Hand Anatomy The details in the hand
The human hand consists of:
- 27 bones
- 27 joints
- 34 muscles
- Hundreds of ligaments
- Nerves, and
- Blood vessels
All are working together to perform the function of the hand and wrist.
But what makes your hand, your hand?
The Carpal bones connected to the…..
…five metacarpal bones, to be exact.
When it comes to the Carpal bones, there is a total of 8 in your wrist, all connecting to the five metacarpal bones.
Each of these bones is then connected to the ulna and radius nerves of your forearm (further information on nerves can be found below), as well as the five metacarpal bones, to form your palm and wrist joint.
As we move further down into the hand, the five metacarpal bones then connect to each finger at the MCP joint (knuckle joint or the metacarpophalangeal).
Fingers and Thumbs
The bones found within our hands; specifically, the fingers and thumbs are made up of what is known as phalanges.
When you examine your fingers and look at how they bend, you will be able to see you have two joints (interphalangeal joints) and three phalanges (small bones).
When we examine the thumb, however, this is slightly different as it only has two phalanges supported by a single interphalangeal joint.
Again, examining your fingers, the joint nearest to your knuckle is known as `proximal interphalangeal` – PIP for short.
Working your way up the finger towards the tip, you will find the DIP joint or what we might refer to as the distal interphalangeal joint.
PIP and MCP joints act as hinges, allowing the fingers to move, grip, etc. as they straighten and bend to carry out daily activities and tasks.
(There’s a lot of acronyms when it comes to the hand…a lot!)
We have a various number of soft tissue in our hands, helping to hold all bones in place.
These soft tissues can include:
- Ligaments – Ligaments are strong tissue that helps to connect and hold the bones together. Ligaments are known to help provide hand joints with additional stability and protection.
- Articular cartilage cushions the bones at their 27 joints, acting as a shock absorber and allowing the hand to function and move smoothly.
Tendons and Muscles – similar to ligaments, tendons and muscles help to manage the hand’s flow and function.
How strong are your muscles?
The muscles found in our hands are made up of fibrous tissues. A tissue that helps movement in hand by contracting.
Muscles of the hand consist of:
- Intrinsic muscles
- Extrinsic muscles
Small in size, intrinsic muscles start at the wrist/hand and are what control the fine motor skills and movement in our fingers, helping us to write, type, play the piano, etc.
Extrinsic muscles begin in your elbow or forearm and help control movement of your hand (gross hand movement), i.e., they help set the wrist/hand in place as the intrinsic muscles get to work in the fingers.
Controlling movement, you will find three intrinsic and extrinsic muscles contained in each finger. However, an additional extrinsic extensor can be found in the little finger and index finger.
The role of Tendons
A tendon is a soft tissue that connects the muscles to the bones.
When a muscle contracts, the tendon will pull the bone, making the finger function.
Extrinsic muscles (mentioned above) attach to the bones in the fingers through extended tendons. These tendons extend from a person’s forearm right thought to the wrist.
Flexor tendons are tendons within the palm, which help with the bending of fingers.
Extensor tendons are tendons located on the top of your hand and help straighten fingers.
Tendon damage can occur in those who play sports heavily or from a severe fall where the hand has been placed on the ground first. Damage to tendons can be quite painful, and you should seek treatment immediately if you feel your wrist and fingers are affected in any way.
How are your nerves?
Nerves are what the body uses to send electrical currents/signals from our brains to parts of our body, specifically the muscles running through our forearms and hands, enabling them to move.
Nerves allow us to feel the sensation of touch, temperature fluctuations, and pain, sending signals from hand to brain and back again.
The main nerves found in hand include:
Radial Nerve. The radial nerve travels down your arm on the thumb side (the underside) and plays a vital role when it comes to extending the wrist and fingers as well as providing sensation on the back of the hand.
Ulnar Nerve – starting in the neck and travelling through the shoulder and down into the wrist and fingers, stimulating the flexor muscles in hand and providing sensation to part of your fourth finger and your little digit.
Median Nerve. This particular nerve moves through the wrist’s carpal tunnel, providing sensation in the index finger, thumb, a section of the fourth finger (ring finger), middle finger, and palm.
All three nerves start at your shoulder and travel down the arm into the hand, with each specific nerve providing a particular sensory and motor component.
Ultimately, blood vessels supply the forearm and hand with a sufficient flow of blood, with radial artery being one of two of the major blood vessels found in hand.
After travelling across the wrist and hand, this particular artery will then branch out to form a network of blood vessels in hand.
Your pulse is taken at the spot of your radial artery.
The second major artery in hand is the Ulnar.
Travelling beside the ulnar nerve is the ulnar artery, which weaves its way through the wrist in the Guyon canal.
Synovial bursae are tiny sacs filled with fluid that help to provide a cushion between the bones and tendons/muscles around the joints in the hand, helping to decrease friction and protect from any damage/wear and tear in the joints.
The Manchester Hand Surgeon
At The Manchester Hand Surgeon, our team specialises in all aspects of the hand. We continue to stay up to date and abreast of new treatments and procedures to help with all hand conditions and provide our patients with a range of suitable options as well as first-class care and attention.
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