Dominic Stone
The human hand is a complex network of bones, muscles, nerves, connective tissue, and blood vessels. There are over 30 muscles in the hand, which work together to allow for movement and dexterity. However, despite common misconception, the fingers themselves do not contain muscles. So, how do our fingers move? The muscles in the forearm transmit movement to the tendons in the hand, which then help us move our fingers.
| Characteristics | Values |
|---|---|
| Number of muscles in the hand | 30 |
| Number of bones in each finger | 3 |
| Number of bones in the thumb | 2 |
| Number of joints in each finger | 3 |
| Number of muscles in the fingers | 0 (except for the arrector pili muscle) |
| Number of tendons in the fingers | 17 in the palm, 18 in the forearm |
| Number of nerves in each finger | 4 |
| Number of blood vessels in each finger | 4 |
| Number of touch receptors and nerve endings in the palm | 17,000 |
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What You'll Learn
- Fingers have no muscles, except for the arrector pili muscle
- Tendons in the hand transmit movement from forearm muscles to the fingers
- The hand is supplied with blood through two main arteries
- The hand has two types of muscles: extrinsic and intrinsic
- The hand has two groups of tendons: extensor and flexor tendons
Fingers have no muscles, except for the arrector pili muscle
The human hand is a complex network of bones, muscles, nerves, tendons, ligaments, and blood vessels. The fingers, however, do not contain muscles, except for the arrector pili muscle. The muscles that move the finger joints are located in the palm and forearm. Tendons, which generally connect muscles to bones, transmit the movement initiated by these muscles to the tendons in the hand, enabling finger movement.
The muscles of the hand can be divided into two groups: extrinsic and intrinsic. The extrinsic muscle groups are the long flexors and extensors, with the muscle belly located in the forearm. The intrinsic group comprises smaller muscles located within the hand itself, including the thenar (thumb) and hypothenar (little finger) muscles, the interossei muscles, and the lumbrical muscles. The intrinsic muscles provide intrinsic support for coordination and fine movements, such as playing a keyboard instrument.
The flexor carpi radialis, an elbow muscle, crosses the elbow and wrist and attaches to the base of the second hand bone. Its primary function is to bend the wrist. The flexors, or bending tendons, run through the palms to the fingers, allowing for the actual bending of the fingers. The extensors, on the other hand, are located on the back of the forearm and are connected to the flexors and interosseous and lumbrical muscles to form the extensor hood mechanism. Their primary function is to straighten the digits.
The interossei muscles, located between the bones of the hand, consist of four dorsal and three palmar interossei muscles. While all interossei muscles bend the MCP joints, the dorsal interossei enable us to spread our fingers apart, and the palmar interossei pull our fingers together. The adductor pollicis, meanwhile, fills the space between the thumb and index finger and is responsible for providing power for pinching.
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Tendons in the hand transmit movement from forearm muscles to the fingers
The human hand is a complex network of bones, muscles, nerves, tendons, ligaments, blood vessels, and parts of the lymphatic system. The forearm muscles are essential to the fine motor actions of the upper limb, allowing for complex movements of the arm, wrist, and fingers. The forearm muscles are divided into two compartments: the anterior flexor compartment and the posterior extensor compartment.
The muscles of the hand can be further subdivided into two groups: the extrinsic and intrinsic muscle groups. The extrinsic muscle groups are the long flexors and extensors, so-called because the muscle belly is located on the forearm. The intrinsic group, on the other hand, are the smaller muscles located within the hand itself. The intrinsic muscle groups are the thenar (thumb) and hypothenar (little finger) muscles, the interossei muscles, and the lumbrical muscles. The fingers have two long flexors, located on the underside of the forearm, which insert by tendons into the phalanges of the fingers. The deep flexor attaches to the distal phalanx, and the superficial flexor attaches to the middle phalanx. The flexors allow for the actual bending of the fingers.
The extensors are located on the back of the forearm and are connected to the dorsum of the fingers. The tendons of the extensors unite with the interosseous and lumbrical muscles to form the extensor hood mechanism. The primary function of the extensors is to straighten out the digits. The thumb has two extensors in the forearm, and the index finger and little finger have an extra extensor. The extensors are situated within six separate compartments. The first four compartments are located in the grooves on the dorsum of the inferior side of the radius, while the fifth compartment is between the radius and ulna. The sixth compartment is in the groove on the dorsum of the inferior side of the ulna.
The tendons of the forearm muscles pass through the carpal tunnel, a rounded space in the wrist, to reach the rest of the hand. The carpal tunnel is made up of strong connective tissue and carpal bones. Nine tendons, four ligaments, and one nerve pass through it. The flexor digitorum profundus, for example, arises from the ulna and interosseous membrane. Four tendons emerge from this muscle, passing through the carpal tunnel and inserting into the tips of the index, middle, ring, and small fingers. The flexor digitorum superficialis, on the other hand, has four independent muscle bellies from which four tendons arise. These tendons cross the wrist through the carpal tunnel and insert at the base of the middle phalanx of digits two through five.
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The hand is supplied with blood through two main arteries
The human hand is a complex structure, with over 30 muscles working together to allow for movement and dexterity. The hand is supplied with blood through two main arteries: the radial artery and the ulnar artery. These arteries are responsible for providing oxygen-rich blood to the hand and fingers, ensuring their proper functioning.
The radial artery is one of the two major blood vessels that supply blood to the forearm and hand. It originates from the brachial artery, which begins near the heart and travels under the clavicle bone towards the shoulder. The brachial artery then splits into the radial and ulnar arteries at the elbow. The radial artery travels across the front of the elbow and deep under the muscles in the forearm until it reaches the wrist. Here, you can feel its pulse just under the skin on the thumb side. As it crosses the wrist, it branches out to form a network of blood vessels in the hand, supplying blood to the thumb and index finger.
The ulnar artery is the second major blood vessel supplying blood to the forearm and hand. Similar to the radial artery, it also originates from the brachial artery and travels across the front of the elbow. In the forearm, it runs deep under the muscles along the side of the little finger. After crossing the wrist, it, too, branches out to create a network of blood vessels in the hand, supplying blood to the fingers.
Together, these two main arteries form an arch-shaped loop in the palm of the hand, ensuring a constant supply of oxygenated blood. This double loop has branches of blood vessels that extend into each finger, providing essential nutrients and removing waste products. Each finger is supplied by four bundles of nerves and blood vessels, allowing for precise control and sensation.
In addition to the radial and ulnar arteries, there are several other important blood vessels in the hand, including the common digital arteries, which stem from the palmar arches and supply blood to the fingers, and the proper digital arteries, which split to provide blood to two different fingers each. The hand also receives sensory information through the radial nerve, which activates the finger extensors and carries sensations from the skin on the back of the hand to the brain.
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The hand has two types of muscles: extrinsic and intrinsic
The human hand is a complex network of bones, muscles, nerves, tendons, ligaments, blood vessels, and parts of the lymphatic system. The muscles in the hand are the skeletal muscles responsible for the movement of the hand and fingers. There are over 30 muscles in the hand, working together in a highly intricate way.
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The hand has two groups of tendons: extensor and flexor tendons
The human hand is a complex network of bones, muscles, nerves, tendons, ligaments, blood vessels, and parts of the lymphatic system. The hand and wrist have two groups of tendons: extensor and flexor tendons. Tendons are like strong, flexible ropes that link muscles to bones.
Extensor tendons help to extend and straighten the fingers, hand, and wrist. They are located on the back of the forearm and are connected to the dorsum of the fingers. The thumb has two extensors in the forearm, and the index finger and little finger have an extra extensor, which is used for pointing. The extensors are situated within six separate compartments. The first four compartments are located in the grooves on the dorsum of the inferior side of the radius, while the fifth compartment is between the radius and ulna. The sixth compartment is in the groove on the dorsum of the inferior side of the ulna. The extensor retinaculum prevents the bowstringing of tendons at the wrist level and separates the tendons into these six compartments. The index and small fingers each have an independent extension function through the extensor indicis proprius and extensor digiti minimi.
Flexor tendons help to flex and curl the fingers, hand, and wrist. They run through the palms to the fingers. The fingers have two long flexors, located on the underside of the forearm, which insert by tendons to the phalanges of the fingers. The deep flexor attaches to the distal phalanx, and the superficial flexor attaches to the middle phalanx. The flexors allow for the actual bending of the fingers. The thumb has one long flexor and a short flexor in the thenar muscle group. The human thumb also has other muscles in the thenar group (opponens and abductor brevis muscle), which move the thumb in opposition, making grasping possible.
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Frequently asked questions
No, fingers do not have muscles, except for the arrector pili muscle (APM) which is attached to the hair follicles. The muscles that move the finger joints are in the palm and forearm.
Tendons are tough, fibrous tissues that connect the muscles to bones. The muscles in the forearm end up as tendons in the hand, which transmit movement to the tendons in the hand and help us move our fingers.
The extrinsic muscles arise from the elbow and forearm and connect to the fingers as tendons. The intrinsic muscles, on the other hand, originate within the hand and insert into the fingers, providing intrinsic support for coordination and fine movements.
It is important to avoid excessive strain, use proper techniques during physical activities, and wear protective gear when necessary. Stretching after exercise, warming up before intense exercise, and scheduling regular rest days can also help prevent tendon injuries.
