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
Ch. 14 (15)
The Nervous System III: The Peripheral Nervous System (PNS)
| Question | Answer |
|---|---|
| PNS consists of the nervous system structures | outside the brain and spinal cord |
| the nerves thread through | almost every part of the body |
| nerves | cord-like organs in the PNS consisting of many axons arranged in parallel bundles which are enclosed by successive wrappings of CT |
| epineurium | external tough fibrous CT sheath surrounding a whole nerve, which consists of several fascicles and blood vessels |
| fascicles | bundles of neuronal axons |
| perineurium | CT surrounding each fascicle |
| the perineurium forms the | nerve-blood barrier |
| endoneurium | delicate CT fibers that surround the individual axons of fascicles |
| most nerves are | mixed, carrying both sensory and motor axons |
| the CNS is connected to the | PNS via cranial and spinal nerves |
| the PNS is further subdivided into two divisions | sensory and motor divisions |
| the sensory (afferent) division contains | somatic and visceral sensory areas |
| the motor (efferent) division contains | somatic, branchial, and visceral motor areas |
| the visceral motor areas comprise the | autonomic nervous system (ANS) and the brachial motor division |
| the ANS is further categorized into two functional divisions that serve | most of the same organ but generally cause opposing or antagonistic effects |
| the divisions of the ANS are | parasympathetic and sympathetic |
| parasympathetic | rest and digest |
| sympathetic | fight or flight division |
| basic structural components of the PNS | sensory receptors, motor endings, nerves, ganglia |
| peripheral sensory receptors pick up | stimuli from inside and outside the body then initiate impulses in sensory axons |
| the two main categories of peripheral sensory receptors | dendritic endings of sensory neurons and complete receptor cells |
| complete receptor cells = | specialized epithelial cells or small neurons that transfer special senses info |
| receptors may be classified by the | location of their stimuli, they type of stimuli detected and their structure |
| peripheral motor endings | axon terminals of motor neurons that innervate effectors |
| effectors are | muscles and glands |
| innervation of skeletal muscles - neuromuscular junctions are also known as | motor end plates and are one junction associated with each muscle fiber |
| ACh is the | neurotransmitter that diffuses across the synaptic cleft and binds to receptors on the sarcolemma |
| ACh induces | impulses which signal the muscle cell to contract |
| motor unit | a motor neuron innervating muscle fibers |
| innervation of visceral muscle and glands - simpler arrangement | near the smooth muscle or gland cells that are innervated, a motor axon swells into a row of VARICOSITIES(knobs) which contain synaptic vesicles filled with neurotransmitters |
| peripheral nerves and ganglia | cranial nerves and spinal nerves |
| ganglion | cluster of peripheral cell bodies |
| dorsal root ganglion | PNS ganglion containing the cell bodies of sensory neurons |
| spinal nerves | 31 pairs of spinal nerves arise from and span the length of the spinal cord |
| 31 pairs = | 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal |
| the first branch of each spinal nerve in the thoracic and upper lumbar regions become the...which contains...that continue to an | white ramus ... myelinated PREganglionic axons...autonomic ganglion |
| two groups of...exit the dorsal root ganglion which are.... | unmyelinated fibers...gray ramus and the autonomic nerve |
| gray ramus | carries axons that innervate glands and smooth muscles in the body wall or limbs back to the spinal nerve |
| autonomic nerve | carries fibers (axons) to internal organs |
| rami communicates the | white and gray rami, which collectively carry visceral motor fibers to and from a nearby autonomic ganglion associated with the sympathetic division of the ANS |
| T1-L2's spinal nerves have four branches | white ramus, gray ramus, dorsal ramus, ventral ramus |
| each spinal nerve connects to the spinal cord via | a dorsal root and a ventral root |
| a dorsal root contains | sensory fibers arising from cell bodies in a dorsal root ganglion |
| a ventral root contains | motor fibers arising from cell bodies in the anterior horn of the spinal cord |
| together these sensory and motor fibers | converge and exit the vertebral column as spinal nerves, which branch out as the dorsal ramus and the ventral ramus |
| dorsal ramus supplies | dorsum of the neck and trunk and specific segment of the skin |
| ventral ramus supplies | anterior and lateral regions of neck and trunk and all regions of the limbs |
| together the dorsal and ventral rami supply | somatic regions from the neck inferiorly |
| each pair of spinal nerves monitors a | specific region of the body surface (dermatome) |
| dermatome | an area of skin innervated by the cutaneous branches from a single spinal nerve |
| dermatomes are clinically important because | damage to either a spinal nerve or DRG will produce a characteristic loss of sensation in specific areas of the skin |
| nerve plexuses are | complex, interwoven networks of nerves formed by the ventral rami only |
| nerve plexus occurs as | pairs in the cervical, brachial, lumbar, and sacral regions |
| nerve plexus primarily serves the | limbs |
| cervical plexus | neck, is buried deep in the neck, under the sternocleidomastoid muscle |
| the cervical plexus is formed by | the ventral rami of C1-C4 and some fibers of C5 |
| cutaneous nerves of the cervical plexus supply only the | skin of neck, back of head and most superior region of shoulder |
| the phrenic nerves of cervical plexus supply the | diaphragm |
| the brachial plexus | upper extremity/limb |
| brachial plexus lies partly in the | neck and in the axilla |
| brachial plexus formed by the | ventral rami of C5-T1 |
| brachial plexus innervates the | pectoral girdle and upper extremity |
| the bracial plexus is composed of | five consecutive groups of stems and branches, including the nerves they form |
| the roots of the ventral rami of C5-T1 converge to form the | trunks |
| trunks (superior, middle, inferior) -each of which divides into an | anterior division and posterior division |
| division - each division then converge to form | cords |
| cords | lateral, medial, posterior |
| lateral cord is formed from the | anterior division on the superior and middle trunks |
| medial cord is formed by a | continuation of the anterior division of the inferior trunk |
| posterior cord is formed by the | union of all three posterior divisions of the superior, middle, and inferior trunks |
| nerves arise from | one or more trunks or cords whose names indicate their positions relative to the axillary artery which supplies the upper limb |
| the median nerve is formed by the | lateral and medial cords |
| musculocutaneous nerve is formed exclusively by the | lateral cord |
| ulnar nerve is formed by the | medial cord |
| axillary nerve is formed by the | posterior cord |
| radial nerve is formed by the | posterior cord |
| lumbar plexus | lower extremity/limb |
| lumbar plexus lies within the | psoas major muscle in the posterior abdominal wall |
| lumbar plexus is formed by the | ventral T12-L4 |
| the lumbar plexus innervates the | anterior thigh |
| femoral nerves innervate | anterior thigh muscles, including quadriceps femoris |
| obturator nerves innervate | adductor muscle group and some skin on superomedial thigh |
| sacral plexus | lower extremity/limb |
| sacral plexus lies | immediately caudal to the lumbar plexus |
| sacral plexus is formed by the | ventral rami of L4-S4 |
| the sacral plexus innervates the | butt, lower limb, pelvis, and perineum |
| sciatic nerve is the | thickest and longest nerve in the body |
| sciative nerve innervates all of the | lower limb except anterior and medial thigh regions |
| the sciatic nerve is composed of | two nerves wrapped in a common sheath |
| tibial nerve innervates almost | all muscles in posterior lower limb |
| common fibular nerve innervates | anterolateral aspect of lower limb |
| superior/inferior gluteal nerves innervate | gluteal muscles |
| pudendal nerve innervates | muscles and skin of perineum |
| cranial nerves attach to the | brain and pass through various openings or foramina in the skull |
| CN I - XII | rostral to caudal |
| CN I attaches to the | forebrain |
| CN II-XII attach to the | brain stem |
| CNs serve only | head and neck structures, except for CNX which extends into the abdomen |
| CNs contain | sensory and motor fibers that innervate the head |
| cell bodies of sensory neurons lie either in | receptor organs or within cranial sensory ganglia which lie along CN V, VII-X just external to the brain |
| cell bodies of motor neurons occur in | CN nuclei in ventral gray matter of the brain stem |
| purely sensory nerves | I, II, VIII |
| purely sensory nerves consist of | special somatic sensory fibers for smell, vision, hearing and equilibrium |
| primarily or exclusively motor nerves | III, IV, VI, XI, XII |
| primarily or exclusively motor nerves contain | general somatic motor fibers to skeletal muscles of the eye and tongue |
| mixed nerves | V, VII, IX, X |
| mixed nerves consist of (1) | general somatic sensory fibers to the face |
| mixed nerves consist of (2) | general visceral sensory fibers to the mouth, viscera and taste buds |
| mixed nerves consist of (3) | branchial motor fibers to all pharyngeal arch muscles |
| CN I | olfactory |
| CN II | optic |
| CN III | occulomotor nerves |
| CN IV | trochlear nerves |
| CN V | trigeminal nerves |
| CN VI | abducens nerves (adducts eye) |
| CN VII | facial nerves |
| CN VIII | vestibulocochlear nerves |
| CN IX | glossopharyngeal nerves |
| CN X | vagus nerves |
| CN XI | accessory nerves |
| CN XII | hypoglossal |
| olfactory nerves carry | afferent impulses for sense of smell |
| olfactory nerves arise from | olfactory receptor cells located in the olfactory epithelia of the nasal cavity |
| olfactory nerves project as | olfactory nerve filaments which pass through the cribriform plate of ethmoid bone |
| anosmia | partial or total loss of smell caused by fractured ethmoid bone or lesions of olfactory fibers |
| optic nerves carry | afferent impulses for vision |
| optic nerves have ...fibers that arise from each... | contralateral and ipsilateral...retina to form the optic nerves |
| optic nerves pass through | optic foramina of the orbits and converge to form the optic chiasma |
| optic nerves form the | optic tracts that enter the thalamus and synapse onto the LGN of the thalamus |
| optic nerve fibers then project from | thalamix nuclei as thalamic fibers to the occipital cortex |
| anopsias | visual defects |
| damage to the CNII results in | blindness in the eye served by the nerve |
| damage to the visual pathway, distal to the optic chiasma, results in | partial visual loss |
| oculomotor nerves carry | efferent fibers which pass through superior orbital fissure, from ventral midbrain to eye |
| oculomotor nerves innervate | 4/6 extrinsic eye muscles that help direct the eye and raise the upper eyelid |
| autonomic nervous system efferents | to constrictor muscles of the iris and to the ciliary muscle (lens shape for focusing) |
| proprioceptor afferents from the | 4 extrinsic muscles to the midbrain |
| oculomotor nerve paralysis | eye cannot be moved up or inward |
| at rest, they eye turns | laterally, upper eyelid droops (ptosis), double vision and trouble focusing on close objects |
| trochlear nerves carry | somatic efferents to and proprioceptor afferents from the superior oblique muscle |
| trochlear fibers emerge from the... | dorsal midbrain and course ventrally around the midbrain to enter the orbits of the eyes via superior orbital fissures of the sphenoid, along with CNIII |
| CN IV trauma or paralysis | double vision and reduced ability to rotate eye inferolaterally |
| trigeminal nerves carry | afferents for touch, temp, and pain from the face |
| trigeminal nerves also carry | branchial efferents for chewing muscles |
| ophthalmic division (VI) | afferent fibers run from the face to the pons via supeior orbital fissure of the sphenoid |
| ophthalmic division innervates | skin of anterior scalp, upper eyelid, and nose |
| ophthalmic division contains afferents from | nasal cavity mucosa, cornea, and lacrimal gland |
| maxillary division (V2) | afferent fibers run from the face to the pons via foramen rotundum of the sphenoid bone |
| maxillary division: afferents from | nasal cavity mucosa, palate, upper teeth, skin of cheek, upper lip and lower eyelid |
| mandibular division V3 | afferent fibers run from the face to pons and pass through the skull via foramen ovale of the sphenoid bone |
| mandibular division; afferents from | anterior tongue, lower teeth, skin of chin and temporal region of scalp |
| mandibular division; efferents...and afferents... | to...from muscles of mastication |
| tic doloureux (trigeminal neuralgia) | unknown factors cause CN V inflammation, but may reflect pressure on CN V root |
| tic doloureux causes | symptomatic tics, which involves excruciating, stabbing pain that occurs -100x/day |
| abducens nerves carry mainly | efferent fibers to and some proprioceptor afferents from the lateral rectus muscle of the eye |
| abducens nerve fibers leave the | inferior pons and enter the orbit of the eye via superior orbital fissure |
| CN VI paralysis | eye cannot be moved laterally, at rest, affected eyeball turns medially |
| facial nerves carry | mixed fibers which are the chief motor nerves of the face |
| facial fibers arise from the...enter... | pons...temporal bone via internal acoustic meatus and run within temporal bone before emerging through stylomastoid foramen |
| facial fibers then course to | lateral aspect of the face |
| 5 major branches of the face | temporal, zygomatic, buccal, mandibular, cervical |
| branchial...to and proprioceptor...from the... | efferents...afferents...skeletal muscles of face for facial expression |
| ANS effeents to | lacrimal, nasal, palatine, submandibular and sublingual glands |
| afferents from | taste buds of anterior 2/3 of the tongue and from tiny patch of skin on ear |
| bell's palsy | paralysis of facial muscles on affected side and parital loss of taste sensation |
| bell's palsy is caused by | herpes simplex viral infection which causes inflammation and swelling of CN VIII |
| vestibulococlear nerve carries | afferent impulses for hearing and equilibrium |
| cochlear division of vestibulocochlear nerves carry | afferents from hearing receptors located within the inner ear of temporal bone, pass through internal acoustic meatus |
| cochlear division afferents enter | brain stem at pons-medulla border |
| vestibular division (vestibulocochlear) carry | afferents from equilibrium receptors |
| lesions of CN VII or cochlear receptors cause | central or nerve deafness |
| damage to vestibular division causes | diziness, rapid involuntary eye movements, loss of balance, nausea and vomiting |
| glossopharyngeal nerves carry | mixed fibers which innervate part of the tongue and pharynx |
| glossopharyngeal nerve fibers emerge from | medulla and leave skull via jugular foramen to run to throat |
| (glossopharyngeal) branchial...to and properiocetpor...from the | efferents...afferents...stylopharyngeus muscle which elevates the pharynx during swallowing |
| ANS efferents of glossopharyngeal to | parotid gland |
| afferents of glossopharyngeal conduct | taste and general sensory impulses from pharynx and posterior tongue |
| glossopharyngeal afferents from | chemoreceptors in carotid bodies and pressure receptors of carotid sinus |
| glossopharyngeal afferents also innervate | small area of skin on external ear |
| CN IX damage | impairs swallowing and taste on posterior 1/3 of tongue |
| vagus nerves carry | mixed fibers that serve the pharynx, larynx, heart, lungs, abdominal viscera |
| vagus nerves; this is the only CN to | extend beyond the head and neck region |
| vagus nerve fibers emerge from | medulla, pass through skull via jugular foramen, and descend through neck into thorax and abdomen |
| brnachial efferents of vagus to | skeletal muscles of pharynx and larynx for swallowing |
| ANS efferents of vagus innervate | heart, lungs, and abdominal viscera |
| vagus afferents from | thoracic and abdominal viscera, carotid sinus, carotid and aortic bodies, taste buds of posterior tongue, mucosa of larynx and pharynx |
| vagus nerves also innervate | tiny area of skin on external ear and some of membrane lining middle ear |
| proprioceptor afferents (vagus) from | muscles of larynx and pharynx |
| CN X paralysis | hoarseness or loss of voice, difficulty swallowing, impaired GI mobility |
| total destruction of both CN X is | fatal because these ANS nerves are crucial in maintaining the normal state of visceral organ activity |
| accesory nerves contain | cranial roots and spinal roots |
| cranial roots carry | branchial efferents from lateral aspect of medulla to larynx, pharynx and soft palate |
| spinal roots carry | branchial efferents from superior region of spinal cord to trapezius and sternocleidomastoid muscles |
| spinal root injury of one CN XI causes head to | turn toward injury side due to sternocleidomastoid paralysis, shrugging of the shoulder on the injured side is difficult |
| hypoglossal nerves carry | efferents to intrinsic and extrinsic muscles of tongue |
| hypoglossal nerve fibers arise by a | series of roots from medulla, exit from the skull via hypoglossal canal to travel to the tongue |
| somatic efferents (hypoglossal nerves) to | tongue muscles allow food mixing and manipulation by tongue during chewing |
| somatic efferents of hypoglossal also allow | tongue movements that contribute to swallowing and speech |
| CN XII damage causes | difficulties in speech and swallowing, tongue deviates toward affect sides, paralyzed side eventuaolly beings to atrophy |
| both CNII damaged = | cannot protrude tongue |
Created by:
handrzej
Popular Anatomy sets