Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Chapter 14
Anatomy
| Question | Answer |
|---|---|
| How many inches in diameter is a typical adult spinal cord? | 3/4 of an inch |
| How many centimeters (in length) is a typical spinal cord? | between 42 and 45 centimeters |
| Where does the spinal cord extend from and to? | inferiorly from the medulla oblongata of the brain through the vertebral canal and ends at the inferior border of the L1 vertebra |
| What is the conus medullaris? | the tapering inferior end of the spinal cord |
| What marks the official "end" of the spinal cord proper? | the conus medullaris |
| How many enlargements of the spinal cord are visible in the surface view of the spinal cord? | two |
| What are the (2) enlargements of the spinal cord? | the cervical enlargement and the lumbosacral enlargement? |
| What is the cervical enlargement? | is an enlarged region of the inferior cervical part of the spinal cord |
| What is the lumbosacral enlargement? | is an enlarged region f the mid-lumbar part of the spinal cord. |
| Which enlargement contains the neurons that innervates the upper limbs? | cervical enlargement |
| Which enlargement contains the neurons that innervates the lower limbs? | lumbosacral enlargement |
| The spinal cord is subdivided into how many parts? | five |
| How many pairs of spinal nerves are there? | 31 |
| What are the five parts of the spinal cord? | the cervical part, the thoracic part, the lumbar part, the sacral part, and the coccygeal part. |
| What is the cervical part of the spinal cord? | superiormost part of the spinal cord, it is continuous with the medulla oblongata, contains neurons whose axons contribute to the 8 pairs of cervical spinal nerves |
| What is the thoracic part of the spinal cord? | lies inferior to the cerical part of the spinal cord, it contains the neurons for the 12 pairs of thoracic spinal nerves |
| What is the lumbar part of the spinal cord? | is a shorter segment of the spinal cord that contains the neurons for the 5 pars of lumbar spinal nerves |
| What is the sacral part of the spinal cord? | lies inferior to the lumbar part and contains neurons for the 5 pairs of sacral spinal nerves |
| What is the coccygeal part of the spinal cord? | is the most inferior tip of the spinal cord, one pair of coccygeal spinal nerves arises from this part |
| Why do the different parts of the spinal cord not match up exactly with the vertebrae of the same name? | this is due to the fact that the vertebrae growth continued longer than the growth of the spinal cord itself |
| Thus, the spinal cord in an adult is (shorter, longer) than the vertebral canal that houses it. | shorter than |
| What are the cauda equine? | the rootlets of the more inferior spinal nerves including L2-L5, S1-S5, and Co1 extend inferiorly from the conus medullaris |
| Why are the cauda equine called that? | because they resemble a horse's tail |
| What is the filum terminale and where is it located? | is a thin strand of pia mater that helps anchor the conus medullaris to the coccyx, it is located within the cauda equina |
| How are spinal nerves identified? | by the first letter of he spinal cord part to which it attaches combined with a number |
| How are cranial nerves identified? | designated by CN followed by a roman numeral |
| How many cervical nerves are there and what are they? | 8 cervical nerves called C1-C8 |
| How many thoracic nerves are there and what are they? | 12 thoracic nerves called T1-T12 |
| How many lumbar nerves are there and what are they? | 5 lumbar nerves called l1-l5 |
| How many sacral nerves are there and what are they? | 5 sacral nerves called S1-S5 |
| How many coccygeal nerves are there and what are they? | 1 coccygeal nerve called CO1 |
| What are the characteristics of the spinal nerve? | it is roughly cylindrical but slightly flattened both posteriorly and anteriorly, its external surface has two longitudinal depressions: a narrow groove, the posterior median sulcus and the anterior median fissure. |
| Where is the posterior median sulcus located? | dips internally on the posterior surface; and a slightly wider groove |
| Where is the anterior median sulcus located? | seen on its anterior surface |
| Why are the spinal cord parts that control the upper and lower limbs are larger? | because more neuron cell bodies are located there, and more space is occupied by axons and dendrites |
| The spinal cord is protected and encapsulated by what? | spinal cord meninges |
| What are the spinal cord meninges? | pia mater, subarachnoid space, arachnoid mater, subdural space, dura mater, and epidural space |
| Characteristics of pia mater | directly adheres to the spinal cord, it is the delicate, innermost meningeal layer, which is composed of elastic and collagen fibers that support that some of the blood vessels supplying the spinal cord |
| What are denticulate ligaments? | paired, lateral triangular extensions of the spinal pia mater that attach to the dura mater |
| What is the function of the denticulate ligaments? | to help suspend and anchor the spinal cord laterally |
| Characteristics of the arachnoid mater | lies external to the pia mater, is partially composed of a delicate web of collagen and elastic fibers called the arachnoid trabeculate |
| Characteristics of subarachnoid space | lies immediately deep to the arachnoid, cerebrospinal fluid circulates In this space (both around the spinal cord and around the brain) |
| What is the subdural space? | a potential space between the arachnoid and overlying dura mater |
| What is the outermost layer of the meninges? | dura mater |
| Characteristics of the dura mater | composed of dense irregular connective tissue, consists of just one layer, the dura mater extends between adjacent vertebrae and fuses with the connective tissue layers that surround the spinal nerves |
| What is the function of the dura mater? | provides stability to the spinal cord |
| Where is the epidural space located? | lies between the dura mater and the inner walls of the vertebra, and houses adipose and areolar connective tissues, and blood vessels |
| What is the gray matter consisted of? | neuron cell bodies, dendries, glial cells, and unmyelinated axons |
| What is the white matter consisted of? | primarily of myelinated axons that extend to and from the brain |
| Where is the gray matter in the spinal cord located? | centrally located |
| The shape of the gray matter resembles what? | H or a butterfly |
| What components may the gray matter be subdivided into? | anterior horns, lateral horns, posterior horns, and the gray commissure |
| What are anterior horns? | the left and right anterior masses of gray matter |
| Where is the function of the anterior horns? | primarily houses the cell bodies of somatic motor neurons, which innervate skeletal muscle |
| Where are lateral horns located? | t1-L2 parts of the spinal cord only. |
| What is the function of the lateral horn? | contain the cell bodies of autonomic motor neurons, which innervate cardiac muscle, smooth muscle, and glands. |
| What are posterior horns? | left and right posterior masses of gray matter |
| What are the posterior horns composed of? | axons of sensory neurons and the cell bodies of interneurons |
| What is the gray commissure? | horizontal bar of gray matter that surrounds a narrow central canal |
| What does the gray commissure primarily contain? | unmyelinated axons |
| What is the function of the gray commissure? | serves as a communication route between the right and left sides of the gray matter |
| What is the function of sensory nuclei? | contain interneuron cell bodies |
| What is the function of somatic sensory nuclei? | receive nerve signals from sensory receptors (e.g., pain or pressure receptors in the skin) |
| What is the function of visceral sensory nuclei? | receive nerve signals from blood vessels and viscera (e.g., stretched smooth muscle within viscera) |
| What is the function of motor nuclei? | contain motor neuron cell bodies that send nerve signals to muscles and glands. |
| What is the function of somatic motor nuclei? | innervate skeletal muscle |
| What is the function of autonomic motor nuclei? | innervate smooth muscle, cardiac muscle, and glands |
| How many regions is the white matter of the spinal cord portioned into? | three |
| What are the (3) regions of the white matter of the spinal cord? | posterior funiculus, lateral funiculus, and anterior funiculus |
| Where does the posterior funiculus lie? | between the posterior gray horns on the posterior side of the cord and the posterior median sulucs |
| Where does the lateral funiculus lie? | the white matter on each lateral side of the spinal cord |
| Where does the anterior funiculus lie? | occupies the space on each anterior side of the cord between the anterior gray horns and the anterior median fissure |
| What are tracts? | the axons within each white matter funiculus are organized into these smaller structural units |
| Nervous system pathways are either ____ or _____. | sensory or motor |
| What are sensory pathways also called and why? | ascending pathways because the nerve signals transmitted from sensory receptors ascend through the spinal cord to the brain |
| What are motor pathways also called and why? | descending pathways because they transmit nerve signals that descend from the brain through the spinal cord to muscles or glands |
| What are the general characteristic that most nervous system pathways share? | common location of neuron components, composed of two or more neurons, paired tracts, and decussation |
| What does contralateral mean? | indicate the relationship to the opposite side |
| ipsilateral | means the same side |
| Most pathways are what? | decussate |
| What are sensory pathways? | ascending pathways that relay sensory input from receptors to the brain |
| What does sensory input do to the brain about limb proprioception, touch, temperature, pressure, and pain? | informs |
| Sensory pathways are organized into two categories that are dependent upon the type of receptor involved, what are they? | somatosensory pathways and viscerosensory pathways |
| Describe primary neuron or first-order neuron | the cell body of a primary neuron resides in the posterior root ganglion of a spinal nerve, and the axon extends to a secondary neuron |
| Describe secondary neuron or second-order neuron | is an interneuron that extends from the primary neuron to either the tertiary neuron or to the cerebellum |
| Describe tertiary neuron or third-order neuron | is also an interneuron that extends from the secondary neuron to the cerebrum |
| Pathways that lead to the cerebellum (do, do not) have a tertiary neuron. | Do not |
| What are the three major types of somatosensory pathways? | posterior funiculus-medial lemniscal pathway, anterolateral pathway, and the spinocerebellar pathway |
| What is the function of the posterior funiculus-medial lemniscal pathway? | relays sensory input through the fasciculus gracilis and fasciculus cuneatus |
| What is the function of the anterolateral pathway? | relays sensory input through the lateral and anterior spinothalamic tracts |
| What is the function of the spinocerebellar pathway? | relays sensory input through the lateral and anterior spinocerebellar tracts |
| What are motor pathways or descending tracts? | are descending pathways in the brain and spinal cord that control effectors |
| At least two motor neurons are present in the motor pathway, what are they? | one upper motor neuron and one lower motor neuron |
| Where is the cell body of the upper motor neuron housed? | either within the cerebral cortex, cerebral nuclei, or a nucleus within the brainstem |
| What are the functions of upper motor neurons? | they either excite or inhibit the activities of lower motor neurons |
| Where is the cell body of the lower motor neuron housed? | either within the anterior horn of the spinal cord or within a brainstem cranial nerve nucleus |
| What is the function of the lower motor neuron? | always excitatory because its axon connects directly to the skeletal muscle fibers |
| What are the two types of motor pathways that motor neurons form? | the direct pathway and the indirect pathway |
| What are the direct pathway responsible for? | conscious control of skeletal muscle activity |
| What are the indirect pathway responsible for? | subconscious or reflexive control of skeletal muscle |
| Where do the corticobulbar tracts originate from? | the facial region of the motor homunculus within the primary motor cortex |
| What does the term bulbar mean? | resembling a bulb and is used to indicate the embryonic rhombencephalon in the brainstem |
| Axons of the lower motor neurons of the corticobulbar tracts differ from the others because what? | (1) they do not pass through the spinal cord (2) they involve cranial nerves and not spinal nerves |
| Where do the corticospinal tracts descend? | from the primary motor cortex of the cerebrum through the medulla oblongata and into the spinal cord where they synapse on lower motor neurons in the anterior horn of the spinal cord |
| What two components are the corticospinal tracts composed of? | the lateral and anterior corticospinal tracts |
| In what ways do the lateral and anterior corticospinal tracts differ? | including their point of crossing-over or decussation, their location within the spinal cord, and the specific muscles that they innervate and control |
| What percent of the axons of the upper motor neurons that decussate within the pyramids of the medulla oblongata do the lateral corticospinal tracts include? | about 85% |
| Axons of the lower motor neurons of the lateral corticospinal tracts innervate what muscles that do what? example? | skeletal muscles that control skilled movements in the limbs, such as playing a guitar, dribbling a soccer ball, or typing on your computer keyboard |
| What tracts represent that remaining 15% of the axons of upper motor neurons that extend through the medulla oblongata? | the anterior corticospinal tracts |
| Axons of the lower motor neurons innervate what kind of muscle? | axial skeletal muscle |
| Why is the indirect pathway named that? | because upper motor neurons originate within brainstem nuclei and take a complex, circuitous route through the brain to the spinal cord |
| What is the function of the indirect pathway? | modifies or helps control the pattern of somatic motor activity by exciting or inhibiting the lower motor neurons that innervate the muscles |
| What is the function of the lateral pathway? | regulates and control precise, discrete movements and tone in flexor muscles of the limbs - for example, the type of movements required to gently lay a baby in a crib |
| The lateral pathway consists of what tract? | the rubrospinal tracts that originate in the red nucleus of the midbrain |
| What is the function of the medial pathway? | regulates reflexive muscle tone and gross movements of the muscles of the head, neck, proximal parts of the limbs, and trunk |
| The medial pathway consists of what three groups of tracts? | reticulospinal tracts, tectospinal tracts, and vestibulospinal tracts |
| Where do the reticulospinal tracts originate from? and what do they do? | the reticular formation in the midbrain and they help control reflexive movements related to posture and maintaining balance |
| What do the tectospinal tracts do? | conduct motor output from the superior and inferior colliculi in the tectum of the midbrain to help regulate reflexive positional changes of the upper limbs, eyes, head, and neck as a consequence of visual and auditory stimuli. |
| Where do the vestibulospinal tracts originate from? | within vestibular nuclei of the brainstem and nerve signals conducted within these tracts regulate reflexive muscular activity that helps maintain balance during sitting, standing, and walking. |
| Each spinal nerve is formed by two roots - what are they? | anterior root and posterior root |
| What do each anterior roots or ventral roots contain? | motor axons only |
| What are anterior roots or ventral roots formed by? | is formed from the merging of multiple anterior rootlets |
| The posterior root or dorsal root contains what? | contains sensory axons only |
| What are posterior roots or dorsal roots formed by? | from the merging of multiple posterior rootlets |
| Where are the cell bodies of these sensory neurons located? | posterior rot ganglion |
| All spinal nerves are what kind of nerves? Why? | mixed nerves because each spinal nerve contains both motor axons and sensory axons |
| What is the smaller of the two main branches of the spinal nerves? | the posterior ramus |
| What is the function of the posterior ramus? | innervates the muscles of the deep back and the skin of the back |
| What is the larger of the two main branches of the spinal nerves? | the anterior ramus |
| What is a dermatome? | a specific segment of skin innervated by a single spinal nerve |
| What is the only spinal nerve that is not innervated by a segment of skin? | c1 |
| Why are dermatomes clinically important? | because they can indicate potential damage to one or more spinal nerves |
| What is referred visceral pain? | a phenomenon in which pain or discomfort from one organ is mistakenly referred to a dermatome |
| What is a nerve plexus? | a network of interweaving anterior rami of spinal nerves |
| What are the main plexuses? | the cervical plexuses, brachial plexuses, lumbar plexuses, and sacral plexuses |
| Damage to a single segment of the spinal cord or damage to a single spinal nerve generally (does, does not) result in complete loss of innervation to a particular muscle or region of skin | does not |
| Most of what spinal nerves do not form plexuses? | thoracic spinal nerves as well as nerves S5-CO1 |
| What are the intercostal nerves? and why? | The anterior rami of spinal nerves T1-T11 because they travel in the intercostal space sandwiched between two adjacent ribs |
| What is T12 called and why? | subcostal nerve because it arises inferior to the ribs, not between two ribs |
| With the exception to what nerve, intercostal nerves do not form plexuses. | T1 |
| Where are the left and right cervical plexuses located? | deep on each side of the neck |
| What are the left and right brachial plexuses? | networks of nerves that supply the upper limb |
| What is each brachial plexus formed by? | the anterior rami of spinal nerves C5-T1 |
| Structurally, each brachial plexus is (more, less) complex than a cervical plexus. | more |
| The five rami unite in the posterior triangle of the neck to form what? | the superior, middle, and inferior trunks |
| What are the five major terminal branches that emerge from the three cords? | the axillary nerve, median nerve, musculocutaneous nerve, radial nerve, and ulnar nerve |
| What is the function of the axillary nerve? | receives sensory nerve signals from the superolateral part of the arm |
| What is the function of the median nerve? | it receives sensory nerve signals from the palmar side of the lateral 3 1/2 finger and from the dorsal tips of these same fingers |
| What is the function of the musculocutaneous nerve? | also receives sensory information from the lateral surface of the forearm |
| What is the function of the radial nerve? | receives sensory nerve signals from the posterior arm and forearm surface and the dorsolateral side of the hand |
| What is the function of the ulnar nerve? | receives sensory input from the skin of the dorsal and palmar aspect of the medial 1 1/2 fingers |
| What is the main nerve of the posterior division of the lumber plexus? | the femoral nerve |
| What is the function of the femoral nerve? | receives sensory input from the anterior and inferomedial thigh as well as the medial aspect of the leg |
| What is the main nerve of the anterior division of the lumbar plexus? | the obturator nerve |
| What is the function of the obturator nerve? | receives sensory input from the superomedial skin of the thigh |
| The lumbar and sacral plexuses are sometimes considered together as what? | the lumbosacral plexus |
| The nerves that are formed from the anterior division tend to innervate muscles do what? | that flex parts of the lower limbs |
| The nerves that are formed from the posterior division tend to innervate muscles that do what? | that extend parts of the lower limbs |
| What is the largest and longest nerve in the body? | the sciatic nerve also known as the ischiadic nerve |
| What forms the sciatic nerve? | portions of both the anterior and posterior divisions of the sacral plexus |
| What two divisions is the sciatic nerve actually composed of? | the tibial division and the common fibular division |
| What is the tibial nerve formed from ? | the anterior divisions of the sciatic nerve |
| What is the common fibular nerve formed from? | posterior division of the sciatic nerve |
| The common fibular divides into what two divisions? | the deep fibular nerve and the superficial fibular nerve |
| What is the function of the deep fibular nerve? | this nerve receives sensory input from the skin between the first and second toes on the dorsum of the foot |
| What is the function of the superficial fibular nerve? | receives sensory input from most of the dorsal surface of the foot and the anteroinferior part of the leg |
| What are reflexes? | rapid, preprogrammed, involuntary responses of muscles or glands to a stimulus |
| What is an example of a reflex? | when you accidentally touch a hot burner on a stove, you immediately remove your hand from the stimulus, even before you are completely aware that your hand was touching something extremely hot. |
| A stimulus: | required to initiate a reflex |
| A rapid response: | requires that few neurons are involved and synaptic delay is minimal |
| A preprogrammed response: | occurs the same way every time |
| An involuntary response: | requires no conscious intent or preawareness of the reflex activity thus, reflex are usually not suppressed |
| What is a reflex considered and why? | a survival mechanism because it allows us to quickly respond to a stimulus that may be detrimental to our well-being without having to wait for the brain to process the information |
| What does a reflex arc include? | a sensory receptor, an effector, and the neural "wiring" between the two |
| How many steps are involved in a reflex? | 5 |
| Step 1: | A stimulus activates a sensory receptor |
| Step 2: | The sensory neuron transmits a nerve signal to the CNS |
| Step 3: | Information from the nerve signal is processed in the integration center by interneurons |
| Step 4: | The motor neuron transmits a nerve signal from the CNS to an effector |
| Step 5: | The effector responds to the nerve signal from the motor neuron |
| How many different ways of classifying a reflex? | 5 |
| The first way to classify a reflex? | Spinal reflex or cranial reflex |
| The second way to classify a reflex? | Somatic reflex or visceral reflex |
| The third way to classify a reflex? | Monosynaptic reflex or polysynaptic reflex |
| The fourth way to classify a reflex? | Ipsilateral reflex or contralateral reflex |
| The fifth way to classify a reflex? | Innate reflex or acquired reflex |
| Spinal reflexes involve what? | the spinal cord |
| Cranial reflexes involve what? | the brain |
| Somatic reflexes involve what? | skeletal muscle as the effector |
| Visceral reflexes involve what? | cardiac muscle, smooth muscle, or a gland as the effector |
| What is the characteristic of a monosynaptic reflex? | has only a sensory neuron and motor neuron |
| What are the simplest and most rapid reflexes? | monosynaptic reflexes |
| What is the characteristic of a polysynaptic reflex? | has one or more interneurons positioned between the sensory and motor neuron |
| What are the more complicated and not as rapid reflexes? | polysynaptic reflexes |
| What is an ipsilateral reflex? | where both the receptor and effector organs are on the same side of the spinal cord |
| What is a contralateral reflex? | reflex that involves an effector on the opposite side of the body of the receptor that detected the stimulus |
| What is an innate reflex? | reflex that you are born with |
| What is an acquired reflex? | is one that you developed after birth |
| What are some common spinal reflexes? | the stretch reflex, the Golgi tendon reflex, the withdrawal reflex, and the crossed-extensor reflex |
| What two reflexes are initiated by a proprioceptor? | the stretch reflex and the Golgi tendon reflex |
| What is a proprioceptor and what does it do? | resides in a muscle or tendon and detects any change to that structure, such as change in stretch or tension |
| What are the two principal proprioceptors? | the muscle spindle and the Golgi tendon organ |
| What is a muscle spindle? | a proprioceptor that detects changes in stretch of a muscle |
| Why are gamma motor neurons named that? | because the term gamma refers to motor neurons with small diameter axons |
| What do gamma motor neurons detect? | changes within the muscle |
| Why are alpha motor neurons named that? | because these motor neurons have the largest diameter axons |
| What is a stretch reflex? | a muscle reflexively contracting in reponse to stretching of a muscle |
| What is an example of a stretch reflex? | biceps reflex |
| What kind of reflex is the Golgi tendon reflex? | a polysynaptic reflex |
| What does a withdrawal reflex involve? | muscles contracting to withdraw the body part away from a painful stimulus |
Created by:
1750649968530372