Logan Steele
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 (APM) which is attached to the hair follicles. The muscles that move the finger joints are located in the palm and forearm. These muscles transmit movements through tendons, which are fibrous connective tissues that act as a bridge between muscles and bones, allowing movement to occur. The muscles in the forearm end up as tendons in the hand, which help us move our fingers.
| Characteristics | Values |
|---|---|
| Do fingers have muscles? | No, fingers do not contain muscles (other than arrector pili). The muscles that move the finger joints are in the palm and forearm. |
| Muscles in the hand | The muscles of the hand can be subdivided into two groups: the extrinsic and intrinsic muscle groups. |
| Intrinsic muscle groups | Thenar (thumb) and hypothenar (little finger) muscles, interossei muscles, and lumbrical muscles. |
| Extrinsic muscle groups | Long flexors and extensors. |
| Function of extensors | To straighten out the digits. |
| Function of flexors | To bend the fingers. |
| Function of interossei muscles | Dorsal interossei allow us to spread our fingers away from each other. Palmar interossei pull our fingers together. |
| Function of lumbrical muscles | Allow the fingers to straighten and help bend the MCP joints, which are at the knuckle. |
| Function of adductor pollicis | Provide power for pinching. |
| Function of abductor pollicis longus | Passes through the 1st dorsal compartment of the wrist. |
| Function of biceps | The main supinator of the forearm (which helps us rotate the palm up and down) and helps the brachialis and brachioradialis in bending the elbow. |
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What You'll Learn
- Fingers do not contain muscles, except for the arrector pili muscle
- The muscles that move the finger joints are in the palm and forearm
- The muscles in the forearm end as tendons in the hand, which help move the fingers
- The intrinsic muscle groups are the thenar (thumb) and hypothenar (little finger) muscles
- The extrinsic muscle groups are the long flexors and extensors
Fingers do not contain muscles, except for the arrector pili muscle
The human finger does not have muscles. The muscles that control the movement of the finger joints are located in the palm and forearm. These muscles include the flexors, which allow for the bending of the fingers, and the extensors, which straighten the digits. The finger joints are moved by long tendons that deliver motion from the forearm muscles.
The intrinsic muscle groups of the hand are the thenar (thumb) and hypothenar (little finger) muscles. The interossei muscles, which allow us to spread our fingers away from each other and pull them together, originate between the metacarpal bones. The lumbrical muscles, which arise from the deep flexor, allow the fingers to straighten.
The only muscle in the fingers is the arrector pili muscle, which is attached to hair follicles in mammals. The contraction of these muscles causes the hairs to stand on end, known colloquially as goose bumps (piloerection). Each arrector pili is composed of a bundle of smooth muscle fibres that attach to several hair follicles. The contraction of the arrector pili muscles in response to a perceived threat can make an animal seem more intimidating.
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The muscles that move the finger joints are in the palm and forearm
The human hand is structured to allow movement, flexion, and rotation of the wrist joint, as well as the ability to grab and touch objects. The wrist acts as a pivot point that enables the hand to move in almost any direction. The muscles that control the movement of the fingers are located in the palm and forearm. These muscles work together to provide strength and dexterity to the hand.
The muscles of the hand can be divided into two groups: the extrinsic and intrinsic muscle groups. The extrinsic muscle groups are the long flexors and extensors, with the muscle belly located on the forearm. The intrinsic group comprises smaller muscles within the hand itself, including the thenar (thumb) and hypothenar (little finger) muscles, the interossei muscles, and the lumbrical muscles. The intrinsic muscles are special because they have no bony origin and insert into the dorsal extensor hood mechanism.
The thenar muscles, which control the thumb, can be felt as a bulge at the base of the thumb in the palm. The hypothenar muscles line the outer edges of the palm near the pinkie finger and control the area opposite the thumb. The interossei muscles are located between the metacarpal bones in the palm and help the fingers move side-to-side. The lumbrical muscles, meanwhile, are found at the base of the four non-thumb fingers and assist in finger flexion.
The long flexors, located on the underside of the forearm, insert via tendons into the phalanges of the fingers. The deep flexor attaches to the distal phalanx, while the superficial flexor attaches to the middle phalanx. These flexors enable finger bending. The thumb has one long flexor and a short flexor in the thenar muscle group, which allows for opposition and grasping.
The extensors, situated on the back of the forearm, are connected to the dorsum of the fingers. Their primary function is to straighten the digits. The thumb has two extensors, and the index and little fingers have an additional extensor each, which is used for pointing. The extensors are housed within six separate compartments, with the first four located on the dorsum of the inferior side of the radius, the fifth between the radius and ulna, and the sixth on the ulna's inferior side.
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The muscles in the forearm end as tendons in the hand, which help move the fingers
The human hand is a complex part of the body, with a network of bones, muscles, nerves, tendons, ligaments, blood vessels, and parts of the lymphatic system. The muscles in the forearm that move the fingers are called extrinsic muscles, and they work together with the intrinsic muscles inside the hand to give it strength and dexterity.
The extrinsic muscles are the long flexors and extensors, and they are called extrinsic because the muscle belly is located on the forearm. The flexors are primarily responsible for bending the fingers, while the extensors straighten the digits. The extensors are connected in a more complex way than the flexors to the dorsum of the fingers. The flexors include the flexor digitorum superficialis, one of the largest superficial muscles in the forearm, which plays a crucial role in flexing the digits. The flexor digitorum profundus arises from the ulna and interosseous membrane, and four tendons emerge from it, which insert into the distal phalanges of the fingers. The extensors include the extensor digitorum, which divides into four tendons that insert into the middle and distal phalanges of the fingers.
The intrinsic muscle groups are the thenar (thumb) and hypothenar (little finger) muscles, the interossei muscles, and the lumbrical muscles. The thenar and hypothenar muscles are located at the base and outer edges of the thumb and pinkie finger, respectively, and control the movement of the thumb and the area of the hand opposite the thumb. The interossei muscles are located 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 flex the fingers.
The muscles in the forearm end as tendons that attach to the wrist or continue into the hand, helping to move the fingers. Tendons are strong connective tissues that link muscles to bones. Sesamoid bones are small bones embedded in tendons that help them move smoothly. The tendons of the forearm muscles are protected and stabilized by tendon sheaths and deep fascia, which form fibrous bands called retinacula that hold the tendons in place.
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The intrinsic muscle groups are the thenar (thumb) and hypothenar (little finger) muscles
The human hand is made up of extrinsic and intrinsic muscle groups. The intrinsic muscle groups are the thenar (thumb) and hypothenar (little finger) muscles. These are the smaller muscles located within the hand itself.
The thenar muscles are three short muscles located at the base of the thumb. They produce a bulge, known as the thenar eminence. The median nerve innervates all the thenar muscles. The opponens pollicis is the largest of the thenar muscles and lies underneath the other two. It originates from the tubercle of the trapezium and the associated flexor retinaculum and inserts onto the lateral margin of the first metacarpal. The opponens pollicis is responsible for opposing the thumb, by medially rotating and flexing the metacarpal on the trapezium, making grasping possible. 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.
The hypothenar muscles form the hypothenar eminence, a muscular protrusion on the medial side of the palm, at the base of the little finger. The abductor digiti minimi is the most superficial of the hypothenar muscle group. It originates from the pisiform and the tendon of the flexor carpi ulnaris and attaches to the base of the proximal phalanx of the little finger. The flexor digiti minimi brevis lies laterally to the abductor digiti minimi in the hand. It originates from the hook of hamate and adjacent flexor retinaculum and inserts into the base of the proximal phalanx of the little finger. The hypothenar muscles are innervated by the ulnar nerve.
The intrinsic muscles provide fine motor movements. The extrinsic muscles, on the other hand, provide strength to the hand.
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The extrinsic muscle groups are the long flexors and extensors
The muscles that control the movements of the fingers and hands can be categorized into two groups: the intrinsic and extrinsic muscle groups. The extrinsic muscle groups are responsible for the long flexors and extensors of the fingers and are essential for the complex movements of the hand and fingers. These muscles originate in the forearm and attach to the bones of the hand and fingers via tendons. Tendon sheaths, or tunnels, surround these tendons, allowing them to glide smoothly as the muscles contract and relax. This anatomical design enables precise and controlled finger movements.
There are two long flexors in the forearm, namely the flexor digitorum superficialis and the flexor digitorum profundus. These muscles work together to flex the fingers and are responsible for the actual bending of the fingers. The flexor digitorum superficialis flexes the fingers and also contributes to their movement toward the middle finger, a process known as flexion. The flexor digitorum profundus, as the name suggests, runs deeper and attaches to the distal phalanges of the fingers, allowing for more powerful and precise flexion.
On the other hand, the extensors are responsible for straightening the fingers and work in opposition to the flexors. There are three primary extensors in the forearm: the extensor digitorum, extensor digiti minimi, and extensor indicis. The extensor digitorum is responsible for extending the fingers, moving them away from the palm, and also contributes to their adduction, bringing them closer together. The extensor digiti minimi, as the name implies, specifically extends the little finger, while the extensor indicis controls the extension of the index finger.
The balance and coordination between these flexor and extensor muscles is crucial for the precise and delicate movements of the fingers. This intricate system allows for a wide range of tasks, from writing and typing to more intricate activities such as playing a musical instrument or performing surgery. The tendons connecting these muscles to the bones of the hand and fingers slide through the tendon sheaths, ensuring smooth and controlled movements. Any inflammation or injury to these tendons or their sheaths can lead to pain and impaired finger function, underscoring the importance of maintaining the health of these muscle groups and associated structures.
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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.
The muscles in the forearm end up as tendons in the hand. These muscles initiate the movements which are transmitted to the tendons in the hand, helping us move our fingers. Tendons are tough, fibrous tissues that connect the muscles to bones.
The muscles in the forearm that help move the fingers include the flexor carpi radialis, the biceps, the supinator, the adductor pollicis, and the interossei and lumbrical muscles.
