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Test#9
Cranial nerves
Question | Answer |
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1. Know the actions of each head/neck muscles. | |
The Skull | the body’s most complex bony structure, is formed by the cranium and facial bones |
Cranium | protects the brain and is the site of attachment for head and neck muscles |
Anatomy of the Cranium | Eight cranial bones – two parietal, two temporal, frontal, occipital, sphenoid, and ethmoid |
Cranial bones | are thin and remarkably strong for their weight |
Frontal Bone | Forms the anterior portion of the cranium Articulates posteriorly with the parietal bones via the coronal suture Major markings include the supraorbital margins, the anterior cranial fossa, and the frontal sinuses (internal and lateral to the glabella) |
Parietal Bones and Major Associated Sutures | Form most of the superior and lateral aspects of the skull |
Four sutures mark the articulations of the parietal bones | Coronal suture, Sagittal suture, Lambdoid suture, Squamosal or squamous suture |
Coronal suture | articulation between parietal bones and frontal bone anteriorly |
Sagittal suture | where right and left parietal bones meet superiorly |
Lambdoid suture | where parietal bones meet the occipital bone posteriorly |
Squamosal or squamous suture | where parietal and temporal bones meet |
Occipital Bone | Forms most of skull’s posterior wall and base Major markings include the posterior cranial fossa, foramen magnum, occipital condyles, and the hypoglossal canal |
Temporal Bones | Form the inferolateral aspects of the skull and parts of the cranial floor |
Temporal Bones | Divided into four major regions – squamous, tympanic, mastoid, and petrous |
Temporal Bones | Major markings include the zygomatic, styloid, and mastoid processes, and the mandibular and middle cranial fossae |
Temporal Bones | Major openings include the stylomastoid and jugular foramina, the external and internal auditory meatuses, and the carotid canal |
Sphenoid Bone | Butterfly-shaped bone that spans the width of the middle cranial fossa Forms the central wedge that articulates with all other cranial bones |
Sphenoid Bone | Consists of a central body, greater wings, lesser wings, and pterygoid processes Major markings: the sella turcica, hypophyseal fossa, and the pterygoid processes |
Sphenoid Bone | Major openings include the foramina rotundum, ovale, and spinosum; the optic canals; and the superior orbital fissure |
Ethmoid Bone | Most deep of the skull bones; lies between the sphenoid and nasal bones Forms most of the bony area between the nasal cavity and the orbits |
Ethmoid Bone | Major markings include the cribriform plate, crista galli, perpendicular plate, nasal conchae, and the ethmoid sinuses |
Muscles of Facial Expression | When they contract, muscles move the skin rather than a joint. CN VII innervates |
1. Frontalis | draws scalp anteriorly, raises eyebrow, wrinkles skin |
Occipitalis | draws scalp posteriorly |
Orbicularis oris | closes and protrudes lips kissing muscle |
Zygomaticus major | draws angle of mouth superiorly & laterally, as in smiling |
Buccinator | presses cheeks against teeth and lips, as in whistling, blowing, sucking |
Platysma | depresses mandible |
Orbicularis oculi | closes eye |
Muscles of Mastication | CN V innervates |
Masseter | elevates (closes mouth) & retracts(thrust it backward=chin back) mandible |
Temporalis | elevates (close mouth)& retracts mandible |
Medial pterygoid | elevates (closes mouth) & protracts(thurst it foward=chin foward) mandible |
Lateral pterygoid | depresses(open mouth) & protracts mandible |
Suprahyoid (Submandibular) | |
Digastric | elevates hyoid bone and depresses mandible superficial |
Mylohyoid | elevates hyoid bone and depresses mandible deeper than digastric, also horizontal fiber |
Infrahyoid muscles | Omohyoid |
Omohyoid = shoulder, scapular bone, swing up scapula muscle | depress hyoid bone |
Sternohyoid | depress hyoid bone |
Sternothyroid | depresses thyroid cartilage of larynx |
Thyrohyoid | elevates thyroid cartilage & depresses hyoid bone |
Muscles of the Neck | Sternocleidomastoid, |
Sternocleidomastoid | bilaterally: flex cervical vertebrae, extend head; unilaterally: lateral flex and rotate head to side opposite contracting muscle |
Scalene Muscles | |
Anterior, middle , posterior Scalene Muscles | bilaterally: flex head and; unilaterally: lateral flex and rotate head to side opposite contracting muscle. |
Eye muscles | |
Superior rectus | moves eyeball superiorly and medially |
Inferior rectus | moves eyeball inferiorly and medially =look down floor |
Lateral rectus | moves eyeball laterally |
Medial rectus | moves eyeball medially |
Superior oblique | moves eyeball inferiorly and laterally roll down |
Inferior oblique | moves eyeball superiorly and laterally roll up trochlea joint pulling trochlear nerve CN IV |
Know the general features of the brain stem (p.93) | Consists of three regions – midbrain, pons, and medulla oblongata |
brain stem | Similar to spinal cord but contains embedded nuclei Controls automatic behaviors necessary for survival Provides the pathway for tracts between higher and lower brain centers Associated with 10 of the 12 pairs of cranial nerves |
Medullar Oblongata | Most inferior part of the brain stem Five pairs of cranial nerves originate from here (VIII to XII) |
Medullar Oblongata | Pyramids – two longitudinal ridges formed by corticospinal tracts Decussation of the pyramids – crossover points of the corticospinal tracts Cardiovascular control center – adjusts force and rate of heart contraction |
Medullar Oblongata | Respiratory centers – control rate and depth of breathing Reflex centers: sneezing, coughing, swallowing, and vomiting |
Pons = bridge | Bulging brainstem region between the midbrain and the medulla oblongata Fibers of the pons: Connect higher brain centers and the spinal cord Relay impulses between the motor cortex and the cerebellum |
Pons | Origin of cranial nerves V (trigeminal), VI (abducens), VII (facial), and VIII Contains nuclei of the reticular formation Minor respiratory centers |
Midbrain (mesencephalon) | Located between the diencephalon and the pons |
Midbrain structures include: | Cerebral peduncles – two bulging structures that contain descending pyramidal motor tracts Cerebral aqueduct – hollow tube that connects the third and fourth ventricles |
Midbrain Nuclei | Nuclei that control cranial nerves III (oculomotor) and IV (trochlear) |
Tectum | four domelike protrusions of the dorsal midbrain Superior colliculi – visual reflex centers Inferior colliculi – auditory relay centers |
Substantia nigra: | neurons that release dopamine extend from the substantia nigra to the basal ganglia and help control subconscious muscle activities. Loss of these neurons is associated with Parkinson’s disease. |
Red nucleus | largest nucleus of the reticular formation; red nuclei are relay nuclei for some descending motor pathways |
Reticular Formation | Gray matter network among threads of white matter in brainstem, spinal cord & thalamus. Alerting the cerebral cortex to incoming sensory signals. |
Reticular activating system (RAS): | maintaining consciousness and awakening from sleep. |
3. The regions of the brain stem involved in the control of respiration are ___ and ___. | medulla oblongata n pons |
4. What make up the tectum of the midbrain and what is the function of these structures? | |
tectum of the midbrain tectum = roof | is The posterior part of the midbrain contains four rounded elevations p. 636 |
tectum = roof | four domelike protrusions of the dorsal midbrain; 2 Superior colliculi – visual reflex centers 2 Inferior colliculi – auditory relay centers |
two superior elevations are known as the superior colliculi ( little hills; singular is colliculus) | visual reflex centers |
superior colliculi | Through neural circuits from the retina of the eye to the superior colliculi to the extrinsic eye muscles, visual stimuli elicit eye movements for tracking moving images (such as a moving car) |
superior colliculi | and scanning stationary images (as you are doing to read this sentence) |
Other superior colliculi | reflexes are the accommodation reflex that adjusts the shape of the lens for close versus far vision and reflexes that govern movements of the eyes, head, and neck in response to visual stimuli. |
The two inferior elevations, the inferior colliculi, | auditory relay centers |
inferior colliculi | are part of the auditory pathway, relaying impulses from the receptors for hearing in the ear to the thalamus. |
inferior colliculi | These two nuclei also are reflex centers for the startle reflex, sudden movements of the head and body that occur when you are surprised by a loud noise such as a gunshot. |
5. Know the structures and functions of the medulla oblongata, pons, midbrain | |
Medullar Oblongata | Most inferior part of the brain stem Five pairs of cranial nerves originate from here (VIII to XII) |
Medullar Oblongata | Pyramids – two longitudinal ridges formed by corticospinal tracts Decussation of the pyramids – crossover points of the corticospinal tracts Cardiovascular control center – adjusts force and rate of heart contraction |
Medullar Oblongata | Respiratory centers – control rate and depth of breathing Reflex centers: sneezing, coughing, swallowing, and vomiting |
Pons | Bulging brainstem region between the midbrain and the medulla oblongata |
Pons | Fibers of the pons: Connect higher brain centers and the spinal cord |
Pons | Relay impulses between the motor cortex and the cerebellum Origin of cranial nerves V (trigeminal), VI (abducens), VII (facial), and VIII Contains nuclei of the reticular formation Minor respiratory centers |
Midbrain (mesencephalon) | Located between the diencephalon and the pons |
Midbrain (mesencephalon) | Midbrain structures include: Cerebral peduncles – two bulging structures that contain descending pyramidal motor tracts Cerebral aqueduct – hollow tube that connects the third and fourth ventricles |
Midbrain (mesencephalon) | Midbrain Nuclei Nuclei that control cranial nerves III (oculomotor) and IV (trochlear) Tectum – four domelike protrusions of the dorsal midbrain Superior colliculi – visual reflex centers Inferior colliculi – auditory relay centers |
Midbrain (mesencephalon) | Substantia nigra: neurons that release dopamine extend from the substantia nigra to the basal ganglia and help control subconscious muscle activities. Loss of these neurons is associated with Parkinson’s disease. |
Midbrain (mesencephalon) | Red nucleus – largest nucleus of the reticular formation; red nuclei are relay nuclei for some descending motor pathways |
6. Which area/structure maintains one’s consciousness and awakening from the sleep? | reticular activating system (RAS) |
7. What are the structures and functions of the thalamus? | Makes up 80% of the diencephalons A bridge of gray matter called the intermediate mass joins the right and left halves |
thalamus structures | Internal capsule: axons that connect the thalamus and cerebral cortex pass through it, a thick band of white matter lateral to the thalamus |
thalamus fxn | The thalamus is the principal relay station for sensory impulses that reach the cerebral cortex from other parts of the brain and the spinal cord |
thalamus fxn | Sensory relay center Allows for crude sensory awareness Positively reinforces voluntary motor activity |
thalamus fxn | is the major relay station for sensory impulses (except smell) that reach the primary sensory areas of the cerebral cortex from the spinal cord, brain stem, and midbrain |
thalamus fxn | contributes to motor functions by transmitting information from the cerebellum and basal nuclei to the primary motor area of the cerebral cortex. |
thalamus fxn | It also relays nerve impulses between different areas of the cerebrum and plays a role in the regulation of autonomic activities and the maintenance of consciousness. p 642 |
8. What are the structures and functions of the hypothalamus? | Located below the thalamus, it caps the brainstem and forms the inferolateral walls of the third ventricle |
structures of the hypothalamus | Mammillary bodies Infundibulum |
Mammillary bodies | Small, paired nuclei bulging anteriorly from the hypothalamus Relay station for olfactory pathways |
Infundibulum | talk of the hypothalamus; connects to the pituitary gland Main visceral control center of the body: Hypothalamic Nuclei |
Hypothalamic Function | Regulates blood pressure, rate and force of heartbeat, digestive tract motility, rate and depth of breathing, and many other visceral activities |
Hypothalamic Function | Is involved with perception of pleasure, fear, and rage Controls mechanisms needed to maintain normal body temperature Regulates feelings of hunger and satiety |
Hypothalamic Function | Regulates sleep and the sleep cycle Endocrine Functions of the Hypothalamus |
9 . A midsagittal section of the brain would pass what structures? (examples are longitudinal fissure, corpus callosum, ___, ___) | sagittal suture, superior sagittal sinus, longitudinal fissure, corpus callosum |
10. Define sulci, gyri, folia, vermis. | |
sulci = grooves | are the shallower grooves |
gyri = circles | are the folds |
folia = leaves | belong to cerebellum The superficial layer of the cerebellum, called the cerebellar cortex, consists of gray matter in a series of slender, parallel ridges called |
Vermis = worm | The central constricted area of the cerebellum that separates the two cerebellar hemispheres.p 639 |
11. What structure allows information to travel between the two cerebral hemispheres? | corpus callosum (commissural tracts) |
12. What are the structures and functions of the frontal lobe? | |
What are the structures of the frontal lobe? | Primary Motor Cortex(area 4 in K. Brodmann’s map f the cerebral cortex) Premotor Cortex Broca’s speech Area (areas 44 and 45) Prefrontal Cortex |
functions of the frontal lobe? | |
1. Primary Motor Cortex (area 4 in K. Brodmann’s map f the cerebral cortex) | Located in the precentral gyrus Composed of pyramidal cells whose axons make up the corticospinal tracts Allows conscious control of precise, skilled, voluntary movements |
2. Premotor Cortex | Located anterior to the precentral gyrus Controls learned, repetitious, or patterned motor skills Coordinates simultaneous or sequential actions Involved in the planning of movements |
3. Broca’s speech Area (areas 44 and 45) | Located anterior to the inferior region of the premotor area Present in one hemisphere (usually the left, 97% population) A motor speech area that directs muscles of the tongue Is active as one prepares to speak |
3. Broca’s speech Area (areas 44 and 45) | Lesion: person can still have clear thoughts, but are unable to form word, nonfluent aphasia |
Broca’s speech area | Motor area of the brain in the frontal lobe that translates thoughts into speech. Also called the motor speech area. |
4. Prefrontal Cortex (frontal association area) | Located in the anterior portion of the frontal lobe Involved with intellect, cognition, recall, and personality Necessary for judgment, reasoning, persistence, and conscience |
13. Where is the precentral gyrus located? and its function? | frontal lobe, primary motor area (area 4) frontal lobe of the cerebral cortex |
precentral gyrus fxn | is a major control region for planning and initiating voluntary movements. Allows conscious control of precise, skilled, voluntary movements |
precentral gyrus | Gyrus of cerebral cortex located immediately anterior to the central sulcus; contains the primary motor area. |
postcentral gyrus | Gyrus of cerebral cortex located immediately posterior to the central sulcus; contains the primary somatosensory area |
14. Where is the postcentral gyrus located? and its function? | Parietal Lobe, Primary Somatosensory Cortex (areas 1, 2, and 3) |
postcentral gyrus function? | Receives information from the skin and skeletal muscles: touch, proprioception, temperature, and pain |
15. Broca’s speech area is located in which lobe? What is the function of the area? | frontal lobe; fxn primary motor cortex, motor speech area |
16. What is the function of parietal lobe, | |
parietal lobe | 1. Primary Somatosensory Cortex (areas 1, 2, and 3) 2. Somatosensory Association Cortex |
1. Primary Somatosensory Cortex (areas 1, 2, and 3) | Located in the postcentral gyrus, this area: Receives information from the skin and skeletal muscles: touch, proprioception, temperature, and pain |
2. Somatosensory Association Cortex | Located posterior to the primary somatosensory cortex Integrates sensory information Forms comprehensive understanding of the stimulus |
16. What is the function of occipital lobe ? | |
occipital lobe | 1. Primary visual (striate) cortex 2. Visual association area |
1. Primary visual (striate) cortex | Seen on the extreme posterior tip of the occipital lobe Receives visual information from the retinas |
2. Visual association area | Surrounds the primary visual cortex Interprets visual stimuli (e.g., color, form, and movement) |
16. What is the function of temporal lobe? | |
Temporal Lobes: | 1. Primary auditory cortex 2. Speech: Wernicke’s area: (22, 39, and 40) 3. Olfactory |
1. Primary auditory cortex | Located at the superior margin of the temporal lobe Receives information related to pitch, rhythm, and loudness |
1. Primary auditory cortex | Auditory association area Located posterior to the primary auditory cortex Stores memories of sounds and permits perception of sounds |
2. Speech: Wernicke’s area: (22, 39, and 40) | Left temporal and parietal lobes Allows for comprehension of written/spoken word |
2. Speech: Wernicke’s area: (22, 39, and 40) | Lesion: can still speak, but cannot arrange words in a coherent fashion, fluent aphasia or “word salad”. |
17. What is the function of basal nuclei (ganglia)? | inhibitory, suppresses , select ur movement |
SUBCORTICAL REGION Basal ganglia = basal nuclei contains | caudate nucleus, putamen, globus pallidus |
Basal ganglia = basal nuclei contains | Three nuclei buried deep in white matter in parts of thalamus, cerebrum and midbrain |
Basal ganglia = basal nuclei contains | Selects purposeful activity, suppresses unwanted activity Inhibits muscle tone Monitors/coordinates slow, sustained contractions Inhibits thalamus |
Parkinson’s: | 1. Resting tremors 2. Rigidity 3. Difficulty initiating new movement 4. Bradykinesia and hypokinesia |
18. The functions of the limbic system involve ___, ___, and ___. | Motivation, Memory, and Emotional behavior |
The Limbic System | A ring of structures encircling the upper part of the brain stem and the corpus callosum Includes the rhinencephalon, amygdala, hypothalamus, and anterior nucleus of the thalamus Motivation, Memory, Emotional behavior Cerebrovascuar Accident (CVA)/Str |
Cranial Nerves (CN) (p.101) | |
1. Need to know everything from the table. What is the name and the number of each CN. Is it a sensory or motor? Its exit? Its function? and some injuries. | |
I Olfactory | Sensory; nasal mucosa->foramina in cribriform plate->olfactory bulb-> tract-> olfactory area (temporal lobe) fxn: smell |
II Optic | Sensory; retina->optic f.->optic chiasm-> optic tract->thalamus-> primary visual area fxn: vision Lesion: blindness/anopia |
III Oculomotor | Motor; midbrain; Superior Orbital fissure (SOF) fxn: Superior, medial & inferior rectus; Inferior oblique; movement of eyeball |
IV Trochlear | Motor; (smallest), midbrain, SOF fxn: Superior oblique muscle |
V Trigeminal | Mixed; (largest), pons, fxn : Sensory: skin, muscle, mucosa, tooth, (face, neck) Motor: chewing muscles Lesion: neuralgia (pain) |
V Trigeminal | ophthalmic, SOF maxillary, f. rotundum mandibular, f. ovale-> mandibular f. and mental f. |
VI Abducens | Motor; pons, SOF fxn: Lateral rectus muscle |
VII Facial | Mixed; pons, internal auditory meatus-> stylomastoid f |
VII Facial | fxn: Taste: ant. 2/3 of tongue Motor: facial expression m. Lesion: Bell’s palsy |
VIII Vestibulochochlear | Sensory; pons, internal auditory meatus fxn: Equilibrium Hearing |
IX Glossopharyngeal | Mixed; medulla, jugular f. fxn: Taste: post. 1/3 of tongue Motor: elevates pharynx |
X. Vagus | Mixed; medulla, jugular f. fxn: Pharynx, larynx, visceral organs in thorax and abdomen |
XI accessory | Motor; medulla & C1-C5, jugular f. fxn: Sternocleidomastoid, trapezius |
XII Hypoglossal | Motor, medulla, hypoglossal canal fxn: Motor, medulla, hypoglossal canal |
sensory CN | I olfactory, II optic, VIII vestibulochochlear |
Motor CN | III Oculomotor, IV trochlear, VI abducens, XI accessory, XII hypoglossal |
Mixed CN | V trigeminal, VII facial, IX glossopharyngeal, X vagus |
Exit foramina in cribriform plate | I olfactory |
exit optic f | II optic |
exit SOF | III oculomotor,IV trochlear, V trigeminal- a. ophthalmic, VI abducens |
exit SOF, supraorbital foramen/notch | V trigeminal- a. ophthalmic |
exit f. rotundumm, infraorbital foramen | V trigeminal- b. maxillary |
exit f. ovale, mandibular f, and mental f. | V trigeminal - c. mandibular |
exit internal auditory meatus | VII faciall, VIII vestibulochochlear |
exit internal auditory meatus, stylomastoid f. | VII facial |
exit jugular f | IX glossopharyngeal, X vagus, XI accessory |
exit hypoglossal canal | XII hypoglossal |
2. What nerves control eyeball movement? | CN III oculomotor |
3. The smallest cranial nerve is _____ and the largest one is ______. | smallest= IV trochlear largest= V trigeminal |
4. What muscles are innervated by the third cranial nerve? CN III, 4 muscles | Superior, medial, & inferior rectus muscles; inferior oblique muscle |
What muscles are innervated by CN IV? 1 muscle | superior oblique muscle |
What muscles are innervated by CN VI? 1 muscle | lateral rectus muscle |
5. The damage of the _____ nerve may cause the blindness. | CN II, Optic |
6. What muscles are innervated by facial nerve? | Motor: facial expression muscles |
7. What muscles are innervated by trigeminal nerve? | Motor: chewing muscles |
8. The taste buds of the anterior region of the tongue are innervated by which CN? | VII Facial Taste: ant. 2/3 of tongue |
The posterior region is innervated by which CN? | IX Glossopharyngeal Taste: post. 1/3 of tongue |
9. Which CN innervates trapezius and sternocleidomastoid muscles? | XI accessory |
10. Which CN innervates muscles of pharynx? | X. Vagus |
11. Which CN innervates the visceral organs in the thorax and abdomen? | X Vagus |
12. Which CN is the last pair of cranial nerve; innervates muscles of tongue? | XII Hypoglossal |
13. What are the 3 branches of CN V? A block of which nerve would provide anesthesia to the lower teeth and chin? | ophthalmic maxillary mandibular |
CN V: A block of which nerve would provide anesthesia to the lower teeth and chin? | CN V . mandibular nerve, 3rd branch |
14. Which three nerves are sensory cranial nerves? | CN I olfactory, CN II optic, CN VIII vestibulochochlear |
15. Which nerves (4) pass through the superior orbital fissure? SOF | CN III oculomotor CN IV trochlear CN V trigeminal, a. ophthalmic CN VI abducens |
16. Which nerves (3) pass through the jugular foramen? | CN IX glossopharyngeal CN X vagus CN XI accessory |