Kyūsho

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Kyūsho (literally: “places of suffering”) are the anatomical weak points within the human body. Kyūsho are susceptible to the application of force or pressure, which will result in pain, injury, unconsciousness, or death. The magnitude of the applied force, the area where the force is applied, and the technique used to apply the force must always be seriously contemplated.

Avoid striking muscular or fatty areas. Muscle and fat are a natural safety padding which dampens impacts. While striking these areas causes painful bruising, these bruises will not set in until after the confrontation has ended. To quickly incapacitate an attacker, you must attack sensitive soft tissues, break small bones, or dislocate major joints. Fighting requires a functioning skeleton.

There are a number of popular books which explain vital point locations, and list their effects. However, these books are typically derived from traditional Chinese medical practices (i.e., acupuncture) and lack a scientific basis in anatomy or physiology. The only non-pseudoscience kyūsho book is Deadly Karate Blows: The Medical Implications, by Brian C. Adams; sadly, this book is currently out-of-print. If you cannot obtain a used copy of this book, we suggest critically reading standard medical reference texts, such as Gray’s Anatomy.

A list of kyūsho is provided in the table below, listed from the top of the body to the bottom, because that is easier to memorize:

Kyūsho
Skull Temples Eyes Ears Bridge of the nose
Philtrum Chin Side the of jaw Side of the neck Base of the skull
Windpipe Collarbone Armpit Elbow joint Fingers
Floating ribs Inner wrist Solar plexus Upper back Lower back
Abdomen Kidneys Bladder Tailbone Groin
Hollow of knee Side of the knee Shin Achilles’ tendon Instep

Every technique must always be directed towards one of these thirty kyūsho. Even when performing kata, you must envision striking the kyūsho of an imaginary attacker matching your height and build.

Skull

Do not punch someone in the skull. Heads are incredibly hard, and you can easily break your hand trying to crack one open. (This is why boxers wear padded gloves.) Attacks to the skull should only be conducted with your most robust body parts (e.g., hammerfist, elbow, knee, or heel). Even then, skull fractures are unlikely, but closed-head trauma is certain.

Closed Head Trauma

The brain floats in cerebrospinal fluid, like the yolk in an egg. While a strong localized forces can crack the skull like an eggshell, a less-powerful blow can rapidly move the head, such that the brain remains stationary while the head moves around it. This bruises the brain, when it strikes the side of the skull. The brain oscillates like a pendulum inside the head, repeatedly striking both sides of the skull until the impacts and cereberospinal fluid dampen the motion. The results in a concussion, which can lead to unconsciousness and death, depending on its severity. The severity is increased by not allowing the head to roll with the shockwave. The effect is greatest at the joint between frontal and parietal bones, where the skull's weakest point.

The brain has many redundant pathways and connections, so a single knock-out for < 30 s causes little long-term damage. However, knockouts have a cumulative effect, depleting these pathways and causing chronic traumatic encephalopathy (CTE). CTE is a permanent, irreparable degenerative condition which renders people "punch drunk;" and resembles having Alzheimer's disease and Parkinson's disease simultaneously.

Additionally, the sudden change in head position can cause whiplash.

Temples

Contrary to popular belief, the temples are comprised of bone which is just as thick as the rest of the skull. The temple is a kyūsho because it's flat surface allows for more effective transfer energy. A strike to the temple can hit dead-on, whereas strikes to the skull will glance off of its rounded surface. This can have a number of dire consequences, including:

Concussions

Any strike to the head can potentially cause a concussion, which can lead to unconsciousness and death.

Brain Compression

A powerful strike can rupture the meningeal artery, either from the direct shock of impact, or from being pinched by broken bone. Jagged bone edges could also cut the artery. This hemorrhaging causes a buildup of hydrostatic pressure within the skull, compressing the brain. Immediate headaches, nausea and vomiting, will ensue, leading to coma and death. Depending on the severity of the rupture, the full effect could occur instantly, or take up two weeks.

Secondary Effects

A mistargeted temple strike can rupture the opponent's eardum, or fracture the zygomatic arch, rending them unable to eat.

Eyes

The eyes are extremely vulnerable to damage, so all attacks to the eyes are forbidden in kumite and should only be practiced with great care under controlled conditions, if at all. Attacking the eyes should be considered as a desperate, last-resort.

Even light strikes to the eyes will result in tremendous jarring pain, uncontrollable watering of the eyes, and blurred vision in the remaining eye, which can incapacitate an opponent. Most strikes to the eyes will pierce it, causing the vitreous humor to leak out, and/or tearing the retina. Blindness will result, either from the injury, or from the infection which likely follows.

The bone behind the eye is unusually thin. Though it is extremely unlikely, strong eye-poke could break this bone and pierce the brain itself.

Ears

Smacking the ears with cupped hands compresses the air within the ear canal, rupturing the opponent's eardrums. As such, these "bear-paw strikes" (kumade uchi) are forbidden in kumite and should only be practiced with great care under controlled conditions, if at all. These strikes can potentially damage the nearby nerves and blood vessels which feed and control the jaw. While bear-paw strikes are rarely fatal, any blow to the head can cause concussions, which can lead to unconsciousness or death.

The outer ear structure is poorly moored to the head, and can be torn off like the rind of a grapefruit. This is a desperation move, which should only be used as a last-ditch effort to escape from a violent attacker's hold. This disfiguring injury can help law enforcement identify your attacker. Tearing the opponent’s ear off may also impair the opponents vision, since the ears are anchor points for most styles of eyeglasses.

The mastoid process is located in the small valley behind the earlobe. This small bone protrusion causes pain when flexed, making it one of the few reliable "pressure points."

Bridge of the nose

Striking the bridge of the nose has a variety of effects, depending upon the attack's power:

Impaired Vision

The high nerve density causes all strikes to the nose to result in an involuntary watering of the eyes, which can temporarily impede the opponent's vision. This will not stop an opponent, but it will slow them down; this is why a backfist strike to the side of the nose is an ideal atemi.

Skeletal Trauma

A powerful strike to the nose can fracture or dislocate the nasal bone and septum, resulting in pain, shock, and a severe nosebleed. Due to the small target area, it is likely that a strike to the side of the nose will miss and land just under their eye, fracturing their orbit. This can be dangerous, since this fracture can extend into the ethmoid bone, and tear the brain casing. This results in severe headaches as the cerebrospinal fluid leaks out; this is exacerbated by the fact that cerebrospinal fluid leaks are often mistaken for runny noses, and ignored.

Indirect Death

While a strike to the nose is not directly fatal, the pain and shock can induce unconsciousness, which can always be indirectly fatal from:

  • The trauma of the opponent's head striking the ground.
  • The unconscious opponent choking to death on their own blood.

Philtrum

The philtrum is the groove centered on the upper lip, directly under the nose. A strike to the philtrum has a variety of results, depending on the impact's severity:

  • The nose's high nerve density causes an involuntary watering of the eyes whenever the nose is struck. This can temporarily impede the opponent's vision.
  • Split lips are likely.
  • Chipped, fractured, or dislocated teeth are likely.
  • Whiplash is possible.
  • Due to the skull's sphere-like geometry, a sudden pressure pressure spike in this region can cause a bursting fracture of the maxilla (upper jaw) under the eye, beside the nose, and above the canine teeth. These fractures typically occur on the opposite side of the face, but same-side bursting fractures are possible. Eating becomes excruciatingly painful until these fractures heal.
  • Unconsciousness can result, either from a concussion or from shock.
  • Death can occur. Please note that contrary to popular portrayals in television, movies, and comics, a rising palmheel skrike to the philtrum will not cause instantaneous death via piercing the opponent's brain with their fractured nasal bone. This is physiologically impossible; the only intra-skull passages leading to the brain are for the nerves and blood vessels, which are too small to accommodate the nose structure, and their direct upward angle offers no convenient attack vector. It is unlikely -- but possible -- to die from any forceful blow to the head as a result of:
    • Concussions.
    • Choking on blood and/or tooth fragments. Inhaling blood and/or teeth can cause vocal cord spasms, which can seal off the trachea (windpipe), causing death by suffocation.
    • Epidural hematoma caused by rapid head motion tearing or rupturing the middle meningeal artery.

Chin

Striking the chin causes the jawbone to act as a lever, rapidly rotating the opponent's head to efficiently induce closed-head trauma, leading to unconsciousness and concussions. To best exploit this weakness, strike the side of the chin, 1" (2.5 cm) above it's tip; boxers call this spot "the button," since it acts like an on/off switch for your opponent's brain.

Striking the chin from underneath has a similar effect, which is amplified by the fact that rising strikes are hard to detect and defend against. Whiplash may result. Unprepared opponents may inadvertently bite through their tongue, leading to pain, intense bleeding, and the inability to speak.

Side of jaw

Powerful strikes can fracture or dislocate the jaw. Broken jaws must be wired shut to heal, rendering the opponent unable to speak or eat solid food.

A mistargeted jaw strike can fracture the cheekbone, rupturing the sinuses and causing a severe nosebleed. If the opponent were to loose consciousness, they could choke to death on their own blood.

Additionally, facial nerves may be pinched or abraded, causing facial paralysis.

Side of the neck

The neck is a target-rich environment, due to its large number of major nerves and blood vessels. Therefore, striking the side of the neck can result in one or more multiple severe or fatal injuries:

Circulatory Failure

Fatal hemorrhaging and/or thrombosis can result from one or more of the following sources:

  • The internal jugular vein becomes rigid during exhalation, and can be crushed against the cervical vertibrae.
  • Internal corotid vein spasms restrict bloodflow, eventually causing cerebral thrombosis.
  • Chipped or fractured spiny vertebral processes can crush or lacerate the vertebral artery, causing fatal hemorrhaging or cerebral thrombosis.

In addition to hemorrhaging, hematoma will grow in the vessel sheaths with each heartbeat until they strangulate the opponent from within.

Nerve Failure

Powerful blows can always compress or pinch nerves, leading to partial or total paralysis of the affected organ or appendage. Powerful strikes to the side of the neck are especially dangerous, because they will impact:

Skeletal Trauma

Shards of broken or dislocated vertebra can compress, lacerate, or sheer the spinal cord, leading to severe paralysis (e.g., paraplegia, quadriplegia), and/or immediate death. This effect is amplified by the broken neck's inability to support the weight of the opponent's head.

Base of the skull

A strong, well-aimed attack to the base of the skull can dislocate or sever the spinal cord, separating it from the brainstem entirely, which essentially decapitates the opponent. These "rabbit punches" are universally banned by every sporting organization for this reason.

Less severe strikes to this region can still cause paralysis and death from pinching or compressing the spinal cord, or from sharp bone fragments lacerating the spinal cord. Whiplash is almost certain. Concussions are possible, and will likely cause death since the medulla (which autonomously regulates reflexes and homeostatic processes) receives the brunt of the damage.

Windpipe

Any across-the-throat chokes, strikes, or other pressure sources can easily crush the thyroid cartilage (the "Adam’s apple") or trachea (windpipe), resulting in death without an emergency tracheotomy.

A lesser blow can compress the nearby laryngeal nerves. The resulting larnyx spasms can trigger the gag reflex, which can cut off airflow, causing suffocation.

Collarbone

A collarbone fracture will incapacitate that arm, as the clavicle is one of the more painful bones to break. The jagged bone ends can potentially lacerate the brachial plexus or subclavian artery, possibly creating arterial blood clots (i.e., thrombosis) and/or gangrene.

Extremely penetrating strikes to the collarbone can can drive bone shards into the chest, puncturing and collapsing the lungs. Collapsed lungs can cause shortness of breath, painful breathing, dizziness, irregular heartbeat, coma, and possibly death.

Armpit

Though it is unlikely to present itself during an altercation, the brachial plexus lies in this region, close to the skin, where there is little to no muscle to act as padding. All of the nerves controlling the arm and hand branch from this point, so striking this area can compress this nerve cluster, causing severe pain and temporary paralysis (i.e., a "burner" or "stinger").

Elbow joint

Striking the inside of the elbow joint folds opponent's arm, making them bend forward. This can break an opponent's balance and setup a takedown. Striking the outside of the elbow joint, like with an elbow break, can have a variety of outcomes, all of which painfully incapacitates the arm. The power of the blow determines the injury's additional severity:

Painful Swelling

Moderate strikes to the outside of the elbow will tear its bursa ("student's elbow") and tendons ("tennis elbow"), causing pain and extreme swelling which impedes mobility.

Skeletal Trauma, with Complications

Powerful strikes can fracture the humerus, just above the elbow joint, resulting in extreme pain, nausea, and anxiety. This injury can exhibit severe secondary effects:

Fingers

Individual fingers can be grabbed, peeled off, and quickly snapped backwards or sideways to break out of grabs and holds, for an escape with a built-in atemi. The fingers contain numerous small long bones, which can easily be broken with strikes from lateral directions. If these do not incapacitate the opponent's hand, it will severely reduce their grip and dexterity, rendering them unable or less able to use grabs, weapons, or tools.

Floating ribs

The lowermost (i.e., the 11th and 12th) pairs of ribs are structurally weak because their "floating" end does not connect to the sternum, or its cartilage. Powerful attacks to the floating ribs can result in:

Kidney Damage

The hydrostatic shock from a strike to the floating ribs can rupture the opponent's kidney. Broken floating rib fragments can lacerate the kidneys, resulting in weeks of mandatory bed rest to recover from peritonitis. Extreme pain, bloody urine, coma, and possible death will also result.

Glancing blows to the floating ribs can tear the membranes holding the kidney in place, causing internal bleeding and a possible bend or kink in the urethra, causing urethral blockage, infection, and possible death.

Respiratory Damage

Shattered rib fragments can pierce the diaphragm, resulting in short, quick, "shallow" breathing as the body restricts diaphragm motion to prevent further piercing. Internal bleeding will irritate the diaphragm and cause painful hiccupping. This restricted air intake can lead to asphyxia-induced unconsciousness, coma, and death.

There is a tendency to miss the floating ribs and strike higher up on the chest. This can break the short ribs (i.e., the 8th, 9th, and 10th ribs), creating sharpened bone fragments which can resulted in punctured or collapsed lungs. Collapsed lungs can cause shortness of breath, painful breathing, dizziness, irregular heartbeat, coma, and possibly death.

Inner wrist

The inner wrist contains many nerves, tendons, and major blood vessels which control and feed the hand. All of these are close to the surface, in a region where there is little muscle tissue to cushion impacts. Striking the inner wrist can involuntarily open its hand; this can be exploited to disarm attackers. Powerful strikes to this area causes wrist sprains. Radius and/or ulna fractures are possible. Both of these injuries will cause pain, swelling, and a greatly weakened grip.

Solar plexus

The solar plexus is a large nerve cluster located where the rib cage (thorax) and abdomen meet. The solar plexus is oriented along the centerline, behind the diaphragm, in front of the first lumbar vertebrae. The nerves controlling many major organs emanate from the spinal cord at this point, like rays from the sun (thus, the name). Martial artists typically do not attacking this nerve cluster per se; they attack its general location, because attacks to this region can have a number of adverse effects on the opponent's major organs, as described below:

Respiratory Paralysis

Blows to to solar plexus can send the diaphragm into Charley Horse-like spasms. While the intercostal muscles ("rib meat") will function as a redundant diaphragm in this emergency, these muscles are inefficient and will quickly tire, leading to respiratory paralysis which "knocks the wind out" of the opponent. Complete incapacitation for 1-2 minutes will likely result, spelling doom in an altercation. Lapsing into asphyxia-induced unconsciousness from such a blow is unlikely, but possible.

Experience indicates that respiratory paralysis mostly occurs when opponents are struck during inhalation. As such, all inhalations must be sharp and quick, to minimize this vulnerability.

Organ Damage

Attacks to the solar plexus can damage and/or rupture various organs, depending on the attack's angle and force. Any of these cause shock from blood loss, vomiting, and an influx of organ fluids into the abdominal cavity. Unconsciousness can result, and if so, will often lead to death before the damage can be surgically corrected. The jarring shock of a powerful solar plexus attack can tear lung tissue, leading to short and painful breathing.

Straight attacks to the solar plexus cause the lumbar vertebrae to act as an anvil or chopping block, vectoring all of the attack's power into deforming and possibly rupturing the pancreas, duodenum, and/or aorta. While any organ rupture causes internal bleeding, ruptured aortas commonly result in fatal hemorrhaging.

A strike at the opponent's solar plexus, angled towards their left can compress and rupture the opponent's stomach and duodenum. Without surgery, uncontrollable hiccupping, gastrointestinal disturbances, vomiting, shock, and eventually death will result as the body cavity is filled with, and eventually dissolved by, a mixture of blood and stomach acid. Additional compression many bruise or rupture the spleen. A bruised spleen will weaken, and carry a 2-year spontaneous rupture risk. Ruptured spleens cause death from massive hemorrhaging within 48 hours.

A strike at the opponent's solar plexus, angled towards their right can compress and rupture the opponent's liver and gallbladder. Without surgery, uncontrollable hiccupping, gastrointestinal disturbances, vomiting, shock, and eventually death will result as the body cavity is filled with, and eventually dissolved by, a mixture of blood and bile.

Upper back

Attacking the spine is a last-resort option due to its dire consequences:

Paralysis

Powerful strikes to the upper back (i.e., between the shoulder blades) can crush or dislocate the thoracic vertebra, lacerating or sheering the spinal cord leading to limited or full paraplegia, urinary and fecal incontinence, and sexual dysfunction. Neurogenic shock is possible, and potentially fatal. In general, the higher such an injury occurs, the more profound its effects will be.

Less powerful blows will cause similar effects, but to a lesser degree, through herniated discs compressing the spinal cord. Whiplash is likely.

Secondary Effects

Mistargeted attacks can break the opponent's ribs, and cause punctured lungs from the broken rib fragments.

The hydrostatic shock of a powerful strike could potentially act as a precordial thump, sending the opponent's heart into fibrillation.

Lower back

Attacking the spine is a last-resort option due to its dire consequences:

Paralysis

Powerful strikes to the lower back (i.e., between the shoulder blades) can crush or dislocate the lumbar vertebra, lacerating or sheering the spinal cord leading to limited or full paraplegia, urinary and fecal incontinence, and sexual dysfunction. Neurogenic shock is possible, and potentially fatal. In general, the higher such an injury occurs, the more profound its effects will be.

Less powerful blows will cause similar effects, but to a lesser degree, through herniated discs compressing the spinal cord. Whiplash is likely.

Abdomen

Poorly-conditioned, fatigued, or relaxed abdominal muscles can be sent into painful spasms when struck. Vomiting is unlikely, but possible. A well-timed attack can cause respiratory paralysis if they are struck during inhalation, "knocking the wind out" of an opponent. Organ damage, as described in the solar plexus entry, is possible though less likely.

Note that attacks to the abdomen are less effective against opponents with highly-developed tensed abdominal muscles, which can act as sort of natural armor plating. This is one reason why boxers spend much time on abdominal conditioning, and why kung-fu practitioners cross train in Iron Shirt Qigong.

Kidneys

If the kidneys present themselves as a target in a fight, it is because your opponent has rendered themselves defenseless through the error they have made, and through your skill at exploiting those mistakes. If striking the kidney becomes an option, the opponent is in a position where it is difficult or impossible to escape without injury. The is exacerbated by the terrible consequences which result from striking this target, including:

Kidney Rupture

A direct blow to the kidney can cause it to rupture, either from hydrostatic shock, or from being pieced or lacerated by broken floating or short rib fragments. Internal bleeding, peritonitis, bloody urine, coma and death will result if left untreated.

Kidney Dislocation

A glancing blow can sheer the kidney from its moorings, causing internal bleeding and kinking the urethra, leading to blocked urine flow. While this is not itself fatal, the resulting infection can be.

Secondary Effects

Because of the kidney's location, strikes to the kidney strike the solar plexus form the other side. Thus, kidney strikes can also affect the diaphragm and puncture lungs with broken rib fragments.

Bladder

In addition to explicit bladder attacks (i.e., gyaku-sukuite), most groin strikes can also damage the bladder, since it is conveniently nearby. This can have different adverse effects:

Bladder Rupture

A filled urinary bladder can pop like a water balloon when struck, flooding the opponent’s abdominal cavity with blood and urine. This will cause extreme tenderness, the inability to urinate, and an urinary tract infection. (The bladder will unconscious voids to prevent this, as part of the fight-or-flight response. This is why frightened people pee their pants.)

Skeletal Trauma

Severe blows to the bladder can fracture the pelvis, and its sharp, jagged edges can puncture or tear the bladder and/or colon. This results in internal hemorrhaging, shock, and painful breathing caused by the weight of the gastrointestinal system bearing down on the broken pelvis.

Hernias

Men run the additional risk of receiving risk of inguinal, femoral, or scrotal hernias following bladder strikes, due to the unsupported hollow spots left in that region after their testicles descended. Femoral hernias are particularly dangerous, as they have the following potential side effects:

  • Protruding sections of the intestine or abdominal membranes (https://en.wikipedia.org/wiki/Peritoneum peritoneum) may become constricted and receive decreased blood flow, leading to gangrene.
  • Pressure on the femoral nerve may lead to partial paralysis of the affected leg.
  • Blood clots in the femoral vein can cause thrombosis, which can lodge themselves in the opponent's lungs, causing death.

Tailbone

Contrary to popular belief, the tailbone does serve a purpose -- it anchors the anal sphincter muscle. Fracturing this small bone can lead to extreme pain, especially when sitting or defecating. Fecal incontinence may also result.

Groin

The proper usage of the word "groin" refers to the hip adductor muscles located in the upper inner thigh. Rising ridgehand strikes to this region can send those muscles into spasms (i.e., Charley horses).

However, we will use "groin" in the common usage, as a polite (read: parent and school administrator friendly) way of referring to a male attacker's testicles. So, let’s just drop the façade and talk about testicles directly, like adults.

In Goshin-Jutsu, attacking the testicles is not permitted -- it is encouraged. Groin strikes are painful, debilitating, and humiliating; so they should be a part of most waza -- but they should not always be the initial attack. There is no element of surprise in groin attacks; literally everyone, everywhere, knows this trick. Groin strikes are not a solves-all since every boy must develop a groin-protecting sixth-sense in order to survive middle school. However, this reflex can be exploited to your advantage. All groin attacks can be used as atemi, by using this flinch response as a distraction. When the opponent frantically covers his groin, he momentarily stops thinking about protecting his head, leaving him open to counterattack.

Be mindful that strikes to the testicles are not always immediately painful, and the opponent might have to take a few steps, and/or wait up to 10 minutes before feeling the full effect.

Severe groin strikes can have the following dire consequences:

Bladder Rupture

Groin strikes often impact the bladder also, doubling the damage potential.

Pelvic Fracture

Severe groin strikes can fracture the pubis (i.e., the bottom-most pelvis linkage). Walking becomes excruciatingly painful, due to the fractured bone's jagged edges rubbing against each other. The opponent must then curl up into a fetal ball, for lack of other options.

Crushed Testicles

Crushed testicles cause extreme pain, loss of breath, and nausea. Vomiting can occur. Exceptionally severe cases can send an opponent into shock, leading to unconsciousness or death. Severely crushed testicles can result in sterility. Testicular rupture requires surgery, and depending on the severity, may end with the partial or whole amputation of the damaged testicle.

Hollow of the knee

Light pressure can cause the knee to buckle, destroying an opponent's stance and forcing them to kneel. Because of the risk involved, these "knee depression" techniques should only be practiced in a highly-controlled manner, if at all. Even light strikes can tear ligaments and cartilage, or dislocate the kneecap, causing extreme pain and a loss of mobility.

A moderate strike behind the knee can rupture or abrade the popliteal artery, resulting in hemorrhaging and painful swelling. This can be compounded by nerve abrasions, which can cause partial paralysis.

Powerful attacks to the back of the knee can tear its muscles, ligaments, and even the kneecap itself, leading up to dislocation of the knee. Any of these will cripple an opponent until it is surgically corrected.

Side of the knee

The side of the knee is inherently fragile, and even light pressure can cause rehabilitating or crippling injury. For this reason, attacks to the side of the knee are forbidden in kumite, and are strongly discouraged even in controlled settings.

Even light strikes can tear ligaments, cartilage, and bursa causing extreme pain which limits mobility. Moderate strikes can dislocate the knee or its cartilage, which can cripple an opponent until it is surgically corrected.

Powerful attacks to the side of the knee can damage the femur, by dislocating ligaments with such vigor that they tear out chunks of the bone which they anchor too. This will also cripple an opponent until it is surgically corrected.

Shin

Shin attacks can render your opponent helpless, via:

Skeletal Trauma

The shinbones are close to the surface of the skin, and there is little muscle in that region to cushion impacts. Pain, broken skin and bone bruises (i.e., the bruising of the spongy, bone-forming tissue surrounding the marrow) are likely. Tibia and fibula fractures are possible from stomp kicks while wearing hard-soled shoes or boots. Since shinbones come in pairs, a fracturing one of them may not be obvious, even though the ruptured blood vessels surrounding the fracture will cause extreme swelling. If one bone is broken, the opponent can walk with extreme pain. If both bones are broken, the opponent will be immobilized, since they cannot support their own bodyweight.

Arterial Embolism

Shin attacks are unlikely to kill an attacker. However, bone fragments, torn subcutaneous fat, and blood clots can always clog blood vessels and cut off circulation, resulting in gangrene and/or death.

Achilles’ tendon

Attacking the Achilles’ tendon could overstretch or tear this ligament and the surrounding muscle, leading to a sprained ankle. Ankle dislocation is possible, as are fractures of the tibia, fibula, tarsus, or metatarsals. Any of these outcomes would result in extreme pain under applied weight, and make standing, walking, or fighting impossible.

Instep

The instep contains numerous small long bones, which are prone to fracture when struck from a lateral direction. To avoid injuring them, karate kicks make impact with the balls of their feet, and not with the insteps, like in many Korean martial arts styles.

Stomping on an opponent’s instep is a common atemi in waza involving opponent who grab you from behind. Crushing their instep literally leaves them without a leg to stand on, since the foot is essentially a tripod comprised of the heel and the first and fifth metatarsals. Foot stomps should always be directed to the opponent's instep, and not their toes because: