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Anatomy of the Hand and Wrist: Bones, Muscles, Tendons, Nerves

The wrist links the hand to the arm. The wrist is a complex mechanical system of 8 small bones known as the carpal bones. The carpal bones are arranged in 2 interrelated rows. One row connects with the ends of the bones in the forearm—radius and ulna. If you hold your hand in the thumbs-up position, the bone on the top of your forearm is the radius; the one on the bottom is the ulna.

The other row of carpal bones connects with the bones of the palm of the hand. There are synovial joints between the carpal bones and the wrist. The joint surfaces, where the bones meet, are covered with articular cartilage which helps movement.

Knuckle cracking does not serve any beneficial purpose and may be harmful to the fingers due to the stretching of the joint capsule. The hand has 19 bones: 5 elongated metacar

pal bones, which are next to the wrist and make up the palm; 14 phalanges which make up the fingers. Each finger has 3 phalanges, the thumb has 2. These 19 bones collectively form 14 separate joints. The knuckle joints, metacarpophalangeal (MCP) joints, join the fingers to the palm. The interphalangeal (IP) joints are the finger joints. There are synovial joints between the metacarpals and phalanges—these bones are also covered with articular cartilage.

The adult skeleton is mainly made of bone and a little cartilage in places. Bone and cartilage are both connective tissues, with specialized cells called chondrocytes embedded in a gel-like matrix of collagen and elastin fibers. Cartilage can be hyaline, fibrocartilage and elastic and differ based on the proportions of collagen and elastin.

Cartilage is a stiff but flexible tissue that is good with weight bearing which is why it is found in our joints. Cartilage has almost no blood vessels and is very bad at repairing itself. Bone is full of blood vessels and is very good at self repair. It is the high water content that makes cartilage flexible.

Hand Muscles and Hand Tendons

The muscles in the forearm and palm (thenar muscles) all work together to keep the wrist and hand moving, stable, and aligned. The image below shows the bones from the back side of the hand. The red lines show where the tendons attach the muscles to the bones.

The muscles that move the fingers and thumb are above the wrist in the forearm. Long flexor tendons extend from the forearm muscles through the wrist and attach to the small bones of the fingers and thumb. When you bend or straighten your finger, these flexor tendon slide through a snug tunnel, called the tendon sheath, that keeps the tendon in place next to the bones.

Bones of the back of the left hand, carpal, metacarpal, phalangesTendons are white, flexible fibrous cords at the ends of muscles that attach the muscles to the radius, ulna, carpals, metacarpals and phalanges. When the muscles contract, they pull on the tendons to move the bone. The tendons that run down our fingers are held in place by a series of ligaments, called pulleys, that arch over the tendons forming a “tunnel-like” sheath. Normally, the tendons glide easily through the tunnel. Some tendons also serve as stabilizers.

A series of ligaments in a tunnel-like arrangement hold the tendons in place on the bones. A slippery coating, called tenosynovium, surrounds the tendons and keeps the tendons moving smoothly under the ligaments when the hand grasps objects.

Ligaments

Ligaments of the back of the hand

Ligaments of the back of the hand

Hand Ligaments are tough bands of fibrous tissue that join bones together. Six major ligaments give stability to the wrist by joining the radius to the carpal bones and binding the two rows of carpal bones together. These ligaments joint with others to link the wrist to the hand.

Joint Capsule

Other stabilizers in the hand include joint capsules, which are made of fibrous connective tissue that surrounds the joints. A synovial membrane inside the joint capsules provides synovial fluid to lubricate all the joints.

Hand Nerves

The median, radial and ulnar nerves are the three major nerves that run the length of the arm through the wrist and down into the hand. These nerves contract specific muscles and gives us sensations of touch, and to feel hot, cold, and pain.

Problems in the Hand and Wrist

Comments

  1. Will Danker says

    I tripped and fell last summer using hands to catch my fall. Since then I have been experiencing swelling/pain in the wrist and hand area with some numbness in fingers. X-rays show no bone damage and docs have been unable to diagnose problem. Initially they recommended heat and alleve with splint but it has provided solution. What’s going on?

  2. Theresa McFadden says

    I have lost muscle in the palm of my hand , having carpal tunnel surgery didn’t help, what can be done to improve muscle

  3. I crack my knuckles and hands because I had rubella when I was 4. Because of it I have osteoarthritis in every joint in my body. I crack my knuckles because it alleviates the stiff in my hands. It relieves it quite well, and I don’t have any permanent tendon damage because of it. I know that it irritates some people if I crack my knuckles around them, so I try to do it when there isn’t anyone around who are irritated by it. I think others crack their knuckles for similar reasons. Then there are people who do it to intimidate or otherwise cause a reaction in the people around them. So the blanket statement of it being bad for everyone isn’t accurate. Thank you for your post.

  4. l cut my hand on glass and now l cant move my little finger all other ones are ok, what would cause this?

  5. Carol Matus says

    what does5/5 graded muscle strength of the finger and thumb flexors mean

  6. Yes I have a small size lump on my wrist a on top of my hand its dat harmful

  7. Nanita Daniels says

    I had a dog bite my hand yesterday. This dog is completely up to date on all vaccinations, etc.
    he got the top of my hand which has swollen considerably, along with my knuckles and middle finger. It hurts tremendously to flex it in any way. What could he have possibly hit to cause this swelling and pain?

  8. Carol A Moreau says

    I fell in may and broke my Radius a ULNA bone and fractured my elbow. I have been in therphy for over six months. I have a cold hAND AND MY FINGERS ARE VERY STIFF AND IT TAKES OVER AN HOUR EACH MORNING TO MAKE A FIST. My fingers feel like bubble wrap and my wrist does not bend well at all. DO I HAVE NERVE DAMAGE OR WILL THIS IMPROVE OVER TIME? very worried that this will not improve!

  9. Azrin baharin says

    Hye, hello
    I found out that, what i flex my elbow joint,
    And extend my little finger, my biceps of arm like moving, n what is that?
    Isnt finger only connect with forearm’s muscle?

  10. Candice Warlick says

    My left hamds hurts really bad. My Thumb still works but other fingers are frozen and wont bend. It started out that the fingers would freeze then pop out. Now I cant make a fist. None of the fingers ill go down. What can I do? Please help.

  11. Cindy Schmidler says

    Best wishes to you in your recovery!

  12. CHARLES GRAY says

    ON JUNE 20, 2018 USING MY TABLE SAW WITH A PUSH STICK HOLDING THE OTHERSIDE WITH MY RIGHT HAND, THE OUTER BOARD KICKED UP AND MY LEFT HAND WENT INTO THE BLADE. LOST MIDDLE AND RING FINGER AT FIRST KNUCKLE AND CUT MY POINTER AND LITTLE FINGER DOWN TO THE TENDONS. TO 28 STICHES AND 2 PINS TO REPAIR THEM . START OCCUPATIONAL THERAPY NEXT WEEK

  13. Injury at work – left arm- tendon cut a couple inches above the wrist, couldn’t have surgery for 5 days, couldn’t work for approx. 2 months, but about a month in something else was causing problems, surgeon says it has nothing to do with anything he did and if it persists to see family dr. about referral to neurologist. Went to follow-up appt. and told him it’s worse, already went back to work for a week by now, and he gets mad about it, I ask if I should even go to work with the way it is, get told there’s no reason I CAN’T work, couldn’t be that bad and still denies it has anything to do with original injury, says he’ll refer me and neurologist will contact me about when I can be seen, which isn’t for another 3 months. Now I can’t perform full duties at work( can’t do a lot of things right now), have no income, and trying to find a way to get dr. that will take a look at it being as the surgeon wouldn’t. Now, the question is did he just not see a damaged nerve, did he slightly damage it during surgery, or – as he claims – I did something to it and there wasn’t anything wrong with it before, but I tell him I’ve been pretty close to it for 40 years and I never had any problems until now. Well, he’s pissed now. The therapist I was going to even told me to tell/ask him about it but no real answers. But I think it’s pretty much established that it’s the ulnar nerve because of the location and how it feels, I can understand why the 2 fingers were painful, but why everything from the pulse to the fingertips? But after I relaxed it a little, mainly the wrist and 2 fingers, and still think he should’ve ordered some x-rays or tests of some sort before he grabbed a knife, or even afterwards when I told him something ain’t right, but instead he denies that anything is wrong, bitches at me a little, and says I don’t need to see him again. Workman’s compensation isn’t liable for anything being as drs. orders was good to go back to work, and would need a dr. to say that something IS wrong and needs attention, but they will try to help me get in to see a dr. sooner than 3 months, and would need a statement saying that it’s a result of the injury, surgery, or the like to receive benefits. All I want is to basically have it fixed soon, and I’m still wondering if he just didn’t catch it, or got too close to it during surgery. I couldn’t have done anything to it myself, besides that I had a similar incident 20 years prior and it was a nerve AND tendon that got tied back together at the same time. Also what’s so horrible about saying “gee, maybe we did miss something there so let’s take a look at it and see where it’s coming from”? I don’t exactly have a lot to work with on this issue but I guess it’s something and not sure what to do or how it’s going to turn out but I would like to see it back to normal and be able to go back to work to stay, I can’t stand not being able to do anything.

  14. Helen Ramsey says

    I have a severely painful left thumb. It is hard to determine exactly the problem. The bones are out of place, (maybe from a double jointed thumb), making it impossible to do much that involves the thumb. It is beginning to fall toward the palm of my hand with so much constant pain that radiates up my arm and into my shoulder. An orthopedic dr. did not give me much of an explanation as he tried to push the bone back in place only to have it roll back. I would love to know if all cartilage has deteriorated and how much worse it will get., as of this moment, the pain is pretty unbearable. Any advice, anyone?

  15. Had my finger and a saw get into a fight a cpl months ago, saw won:( The doctor amputated my left index finger from the 1st joint past the knuckle. I still can not bend my knuckle on that finger, it’s not painful per say, more just really stiff. Why?

  16. I fell in December and hurt my left hand and my 3rd finger hunrts down through my wrist, it is swollen and a big bump at the base of my middle finger.
    Cant find how to heal it

  17. I have a right hand index finger that has recently for no known reason become so painful to use that I try to avoid it. If I bump into anything it hurts so bad it almost brings tears to my eyes. What is causing this? I am 61 yrs. Old

  18. Nazeem Moerat says

    My left hand. If I keep my thumb up and try to move it towards my wrist, I get an enormous pain in my wrist. Saw a chiropractor twice who put me on some machine. Not healed. He suggested consulting a hand specialist who will inject. Is this advisable?

  19. Joseph Cortes says

    I was stung by scorpion about a month ago my hand was swollen very much my question is after all the information and the antibiotics they put in me my hand has almost gone back to normal but it is very difficult for me to make a fist on my right hand I am concerned that it will not go back to normal because it is still very painful with physical rehab will it go back to normal or am I domed as I am.

  20. I have experienced pain in my lower thumb down to wrist for about a month or so. At first I thought I was just getting arthritis, but it has
    gradually worsened & is swollen. It is my right hand, which is my dominant hand. If there is a fracture of some small bone, what could be done
    to repair. I’m not a surgical candidate (breast cancer, mastectomy & removal of lymph nodes on right), cannot have needles or blood pressure on right arm. I’d rather not bother the emergency room for an x-ray, if all that can be done is to splint & wrap. Thank you for your time & expertise.

  21. I cut the top of my hand . The right one. The middle finger will move down but not up. I did this about 2 weeks ago. The cut is almost heeled it was 1/4 inch deep. There is still swelling.
    Do I need surgery to fix it? Haven’t been to a doctor yet. Gardening and transplanting small seedlings would be impossible. Prepping dinner, chopping and cutting and peeling forget it.

  22. Is there a way to heal the Trapezium-metacarpal joint ? I have retired because of my thumbs and I had surgery on my right hand before retiring and now my left hand aches constantly. The joint is warn out.

  23. Andre Olivier says

    The area around my wrist is white and painful when I bend it . What is the cause ?

  24. Valerie Kocab says

    my daughter (32 years old) went to pic up something heavy and her wrist went off! she is in a lot of pain ! X rays were taken and everything is normal, she can move her fingers but her wrist hearts a lot! is it dislocated? does she needs traction? how do Drs can put it back?

  25. I fell in May 2016 and hurt my left hand and my 3rd finger hunrts down through my wrist hard to bend it . had x-ray done say every thing is normal
    what should I do now? Mary says

  26. I keep getting a warm sensation down the lateral side if my right wrist, I’ve had it for about a week but cannot see a cause, any ideas?

  27. naimat sarwar says

    due to accident I got 3 major fractures I.e humorous ulna and radius,byt minor fractures in my wrist and bottom of thumb finger are still swelled and I cant move it clockwise and also fingers are not moving uppish but partially moving up and down. plating areas are clear but mknor fractures areas are swelled yet. what is the problem and whatvi should do.this is the 4rth month of my operation. plz help

  28. I have a fractured Ulna and radius (w rist) , 5 weeks since fracture, wrist feels ok ish. Problem with thumb, can bend inwards. Can’t do a ‘thumbs up’. Is this normal following a fracture?

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