HHS 271 - Exam 2 Study Guide (Final Revision)

HHS 271 - Exam 2 Study Guide (Final Revision)

spinal cord

What is enclosed in the vertebral column?

foramen magnum; L1/L2 vertebra

Where does the spinal cord begin and end?

conus medullaris

What is the ending of the spinal cord called?

cushion of fat and network of veins in space between vertebrae and spinal dura mater

What is epidural space?

Dural and arachnoid membranes extended at sacrum, beyond end of SC at L1/L2

Where is the site of lumbar puncture?

31

How many spinal nerves are there?

Collection of nerve roots at inferior end of vertebral anal (nerves after L1/L2)

What is the cauda equina?

Ventral (anterior) median fissure; dorsal (posterior) median sulcus

What are the two lengthwise grooves that run length of cord partially and divided it into right and left halves?

dorsal horns, ventral horns, lateral horns

What are three areas of gray matter found in the spinal cord?

the bridge of gray matter that connects masses of gray matter of either side and encloses the central canal

What is the gray commissure?

bundle of motor neuron axons that exit the spinal cord

What are ventral roots?

roots that provide sensory input to cord

What are dorsal roots?

cell bodies of sensory neurons

What are the dorsal root ganglia?

nerves formed by fusion of dorsal and ventral roots

What are spinal nerves?

Somatic sensory (SS), visceral sensory (VS), visceral motor (VM), somatic motor (SM)

What four groups is gray matter divided into?

ascending (sensory), descending (motor), transverse (commissural fibers)

What three directions does white matter run?

dorsal, lateral, and ventral

What three white columns (funiculi) is white matter divided into?

Damage to dorsal roots, results in sensory function loss

What is paresthesia?

Damage to ventral roots, results in motor function loss

What is paralysis?

Flaccid, spastic

What are the two types of paralysis?

Damage to ventral root/ventral horn; impulses do not reach muscles

What is flaccid paralysis?

Damage to upper motor neurons of primary motor cortex; spinal neurons remain intact; muscles are constantly being stimulated

What is spastic paralysis?

Spinal pathways crossing from one side of CNS to another side

What is decussation?

Consists of a chain of two or three neurons

What is a relay?

Precise spatial relationship in CNS that corresponds to spatial relationship in body

What is somatotopy?

Spinal pathways are paired symmetrically

What is symmetry?

Starting point of impulse; synapses w/ second-order neuron

What is a first-order neuron?

Interneuron; cell body in dorsal horn/medullary nuclei; axons extend to spinal cord, thalamus, or cerebellum

What is a second-order neuron?

Interneuron; cell bodies in thalamus; axon extends to somatosensory cortex

What is a third-order neuron?

Dorsal column-medial lemniscal pathway, spinothalamic pathways

What two pathways transmit somatosensory information to sensory cortex via thalamus?

Spinocerebellar tracts

What pathway is terminated in the cerebellum?

Transmits input for discriminative touch and vibrations; contains fasciculus components

What does the dorsal column-medial lemniscal pathway do?

Transmit pain, temperature, coarse touch, and pressure impulses

What do spinothalamic pathways do?

Ventral and dorsal tracts; convey information about muscle/tendon stretch to cerebellum; used to coordinate muscle activity

What do spinocerebellar tracts do?

Direct pathways (pyramidal tracts) and indirect pathways (everything else)

What are the two groups of descending pathways?

Upper motor neurons (pyramidal cells in primary motor cortex), lower motor neurons (ventral horn motor neurons)

What are the two neurons involved in motor pathways?

Pathways with no stops until impulse reaches innervated muscle; regulate fast/skilled movements

What are direct/pyramidal pathways?

Pathways with stops; regulate axial muscles, coarse limb movements, head, neck, eye movements

What are indirect/multineural pathways?

Reticulospinal, vestibulospinal, rubrospinal, tectospinal tracts

What are the four major indirect pathways?

Turning the head so eyes can follow moving object

What is function of tectospinal tracts?

Motor impulse transmission that maintain muscle tone; help maintain balance during standing and moving

What is the function of vestibulospinal tracts?

Controls muscle tone of distal limb muscles; largely assumed by corticospinal tracts

What is the function of rubrospinal tract?

Transmit impulses concerned with muscle tone and many visceral motor functions

What is the reticulospinal tract?

1. Ectoderm thickens, forming neural plate; forms neural groove flanked by neural folds
2. Neural crest forms from migrating neural fold cells
3. Neural groove deepens, edges fuse forming neural tube

...

neuromuscular disability involving poorly controlled/paralyzed voluntary muscles

What is cerebral palsy?

Cerebrum and parts of brain stem never develop because of neural fold fusion failure; child is vegetative and dies soon after birth

What is anencephaly?

Incomplete formation of vertebral arches; typically involves lumbosacral region

What is spina bifida?

Receptors that are specialized to respond to changes in environment

What are sensory receptors?

type of stimulus, body location, structural complexity

What are the three ways to classify receptors?

Receptors that respond to touch, pressure, vibration and stretch

What are mechanoreceptors?

Receptors that are sensitive to changes in temperature

What are thermoreceptors?

Receptors that respond to light energy

What are photoreceptors?

Receptors that respond to chemicals

What are chemoreceptors?

Receptors that are sensitive to pain-causing stimuli

What are nociceptors?

Receptors that respond to stimuli arising outside body

What are exteroceptors?

Visceroreceptors; respond to stimuli arising in internals

What are interoceptors?

Receptors that respond to stretch in muscles, joints, ligaments; inform brain of movements

What are proprioceptors?

Receptors that monitor general sensory info; found throughout body

What are simple receptors of the general senses?

Receptors that monitor vision, hearing, equilibrium, smell, taste; housed in complex sense organs

What are receptors for special senses?

Encapsulated nerve endings are encased in a connective tissue capsule

What is the difference between nonencapsulated and encapsulated nerve endings?

Spindle-shaped proprioceptors that respond to muscle stretch

What are muscle spindles?

Proprioceptors located in tendons that detect stretch

What are tendon organs?

sensation and perception

What are the two things that survival depends upon?

Part of sensory system that supports the body wall and limbs

What is the somatosensory system?

1. Receptor level
2. Circuit level
3. Perceptual level

What are the 3 levels of neural integration in sensory system?

Pain from one body region that is perceived as coming from different region; visceral and somatic pain fibers travel along the same nerves

What is referred pain, and why does it happen?

Loose connective tissue that surrounds each axon their myelin sheath

What is the endoneurium?

Coarse connective tissue that binds groups of axons into groups called fascicles

What is the perineurium?

Touch fibrous sheath around all fascicles to form the nerve

What is the epineurium?

Nervous system's ability to reorganize itself by forming new neural connections

What is neuroplasticity?

length of muscle (spindle) and amount of tension in muscle (tendon)

What two pieces of information must the nervous system have to smoothly coordinate skeletal muscle?

Automatic withdrawal of threatened body part; ipsilateral and polysynaptic

What is flexor/withdrawal reflex?

Flexor reflexes in weight-bearing limbs to maintain balance

What is crossed extensor reflex?

dorsal ramus, ventral ramus, meningeal branch

What three ways are spinal nerves divided?

Connect spinal cord to spinal nerve

What do rami do?

Roots lie medial to and form spinal nerves - each root is purely sensory or motor; Rami lie distal to and are lateral branches of spinal nerves - can carry both sensory and motor

What is the difference between roots and rami?

Interlacing networks in all ventral rami (except Thoracic region)

What are nerve plexuses?

Five ventral rami (C5-T1) that unite to form trunks, divisions, and cords

What are the roots of the brachial plexus?

8 pairs of cervical nerves
12 pairs of thoracic nerves
5 pairs of lumbar nerves
5 pairs of sacral nerves
1 pair of tiny coccygeal nerves

What are the 31 pairs of spinal nerves divided into?

Ventral rami: C1-C4, some C5
Phrenic nerve

What are the characteristics of the cervical plexus?

Ventral rami: C5-T1
Axillary, musculocutaneous, median, radial, ulnar nerves

What are the characteristics of the brachial plexus?

Ventral rami: L1-L4
Femoral, obturator nerves

What are the characteristics of the lumbar plexus?

Ventral rami: L4-S4
Sciatic nerve

What are the characteristics of the sacral plexus?

12 pairs; two attach to forebrain, and the rest with brain stem

How many cranial nerves are there?

Smooth muscles, cardiac muscles, glands

What does the autonomic nervous system innervate?

Parasympathetic and sympathetic division

What are the two arms of the autonomic nervous system?

When visceral organs are innervated by both parasympathetic and sympathetic nerves

What is dual innervation?

PS: maintenance, energy conservation
S: body mobilization during activity

What does the parasympathetic division and sympathetic division do?

Rest-and-digest

Is the parasympathetic division rest-and-digest or fight-or-flight?

Fight-or-flight

Is the sympathetic division rest-and-digest or fight-or-flight?

Brain & sacral spinal cord (craniosacral)

Where do parasympathetic fibers originate?

Thoracic & lumbar regions of spinal cord (thoracolumbar T1-L2)

Where do sympathetic fibers originate?

vision, taste, smell, hearing, equilibrium

What are the five special senses of the body?

External (hearing), middle (hearing), internal ear (hearing and equilibrium)

What are the three major areas of the ear?

The boundary in between the external and middle ears; vibrates in response to sound; transfers sound energy to bones in middle ear

What is the tympanic membrane?

bony labyrinth, membranous labyrinth

What are the two divisions of the internal ear?

Vestibule, semicircular canals, cochlea

What are the three regions of the bony labyrinth?

Egg-shaped cavity of bony labyrinth that functions as equilibrium; contains utricle and saccule sacs

What is the vestibule of the internal ear?

Equilibrium receptor regions that respond to gravity and changes in position of head

What are maculae?

Functions as equilibrium; three canals; contains ampulla and crista ampullaris

What are the semicircular canals of the ear?