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What is the term for toes that pull together with an upstep?


I fairly recently learned the termdigitigrade, to describe the anatomy of a creature that stands on its toes rather than on the flat of its foot, like cats and birds.

I'm trying to narrow that down a little more now. Some animals like a cat or dog (or us), the toes are fairly static as they walk. Contrast that to the toes of a bird where on the upstep the toes… pull together, for lack of a better description, and spread apart as they step down on the foot, as shown in this video.

What is the proper term used to describe that motion and style of walking, or that type of functional foot, where the toes pull together and then spread apart as the foot goes up and down?


Is there a scientific term for webbed feet in birds?

I have been interested in wildlife from an early age and this lead me to a degree in Animal management. During my time at university, I developed an interest in conservation work which took me to a job with the Mauritian Wildlife Foundation as a field biologist, working with threatened species of birds and reptiles. Now I have returned to the UK, I am very pleased to be helping to conserve our native wildlife.

Sent in by Wayne Murray, Lincolnshire

Yes - there are several terms! Like a bird's bill or beak, its feet can tell us a lot about its lifestyle.

Feet are obviously important to birds for standing and perching, but they can also be a means of propulsion in aquatic species, a major weapon in predatory species and for some birds their equivalent of a hand, being used to grasp and hold objects during feeding.

Most birds have four toes. The first points backwards in most species while the second, third and fourth toes are arranged from the inside of the foot out. The fifth toe is lost completely, except in some birds where it has become a defensive spur, such as the chicken.

The individual characteristics of a species' feet, i.e. size and shape, arrangement and length of the toes and the degree of webbing all depend on what the bird uses its feet for and where it lives.

The feet of birds are all structurally similar but there is variation among species. The most common difference in waterfowl is in the amount of webbing between the birds' toes.

Types of feet

The most common type of webbed foot found in ducks, geese, swans, gulls, terns, and other aquatic birds are known as palmate. Palmate means that three toes are completely webbed, enabling efficient propulsion in water. However, only the front toes are connected, while the toe at the back is separate.

Aquatic birds such as gannets, boobies, cormorants, and pelicans have feet that are known as totipalmate. Totipalmate refers to all four toes being joined by webbing.

Semipalmate feet have partial webbing present only at the base of the front toes, an adaptation that is useful for occasional swimming or walking on soft surfaces. This type is found in some sandpipers and plovers, all grouse, and some domesticated breeds of chickens.

Lobate feet are found in grebes and coots, though some palmate-footed ducks have lobes of skin on the rear toe (or hallux). The front toes have a series of webbed lobes that open and close when the foot is pushed backwards and forwards.

Put your foot in it

The legs and feet of waterfowl play an important role in thermoregulation. To conserve heat in cold weather, waterfowl reduce the amount of blood flowing to their feet by constricting blood vessels in their legs. To further minimise exposure in cold weather, waterfowl will often be seen standing on one leg at time, tucking the other leg into their body feathers to protect it from the elements. They can also release excess body heat through their feet. By standing or swimming in water that is cooler than the air, waterfowl can avoid heat stress on hot days.

Waterfowl also use their feet while flying, almost like a rudder or flaps on an aeroplane. Ducks, geese and swans lower their feet and spread the webbing between their toes before they land, creating drag to help them slow down. When they want to achieve maximum flight speed and efficiency, they pull their feet close into their body, like an aircraft landing gear, to maximise their aerodynamics.

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Chimpanzees Form Trusting Friendships, Not Unlike Humans

If you thought that humans were the only animals that could form friendships and trust one another, think again.

A study published Thursday in the journal Current Biology found that chimpanzees trust their friends significantly more than those to whom they aren't particularly close.

In the paper, the researchers examined the interactions of 15 chimpanzees in the Sweetwaters Chimpanzee Sanctuary in Kenya over a five-month period, recording the amount of time the primates spent grooming one another and eating together, to quantify how close various pairs were.

They then matched up chimps with their friends and non-friends, in a two-player activity called "the trust game." In it, each participant has a choice between two options, explains study co-author Jan Engelmann, of the Max Planck Institute for Evolutionary Anthropology in Germany: The chimp can pull the "no-trust rope," which opens a compartment that gives the puller access to a small but not-enormously-desirable amount of food (two banana pieces). Or it can pull the "trust rope," which gives the other chimp access to a tastier and larger food cache (three banana pieces and three apple slices), with the important caveat that the second chimp has the option of giving some of it back. So if the first chimp trusts the second, it makes sense to pull the ol' trust rope&mdashif the second chimp is friendly enough, it may result in getting a good snack back versus a mediocre one.

Engelmann and colleague Esther Herrmann did a statistical analysis that showed a strong link between whether the chimps were friends and whether or not they pulled the trust rope. In other words, friends were much more likely to trust each other. If the chimps didn't have something like trust-based friendships, they would be likely to behave similarly toward friends and non-friends. But the animals consistently acted in a way that defied this expectation.

"This is an unexpected finding, as it suggests that chimpanzees do not regulate their behavior toward partners exclusively as a function of received rewards," Engelmann says. "Instead, they seem to form deep emotional bonds with their friends, which are, at least to some extent, independent of short-term payoffs."

The study shows that "long before humans started to develop culturally mediated forms of friendships, our ancestors likely engaged in many of the patterns&hellipof modern human bonds," he adds.


What makes the AR-15 style rifle the weapon of choice for mass shooters?

Some of the worst massacres in recent memory have had something in common: the AR-15 style rifle. Scott Pelley reports on why the high-velocity rounds used in the gun make it so deadly.

  • 2021 Jun 13
  • Correspondent Scott Pelley
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The mass shooting this past April at an Indianapolis FedEx facility has something in common with the deadliest massacres - the AR-15 semiautomatic rifle. Variations of the AR-15 were used to kill at a Boulder, Colorado, supermarket, a Pittsburgh synagogue, Texas church, a Las Vegas concert, a high school in Florida, and Sandy Hook Elementary School. The AR-15 is the most popular rifle in America. There are over 19 million and they are rarely used in crime. Handguns kill far more people. But as we first reported in 2018, the AR-15 is the choice of our worst mass murderers. AR-15 ammunition travels three times the speed of sound. And tonight, we're going to slow that down &ndash so you can see why the AR-15's high-velocity ammo is the fear of every American emergency room.

Mass shootings were once so shocking they were impossible to forget. Now they've become so frequent it's hard to remember them all. In October 2018, at a Pittsburgh synagogue, eleven were killed, six wounded.

Roses memorialize the people who died in the Sutherland Springs, Texas shooting

FBI Special Agent Robert Jones: This is the most horrific scene I've seen in 22 years with the Federal Bureau of Investigations. Members of the Tree of Life Synagogue conducting a peaceful service in their place of worship were brutally murdered by a gunman targeting them simply because of their faith.

Just 11 months before, it was a church in Sutherland Springs, Texas. Assistant fire chief Rusty Duncan was among the first to arrive.

Rusty Duncan: 90 percent of the people in there were unrecognizable. You know the blood everywhere, I mean it just covered them from head to toe. They were shot in so many different places that you just couldn't make out who they were.

The church is now a memorial to the 26 who were murdered.

Rusty Duncan: I've never had the experience, not with any kind of weapon like this. For me to see the damage that it did was unbelievable, it was shattering concrete, I-- you know, you can only imagine what it does to a human body.

Scott Pelley: The police estimate that he fired about 450 rounds.

Rusty Duncan: Oh, I believe it. I saw the damage it did. I saw the holes in the church from one side to the other, all the pews, the concrete, the carpet, I saw it all.

A gunshot wound is potentially fatal no matter what kind of ammunition is used. But Cynthia Bir showed us the difference in an AR-15 round against gelatin targets in her ballistics lab at the University of Southern California.

Cynthia Bir with correspondent Scott Pelley

Cynthia Bir: Years of research have gone in to kind of what the makeup should be of this ordnance gelatin to really represent what damage you would see in your soft tissues.

Scott Pelley: So this is a pretty accurate representation of what would happen to a human being?

Cynthia Bir: Yeah, this is currently considered kind of the state of the art.

"Organs aren't just going to tear or have bruises on them, they're going to be, parts of them are going to be destroyed."

This is a 9-millimeter bullet from a handgun, which we captured in slow motion. The handgun bullet traveled about 800 miles an hour. It sliced nearly straight all the way through the gel.

Now look at the AR-15 round.

Cynthia Bir: See the difference?

It's three times faster and struck with more than twice the force. The shockwave of the AR-15 bullet blasted a large cavity in the gel unlike the bullet from the handgun.

Scott Pelley: Wow. There's an enormous difference. You can see it right away.

Cynthia Bir: Yeah, exactly. There are fragments in here. There's, kind of took a curve and came out. You can see a much larger area in terms of the fractures that are inside.

Now watch from above. On top, the handgun, at bottom, the AR-15.

Scott Pelley: It's just exploded.

Cynthia Bir: It's exploded and it's tumbling. So what happens is, this particular round is designed to tumble and break apart.

The 9 mm handgun round has a larger bullet, but this AR-15 round has more gunpowder, accelerating its velocity. Both the round and the rifle were designed in the 1950's for the military. The result was the M16 for our troops and the AR-15 for civilians.

Cynthia Bir: There's going to be a lot more damage to the tissues, both bones, organs, whatever gets kind of even near this bullet path. The bones aren't going to just break, they're going to shatter. Organs aren't just going to tear or have bruises on them, they're going to be, parts of them are going to be destroyed.

That fairly describes the wounds suffered by 29-year-old Joann Ward. At Sutherland Springs Baptist Church she was shot more than 20 times while covering her children. Ward was dead, her daughters mortally wounded, as assistant fire chief Rusty Duncan made his way from the back of the sanctuary.

Rusty Duncan

Rusty Duncan: As I got a couple of rows up, Ryland's hand reached out from under his stepmom and grabbed my pant leg. I wouldn't even known he was alive until he did that. I didn't even see him under her. Well, that's where me and him made eye contact for the first time.

Joann Ward's five-year-old stepson Ryland Ward was hit five times and was nearly gone when he reached trauma surgeon Lillian Liao at San Antonio's University Hospital.

Scott Pelley: How much of Ryland's blood do you think was lost before he came to you?

Lillian Liao: At least half.

Lillian Liao: You see the two bullet fragments that are in him.

Scott Pelley: The X-ray shows you the solid fragments of the shrapnel and the bullets, but it doesn't tell you much about the damage to the soft tissue.

Lillian Liao: No, and it doesn't tell you what's on the inside. I mean a bomb went off on the inside. And our job is to go in there and clean it up.

Scott Pelley: A bomb went off on the inside because of the shockwave from these high-velocity rounds.

Ryland endured 24 surgeries to repair his arm, leg, pelvis, intestines, kidney, bladder and hip.

Lillian Liao: At some point it's like putting Humpty Dumpty back together again.

Scott Pelley: What do you mean?

Lillian Liao: Well his organs are now in different pieces and you have to reconstruct them. The arm was missing soft tissue, skin, muscle and part of the nerves were damaged. The bowel has to be put back together some of the areas of injury has to heal itself so you can see that he can walk around like a normal child and behave as normal as possible.

Lillian Liao

With the AR-15, it's not just the speed of the bullet, but also how quickly hundreds of bullets can be fired. The AR-15 is not a fully automatic machine gun. It fires only one round with each pull of the trigger. But in Las Vegas, it sounded like a machine gun.

A special add-on device called a bump stock allowed the killer to pull the trigger rapidly enough to kill 58 and wound 489. In other mass killings the AR-15 was fired without a bump stock, but even then, it can fire about 60 rounds a minute. Ammunition magazines that hold up to 100 rounds can be changed in about five seconds.

Maddy Wilford: I remember hearing the gunshots go off and being so nervous and scared and all of the sudden I felt something hit me.

Scott Pelley: You'd been shot how many times?

Scott Pelley: How many surgeries?

Maddy Wilford: Three. For my arm, my stomach and my ribs and lung.

Maddy Wilford

In February of 2018, 17-year-old Maddy Wilford was at school, Marjorie Stoneman Douglas High School in Parkland, Florida. 17 were murdered, 17 wounded.

Maddy Wilford: And I just remember thinking to myself, there's no way, like, not me, please, not me. I don't wanna go yet.

Laz Ojeda: Her vital signs were almost nonexistent. she looked like all the blood had gone out of her body. She was in a state of deep shock.

Paramedic Laz Ojeda saved Maddy Wilford, in part, because Broward County EMS recently equipped itself for the battlefield wounds that the AR-15 inflicts.

Laz Ojeda: We carry active-killer kits in our rescues.

Scott Pelley: Active-killer kits?

Scott Pelley: What is that?

Laz Ojeda: That is a kit that has five tourniquets, five decompression needles, five hemostatic agents, five emergency trauma dressings.

Dr. Peter Antevy, Broward County Medical Director, told us today's wounds demand a new kind of training.

Peter Antevy: If I take you through one of our ambulances or take you through our protocols, almost everything we do is based on what the military has taught us. We never used to carry tourniquets. We never used to carry chest seals. These were things that were done in the military for many, many years.

Scott Pelley: When did all of that change?

Peter Antevy: It really changed I think after Sandy Hook.

After Sandy Hook Elementary School where 20 first graders and six educators were killed with AR-15 rounds, a campaign called "Stop the Bleed" began nationwide. Antevy and doctors including Lillian Liao in San Antonio, are training civilians who are truly the first responders. There have been more than 88,000 classes like this in the last six years.

Peter Antevy: The day after the shooting, my kids, they're waking up, and they're "time to go to school." And, my son heard kind of heard what happened the night before, when I was on the scene, and he looked at me with the fear of God that he had to go to school that day. My first instinct was, "He needs a bleeding kit." My son today has a bleeding kit on his person.

Scott Pelley: How old is he?

Peter Antevy: 12 years old. Here it is. This is it. We, we, I've given him this and I've taught him how to use it.

Scott Pelley: You believe that these mass casualty events have become so common &ndash

Scott Pelley: &ndash that it is important for everyone in this country to be prepared.

Scott Pelley: That's where we are in America today?

Peter Antevy: That's where we are.

Ryland Ward

Ryland Ward survived the church massacre because firefighter Rusty Duncan used his belt as a tourniquet.

For over a year Ryland has worked, often six days a week, learning to sit, stand, and walk again.

Ryland Ward: I'm going to see if this actually goes in the hospital. Yep.

Scott Pelley: Did you meet some new people in the hospital? You were there for a long time.

Ryland Ward: How do you know?

Scott Pelley: They told me. I talked to some of the people who helped you.

Scott Pelley: There was, uh, Doctor &ndash

Scott Pelley: Doctor Liao, yes.

He has his strength back. Its remarkable, really. But healing from the loss of his stepmother and sisters won't be as quick.

Maddy Wilford is also moving forward. Like many who suffer physical trauma, her interests have turned to medicine and an internship where she is studying the kind of surgeries that saved her.

Not long ago, many communities assumed mass murder would never come to them

Today, all Americans are being asked to prepare for the grievous wounds of high-velocity rounds.

Since our story first aired in 2018, Ryland Ward - now 9 years old - has had several more surgeries to remove shrapnel from his arm and to treat ongoing heart, stomach and kidney problems. Parkland student Maddy Wilford is in her second year of college, majoring in biology and on track for med school.


Plantar Flexion-Associated Pain and Injury

Problems performing plantar flexion or pain when performing the movement are usually associated with ankle injuries.

Conversely, frequent plantar flexion can also cause ankle problems, such as posterior ankle impingement syndrome. This is commonly referred to as ‘dancer’s heel,’ and is very common in ballet dancers, athletic jumpers, and soccer players. It causes pain during plantar flexion and sometimes requires surgery to correct.

Another injury associated with excessive plantar flexion is os trigonum syndrome. The os trigonum is an accessory bone that sometimes develops behind the ankle but is not present in all individuals. Plantar flexion causes the ankle and heel bones to come together, and with repetition of the movement can cause them to crush the os trigonum. As a result, the tendons and ligaments pull and detach from the bone, causing significant pain, especially when in the foot is in plantar flexion.

Plantar Flexion Contracture

Plantar flexion contracture occurs because the plantar flexion muscles are contracted, causing the ankle joint to have a reduced range of motion. This causes walking and other tasks that require ankle movement to become challenging.

Contracture is especially movement-limiting in severe cases, which frequently occur in individuals with cerebral palsy, or as a result of central nervous system damage or disease.


Gallery: The ambitious urban surrealism of Alex Chinneck

British artist Alex Chinneck has been distorting and twisting the physical world into surreal and mind-bending permutations for nearly a decade now. His latest work returns to the more humble world of indoor sculpture after five years of extraordinary large-scale work.

Chinneck's first major architectural installation came in 2012 with a work called Telling the Truth Through False Teeth. Attempting to subvert the classically held notion that a building filled with broken windows was an indication of a community accepting a type of social decline, Chinneck took over a derelict factory and fitted it with 312 identically broken windows.

Telling the truth through false teeth – one of Chinneck's first large-scale installations

Over the next few years, Chinneck produced a series of stunning large-scale installations that literally deconstructed familiar architectural principles. From the Knees of my Nose to the Belly of my Toes melted a facade of a house down into its front garden, while Six pins and half a dozen needles cracked a brick wall into two as if it were an eggshell.

Perhaps one of Chinneck's most compelling pieces came in 2014. Called A Pound of Flesh for 50p, this was a temporary installation resembling a full-size house but made of 7,500 wax bricks. Each day Chinneck and his team took to the house with hand torches, slowly melting it down over a couple of months.

A pound of flesh for 50p – displayed a slowly melting house, made out of wax bricks, disappearing over two months

His latest work moves back to a smaller sculptural scale but is no less fantastic. Employing impressively sophisticated wood-working techniques, the new pieces literally tie in knots common materials that generally impress as solid. These logic-defying sculptures knot up wooden pillars and grandfather clocks, creating a bizarre final object that seems to subvert its own material quality.

Growing up gets me down contorts a grandfather clock into an unlikely position

Take a look through our gallery for a closer look at Chinneck's magnificently surreal work.


Foot Exam

The foot is a complex structure composed of numerous bones and articulations. It provides flexibility, is the essential contact point needed for ambulation, and is uniquely suited to absorb shock. Because the foot must support the weight of the entire body, it is prone to injury and pain. When examining the foot, it is important to remove shoes and socks on both sides, so that the entire foot can be inspected and compared. It is important to closely compare the injured or painful foot to the uninvolved side. The essential parts of the evaluation of the foot include inspection, palpation (which should include vascular assessment), testing of the range of motion (ROM) and strength, and the neurological evaluation.

Procedure

  1. Inspect and compare both fully exposed feet from the front, the side, and from behind.
  2. Note any asymmetry, swelling, ecchymosis, and arch deformities.
  3. Inspect the skin and nails for evidence of infection, calluses, and corns.
  4. Inspect the shoes for abnormal wear patterns.

With the patient seated, palpate for tenderness, swelling, or deformity in the foot using the tips of the index and middle fingers.

  1. Dorsal foot
    1. Palpate the top of the foot, looking for tender spots along the tarsal bones (navicular, cuboid, and three cuneiform bones), metatarsal bones, phalanges, metatarsophalangeal (MTP) joints, and extensor tendons of the toes. Tenderness and numbness between the third and fourth metatarsal heads is seen with a Morton's neuroma.
    2. Palpate the dorsalis pedis pulse in the midline of the mid-foot.

    MTP joints and toes should be assessed first actively and then passively, comparing both feet and checking for limited motion and/or pain.

    1. Forefoot abduction (normal ROM: 5°): Grasp the calcaneus with one hand to hold it steady and then using the other hand, push the forefoot laterally.
    2. Forefoot adduction (normal ROM: 5°): Grasp the calcaneus with one hand to hold it steady while using the other hand to push the forefoot medially.
    3. Great toe extension (normal ROM: 70°) and flexion (normal ROM: 45°): Test actively first by asking the patient to flex and extend the toe and then by grasping the toe and passively extending (dorsiflexing) and flexing (plantarflexing) it.
    4. Lesser toes extension and flexion - test active motion by asking the patient to flex and extend all their toes at the same time, while comparing sides, and the passive motion by pushing each toe up and down with your fingers, comparing between the sides.

    Strength testing is performed as resisted isometric movements. Check for muscle weakness and/or pain.

    1. Resisted great toe extension is tested by pushing down on the toe against resistance to check the extensor halluces longus, which is innervated by the peroneal nerve.
    2. Resisted great toe flexion is tested by asking the patient to flex their big toe while you try pull it into extension. This tests the flexor halluces longus, which is innervated by the tibial nerve.
    3. Resisted lesser toe flexion and extension are generally done testing all toes at once in a similar fashion as above.

    Assess the sensation in the foot by lightly touching it with your fingertips in the following areas and comparing one side to the other for deficits.

    1. Lateral border of the foot (innervated by the sural nerve).
    2. Web space between the first and second toe (innervated by the deep peroneal nerve).
    3. Dorsum of the foot (innervated by the superficial peroneal nerve).
    4. Plantar aspect of the heel and foot (innervated by the posterior tibial nerve).

    The structure of the foot makes it uniquely suited for ambulation and shock absorption. It also provides flexibility on uneven terrain.

    A foot is composed of three units: hindfoot, midfoot and forefoot. The hindfoot is formed by the calcaneus and talus. These bones form the subtalar joint, which allows for the foot inversion and eversion. The midfoot is composed of the navicular, cuboid and three cuneiform bones. Finally, the forefoot consists of the five metatarsal bones and the phalanges of the toes, which are connected by the metatarsophalangeal, or the MTP, joints. The bones and joints of the foot are supported by numerous ligaments, tendons, and muscles. One of the most notable structures is the plantar fascia, which is a band of a fibrous tissue that runs from the heel to the forefoot, to support the foot's arch.

    Due to their role in weight bearing and ambulation, the feet are especially prone to injury, inflammation, and pain. Foot pain may also result from the disorders of vascular system, peripheral nerves or nerve roots. Therefore, a foot exam should also include assessment of the peripheral pulses and the neurological evaluation.

    Foot and ankle examination are usually performed together. However, this presentation will just display the maneuvers that a physician should perform to evaluate the integrity and functioning of key foot structures. The ankle examination is covered in a separate video of this collection.

    The foot exam is performed in a systematic way, starting with careful inspection and palpation of both feet.

    Before starting the exam wash your hands thoroughly. Ask the patient to remove their shoes and socks, and sit on the examination table. Begin with inspection of both feet. Look at them from all aspects. Note any asymmetry, swelling, ecchymoses and deformities, while comparing between sides.

    Carefully examine the skin and nails for calluses, corns, ulcers, and signs of fungal nail infection, such as deformity and discoloration of nails. Also look for Tinea Pedis, which refers to the redness and peeling of the skin between the toes and on the bottom of the feet. Lastly, inspect the patient's shoes for abnormal wear pattern.

    Following inspection, palpate the tarsal bones, the metatarsals, the extensor tendons, and each of the toes checking for any tenderness, swelling, or deformities. Next, move on to the spaces between the metatarsal heads. Tenderness and numbness between the third and fourth metatarsal heads is seen in people with Morton's Neuroma - referring to the thickening of the nerve tissue. If present, squeezing the metatarsal heads together would accentuate the pain. Also, feel for the dorsalis pedis pulse in the midline of the midfoot, which can be weak or even absent in patients with peripheral arterial disease.

    Subsequently, move onto the medial foot and palpate along the navicular bone, first metatarsal bone, and plantar fascia. Note any bunion, which is the prominence at the first MTP joint caused by rubbing of the shoes. Then examine the lateral foot along the fifth metatarsal bone up to the fifth toe. A prominence at the fifth MTP joint, called the bunionette, can be seen due to excessive rubbing in this area. Finally, palpate the plantar surface of both feet starting at the heel pad and calcaneus, moving distally along the plantar fascia, the metatarsal heads, and the phalanges. Tenderness at the proximal plantar fascia is seen with plantar fasciitis.

    Next part of the systematic foot examination is range of motion testing. During these maneuvers, compare between sides and note any limited motion or pain.

    Start by grasping the patient's calcaneus with one hand, to hold it steady. Then with your other hand, push the forefoot laterally. This tests foot abduction, for which the normal range of motion is approximately 5°. Similarly, test foot adduction by pushing the forefoot medially. Again, the maximum range is about 5°.

    For the following maneuvers, ask the patient to perform instructed actions actively. To assess great toe extension and flexion instruct the patient to only point the great toe up towards the ceiling and then down towards the floor. Normally, the range of motion for great toe extension is 70° and for flexion is 45°. Similarly, test the lesser toes extension and flexion by asking the patient to extend and then flex all their toes at the same time. As patient does that, compare the range of motion between feet. Normally, the ranges are about the same.

    The following section describes strength testing, which is performed as a series of resisted isometric movements, while checking for pain or muscle weakness.

    Start by asking the patient to maximally extend their great toe and keep it in this position, while you attempt to push it down. This maneuver tests the strength of the extensor halluces longus muscle, which is innervated by the peroneal nerve.

    Next, test great toe flexion by asking the patient to bend their great toe down, while you try to push it up. This examines the flexor halluces longus muscle, which is innervated by the tibial nerve.

    Subsequently, perform the resisted lesser toe flexion and extension by testing all toes at once in a similar fashion as described before. This maneuver tests the flexor digitorum brevis muscle innervated by L4, L5, S1, and the extensor digitorum brevis muscle innervated by L5, S1.

    Complete the foot examination by testing the sensation in the feet. Now with the patient sitting and eyes closed lightly touch the skin at the lateral border of the foot, which is innervated by the sural nerve. Ask the patient if they can feel the sensation. Then touch the same area on the contralateral foot and ask the patient to compare the feeling between sides.

    Similarly, test the web space between the first and second toe, which is innervated by the deep peroneal nerve , followed by the dorsum of the foot, innervated by the superficial peroneal nerve. Lastly, assess sensation in each of the dermatome of the plantar aspect of the foot. 

    You've just watched JoVE's video on foot exam. Here, we first reviewed inspection and palpation of the foot followed by the range of motion maneuvers and muscle strength testing. We also demonstrated how to evaluate feet for neurological deficits by doing a few simple sensory tests. As always, thanks for watching!

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    Applications and Summary

    Examination of the foot is best done with the patient first in a standing and then sitting position. The exam should follow a stepwise approach, and it is important that shoes and socks be removed from both of the patient's feet to allow easy inspection and comparison. The exam should begin with inspection, looking for asymmetry between the involved and uninvolved foot. Palpation of key structures is done next, looking for tenderness, swelling, or deformity. This is followed with assessing ROM in the forefoot and toes, first actively and then passively. Next, the same motions are tested against resistance to assess the strength and look for pain or weakness. Finally, the sensation across the dorsal and plantar surfaces of the foot is assessed by lightly touching in these areas.

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    Transcript

    The structure of the foot makes it uniquely suited for ambulation and shock absorption. It also provides flexibility on uneven terrain.

    A foot is composed of three units: hindfoot, midfoot and forefoot. The hindfoot is formed by the calcaneus and talus. These bones form the subtalar joint, which allows for the foot inversion and eversion. The midfoot is composed of the navicular, cuboid and three cuneiform bones. Finally, the forefoot consists of the five metatarsal bones and the phalanges of the toes, which are connected by the metatarsophalangeal, or the MTP, joints. The bones and joints of the foot are supported by numerous ligaments, tendons, and muscles. One of the most notable structures is the plantar fascia, which is a band of a fibrous tissue that runs from the heel to the forefoot, to support the foot's arch.

    Due to their role in weight bearing and ambulation, the feet are especially prone to injury, inflammation, and pain. Foot pain may also result from the disorders of vascular system, peripheral nerves or nerve roots. Therefore, a foot exam should also include assessment of the peripheral pulses and the neurological evaluation.

    Foot and ankle examination are usually performed together. However, this presentation will just display the maneuvers that a physician should perform to evaluate the integrity and functioning of key foot structures. The ankle examination is covered in a separate video of this collection.

    The foot exam is performed in a systematic way, starting with careful inspection and palpation of both feet.

    Before starting the exam wash your hands thoroughly. Ask the patient to remove their shoes and socks, and sit on the examination table. Begin with inspection of both feet. Look at them from all aspects. Note any asymmetry, swelling, ecchymoses and deformities, while comparing between sides.

    Carefully examine the skin and nails for calluses, corns, ulcers, and signs of fungal nail infection, such as deformity and discoloration of nails. Also look for Tinea Pedis, which refers to the redness and peeling of the skin between the toes and on the bottom of the feet. Lastly, inspect the patient's shoes for abnormal wear pattern.

    Following inspection, palpate the tarsal bones, the metatarsals, the extensor tendons, and each of the toes checking for any tenderness, swelling, or deformities. Next, move on to the spaces between the metatarsal heads. Tenderness and numbness between the third and fourth metatarsal heads is seen in people with Morton's Neuroma - referring to the thickening of the nerve tissue. If present, squeezing the metatarsal heads together would accentuate the pain. Also, feel for the dorsalis pedis pulse in the midline of the midfoot, which can be weak or even absent in patients with peripheral arterial disease.

    Subsequently, move onto the medial foot and palpate along the navicular bone, first metatarsal bone, and plantar fascia. Note any bunion, which is the prominence at the first MTP joint caused by rubbing of the shoes. Then examine the lateral foot along the fifth metatarsal bone up to the fifth toe. A prominence at the fifth MTP joint, called the bunionette, can be seen due to excessive rubbing in this area. Finally, palpate the plantar surface of both feet starting at the heel pad and calcaneus, moving distally along the plantar fascia, the metatarsal heads, and the phalanges. Tenderness at the proximal plantar fascia is seen with plantar fasciitis.

    Next part of the systematic foot examination is range of motion testing. During these maneuvers, compare between sides and note any limited motion or pain.

    Start by grasping the patient's calcaneus with one hand, to hold it steady. Then with your other hand, push the forefoot laterally. This tests foot abduction, for which the normal range of motion is approximately 5°. Similarly, test foot adduction by pushing the forefoot medially. Again, the maximum range is about 5°.

    For the following maneuvers, ask the patient to perform instructed actions actively. To assess great toe extension and flexion instruct the patient to only point the great toe up towards the ceiling and then down towards the floor. Normally, the range of motion for great toe extension is 70° and for flexion is 45°. Similarly, test the lesser toes extension and flexion by asking the patient to extend and then flex all their toes at the same time. As patient does that, compare the range of motion between feet. Normally, the ranges are about the same.

    The following section describes strength testing, which is performed as a series of resisted isometric movements, while checking for pain or muscle weakness.

    Start by asking the patient to maximally extend their great toe and keep it in this position, while you attempt to push it down. This maneuver tests the strength of the extensor halluces longus muscle, which is innervated by the peroneal nerve.

    Next, test great toe flexion by asking the patient to bend their great toe down, while you try to push it up. This examines the flexor halluces longus muscle, which is innervated by the tibial nerve.

    Subsequently, perform the resisted lesser toe flexion and extension by testing all toes at once in a similar fashion as described before. This maneuver tests the flexor digitorum brevis muscle innervated by L4, L5, S1, and the extensor digitorum brevis muscle innervated by L5, S1.

    Complete the foot examination by testing the sensation in the feet. Now with the patient sitting and eyes closed lightly touch the skin at the lateral border of the foot, which is innervated by the sural nerve. Ask the patient if they can feel the sensation. Then touch the same area on the contralateral foot and ask the patient to compare the feeling between sides.

    Similarly, test the web space between the first and second toe, which is innervated by the deep peroneal nerve , followed by the dorsum of the foot, innervated by the superficial peroneal nerve. Lastly, assess sensation in each of the dermatome of the plantar aspect of the foot.

    You've just watched JoVE's video on foot exam. Here, we first reviewed inspection and palpation of the foot followed by the range of motion maneuvers and muscle strength testing. We also demonstrated how to evaluate feet for neurological deficits by doing a few simple sensory tests. As always, thanks for watching!


    All hairstyles are not created equal: Scalp-pulling and hair loss

    In a review of 19 studies, researchers at Johns Hopkins say they can confirm a "strong association" between certain scalp-pulling hairstyles -- many common among African-Americans -- and the development of traction alopecia, gradual hair loss caused by damage to the hair follicle from prolonged or repeated tension on the hair root. An estimated one-third of African-American women suffer from traction alopecia, making it the most common form of hair loss among that group.

    In a report on their analysis, published ahead of print in the Journal of the American Academy of Dermatology, the investigators urge dermatologists to better educate themselves about the damaging hairstyles -- which include tight ponytails, braids, knots and buns -- and advise patients of risks and alternatives.

    "Hair is a cornerstone of self-esteem and identity for many people," says Crystal Aguh, M.D., assistant professor of dermatology at the Johns Hopkins University School of Medicine, "but ironically, some hairstyles meant to improve our self-confidence actually lead to hair and scalp damage." Traction alopecia, she adds, is entirely preventable, and early intervention can stop or reverse it. "We have to do better as care providers to offer our patients proper guidance to keep them healthy from head to toe," she says.

    In their research review, Aguh and her colleagues categorize hair practices into low-, moderate- and high-risk styles based on the degree to which follicles are exposed to tension, weight, heat and hair-altering chemicals, such as straighteners.

    Moderate-risk styles, the authors say, include some of the same styles noted to be high risk, but because they are performed on natural, unprocessed hair, they are less likely to result in hair loss. Low-risk styles generally included low-tension styles, such as loose buns, and loose-hanging styles, such as wearing the hair down, as well as practices that decrease the amount of friction on the hair and scalp and avoid chemical relaxers. Aguh and her colleagues say the highest-risk styles include braids, dreadlocks, weaves and extensions, especially when applied to chemically straightened hair. These styles are popular among African-Americans, she says, because they are low maintenance and chemical-free, but the constant pulling of the hair in one direction, the tight-locking patterns and added weight can result in significant breakage and eventually traction alopecia.

    Damage can also be done if extensions are affixed with adhesive glue put directly on the scalp, especially when the glued-on hair is removed. Chemical straightening weakens the hair shaft, causing breakage.

    In the more moderate risk category are thermal straightening, permanent waving and use of wigs. Temporary thermal or heat-related straightening of the hair, such as the use of flat irons and blow drying the hair -- while not by itself significantly associated with traction alopecia -- can weaken shafts, leading to "significant" hair loss when traction is applied, the researchers conclude. Permanent waves made with ammonium thioglycolate to create or alter curl pattern, together with added tension from chemical treatment, do the same. And wigs attached with clips and adhesives to keep them in place can cause significant breakage.

    Aguh also noted that cotton and nylon wig caps that rub the hairline may also weaken hair shafts, while satin ones are less likely to do so. Observations among clinic patients reported in the reviewed studies, Aguh says, found that loose, low-hanging styles or even updos are low risk for traction alopecia. So are natural styles that avoid chemicals and the use of frequent moisturization with conditioning agents.

    Untreated and unprocessed hair, she says, can withstand greater traction, pulling and brushing, and overall decreases the risk of traction alopecia, regardless of styling.

    In their review, the investigators also offered guidelines for dermatologists and other care providers to prevent and manage hair loss from traction alopecia. The first line of therapy, they say, is to loosen braids and other high-tension styles, as well as weight on the follicle permanently or periodically. Braided hairstyles should be in place no longer than two to three months, they say, and weaves and extensions should also be removed for a period of time after six to eight weeks.

    The investigators also recommend people alternate styles, mainly reducing or avoiding updos, to allow follicles to recover from stress.

    "Dermatologists need to be conscious of the fact that many high- and moderate-risk hairstyles greatly improve hair manageability, and simply telling patients to abandon them won't work for everyone," says Aguh. "Instead, physicians can educate themselves to speak with patients about making the best hairstyling choices to minimize preventable hair loss."


    What is Flexion

    Flexion refers to a movement that decreases the angle between two body parts. The opposite movement of flexion is the extension. Flexion of the elbow, which decreases the angle between ulnar and the humerus, is a general example of flexion. Dorsiflexion, plantar flexion, and lateral flexion are special movements in flexion. Dorsiflexion is the backward bending. Bending of hand or foot are examples of dorsiflexion. Plantar flexion is the forward bending of hand or foot. Dorsiflexion and plantar flexion of the foot are shown in figure 1.

    Figure 1: Dorsiflexion and Plantar Flexion

    Lateral flexion is bending to the side. The bending of the neck either to the left or right side is an example of lateral flexion.


    Ingrown Toenail

    This photo contains content that some people may find graphic or disturbing.

    An ingrown toenail occurs when the edge of the toenail, usually the big toe, grows into the skin next to it (called the lateral nail fold).

    Ingrown Toenail Symptoms

    An ingrown toenail causes pain at the side of the toe along with swelling. It may become infected which can cause redness, increased swelling, and pain, warmth, and/or discharge.   Note that the ingrown aspect of the nail is usually unseen because it is below the skin.

    Causes

    Factors that increase a person's chance of developing an ingrown toenail include:

      or socks
  2. Abnormal toe shape
  3. Nail trauma
  4. Toenails that are clipped too short
  5. A family history of ingrown toenails
  6. Fungal infections
  7. Increasing age
  8. Health problems like poor leg circulation or lung disease  
  9. Treatment

    Treatment for an ingrown toenail can be performed at home unless there is a suspicion of an infection or if you have a medical condition, such as diabetes, nerve damage, or poor circulation.

    The first step for at-home care is to soak your foot in an Epsom’s salt solution using room-temperature water. Then, massage the side of your nail gently to decrease inflammation. Be sure to not cut your toenail and consider wearing open shoes like sandals until the problem resolves.

    In addition, you may have to take a closer look at the fit and shape of your shoes and socks to analyze whether they are what is causing your ongoing problem. It might mean having to choose between cute shoes and cute toes.

    If your doctor suspects an infection, you may need to take an antibiotic. In addition, note that your doctor may need to remove part of or your complete toenail to ease the inflammation.


    Why You Feel the Urge to Jump

    H ave you ever stood in a high place and felt the urge to jump? Judith Dancoff did one beautiful, clear day on Deception Pass Bridge, a narrow two-lane causeway that ribbons between two islands north of Seattle. If she followed her compulsion to leap, death at the bottom of the steep ocean gorge 180 feet below would be almost certain.

    A novelist known for literary flights of fancy, she did not feel suicidal—and never had. Though normally fearful of heights, she strangely was not afraid then, though Deception Pass Bridge is ranked among the scariest in the world. Its slender concrete span cantilevers over jagged cliff-tops and reportedly wobbles in high winds, with only a minimalist 1935 railing separating you from distant roiling waters.

    Temptation: Deception Pass Bridge rises 180 feet above the ocean. Amit Chattopadhyay / Wikipedia

    None of that registered with Dancoff, who was also unaware of the bridge’s history of attracting jumping. Instead, she saw herself as if in a dream, climbing onto the pedestrian railing then diving off. She was so unnerved that she sat down cross-legged on the pavement to stop herself. “It was terrifying because of the possibility of doing it,” she later recalled. “I felt a bit foolish. I thought, ‘where did that come from?’ ”

    The seemingly irrational, but common urge to leap—half of respondents felt it in one survey—can be so disturbing that ruminators from Jean-Paul Sartre (in Being and Nothingness) to anonymous contributors in lengthy Reddit sub-threads have agonized about it. While the French philosopher saw a moment of Existentialist truth about the human freedom to choose to live or die, ramp_tram called it “F***king stupid” when he had to plaster himself to the far wall of a 14th-floor hotel atrium away from the balcony railing because “I was deathly afraid of somehow jumping off by accident.”

    The French explain it as L’Appel du Vide, or call of the void. Are they just French, or can the void really beckon you to kill yourself? New science on balance, fear, and cognition shows that the voice of the abyss is both real and powerful. Heights, it turns out, are not exactly what they seem.

    T raditional theories attribute extreme phobic reactions—whether fixated on heights, snakes, or the sight of blood—to emotional problems, negative thinking, anxious temperament, and past traumas. “With fears and phobias, psychologists like to say that you are afraid of this because you don’t have coping mechanisms or you are afraid because of anxiety,” says Carlos Coelho, known for his groundbreaking psychology research into acrophobia, or the fear of heights. “But where is this anxiety coming from?”

    When it comes to heights, there is more going on than the projection of past anxieties, as once thought. The nature of extreme heights mixes together sense perceptions, body kinesthetics, and our mental states. “We take perception as the grounded truth: Seeing is believing,” said Jeanine Stefanucci, a professor of cognition and neural science at the University of Utah who studies how emotions, age, and physical condition change how we relate to space, especially vertical space.

    The Bugs in Our Mindware

    Three baseball umpires are talking about how they play the game. The first says, “I call ’em as they are.” The second, “I call ’em as I see ’em.” And the third says, “They ain’t nothin’ till I call ’em.”. READ MORE

    Her research belies the truism that seeing is believing. Subjects in her lab see poop on a table (actually a messy blob of chocolate) as closer than it really is, and the width of a plank they’ve been told to walk over as smaller than it is. Other researchers have found that subjects have underestimated the time to encounter a snake or spider, but not a butterfly or rabbit. 1

    Fear may also explain why humans do not see up-down the same as sideways. To understand how that works, let’s stand on a high balcony, near the railing. Look at a disk placed on the ground below, then back up until the railing is as far away from you as the spot is below you. You’ve just matched a vertical and horizontal distance.

    Acrophobia can produce a bizarrely counterintuitive effect: the impulse to yield to the source of panic and willingly jump.

    But you’re probably wrong. Study participants have been observed to overestimate verticals by anywhere from one-third bigger to double their actual size.2 Yet people usually have no problem correctly estimating horizontals. The vertical over-estimation bias makes high places scarier than they are for some people: Stefanucci and others have found that people most afraid of heights overestimated verticals the most, heightening their fear and creating a feedback loop. 3

    “A lot of people who hear about our work want to know why it would be good for someone to overestimate heights. I argue that it’s adaptive,” says Stefanucci. “Taking a step back is a good thing.”

    Inspiration: Jean-Paul Sartre’s famous urge-to-leap passage may have been inspired by a mountain pass in the Pyrenees. V C / Flickr

    Steep drop-offs in high places can also create symptoms related to motion sickness because of conflicts between our visual system and our vestibular system, Coelho hypothesizes. Think of it like a contractor’s level in your head that responds to gravity and motion, made up of liquid in three canals inside our ears. When we experience motion sickness on a boat, for example, the vestibular system knows we’re moving, but we see ourselves as stationary because we rock with the boat. The conflict creates nausea. (It can help to close your eyes.)

    Something similar can happen on a high precipice. Perhaps a mountain pass in the Pyrenees, like where Sartre used to vacation, possibly inspiring his famed urge-to-leap passage in Being and Nothingness, according to Sartre biographer Gary Cox. The view seems to stretch forever, the distant expanses flattening into infinity. With so little earth up close beneath your feet, there are few visual cues to accompany forward motion, and your visual and vestibular systems clash.

    Those who are most likely to feel the urge to leap also tend to worry more about other life issues.

    People who rely more on sight to navigate struggle harder to maintain their balance while moving, making them even more afraid at heights, where the loss of depth of field confounds our visual abilities.

    Others may suffer from poor postural control, which requires muscular-skeletal strength and agility. Coelho measures postural control in his laboratory with the Romberg test, echoed in the drunk driving check requiring you to walk a straight line. To try the tougher lab version, stand barefoot heel to toe, left foot directly in front of the right, cross your hands over your chest, and close your eyes. Now hold that pose for two minutes. Sounds easy, right? Many people only make it a few seconds. The average time in Coelho’s lab was about 40 seconds. The few aces who made it to two minutes were the least afraid of heights. 4

    The difficulties presented by these effects—faulty visual perspective, poor body control, weak vestibular signaling, and overestimation—contribute to making acrophobia, or fear of heights, one of the most common phobias in the world, affecting 1 in 20 people. But unlike snake, spider, or blood phobias, acrophobia can produce a bizarrely counterintuitive effect: the impulse to yield to the source of panic and willingly jump.

    A s complex as our fear of heights is, the urge to jump is even more difficult to explain. Jennifer Hames, a clinical psychology professor at the University of Notre Dame specializing in suicidal behavior, has dubbed the sudden impulse to jump the “High Place Phenomenon.” In a landmark 2012 paper, she and her colleagues found that half of 431 subjects who’d never considered suicide had thought about leaping from high elevations. 5 (Among people with past suicidal thoughts, 75 percent had felt the urge.) She theorizes that the urge may come from a misinterpretation of a signal sent to the conscious brain by the body’s safety systems. Our fear circuitry, which includes the amygdala and other fast-acting subconscious brain regions, may send an alarm to the prefrontal cortex for interpretation. Your conscious processing, which operates at a slower speed than the fear circuitry, recognizes the alarm signal, but may not know why it was sent.

    While your conscious brain would not need to scratch too hard to figure out why your hand recoils from a hot stove, you might be confused why your body automatically pulls back from the edge of a precipice. Because the void is different. You wonder, as Hames explained it: “Why did I back away? I can’t possibly fall. There’s a railing there, so therefore—I wanted to jump.”

    Consistent with this theory is the fact that those people most likely to the feel urge to leap (and who’d never considered suicide) also experience more anxiety, including worrying more about their own body reactions. These sensations can include sweating, heart palpitations, dizziness, and shaky knees, all of which are common responses to high places. How you interpret those sensations can mark the difference between triggering panic, if you think “I’m going to die,” or excitement, if you love the rush of a high. “There is a subjective dimension to all of this,” Coelho said, especially when it comes to vestibular signals. “The way you interpret the vestibular system is much more up to you” than the interpretation of sight, because it operates outside of conscious awareness. Those who are most likely to feel the urge to leap also tend to worry more about other life issues, including the fear of going crazy.

    Half of 431 subjects who’d never considered suicide had thought about leaping from high elevations.

    This kind of anxiety, though, did not correlate with an urge to leap for subjects in Hames’ study who had thought of suicide. Whether their urge to leap reflected an actual death wish or a misinterpreted safety signal was unclear. “That is a good question for further research,” Hames said.

    An alternative theory for the impulse to jump is offered by Adam Anderson, a Cornell University cognitive neuroscientist who uses brain imaging to map behavior and emotion. He suggests that the High Place Phenomenon stems from the human tendency to gamble in the face of great risk. “People are less risk averse when the situation is bad,” said Anderson. “They roll the dice to avoid the bad thing.”

    In the case of high places, the roll of the dice is to jump. “Being somewhat anxious of heights myself, I feel the pull of the ground, as if it is a safe place,” Anderson said. It doesn’t make sense, of course, since jumping would cause death, but our intrinsic biases (including temporal discounting and negative reinforcement) place a greater value on avoiding present loss than a future gain. “Fear of heights and fear of death may not be as connected in our brains as much as we think,” Anderson explained. “We solved the fear of heights problem: jumping. Then we are confronted with the fear of death problem. It’s like the CIA and FBI not communicating about risk assessments.”

    Looming: In experiments, subject underestimate the time it will take them to reach a frightening animal, but not a friendly one. Pixabay

    Our indirect and delayed processing of the possibility of death was also observed by an “Existential Neuroscience” brain imaging study conducted by German psychologists at Osnabrück University and the Max Planck Institute for Biological Cybernetics. 6 In fMRI scans of 17 male university students, they found that contemplating dying triggered areas of the brain associated with the anticipation of anxiety, rather than actually experiencing anxiety. In other words, our brain holds the idea of death at an emotional distance.

    What these theories share in common is their observation that the will to live—and the specter of death—swirl and mix at the edge of an abyss. In some sense, it’s as if the abyss itself exerts a pull on us. Feeling dizzy at the brink of the precipice, as Sartre saw it, is “the vertigo of possibility” when humans contemplate dangerous experiments in freedom. “During vertigo the drop obsesses us,” as Cox explains in his book, The Existentialist’s Guide to Death, the Universe and Nothingness: “The void seems to beckon us down, but really it is our own freedom that beckons us down, the very fact that we can always choose to go down the quick way.”

    It is difficult, or maybe impossible, to know which, if any, of these theories are relevant to those who choose to actually jump. Two years before Dancoff stood there, a 25-year-old man yelled “Yahoo,” then dived from Deception Pass Bridge. Telling his buddies he’d jumped from taller, he hit the water apparently lifeless, was sucked under by a whirlpool, and never seen again. He joined a reported 400 plus others who have died leaping from the bridge since it was built in 1935. Why did he do it? Stupidity, alcohol, a secret death wish, or an existentialist choice?

    Thinking back to her own experience on Deception Pass, Dancoff doesn’t believe that the void beckoned her down. Instead, she says, it beckoned up. “It was the opposite of vertigo. It was the urge to fly,” she tells me, adding that the ecstatic, out-of-body experience reminded her of joyous childhood dreams that she could fly. She adds her own High Place theory into the mix: Her impulse to leap, she says, tapped into age-old myth reflecting humanity’s collective consciousness. It’s all there in the ancient Greek tale of Icarus, whose DIY wax-and-feathers wings melt when he flies too close to the sun, and send him crashing to his death.

    We have been warned. Not everyone listens, as seen in the surge in extreme airborne sports such as BASE jumping, which involves leaping from high places with a parachute or in a wing suit fitted with a late-opening chute. The death rate is steep, around 50 to 100 deaths per 100,000 jumps, dwarfing the United States suicide rate of 13 deaths per 100,000 people, especially since many people jump more than once.

    It reminds us that we should not necessarily feel anxious about feeling anxious in high places, Coelho says. “No fear is more dangerous. Lack of fear kills a lot of people. They don’t go to the doctor, they die.”

    Jessica Seigel is an award-winning journalist, New York University adjunct journalism professor, and former Chicago Tribune national correspondent. Her work has appeared in The New York Times, National Public Radio, Salon, and other publications. @Jessicaseagull

    1. Vagnoni, E., Lourenco, S.F., & Longo, M.R. Threat modulates perception of looming visual stimuli. Current Biology 22, R826-R827 (2012).

    2. Willey, C.R. & Jackson, R.E. Visual field dependence as a navigational strategy. Attention, Perception, & Psychophysics 76, 1036-1044 (2014).

    3. Teachman, B.A., Stefanucci, J.K., Clerkin, E.M., Cody, M.W., & Proffitt, D.R. A new mode of fear expression: Perceptual bias in height fear. Emotion 8, 296-301 (2008).

    4. Coelho, C.M. & Wallis, G. Deconstructing acrophobia: Physiological and psychological precursors to developing a fear of heights. Depression and Anxiety 27, 864-870 (2010).

    5. Hames, J.L., Ribeiro, J.D., Smith, A.R., & Joiner Jr., T.E. An urge to jump affirms the urge to live: An empirical examination of the high place phenomenon. Journal of Affective Disorders 136, 1114-1120 (2012).

    6. Quirin, M. Existential neuroscience: A functional magnetic resonance imaging investigation of neural responses to reminders of one’s mortality. Social Cognitive and Affective Neuroscience 7, 193-198 (2012).


    Watch the video: Gicht: Symptome, Prävention und Therapie (January 2022).