Athena Vale
The human hand is a complex network of bones, muscles, nerves, connective tissue, and blood vessels. There are 34 muscles in each hand, which work with tendons and ligaments to allow for a large amount of movement and dexterity. These muscles can be classified as intrinsic, located within the hand itself and responsible for fine motor functions, or extrinsic, which originate in the forearm and provide strength. Tendons connect muscles to bones, allowing movement, and nerves control the muscles, helping to process sensations such as temperature.
| Characteristics | Values |
|---|---|
| Number of muscles in each hand | 34 |
| Types of muscles | Intrinsic and extrinsic |
| Function of intrinsic muscles | Fine motor movements |
| Function of extrinsic muscles | Provide strength |
| Innervation | Radial, median, and ulnar nerves |
| Tendons | Extensor and flexor |
| Ligaments | Volar plate, collateral ligaments |
| Types of bones | Phalanges, metacarpals, carpals |
| Number of phalanges in each hand | 14 |
| Number of metacarpal bones | 5 |
| Number of carpals bones | 8 |
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What You'll Learn
Intrinsic and extrinsic muscles
The human hand is a complex network of bones, muscles, nerves, connective tissue, and blood vessels. There are 34 muscles in each hand, which work together to allow movement and control of the hand and fingers. These muscles can be categorised into intrinsic and extrinsic muscles.
Intrinsic muscles are located within the hand itself and are responsible for the fine motor functions of the hand. They include muscles such as the adductor pollicis, palmaris brevis, and the thenar muscles, which control the thumb. The hypothenar muscles, which are located on the outer edges of the palm near the pinky finger, are also intrinsic muscles. The interossei muscles are another type of intrinsic muscle, found between the metacarpal bones in the palm, and they help the fingers move side-to-side. Lumbrical muscles, which are crucial for finger movement, are located at the base of the four non-thumb fingers and help with finger flexion.
The extrinsic muscles, on the other hand, are found near the outside of the hand and in the forearm. They include muscles such as the finger extensors and the thumb abductor, which allow for extension at the wrist and metacarpophalangeal joints (knuckles) and abduction and extension of the thumb. The flexors of the wrist and digits, as well as the abductors and opponens of the thumb, are also extrinsic muscles. These muscles are innervated by the radial, median, and ulnar nerves.
The radial nerve controls the finger extensors and the thumb abductor, allowing for extension and abduction of the thumb. The median nerve innervates the flexors of the wrist and digits, as well as the abductors and opponens of the thumb, contributing to the ability to make a precision grip or pinch with the fingers and thumb. The ulnar nerve innervates the remaining intrinsic muscles of the hand, including the interossei and lumbrical muscles.
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Innervation
The hand is a complex part of the body, with 34 muscles in each hand. These muscles work together with the wrist to help us interact with the world around us. The muscles of the hand are innervated by the radial, median, and ulnar nerves. The radial nerve is completely sensory in the hand and provides dorsal cutaneous innervation to the thumb, index, middle, and lateral half of the ring fingers, as well as the lateral aspect of the dorsum of the hand and thumb base. The median nerve passes through the carpal tunnel and provides motor supply to the three thenar muscles and the first and second lumbricals. The ulnar nerve innervates the remaining intrinsic muscles of the hand.
The thenar muscles are muscles that control the thumb and can be felt as a bulge at the base of the thumb in the palm of the hand. The flexor pollicis brevis is a thenar muscle that flexes the metacarpophalangeal joint of the thumb and is innervated by the median nerve. The opponens pollicis and abductor pollicis brevis are also thenar muscles, which move the thumb in opposition, making grasping possible. These muscles are innervated by the median nerve.
The hypothenar muscles line the outer edges of the palm on the outside of the little finger and control the area of the hand opposite the thumb. The abductor digiti minimi is the most superficial of the hypothenar muscles and abducts the little finger. It is innervated by the ulnar nerve. The flexor digiti minimi brevis lies laterally to the abductor digiti minimi and flexes the metacarpophalangeal joint of the little finger. It is also innervated by the ulnar nerve.
The interossei muscles are located between the metacarpal bones in the palm and help the fingers move side-to-side. There are four dorsal and three palmar interossei muscles. The dorsal interossei allow us to spread our fingers away from each other, while the palmar interossei pull our fingers together. The interossei muscles are innervated by the ulnar nerve.
The lumbrical muscles are at the base of the four non-thumb fingers and help flex the fingers. The first and second lumbricals are innervated by the median nerve, while the third and fourth lumbricals are innervated by the ulnar nerve.
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Tendons and ligaments
The hand and wrist are a complex network of bones, muscles, nerves, tendons, ligaments, and blood vessels. Tendons and ligaments play a crucial role in the movement and stability of the hand.
Tendons are bands of connective tissue that attach muscles to bones, enabling the muscles to move the bones. The hand and wrist have two main groups of tendons: extensor tendons and flexor tendons. Extensor tendons help extend and straighten the fingers, hand, and wrist, while flexor tendons help flex and curl them. For example, the FDP tendon helps bend the index, middle, ring, and small fingers at the fingertip joint. The EDC tendon straightens these same fingers, and the EIP tendon straightens the index finger. The EPL tendon straightens the distal joint of the thumb, and the EPB tendon helps move the thumb away from the rest of the hand.
Ligaments, on the other hand, are another type of connective tissue that helps joints move smoothly, protects them from bending too far, and keeps them in proper alignment. They are like thick rubber bands that connect bones to support and stabilize them. Important ligaments in the hand include collateral ligaments, which run along the outside edges of the fingers and thumb, preventing the joint from moving sideways. The volar plate is a ligament that connects the proximal phalanx to the middle phalanx on the palm side of the joint, preventing the PIP joint from bending backward when the finger is straightened. The wrist also has several ligaments that provide support and stability, such as the radial and ulnar collateral ligaments, volar radiocarpal ligaments, and dorsal radiocarpal ligaments.
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Types of grip
Grip strength is a general term for the physical strength of an animal or, for athletes, the muscular power and force generated by the hands. It is an important factor in sports such as rock climbing, powerlifting, weightlifting, and strongman competitions. Grip strength is also a major feature in martial arts and can be useful in professions where people work with their hands.
There are three main types of grip: crushing, pinching, and support. The crushing grip is the most common type of grip strength and involves firmly closing your hand around an object, exerting force to compress it. This could include crushing soda cans, squeezing wet sponges, or using tools like pliers. A strong crush grip is useful for breaking objects with pressure or bone-crushing handshakes. The pinch grip focuses on finger strength, particularly the thumb and fingers working in opposition. Examples of the pinch grip include turning a key or grabbing a climbing hold. The support grip involves using the whole hand and forearm muscles to hold onto something for an extended period. This type of grip is important for carrying heavy objects and is epitomized by the Farmer's Walk competitive event, where participants carry a bucket filled with sand or water over a long distance.
Grip strength training is unique compared to other muscular training regimens due to the constant use of our hands in daily life, which leaves little room for rest and recovery. Training the various grip types can be done through exercises such as plate pinching, deadlifts, rows, pull-ups, and wrist extension exercises.
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Types of bone
The hand is composed of many different bones, muscles, and ligaments that allow for a large amount of movement and dexterity. There are three major types of bones in the hand itself: phalanges, metacarpal bones, and carpal bones.
The phalanges are the 14 bones found in the fingers of each hand and also in the toes of each foot. Each finger has three phalanges (the distal, middle, and proximal), while the thumb only has two. The metacarpal bones are the five bones that make up the middle part of the hand. The carpal bones are the eight bones that create the wrist. The two rows of carpal bones are connected to the two bones of the forearm: the ulna bone and the radius bone. The radius is one of the two forearm bones and is on the thumb side of the forearm near the hand. It twists around the other forearm bone, the ulna, and its position changes depending on the hand's position. The ulna is always in the same position on the inside part of the forearm and does not twist.
The scaphoid is a bone in the wrist that helps link the two rows of wrist bones together. The triquetrum is a bone on the small finger side of the wrist in the first row, adding stability to the wrist and providing a larger surface to bear weight transmitted from the hand. The trapezium is a saddle-shaped bone in the second row of wrist bones where the thumb metacarpal connects to the wrist. The trapezium's shape allows the thumb to move in multiple directions while also stabilising it. The capitate is a large bone in the centre of the second row of wrist bones, forming joints with multiple bones in the wrist and hand. The hamate is a large, unusually shaped, almost triangular bone in the second row of wrist bones. It serves as an attachment point for multiple ligaments and works with multiple other bones.
The muscles in the hand include the hypothenar muscles, which line the outer edges of the palm on the outside of the pinkie finger and control the area opposite the thumb. The interossei muscles are between the metacarpal bones in the palm and help the fingers move side-to-side. The lumbrical muscles are at the base of the four non-thumb fingers and help with finger flexion. The palmaris brevis and adductor pollicis are intrinsic muscles, with the latter being a superficial muscle. The fingers have two long flexors located on the underside of the forearm, with the deep flexor attaching to the distal phalanx and the superficial flexor attaching to the middle phalanx. The thumb has one long flexor and a short flexor in the thenar muscle group. The extensors are located on the back of the forearm and are connected in a more complex way than the flexors to the dorsum of the fingers. The tendons connect the muscles to the bones, allowing for movement.
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Frequently asked questions
Yes, there are over 30 muscles in the hand, working together in a highly complex way.
No, there are no muscles in the fingers. Their function is controlled by muscles in the palms and arms, which are connected to the fingers by tendons.
Palmaris brevis, which is a superficial muscle, and adductor pollicis are intrinsic muscles of the hand. The thumb has one long flexor and a short flexor in the thenar muscle group. The extensors are located on the back of the forearm and are connected to the dorsum of the fingers.
