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This nervous system trivia quiz has 50 free questions with answers, and it covers the wiring of the whole body rather than just the brain. You will be asked how the central and peripheral systems divide up, what a neuron's dendrites and axon actually do, why the knee-jerk reflex never bothers to check in with the brain, how many pairs of spinal nerves and cranial nerves you own, and which nerve earns the nickname 'wandering'. There are rounds on the autonomic system (fight or flight versus rest and digest, and the 'second brain' in your gut), on the meninges and cerebrospinal fluid, on the longest and fastest nerves, and on what goes wrong: multiple sclerosis stripping myelin, Parkinson's and dopamine, rabies creeping along nerves, tetanus, Bell's palsy, carpal tunnel and the funny bone. A few questions look at other animals, from jellyfish nerve nets to octopus arms. It suits biology students revising anatomy and physiology, teachers who need a class quiz, nursing and pre-med study groups, and anyone who enjoys human body trivia. Difficulty runs from easy to expert, and every answer was verified against Wikipedia and standard anatomy references before it went in.
30 of 50 questions with answers and explanations. Play the quiz
Q 01In vertebrates the nervous system has two main parts: the central nervous system and which other?
Peripheral
The peripheral half is not shielded by the skull, the vertebral column or the blood-brain barrier, which makes it more vulnerable to injury and toxins.
Q 02Neurons are typically sorted into three functional types: sensory neurons, motor neurons and what?
Interneurons
They connect neurons to other neurons within the same region. Sensory neurons carry signals in from the sense organs; motor neurons carry orders out to muscles and glands.
Q 03Which part of a neuron carries impulses away from the cell body, sometimes for a metre or more?
The axon
It leaves the cell body at a swelling called the axon hillock. Dendrites, by contrast, branch profusely but only reach a few hundred micrometres.
Q 04The body's longest axons belong to which nerve, running from the spine's base to the big toe?
Sciatic
It is also the widest single nerve in the body, formed from the L4 to S3 spinal roots. Most axons are only about a micrometre across.
Q 05Along with neurons, the nervous system is built from support cells known collectively as what?
Glia
They provide structural and metabolic support. Star-shaped astrocytes are the most abundant kind in the brain, and microglia act as its resident immune cells.
Q 06Which cells, named after a German physiologist, form the myelin sheath outside the brain and spinal cord?
Schwann
Theodor Schwann is the namesake. Inside the brain and spinal cord the same wrapping job is done by different cells, the oligodendrocytes.
Q 07Impulses in myelinated axons seem to jump between gaps in the sheath. What are those gaps called?
Nodes of Ranvier
The leaping style is called saltatory conduction, from the Latin for 'jump'. Louis-Antoine Ranvier described the gaps in the 1870s.
Q 08Which ion floods into a neuron to trigger the rising phase of an action potential?
Sodium
Voltage-gated channels open at a threshold, the interior turns positive, then potassium flows out to restore the resting state. Local anaesthetics work by blocking those sodium channels.
Q 09The fastest myelinated nerve fibres conduct impulses at roughly what speed?
120 metres per second
That is about 432 km/h, glacial next to electricity in a wire but far quicker than blood flow. The slowest unmyelinated fibres crawl along at about half a metre per second.
Q 10Jens Christian Skou, who discovered the neuron's three-out, two-in ion pump in 1957, was of which nationality?
Danish
He collected a Nobel Prize for it forty years later. The pump burns one ATP molecule per cycle and keeps every animal cell electrically ready to fire.
Q 11Roughly how long is the adult human spinal cord?
About 45 cm
It is much shorter than the spinal column that protects it, ending between the first and second lumbar vertebrae before tapering into a bundle of nerve roots.
Q 12The nerve-root bundle below the spinal cord takes its Latin name from its resemblance to what?
A horse's tail
The cauda equina consists of the lower lumbar, sacral and coccygeal nerve pairs. Compressing it is a surgical emergency.
Q 13How many pairs of spinal nerves branch off the human spinal cord?
31
Eight cervical, twelve thoracic, five lumbar, five sacral and one coccygeal. The cervical nerves are numbered by the vertebra below them, the rest by the one above.
Q 21Why can a reflex like the knee-jerk fire faster than a deliberate movement?
The signal loops through the spinal cord without going to the brain first
The brain still receives the input, but it analyses the signal after the reflex has already happened.
Q 22What is the third division of the autonomic nervous system, which runs the gut, called?
Enteric
Often called the 'second brain', it holds five times as many neurons as the spinal cord and can operate independently of the brain.
Q 23Which branch of the autonomic nervous system drives the 'fight or flight' response?
Q 14Conventionally, how many pairs of cranial nerves do humans have?
12
They are labelled with Roman numerals I to XII. Only the first two emerge from the cerebrum; the other ten arise from the brainstem.
Q 15Which cranial nerve, the tenth, takes its name from the Latin for 'wandering'?
Vagus
It is the longest nerve of the autonomic system, reaching from the brainstem to the gut, and it drives the 'rest and digest' response that slows the heart.
Q 16Which cranial nerve, the fifth, serves facial sensation and chewing and is named for its three branches?
Trigeminal
Its ophthalmic, maxillary and mandibular divisions converge just before entering the pons. It is often called the most complex of the cranial nerves.
Q 17The facial nerve also carries which sense from the front two-thirds of the tongue?
Taste
A branch called the chorda tympani carries the taste fibres. Damage to this nerve on one side is what causes the drooping of Bell's palsy.
Q 18The hypoglossal nerve, cranial nerve XII, which drives the muscles of the tongue, is which type of nerve?
Purely motor
Its name means 'under the tongue'. Doctors test it by asking a patient to stick their tongue out and watching for it to deviate to one side.
Q 19Which is the shortest of the twelve cranial nerves, and unusually can regenerate after damage?
Olfactory
It carries the sense of smell and, like the optic nerve, does not come off the brainstem. Regeneration is rare among nerve tracts of the central nervous system.
Q 20The knee-jerk reflex is the classic example of which kind of reflex arc?
Monosynaptic
A tap below the kneecap stretches the quadriceps spindle, the signal loops through L3-L4 in the spinal cord and back, and the leg kicks before the brain hears about it.
Sympathetic
Its nerves emerge from the thoracic and lumbar spinal cord, and the adrenal medulla behaves like one of its ganglia, pumping out adrenaline.
Q 24With nerves emerging from the brainstem and sacral spinal cord, the parasympathetic system has what kind of 'outflow'?
Craniosacral
The fight-or-flight system, by contrast, has thoracolumbar outflow. Parasympathetic fibres travel in the oculomotor, facial, glossopharyngeal and vagus nerves.
Q 25Roughly how many neurons does the human gut's own 'second brain' contain?
500 million
That is about 0.5% of the brain's count but five times the spinal cord's. It signals with acetylcholine, dopamine and serotonin, just like the brain.
Q 26How many layers of meninges surround the brain and spinal cord in mammals?
Three
From outside in: the tough dura mater, the web-like arachnoid mater and the delicate pia mater. Cerebrospinal fluid fills the space under the arachnoid.
Q 27Cerebrospinal fluid is mostly produced by which structures inside the brain's ventricles?
The choroid plexuses
Harvey Cushing demonstrated this in 1914. About 125 mL is present at any moment, but roughly 500 mL is made every day and absorbed back into the blood.
Q 28A lumbar puncture, or spinal tap, was first introduced in 1891 by which German physician?
Heinrich Quincke
The needle goes into the lower back below where the spinal cord ends, to draw cerebrospinal fluid or inject drugs and anaesthetics.
Q 29Which part of the brainstem controls breathing, heart rate, blood pressure and vomiting?
Medulla oblongata
It is the lowest part of the brain and continues directly into the spinal cord through the foramen magnum.
Q 30Which almond-sized brain structure controls temperature and hunger and links to the pituitary gland?
The hypothalamus
It secretes releasing hormones that switch pituitary hormones on and off, and it also governs circadian rhythms and sleep.