Brainstem part 2

Question 1

Reticular Formation (what is it)

Answer 1

large diffuse group of tracts and nuclei

Question 2

Reticular Formation (functions)

Answer 2

~integration of sensory input and to organize generalize response to that input
~somatic motor function- via reticulospinal motor pathways
~alertness and consciousness via the ascending reticular activating system
~pain control- Raphe and periaqueductal gray region

Question 3

ARAS (what does it stand for)

Answer 3

ascending reticular activating system

Question 4

Anatomy of the reticular formation serves (_____) integrations function (and details about this)

Answer 4

(sensory)
~neurons have large highly overlapping dendritic trees
~dendritic trees oriented perpendicular to long axis of brainstem
~as axons of the long ascending and descending tracts transverse the brainstem & have collaterals that intermingle with the neurons of the reticular formation
~each neuron receives information from a wide variety of sources

Question 5

Neurons receives information from a wide variety of sources (details)

Answer 5

~one source may dominate input to each neuron but each neuron probably receives both visceral & somatic input and both motor & sensory input

Question 6

Wide spread output with each reticular formation neuron collateral onto______ other neurons

Answer 6

> 25,000 other neurons

~particularly ascending fibers of the reticular activating system to the cerebral cortex

Question 7

Reticulospinal Pathways

Answer 7

Medial (pontine) and Lateral (medullary)

Question 8

Medial reticulospinal pathway

Answer 8

(pontine)
~arises from oral and causal pontine reticular nuclei
~excites postural muscle to produce a postural set

Question 9

Lateral reticulospinal pathway

Answer 9

(medullary)
~arises from nucleus gigantocellularis reticular nucleus of the medulla
~inhibits postural muscles to get ready for movement

Question 10

Ascending Reticular Activating System

Answer 10

Cholinergic (ACh) Component and Adrenergic (NE) Component

Question 11

Cholinergic (ACh) Component

Answer 11

~Arise from dorsal tegmental nucleus & pedunculopontine nucleus
~important in wakeful and REM sleep states

Question 12

Adrenergic (NE) Component

Answer 12

~arises from locus cerueus

~important in wakeful and slow-wave sleep states

Question 13

Descending Pain Control Pathways

Answer 13

Serotongic (5-HT), Adrenergic (NE), Enkephalinergic

Question 14

Serotongic (5-HT) Component

Answer 14

~Arises from midbrain, prontine raphe nuclei, & nucleus raphe magnus of the medulla
~Descend directly to the spinal cord to the inhibit nociceptive afferents

Question 15

Adrenergic (NE)

Answer 15

~arises from the locus ceruleus

~descend directly to the spinal cord to inhibit nociceptive afferents

Question 16

Enkephalinergic

Answer 16

~Arises from midbrain, periaqueductal grey

~descends directly to spinal cord and relays through raphe nuclei to inhibit nociceptive afferents

Question 17

CN I: Olfactory Nerve

Answer 17

~receptor cells in olfactory muscosa ~olfactory nerve penetrates cribriform plates of ethmoid bone
~relayed by mitral cells of olfactory bulb whose axons form the olfactory tract
~olfactory tract axons end primary olfactory cortex of medial temporal lobe- pyriform area (periamygdalar &perihippocampal)
~projecctions to amygdala, hypothalamus, thalamus, hippocampus, & orbitofrontal cortex as well

Question 18

For CN I, the receptor cells are in

Answer 18

olfactory muscosa

Question 19

For CN I, the Olfactory nerve penetrates

Answer 19

cribriform plate of ethmoid bone

Question 20

For CN I, the olfactory tract ends

Answer 20

primarily in primary olfactory cortex of medial temporal lobe

Question 21

For CN I, projections to

Answer 21

amygdala, hypothalamus, thalamus, hippocampus, and orbitofrontal cortex

Question 22

CN I: Olfactory Nerve (what does it to)

Answer 22

~sense of smell

~anosmia (inability to smell

Question 23

Anosmia may occur with:

Answer 23

~common cold
~trauma to face
~degenerative neural diseases such as Parkinson’s & Alzheimer’s Diseases

Question 24

CN II: Optic Nerve

Answer 24

~ Optic nerve arises from ganglion cells of retina (realty CNS tissue)
~Fibers from nasal (medial) retinal field decussate to opposite side in optic chiasm while fibers from temporal (lateral) retinal field stay ipsilateral
~Optic tract extends from chiasm to the geniculate nucleus of the thalamus
~thalamus axons radiate to the primary visual cortex

Question 25

For CN II, optic nerve arises from

Answer 25

ganglion cells of retina

Question 26

For CN II, optic tracts extends

Answer 26

from optic chiasm to the geniculate nucleus of the thalamus

Question 27

For CN II, the thalamuc axons radiates to

Answer 27

the primary visual cortex

Question 28

For CN II, damage to the optic nerve:

Answer 28

~singe eye (monocular) vision lost

Question 29

For CH II, damage to the optic chiasm:

Answer 29

~loss of peripheral vision (bitemporal hemianopsia)

Question 30

For CN II, damage to the optic tract and later in pathways,

Answer 30

~loss of contralateral visual field (contralateral homomynous hemianopsia)

Question 31

CN III: Oculomotor Nerve

Answer 31

~ arises from medial ventral surface of midbrain ~oculomotor nuclei ~Innervated superior, medual, & inferior rectus and inferior oblique muscles, levator palpebrae ~parasympathetic control of pupillary sphincter and ciliary body for pupillary constriction & near vision lens accommodation respectively

Question 32

For CN III, arises from

Answer 32

medial ventral surface of midbrain

Question 33

For CN III, the oculomotor nuclei

Answer 33

~gives rise to the axons form the oculomotor nerve the come from the nuclear complex located in the dorsal midbrain tegmentum just ventral to the periaquductal gray ~Complex is made up of two parts: Oculomotor nucleus – LMN (somatic motor) & Edinger-Westphal nucleus (visceral motor)

Question 34

For CN III, innervates

Answer 34

``` ~superior rectus (elevation) ~medial rectus (adduction) ~inferior rectus (depression) ~inferior oblique (lateral rotation) ~levator palpebrae (raise eyelid) ```

Question 35

For CN III, parasympathetic control

Answer 35

pupillary sphincter and ciliary body for pupillary constriction & near vision lens accommodation respectively

Question 36

Damage to CN III

Answer 36

(oculomotor ophthalamoplegia) ~lateral strabismus ~Ptosis

Question 37

Lateral strabismus

Answer 37

unopposed lateral rectus (CN VI)

Question 38

Ptosis

Answer 38

drooping eyelid and compensation with frontalis contraction so raised eyebrow & wrinkled forehead

Question 39

CN IV: Trochlear Nerve

Answer 39

~trochlear nucleus in midbrain caudal to oculomotor nucleus & ventral to periaqueductal gray ~only cranial nerve to exit the dorsal brainstem ~innervates the superior oblique ~produces intorsion (medial rotation)

Question 40

For CN IV, arises

Answer 40

~just caudal to the inferior colliculus ~ from lower motor meurons located in the trochlear nucleus in midbrain caudal to oculomotor nucleus & ventral to periaqueductal gray

Question 41

For CN IV, exits

Answer 41

dorsal brainstem (id the only cranial nerve to exit the dorsal brainstem)

Question 42

For CN IV, innervates

Answer 42

superior oblique extraocular eye muscles (procures intorsion- medial rotation)

Question 43

For CN IV, damage

Answer 43

(trochlear ophthalamoplegia) ~paresis/paralysis of superior oblique ~eye moves up and lateral and extortion ~head tilt to unaffected side to reduce diplopia (double vision)

Question 44

CN VI: Abducens nerve

Answer 44

~Abducens nucleus located in caudal pons ~nerve exits medially at pontomedullary junction ~innervates the lateral rectus ~produces ocular abduction

Question 45

For CN VI, arises from

Answer 45

lower motor neurons of the abducens nucleus locates in causal pons

Question 46

For CN VI, exits

Answer 46

ventrl brainstem medially at pontomeduallary junction

Question 47

For CN VI, innervates

Answer 47

lateral rectus, which produces ocular abduction (lateral movement of the eyes)

Question 48

Damage of the CN VI

Answer 48

Produces cross eyed appearance due to lack of opposition of medial rectus muscles (innervated by CN III)

Question 49

CN V: Trigeminal Nerve

Answer 49

~general sensory of face and motor muscle of mastication ~3 sensory division (ophthalmic- V1, Maxillary- V2, Mandibular- V3) ~motor division (mandibular- V3) ~has a 3 neuron sensory pathway to cerebral cortex

Question 50

For CN V, the sensory divisions

Answer 50

Ophthalmic (V1) Maxillary (V2) Mandibular (V3)

Question 51

For CN V, the motor divisions

Answer 51

Mandibular (V3)

Question 52

For CN V, neural sensory pathways to the _____

Answer 52

(cerebral cortex) ~Primary (1*) sensory neuron is the trigeminal nerve primary afferent neuron with its cell bodies in trigeminal sensory ganglion ~Relay: the primary end on the secondary (2*) sensory neuron whose cell bodies are either chief sensory nucleus or spinal nucleus of CN V ~Tertiary (3*)- the secondary neurons of the pathways in either chief sensory nucleus or the spinal nucleus of CN V send their axons via trigeminothalamic tract to 3* sensory neurons whose cell bodies are in the ventral posterior medial (VPM) nucleus of thalamus **these tertiary neurons of the 3 neuron sensory pathway in the VPM nucleus of thalamic have axons which project to primary somatosensory cortex

Question 53

chief sensory nucleus:

Answer 53

for somatosensations of touch and pressure and the spinal nucleus of V for the somatosensation of pain and temperature

Question 54

For CN V, the ______ neurons of muscles of ______ are in motor nucleus of CN V

Answer 54

(Lower motor) neurons {LMN} of muscles of (mastication) are in motor nucleus of CN V

Question 55

For CN V, most common form of damage

Answer 55

Neuralgia (is the most common form of pathology) ~sometimes incorrectly called tic doulourex (which is only the facial spasms associated with the condition) ~characterized by severe shocking or stabbing facial pain

Question 56

CN VII: Facial Nerve

Answer 56

~arises from brainstem laterally at the pontomedullary junction ~function include: general sensory, special sensory, somatic motor, parasympathetic efferent ~

Question 57

For CN VII, arises

Answer 57

from brainstem laterally at the pontomedullary junction

Question 58

For CN VII, functions

Answer 58

~general sensory: external ear & tympanic membrane ~special sensory: taste from anterior 2/3rd tongue (salty, sweet, or sour) ~somatic motor: muscle of facial expressions & stapedius ~parasympathetic efferents: to lacrimal glands and submandibular & sublingual salivary glands

Question 59

For CN VII, damage

Answer 59

Bell's Palsy ~is the most characterized by the loss of voluntary control of the muscles ipsilateral (on the same side) as the damaged nerve

Question 60

CN VIII, Vestibulocochlear Nerve

Answer 60

~Special Sensory Convey: vestibular (balance/ equilibrium) information & Cochlear (hearing/ auditory) information ~enters brainstem at pontomedullary junction very laterally ~involved in both balance and auditory reflexes as well as cognitive awareness of movement and balance and sounds

Question 61

For CN VIII, special sensory conveys

Answer 61

~Vestibular (balance/ equilibrium) information | ~Cochlear (hearing/ auditory) information

Question 62

For CN VIII, enters

Answer 62

brainstem at pontomedullary junction laterally

Question 63

For CN VIII, primary afferents arises

Answer 63

from neurons in the inner ear- cochlear for the auditory fibers and the vestibular complex for the balance/ equilibrium fibers

Question 64

For CN VIII, involved

Answer 64

~both balance and auditory reflex | ~cognitive awareness of movement, balance, and sound

Question 65

CN IX: Glossopharyngeal Nerve

Answer 65

~enters brainstem laterally in rostral medulla | ~Components: general sensory, special sensory, visceral sensory,

Question 66

For CN IX, enters

Answer 66

brainstem laterally in rostral medulla

Question 67

For CN IX, components

Answer 67

~General sensory: from pharynx, middle ear, & posterior 1/3 of tongue ~Special sensory: taste form he posterior 1/3 of tongue ~Visceral sensory: fibers from carotid bodies & carotid bodies ~ Branchial motor to stylopharyngeus muscle ~visceral motor- parasympathetic to parotid gland

Question 68

CN X: Vagus Nerve

Answer 68

~enters brainstem laterally in rostral medulla | ~components: general sensory, visceral sensory, special sensory, branchial (somatic) motor, autonomic efferents

Question 69

For CN X, enters

Answer 69

brainstem laterally in rostral medulla

Question 70

For CN X, Components

Answer 70

~general sensory: pharynx, larynx, trachea, cranial dura, & thoracic & abdominal viscera ~Visceral sensory: aortic baroreceptors ~special sensory of taste from epiglottis ~branchial (somatic) motor to pharyngeal & laryngeal muscles ~autonomic efferents to the thoracic & abdominal viscera

Question 71

CN XI: Accessory

Answer 71

~two main parts: cranial and spinal | ~function is somatic (branchial) motor

Question 72

For CN XI, cranial

Answer 72

~arises from ventral lateral medulla

Question 73

For CN XI, spinal

Answer 73

~rises from upper cervical spinal nerves | ~ascends thru foramen magnum to join cranial portion

Question 74

For CN XI, function

Answer 74

~is somatic (branchial) motor | ~innervates: sternocleidomastoid and upper trapezius (cervical component) & pharyngeal and laryngeal (cranial component)

Question 75

CN XII: Hypoglossal Nerve

Answer 75

~exits from ventral lateral medulla | ~somatic motor- intrinsic and extrinsic tongue muscles

Question 76

For CN XII, exits

Answer 76

from ventral lateral medulla

Question 77

Reflexes

Answer 77

~most basic relationship between sensory input and motor output ~stereotyped motor response to a specific sensory stimulus ~involve afferent limb, integration within the CNS, & efferent (motor) limb

Question 78

In brain stem reflexes, the afferent and efferent limbs may involve (same/different/both) cranial nerves

Answer 78

may involve same or different cranial nerves