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Which section of the ear contains the malleus, incus, and stapes bones?
Sound vibrations from the air are collected by the outer ear, including the cartilaginous pinna. Air vibrations interface with the tympanic membrane, transferring the vibrations to the bones of the middle ear. These bones interface with the oval window to transfer the vibrations to the fluid of the cochlea found in the inner ear, where nerve endings translate the vibrations into electrical signals.
The malleus, incus, and stapes are the bones of the middle ear and are considered the smallest bones in the human body.
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Which of these correctly traces the transmission of sound from the external environment to the nerves that carry the signal to the brain to be interpreted.
Sounds from the external environment are first met by the pinna which directs them towards and into the external auditory meatus (or opening of the ear). Sound travels towards the tympanic membrane or eardrum, which vibrates against the ossicles. The ossicles then transmit these vibrations to the cochlea which convert the vibrations into nerve impulses which travel to the brain through the vestibulocochlear nerve.
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A patient in the clinic has a tumor at the opening of the internal acoustic meatus.
Which of the following consequences are possible?
The internal auditory meatus is a canal within the petrous part of the temporal bone. The canal lies between the posterior cranial fossa and the inner ear. This canal provides passage through which the vestibulocochlear nerve, the facial nerve, and the labyrinthine artery pass from inside the skull to the inner ear and face. It also contains the vestibular ganglion. If a tumor were to grow in this area it would have a number of consequences including affecting taste (via chorda tympani of facial nerve), cause dizziness (via the vestibular ganglion), and cause dry eye (via facial nerve).
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Which of the following senses uses chemoreceptors in order to send signals to the brain?
Chemoreceptors are used to sense taste and smell. Receptors in the nose and the mouth bind to chemicals that enter these regions. Once bound, the receptors send action potentials to the brain in order to stimulate the sensation of smell and taste. Depending on the type of receptor being bound, different sensations can arise.
Vision, hearing, and touch result from photoreceptors and mechanoreceptors. Photoreceptors in the eyes (namely rods and cones) generate electrical signals in response to light. Mechanoreceptors in the cochlea generate action potentials based on the vibrations of sound waves. Mechanoreceptors in the skin respond to pressure and other external stimuli to produce the sensation of touch.
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Which nerve allows for special sensory taste fibers for the anterior two-thirds of the tongue?
The chorda tympani branch of the facial nerve (cranial nerve VII), which is carried by the lingual branch (of the trigeminal nerve), allow for special sensory taste fibers for the anterior two-thirds of the tongue. The general sensory innervation for the anterior two=thirds of the tongue is provided by the lingual branch of the mandibular nerve from the trigeminal nerve (cranial nerve V).
The glossopharyngeal nerve (cranial nerve IX) provides sensory and taste to the posterior one-third of the tongue. Hypoglossal nerve (cranial nerve XII) provides motor innervation for all the muscles of the tongue (except for palatoglossus which is innervated by the pharyngeal branch of the vagus nerve (cranial nerve X).
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Which of the following cranial nerves (CN) is correctly matched to the cranial nerve name?
There are twelve cranial nerves. They are given in order below, with their associated functional classes.
CN I - olfactory nerve - sensory
CN II - optic nerve - sensory
CN III - occulomotor nerve - motor
CN IV - trochlear nerve - motor
CN V - trigeminal nerve - both sensory and motor
CN VI - abducens nerve - motor
CN VII - facial nerve - both sensory and motor
CN VIII - vestibulocochlear nerve - sensory
CN IX - glossopharyngeal nerve - both sensory and motor
CN X - vagus nerve - both sensory and motor
CN XI - accessory nerve - motor
CN XII - hypoglossal nerve - motor
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The frontal lobe, thalamus, midbrain, pons, and medulla all house specific cranial nerve nuclei.
Which cranial nerves originate in the pons?
The twelve cranial nerves and their origins are given below:
I-Olfactory nerve; origin: frontal lobe
II-Optic nerve; origin: thalamus
III-Ophthalmic nerve; origin: midbrain
IV-Trochlear nerve; origin: midbrain
V-Trigeminal nerve; origin: pons
VI-Abducens nerve; origin: pons
VII-Facial nerve; origin: pons
VIII-Vestibulocochlear nerve; origin: pons
IX-Glossopharyngeal nerve; origin: medulla
X-Vagus nerve; origin: medulla
XI-Spinal Accessory nerve; origin: medulla
XII-Hypoglossal nerve; origin: medulla
The nerves to originate in the pons are V, VI, VII, and VIII (the trigeminal, abducens, facial, and vestibulocochlear nerves).
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Which cranial nerves carry parasympathetic fibers?
Select the most complete list.
The parasympathetic nervous system is responsible for the "rest and digest" mechanism. When the body is at rest the following occurs: pupils constrict (ophthalmic branch of the trigeminal nerve), lacrimation and salivation occur (facial nerve and glossopharyngeal nerve), heart rate decreases, respiration rate decreases, and digestion increases (vagus nerve).
In addition to the cranial nerves, sacral nerves 2-4 (pelvic splanchnic nerves) carry parasympathic fibers that control erections, the bladder, and the bowels.
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What cranial nerve is responsible for the sensation of taste on the anterior two-thirds of the tongue?
The facial nerve (CN VII) is responsible for the sensation of taste on the anterior two-thirds of the tongue. CN IX, the glossopharyngeal nerve, is responsible for posterior sensation. CN V, the trigeminal nerve, is also involved in certain sensations throughout the tongue.
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What cranial nerves are responsible for parasympathetic (visceral) reactions of the body?
Cranial nerves 3, 7, 9, and 10 are all responsible for parasympathetic nuclei of the brainstem. Oculomotor CN 3 contains the Edinger-Westphal nucleus which controls the eye smooth muscles (which if damaged would result in a dilated pupil that would not constrict in bright light). Facial CN 7 controls the superior salivatory nucleus which controls the submandibular, sublingual, and lacrimal gland secretion. Glossopharyngeal CN 9 innervates the parotid gland secretions. The vagus CN 10 innervates the heart and lungs down into the chest cavity. Helpful hint** - Students often confuse the superior and inferior salivatory nuclei, remember that on the brainstem the facial nerve exits superior to the glossopharyngeal nerve and thus how it is properly named for their nuclei.
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Which dermatome is responsible for sensation at the level of the nipple?
The dermatome responsible for sensation at the level of the nipple is T4.
C2 is responsible for sensation at the posterior half of the skull "cap" and C4 at the level of a low collar shirt. T10 is responsible for sensation at the level of the navel (to remember this think bellybutton...belly buTEN). L4 includes the kneecaps.
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What are astrocytes?
Astrocytes provide support and nutrition to neurons within the brain and spinal cord. Myelin sheath insulates the axons of some neurons which allows them to conduct impulses faster. Nerve fibers are single nerve axons that are surrounded by a sheath of connective tissue. Nerves themselves are cordlike structures that transmit nerve impulses.
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Which fiber type is associated with chronic pain?
C fibers are associated with chronic pain perception because they transmit "slow pain". This is due to the fibers being unmyelinated. In addition, these fibers send projections to the limbic system and the thalamus which causes the brain to develop chronic pain associations.
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What fiber(s) are associated with the perception of pain?
Both A delta and C fibers are associated with the perception of pain. This can be broken down more specifically to A delta fibers that are slightly mylinated and carry "Fast" sharp pain that is immediately felt. While C fibers carry "slow" pain due to being unmyelinated and is associated with chronic pain.
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Which of the following statements is true concerning the autonomic nervous system?
The autonomic nervous system can be divided into the sympathetic and parasympathetic nervous systems. Although both divisions have target organs and tissues, the parasympathetic postganglionic neurons are usually much closer to the effector organ than sympathetic postganglionic neurons.
The autonomic nervous system is under involuntary control, while the somatic nervous system is under voluntary control. Only sympathetic postganglionic neurons use epinephrine; most autonomic neurons use acetylcholine. Both divisions include neurons that originate from the spinal cord. The cranial nerves have both sensory and motor functions, meaning that they can be involved in either somatic or autonomic innervation.
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Which cranial nerves are part of the visceral efferent parasympathetic in the peripheral nervous system (PNS)?
The cranial nerves that are part of the visceral efferent parasympathetic in the PNS are III, VII, IX, and X. Cranial nerve III (oculomotor) travels to the ciliary ganglion and supplies the pupil of the eye for constriction. Cranial nerve VII (facial) travels to the pterygomandibular and submandibular ganglion and supplies the lacrimal and salivary glands. Cranial nerve IX (glossopharyngeal) travels to the otic ganglion and supplies the Parotid gland. Lastly, cranial nerve X (vagus) travels to the Prevertebral plexus and thoracic plexus in order to supply the gut, heart, and enteric system.
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Atropine is a molecule that is an antagonist to muscarinic cholinergic receptors. Based on your knowledge of autonomic nervous system physiology, how would you expect the pupils to respond to topical administration of atropine?
The pupillary sphincter muscles contain muscarinic cholinergic receptors that help the eyes to respond to parasympathetic tone. When this parasympathetic signal is blocked (antagonized) via atropine, you will observe a "sympathetic response" at the level of the pupil. In this scenario, you would observe the sympathetic response of pupil dilation. Hint: "aTROP'ine" and "seeing a TROPical setting" both cause your pupils to dilate nice and wide!
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Which of these is a feature of the parasympathetic nervous system?
The parasympathetic nervous system conserves energy and is thus know as the "rest and digest" system. It slows heart rate, increases salivation, lacrimation, urination, deification, digestion, and sexual arousal. The nerves of the parasympathetic system arise in the CNS. Specific nerves include cranial nerves, including the oculomotor nerve, facial nerve, glossopharyngeal nerve, and vagus nerve.
In the sympathetic nervous system some sympathetic fibers pass through the paravertebral ganglia, and others synapse there.
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Which of the following nerves carries parasympathetic nerve fibers?
The vagus nerve (CNX) provides the heart and digestive tract with parasympathetic ("rest and digest") control.
Cranial nerves with associated parasympathetic activity include CN III, VII, IX, and X. The sympathetic trunk and the white ramus communicans are associated with the sympathetic nervous system.
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How is the parasympathetic branch of the autonomic nervous system organized?
Cell bodies of preganglionic neurons are located in the central nervous system (CNS); they synapse onto autonomic ganglia. Parasympathetic ganglia are located in or near the effector organs giving them long preganglionic fibers and short postganglionic fiber. Sympathetic ganglia are located in the paravertebral chain, thus they have short preganglionic fibers and long postganglionic fibers.
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