Logan Steele
The human hand is a complex structure that allows us to perform a wide range of tasks, from gripping objects to guiding thread through the eye of a needle. Despite their small size, our hands contain over 30 muscles, working together to enable movement and precision. Interestingly, the fingers themselves do not contain muscles, except for arrector pili muscles. Instead, the muscles that control the fingers are located in the palm and forearm, connected to the fingers by tendons. These muscles include flexors, which close the hand, and extensors, which open it. The hand is also innervated by the radial, median, and ulnar nerves, which carry sensations and enable specific movements.
| Characteristics | Values |
|---|---|
| Number of bones in each hand | 19 |
| Types of tendons in the hand and wrist | Extensor tendons, flexor tendons |
| Function of extensor tendons | Help extend and straighten fingers, hand and wrist |
| Function of flexor tendons | Help flex and curl fingers, hand and wrist |
| Types of ligaments in the hand | Collateral ligaments, volar plate ligaments |
| Function of collateral ligaments | Protect joints from moving too much from side to side |
| Function of volar plate ligaments | Connect the first two finger bones (phalanges) together on each finger |
| Types of muscles in the hand | Intrinsic, extrinsic, interossei, lumbricals, palmaris brevis, adductor pollicis, flexor digitorum superficialis, etc. |
| Function of muscles in the hand | Allow movement and flexibility, provide grip strength and precision, enable various types of grips (power and precision), enable flexion and extension at the MCP joints, etc. |
| Nerves that innervate the muscles of the hand | Radial, median, ulnar |
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What You'll Learn
- The hand and wrist are a complex network of bones, muscles, nerves, connective tissue and blood vessels
- The hand has two groups of tendons: extensor and flexor tendons
- The muscles in the hand are innervated by the radial, median and ulnar nerves
- The thenar muscle group is found at the base of the thumb, allowing for fine movements
- The hypothenar muscle group is formed by three muscles and is found on the small finger side of the hand
The hand and wrist are a complex network of bones, muscles, nerves, connective tissue and blood vessels
The hand and wrist are a complex network of bones, muscles, nerves, connective tissue, and blood vessels. There are 19 bones in each hand, grouped by their location and function. The metacarpals are the bones in the palm that give it its shape, while the phalanges are the individual bones that make up the segments of the fingers and thumb. Bones provide the main structural support in the hand and wrist, giving them their shape and serving as anchors for other pieces.
The muscles in the hand and wrist work together to enable movement and control of the hand and fingers. The hand contains muscles that allow for the bending and stretching of the fingers, as well as the ability to pinch. The thenar muscle group, for example, is found at the base of the thumb and is responsible for the thumb's fine movements. The hypothenar muscle group, on the other hand, is formed by three muscles and is located on the small finger side of the hand. The abductor digiti minimi, one of the muscles in this group, allows the small finger to pull away from the ring finger.
The hand and wrist also contain tendons, which are like strong, flexible ropes that link muscles to bones. There are two types of tendons in the hand and wrist: extensor tendons, which help extend and straighten the fingers, hand, and wrist; and flexor tendons, which help flex and curl the fingers, hand, and wrist. Ligaments are another type of connective tissue in the hand, similar to thick rubber bands, that help joints move smoothly, protect them from bending too far, and keep them in proper alignment.
The hand and wrist are supplied with blood by the ulnar and radial arteries, which cross the wrist and send vessels deep and superficially, forming two anastomoses called the superficial and deep palmar arches. The ulnar artery contributes to the majority of the blood supply for the superficial palmar arch, while the radial artery contributes to the majority of the deep palmar arch.
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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, connective tissue, and blood vessels. The hand and wrist work together to help us interact with the world around us.
The flexor tendons are connected to the flexor digitorum superficialis (FDS) muscles, which arise from the medial epicondyle (an elbow bone) and pass through the carpal tunnel to reach the index, middle, ring, and small fingers. The FDS muscles are responsible for bending the middle joint of each finger, except the thumb, and contribute to the hand's skill in performing tasks requiring precision and fine movements.
The extensor tendons are connected to the finger extensors, which are innervated by the radial nerve. These muscles help to extend the wrist and metacarpophalangeal joints (knuckles) and are crucial for making gestures such as the "stop" sign.
Both tendon groups play a vital role in allowing the hand to perform a wide range of functions, from precision grips like holding a pen to power grips like lifting a heavy box.
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The muscles in the hand are innervated by the radial, median and ulnar nerves
The human hand is a complex network of bones, muscles, nerves, connective tissue, and blood vessels. There are 19 bones in each hand, grouped by location and function. The muscles in the hand are innervated by the radial, median, and ulnar nerves.
The radial nerve is a peripheral nerve that supplies specific parts of the arm, forearm, wrist, and hand. It has both motor and sensory functions. The motor branches stimulate the posterior arm muscles, posterior forearm muscles, and extrinsic wrist and hand extensors. The sensory branches supply the skin on the anterolateral arm, distal posterior arm, posterior forearm, and posterolateral wrist and hand areas. The nerve originates from the ventral rami of the spinal nerves C5 to T1 and is part of the posterior cord of the brachial plexus. The radial nerve's distribution diminishes lateromedially from the thumb to the ring finger.
The median nerve is formed from the C5, C6, C7, C8, and T1 nerve roots of the brachial plexus, a group of nerves that branch from the cervical spine (neck). The median nerve travels along the inside of the arm near the brachial artery and supplies almost all the flexor muscles and all the pronator muscles of the forearm with nerves. Its function allows the wrist and fingers to bend. It also pronates the forearm (rotating the hand to face palm down). The median nerve innervates the digit pads of the lateral 3-1/2 fingers.
The ulnar nerve bends the flexor carpi ulnaris and the flexor digitorum profundus muscles to the small and ring fingers. It provides sensation to the small finger side of the palm, the small finger, and the side of the ring finger next to the small finger. It also provides sensation to the back of the small finger side of the hand. The ulnar nerve can be injured by a cut anywhere along its course, which can lead to the loss of sensation in the small and ring fingers.
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The thenar muscle group is found at the base of the thumb, allowing for fine movements
The human hand is a complex network of bones, muscles, nerves, connective tissue, and blood vessels. There are 19 bones in each hand, grouped by their location and function. The muscles in the hand work together to help us move our hands and fingers, allowing us to touch and control objects.
The thenar muscle group is a collection of three short muscles located at the base of the thumb. These muscles form the muscle bulk on the thumb side of the hand. The three muscles that make up the thenar group are the abductor pollicis brevis, the flexor pollicis brevis, and the opponens pollicis. The opponens pollicis is the largest of the thenar muscles and lies underneath the other two.
The thenar muscles are responsible for the fine movements of the thumb, including abduction and flexion at the metacarpophalangeal (MCP) and carpometacarpal (CMC) joints. The abductor pollicis brevis, the most superficial muscle of the thenar group, is responsible for the abduction of the thumb at the first carpometacarpal joint. It also assists in the flexion and opposition of the thumb. The flexor pollicis brevis is the most medial of the thenar muscles, arising from two muscle heads (superficial and deep) separated by the tendon of the flexor pollicis longus.
The median nerve innervates all the thenar muscles. The blood supply to the thenar muscles is provided by the deep palmar arch and the superficial palmar branch of the radial artery. The coordination of the thenar muscles with the adductor pollicis muscle allows for the opposition of the thumb, a combination of flexion, adduction, and medial rotation. This opposition of the thumb is essential for precision pinching and power gripping, contributing to the hand's skill in performing tasks.
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The hypothenar muscle group is formed by three muscles and is found on the small finger side of the hand
The human hand is a complex network of bones, muscles, nerves, connective tissue, and blood vessels. The hand and wrist muscles work together to help you move your hand and fingers.
The hypothenar muscle group is formed by three muscles: the abductor digiti minimi, the flexor digiti minimi, and the opponens digiti minimi. These muscles form the muscle bulk on the small finger side of the hand. 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 function of the abductor digiti minimi is to allow the small finger to pull away from the ring finger.
The flexor digiti minimi brevis muscle of the hand originates from the hook of the hamate bone and the medial aspect of the flexor retinaculum. It crosses the fifth metacarpophalangeal joint and, together with the abductor digiti minimi, inserts into the medial side of the base of the proximal phalanx of the little finger. The function of the flexor digiti minimi is to allow the small finger to bend at the MCP joint.
The opponens digiti minimi lies deep to the other hypothenar muscles. It originates from the hook of hamate and the associated flexor retinaculum and inserts into the medial margin of metacarpal V. The function of the opponens digiti minimi is to allow us to cup our hands, bringing the small finger towards the thumb.
The hypothenar muscles form the hypothenar eminence, a muscular protrusion on the medial side of the palm, at the base of the little finger. These muscles are similar to the thenar muscles in both name and organisation. The thenar muscle group is found at the base of the thumb, forming the muscle bulk on the thumb side of the hand. It is comprised of three muscles: the abductor pollicis brevis, the flexor pollicis brevis, and the opponens pollicis. The abductor pollicis brevis pulls the thumb away from the index finger, and the flexor pollicis brevis bends the thumb toward the small finger. The opponens pollicis performs one of the most important functions of the human hand: the ability to bring the thumb away from the fingers so that we can grasp objects.
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Frequently asked questions
Yes, the hands and wrists are a complicated network of bones, muscles, nerves, connective tissue and blood vessels.
The muscles in the hand include the thenar muscles, the hypothenar muscles, the interossei muscles, the flexor digitorum superficialis, the flexor carpi radialis, the palmaris brevis, the adductor pollicis, the extensor tendons, the flexor tendons, the volar plate, the collateral ligaments, the abductor pollicis brevis, the flexor pollicis brevis, the opponens pollicis, the abductor digiti minimi, the flexor digiti minimi, and the opponens digiti minimi.
The muscles in the hand work together to help you move your hand and fingers. They also perform two types of grip: power grip and precision grip. Power grip is where your grip strength comes from, such as when you pick up a heavy box or open a jar. Precision grip is using your hand and fingers to move or touch a smaller object, such as picking up a pen off your desk or turning a key in a lock.
