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Roberto Pedreira















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To Punch, or Not to Punch

By Roberto Pedreira

"Teeth often make an involuntary inoculation of bacteria into skin during fist fights. The hero’s decisive punch can then bring him knuckle sepsis as well as victory” (The Pathogenesis of Infectious Disease by C.A. Mims, 3rd ed., Academic Press, 1987, p. 12.


 Everyone understands that the power of a punch comes from a combination of mass and motion, rather than the rigidity of the striking implement (although that can certainly affect the sort of trauma inflicted). This is basic physics and most martial arts are based on physics (1)

 Sometimes though, you just want to close your fist and smash someone's face(2). It feels so much more satisfying. But if you succumb to this temptation, you will probably regret it. The brain is a jelly-like substance. That's why the skull is hard. Because the skull is hard, punches are usually aimed at the softer spots on the face. If you hit the chin on the button, most opponents will drop. But the button is a small spot and people who are being attacked frequently try to get out of the way. Chances of actually hitting that precise target and at just the right angle, are not high, unless you are a very good boxer (in which case, you wouldn't risk injuring a hand would you?)  

It is reasonably probable that if more than a few bombs are dropped, one is going to land on your opponent's teeth. That isn't going to be fun for him. But it could be fatal for you.

The bacterial population of the average human mouth is roughly 1-10 million organisms per milliliter of fluid or gram of scrapings. It is among the "buggiest" parts of the body (More precisely, the mouth is composed of various micro-environments, each supporting a different mix of microorganisms.) Most are strict anaerobes, meaning they flourish inside tissue (rather than on the surface). Broken teeth are sharp. The skin over the metacarpophalangeal joints (the knuckles) is thin.  All the liquids of the body contain anti-microbial defense factors, especially blood, but the blood supply to the hand is poor, because the fingers are operated by a system of cords (tendons and ligaments) attached to muscles in the forearm, that move them by contracting. (Unlike muscles, tendons and ligaments are cartilage and do not require much oxygen, which is also why they heal slowly). 

Most common pathogens found in clenched fist injuries are exactly the same ones that are found in the human mouth: Viridians streptococci, S. aureus, Bacteroides sp. Fusobacterium sp., peptostreptoccoci. Eikenella corrodens. Teeth tend to inject the organisms into joint capsules and bone. Once they are in, they are very hard to get at to kill or contain with antibiotics. If the entire bone becomes infected, the treatment can be unpleasant indeed, including removal of part or all of the  appendage. The good news is you aren't going to die. The bad news is you might not have two hands anymore. And unfortunately, wounds of the hand and foot are more likely to become infected due to many tendon sheaths, fascial planes and compartments that promote persistence and spread of the microorganisms which can come not only from your victim's mouth, but from the surface of your own skin as well. 

A wound left untreated for three hours has a potential bacterial proliferation of more than 1,000,000 organisms/gram of tissue. Presence of even large numbers of organisms (up to 100,000 per gram of tissue) doesn't necessarily mean there is an infection,  but in the case of high risk sites like the hand, joints, and bones, the potential complications  are so serious (extensive tissue destruction and gangrene) that if bites and contamination with saliva are involved, most doctors will advise a 3-7 day prophylactic course of antibiotics whether there is clinical evidence of infection or not. 

If you have  erythema (redness), pain or tenderness, swelling, heat, and pus, then you have an infection. That means there are a lot of microorganisms where they normally wouldn't be and shouldn't be. They will continue to double approximately once every 20-120 minutes, limited only by physical space and nutrient supply. You are eventually going to wish you hadn't punched that guy after all. Your body will fight back. Fever is an attempt to create a temperature that inhibits the growth of the bugs. But it also causes tissue and organ damage and if high enough long enough can scramble your brain cells. You will also feel "unwell" and won't want to eat. That isn't good because you'll be consuming 13 % more energy for every 1 % increase in body temperature. When you are malnourished, your immune system can't produce adequate numbers of T Lymphocytes, which increases your risk of infection and the severity of the infection when it happens.3

 Obviously, all the time you are laid up in bed, you won't be in the academy training.

 There are several other outstanding reasons for not punching someone with your closed fist. One is the high probability of breaking one or more of the 27 bones (all small) in each hand. For the same reason bacteria are hard for your immune system to get to, the bones heal slowly--poor blood supply. 

The human hand is a marvel of natural design and served its evolutionary purpose by way of the survival possibilities opened up by precise manipulation of objects rather than as a substitute for a blunt force weapon. Here is an outline of the anatomy of the human hand.4

 Another reason that will be obvious to any grappler is that with an open hand you can do much more to control your opponent.

 A final reason, but no less important than the others, is that in western cultures that are under the sway of linear logic, a closed fist is perceived as threatening, as a prelude to aggression (whereas in some other cultures, it is used to signal emotional involvement and commitment.) Try this experiment for yourself. Simply walk around and do what you normally do, but do it with your fist closed. Notice the reactions you get. People will give you a bit more space, and your girlfriend and mom will look at you funny and ask you what you are angry about. Why does this matter? (5) If for some reason you get involved in the American criminal justice system you will find out fast. 



Gates, Robert H.: Infectious Disease Secrets.  Philadelphia, Pa: Hanley & Belfus. 1998.

Harvey A. McGehee, Johns, Richard J., McKusik, Victor A., Owens, Albert H., and Ross, Richard S.:The Principles and Practice of Medicine (22nd ed.).  Norwalk, Conn: Appleton & Lange. 1988.

Hoppenfield, Stanley.: Physical Examination of the Spine and Extremities.  Norwalk, Connecticut: Appleton & Lange. 1976.

Mims, C.A.:The Pathogenesis of Infectious Disease. (3rd ed.).  Academic Press, 1987.

Schaecter, Moselio, Medoff, Gerald, Schlessinger David Mechanisms of Microbial Disease.  Baltimore: Williams & Wilkins. 1989.

Tortora, Gerard J.: Principles of Human Anatomy (5th ed.).  New York: Harper & Row. 1989.



(c) 2001, Roberto Pedreira. All rights reserved.

Revised November 25, 2009.

Revised January 1, 2013.

Updated January 7, 2015. 

Updated October 14, 2020.






1. Most, but not all: some are based on gullibility and wishful thinking.

2. Full Instructor (and shooto fighter/stuntman/actor) Chad Stahelski made this comment once during an afternoon class at the Inosanto Academy, circa 1994. Chad has since leaped to Hollywood success as one of the masterminds (writer/director/etc.) behind one or more of the John Wick movies. Roberto hasn't seen any of the series and doesn't plan to. Nothing against Keanu Reeves but really, come on. Instead, keeping it real, he recommends Enter the Dragon and The Chinese Connection.

3. According to a 2007 review, "simple lacerations of the hand" (not involving nerves, tendons, bones, or large blood vessels) seem not to benefit significantly from antibiotics in the absence of manifest infection ( It is assumed however that basic wound care management has taken place, which ideally means a visit to a clinic or ER. The crucial distinction is whether the superficial wound has become infected or not. For open fractures, prophylactic antibiotics is still recommended (

4. Outline of the Anatomy of the Human Hand

Muscles that move wrist, hand, and fingers

 Anterior Group (flexors and pronators)


  Pronator Teres

  Flexor carpi radialis

  Palmaris longus

  Flexor carpi ulnaris

  Flexor digitorum superficialis


  Flexor digitorum profundus

  Flexor pollicis longus

  Pronator quadratus

 Posterior Group (extensors and supinators)



  Extensor carpi radialis longus

  Extensor carpi radialis brevis

  Extensor digitorum

  Extensor digiti minimi

  Extensor carpi ulnaris




  Abductor pollicis longus

  Extensor pollicis brevis

  Extensor pollicis longus

  Extensor indicis


Bones of hand

Hand = carpals (8), metacarpals (5), and phalanges (14)


  Proximal = (from lateral to medial) scaphoid, lunate, triquetral, pisiform

  Distal = trapezium, trapezoid, capitate, hamate

Heads of the metacarpals are the knuckles

Nerves, Tunnels,

27 muscles in hand and fingers (8 of them in thumb). Innervated by median, radial, and ulnar nerves.

6 dorsal tunnels transport extensor tendons

2 palmar tunnels transport flexor tendons and arteries, nerves, and veins


5. In most jurisdictions, simple assault is a crime. Assault is merely an attempt to inflict injury. The attempt does not have to be successful (in any case, the definition of injury is not precise and will have to be decided by legal professionals--for which service you will pay in time, money, and stress). Raising a closed fist in many jurisdictions can be regarded for legal purposes as an assault--an "offer" to inflict injury, as it were. This can be enough to get you arrested, spend time in custody, have to engage a lawyer, and spend time in court. You don't have to actually hit or hurt anyone for this to happen. Being embroiled in the legal process itself is the punishment. Now, if you punch someone, and manage to "inflict injury" (which can be almost anything and can happen accidentally as a consequence of your punch), you will have additional problems. 


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