflexes
involuntary, stereotyped responses to stimuli
ie. remove hand from hot stove |
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Term
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Definition
Nerve tissue cylinder within the vertebral canal
* as thick as a finger
*in an adult the spinal cord only extends to ~L1 *31 pairs of spinal nerves Cervical, Thoracic, Lumbar and Sacral regions
*Named for level of vertebral column where nerves exit
*Medullary Cone (conus medullaris) = tapered tip *Cuada equinae- L2 to S5 Nerve roots resemble horse’s tail |
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Term
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Definition
Dura mater
Arachnoid mater
Pia mater |
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Term
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Definition
tough collagenous membrane
surrounded by epidural space
filled with fat and blood vessels
epidural anesthesia utilized during childbirth |
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Term
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Definition
| layer of simple squamous epithelium lining dura mater and loose mesh of fibers filled with CSF |
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Term
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Definition
delicate membrane adherent to spinal cord
filium terminale (terminal filum) forms part of coccygeal ligament to anchor the cord to coccyx
denticulate ligaments extend through arachnoid to dura to anchor the cord |
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Term
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Definition
Neural tube defects – birth defect due to abnormal development of the neural tube and vertebral column
One in 1000 babies
1+ vertebrae fail to form a complete neural arch for enclosure of the spinal cord
Especially common in lumbosacral region
Spina bifida cystica– sac protrudes from spine
Risk is reduced by folic acid supplements early in pregnancy |
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Term
| Gray matter of Spinal Cord |
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Definition
*Pair of dorsal or posterior horns dorsal root of spinal nerve is totally sensory fibers
*Pair of ventral or anterior horns ventral root of spinal nerve is totally motor fibers
*Connected by gray commissure punctured by a central canal |
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Term
| White matter in Spinal cord |
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Definition
White columns = bundles of myelinated axons that carry signals up and down to and from brainstem
3 pairs of columns or funiculi
dorsal, lateral, and anterior columns
Each column is filled with named tracts or fascicule fibers with a similar origin, destination and function |
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Term
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Definition
Ascending & descending tracts head up or down
Decussation means that the fibers cross sides
Contralateral - origin & destination are on opposite sides
Ipsilateral - origin & destination are on same side |
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Term
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Definition
destroys motor neurons in the brainstem and ventral horn of the spinal cord
signs - muscle pain, weakness, loss of reflexes
paralysis, muscular atrophy, respiratory arrest
spread via fecal contamination of water
vaccine has nearly eliminated new cases |
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Term
| Amyotrophic Lateral Sclerosis |
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Definition
cause unknown (maybe viral)
sclerosis of spinal cord due to astrocyte failure to reabsorb glutamate neurotransmitter
muscular weakness, difficulty speaking, swallowing
sensory and intellectual functions remain unaffected |
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Term
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Definition
a nerve is a bundle of nerve fibers(axons)
Epineurium
covers nerves
Perineurium
surrounds a fascicle
Endoneurium
separates individual nerve fibers
*Blood vessels penetrate only to the perineurium |
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Term
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Definition
31 pairs of spinal nerves (1st cervical above C1)
mixed nerves exiting at intervertebral foramen
PROXIMAL AND DISTAL BRANCHES |
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Term
| Proximal branches of spinal nerves |
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Definition
dorsal root is sensory input to spinal cord
ventral root is motor output of spinal cord
cauda equina is roots from L2 to C0 of the cord |
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Term
| Distal branches of spinal nerves |
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Definition
dorsal ramus supplies dorsal body muscle and skin
ventral ramus to ventral skin and muscles and limbs
meningeal branch to meninges, vertebrae and ligaments |
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Term
| #'s of spinal nerves (per section of vertebrae) |
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Definition
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal |
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Term
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Definition
Cervical in the neck - C1 to C5
supplies neck and phrenic nerve to the diaphragm
Brachial in the armpit - C5 to T1
supplies upper limb and some of shoulder & neck
Lumbar in the low back - L1 to L4
supplies abdominal wall, anterior thigh & genitalia
Sacral in the pelvis - L4, L5 & S1 to S4
supplies remainder of butt & lower limb
Coccygeal - S4, S5 and C0 |
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Term
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Definition
| Each spinal nerve receive sensory input from a specific area of skin called a dermatome Overlap at edges by 50% |
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Term
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Definition
Skin eruptions along path of nerve
Varicella-zoster or Herpes-zoster virus remains for life in dorsal root ganglia
Occurs after age 50 if immune system is compromised
No special treatment |
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Term
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Definition
Quick, involuntary, stereotyped reactions of glands or muscle to sensory stimulation
Automatic responses to sensory input that occur without our intent or often even our awareness |
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Term
| Reflex arc of somatic reflexes |
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Definition
stimulation of somatic receptors
afferent fibers carry signal to dorsal horn of spinal cord
one or more interneurons integrate the information
efferent fibers carry impulses to skeletal muscles
skeletal muscles respond |
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Term
| The Stretch (Myotatic) Reflex |
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Definition
When a muscle is stretched, it contracts and maintains increased tonus
helps maintain equilibrium and posture
head starts to tip forward as you fall asleep
muscles contract to raise the head
stabilize joints by balancing tension in extensors and flexors smoothing muscle actions
Very sudden muscle stretch causes tendon reflex
knee-jerk (patellar) reflex
testing somatic reflexes helps diagnose many diseases
Reciprocal inhibition prevents muscles from working against each other |
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Term
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Definition
10-12,000 people/ year are paralyzed
55% occur in traffic accidents
This damage poses risk of respiratory failure
Early symptoms are called spinal shock
Tissue damage at time of injury is followed by post-traumatic infarction |
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Term
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Definition
Intrinsic muscles are contained within a region such as the hand to
help move the hand. |
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Term
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Definition
| Extrinsic muscles move the fingers but are found outside the region, such as in the arm. |
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Term
| Responsiveness (excitability) of muscle |
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Definition
| capable of response to chemical signals, stretch or other signals & responding with electrical changes across the plasma membrane |
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Term
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Definition
| local electrical change triggers a wave of excitation that travels along the muscle fiber |
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Term
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Definition
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Term
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Definition
| capable of being extended/stretched |
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Term
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Definition
| returns to its original resting length after being stretched |
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Term
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Definition
Voluntary striated muscle attached to one or more bones
Muscle fibers (myofibers) as long as 30 cm
Exhibits alternating light and dark transverse bands or striations
Under conscious control |
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Term
| Series-Elastic Components |
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Definition
Connective tissue elements between muscle fiber and bone or other attachment
endomysium, perimysium, epimysium, fascia, tendon
Not excitable or contractile, but are extensible & elastic |
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Term
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Definition
Multiple flattened nuclei against inside of plasma membrane
-Sarcolemma has tunnel-like infoldings or transverse (T) tubules that penetrate the cell
-Sarcoplasm is filled with myofybrils (bundles of parallel protein microfilaments called myofilaments)
-Sarcoplasmic reticulum is series of dilated, calcium storage sacs called terminal cisternae |
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Term
| Regulatory & contractile proteins |
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Definition
Myosin & actin are contractile proteins
they do work of shortening the muscle
Tropomyosin & troponin are regulatory proteins
act like a switch that starts & stops shortening |
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Term
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Definition
Dark A bands alternating with lighter I bands
A band is thick filament region
I band is a thin filament region |
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Term
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Definition
Skeletal muscle must be stimulated by a nerve or it will not contract (paralyzed)
Cell bodies of somatic motor neurons are in brainstem or spinal cord
Axons of somatic motor neurons are called somatic motor fibers
Each motor neuron and all the muscle fibers it innervates are called a motor unit |
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Term
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Definition
| Synapse is region where nerve fiber makes a functional contact with its target cell (NMJ |
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Term
| Neurotransmitter Junctions |
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Definition
| Neurotransmitter released from nerve fiber causes stimulation of muscle cell (acetycholine) |
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Term
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Definition
Tetanus or lockjaw is spastic paralysis caused by toxin of Clostridium bacteria
blocks glycine release in the spinal cord & causes overstimulation of the muscles |
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Term
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Definition
| Flaccid paralysis with limp muscles unable to contract caused by curare that competes with ACh |
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Term
| Muscle Contraction & Relaxation (4 phases) |
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Definition
Excitation where action potentials in the nerve lead to formation of action potentials in muscle fiber
Excitation-contraction coupling refers to action potentials on the sarcolemma activate myofilaments
Contraction is shortening of muscle fiber or at least formation of tension
Relaxation is return of fiber to its resting length |
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Term
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Definition
Stiffening of the body beginning 3 to 4 hours after death -- peaks at 12 hours after death & diminishes over next 48 hours
Deteriorating sarcoplasmic reticulum releases calcium
Activates myosin-actin cross bridging & muscle contraction
Muscle relaxation requires ATP & ATP production is no longer produced after death
Fibers remain contracted until myofilaments decay |
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Term
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Definition
Latent period (2 msec) is delay between stimulus & onset of twitch
Contraction phase is period during which tension develops and shortens
Relaxation phase shows a loss of tension & return to resting length
Refractory period is period when muscle will not respond to new stimulus |
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Term
| Isometric Muscle Contraction |
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Definition
| develops tension without changing length |
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Term
| Isotonic Muscle Contraction |
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Definition
tension development while shortening = concentric
tension development while lengthening = eccentric |
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Term
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Definition
All muscle contraction depends on ATP
Pathways of ATP synthesis
Anaerobic fermentation (ATP production limited)
occurs without oxygen producing toxic lactic acid
Aerobic fermentation (far more ATP produced)
requires continuous oxygen supply produces H2O & CO2 |
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Term
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Definition
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•Fatigue is the progressive weakness and loss of contractility from prolonged use
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Term
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Definition
•Ability to maintain high-intensity exercise is determined by maximum oxygen uptake
•VO2 max is proportional to body size, peaks at age 20, is larger in trained athlete & males
•Depends on the supply of organic nutrients
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Term
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Definition
•Need to breathe heavily after strenuous exercise
–typically about 11 liters extra is consumed
•Purposes for extra oxygen
–Replace oxygen reserves (myoglobin, hemoglobin, in the lungs & dissolved in plasma)
–replenishing the phosphagen system
–reconverting lactic acid to glucose
–Serving the elevated metabolic ratethat occurs as long as the body temperature remains elevated by exercise
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Term
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Definition
–more mitochondria, myoglobin & capillaries
–adapted for aerobic respiration & resistant to fatigue
–soleus & postural muscles of the back
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Term
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Definition
–rich in enzymes for phosphagen & glycogen-lactic acid systems
–sarcoplasmic reticulum releases calcium quickly
–gastrocnemius muscle
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Term
Factors that increase strength of contraction
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Definition
–muscle size and fascicle arrangement
–Size of motor units and motor unit recruitment
–frequency of stimulations
–length of muscle at start of contraction and fatigue
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Term
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Resistance training (weight lifting)
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Definition
Anaerobic
–stimulates cell enlargement due to synthesis of more myofilaments -- some cell splitting may occur
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Term
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Definition
Aerobic
–produces an increase in mitochondria, glycogen & density of capillaries
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Term
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Definition
•In comparison to skeletal muscle, the cells are shorter, thicker, branched and linked to each other at intercalated discs
•Autorythmic due to pacemaker cells
•Uses aerobic respiration almost exclusively
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Term
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Definition
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•Fusiform cells with one nucleus
•Nerve supply is autonomic, if any is present
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Term
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Definition
•Group of hereditary diseases in which skeletal muscles degenerate & are replaced with
•Mainly a disease of males
–appears as child begins to walk
–rarely live past 20 years of age
•Normal allele makes dystrophin, a protein that links actin filaments to cell membrane
–absence of dystrophin leads to torn cell membranes
Fascioscapulohumeral MD -- facial & shoulder muscle only |
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Term
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Definition
•Autoimmune disease where antibodies attack NMJ and bind ACh receptors together in clusters
–fibers remove the receptors
–less and less sensitive to ACh
•Drooping eyelids and double vision
•difficulty swallowing
•weakness of the limbs
•Respiratory failure
•Disease of women between ages of 20 and 40
•Treated with cholinesterase inhibitors, thymus removal or immunosuppressive agents
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Term
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Definition
•Vulnerable to sudden and intense stress
•Proper conditioning and warm-up is needed
•Common injuries
–shin splints
–pulled hamstrings
–Tennis-elbow (lateral epicondylitis)
•Treat initially with rest, ice, compression and elevation
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