Alec Titan
Our hands are a complex network of bones, muscles, nerves, connective tissue, and blood vessels. There are 34 muscles in each hand, which work together to allow us to move our hands and fingers. These muscles can be categorised as extrinsic or intrinsic. Intrinsic muscles are located within the hand itself and are responsible for fine motor functions. Extrinsic muscles are located near the outside of the hand and in the forearm, providing strength and dexterity. The hand muscles are innervated by the radial, median, and ulnar nerves and can be classified by innervation. Tendons connect muscles to bones, allowing movement, and ligaments help bind the joints together.
| Characteristics | Values |
|---|---|
| Number of muscles in each hand | 34 |
| Types of muscles | Intrinsic, extrinsic |
| Types of intrinsic muscles | Thenar, hypothenar, interossei, lumbrical, palmaris brevis, adductor pollicis |
| Types of extrinsic muscles | Flexor digitorum superficialis |
| Function of intrinsic muscles | Fine motor functions of the hand |
| Function of extrinsic muscles | Give the hand its strength and dexterity |
| Function of thenar muscles | Control thumb, responsible for fine thumb movements |
| Function of hypothenar muscles | Line the outer edges of the palm on the outside of the pinkie finger |
| Function of interossei muscles | Help fingers move side-to-side |
| Function of lumbrical muscles | Allow fingers to straighten, help bend MCP joints, help finger movement |
| Function of adductor pollicis | Provide power for pinching |
| Function of flexor digitorum superficialis | Help extend and straighten fingers |
| Nerves connected to muscles | Radial, median, ulnar |
| Tendons | Extensor, flexor |
Explore related products
What You'll Learn
Intrinsic and extrinsic muscles
The hand is composed of intrinsic and extrinsic muscles. Intrinsic muscles are located entirely within the hand and are responsible for fine motor functions. They are covered by the fibrous palmar fascia, which divides them into four main compartments: the thenar, hypothenar, adductor, and central compartments. The thenar compartment is located below the thumb, the hypothenar below the little finger, the adductor in the lateral part of the hand, and the central compartment in the centre of the palm. The intrinsic muscles are important for various hand functions, such as pinch and grip strength.
The extrinsic muscles, on the other hand, are forearm muscles that act on the hand and fingers through their long tendons. The muscle belly of the extrinsic muscles originates in the forearm. 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 thumb has one long flexor and a short flexor in the thenar muscle group, which allows for movements like flexion, extension, abduction, adduction, opposition, and reposition.
The lumbricals are another important group of muscles in the hand. They arise from the flexor digitorum tendon and pass through the carpal tunnel to insert onto each digit. Lumbricals are responsible for flexion of the MCP and extension of the DIP and PIP joints. They are innervated by the median and ulnar nerves. The interossei muscles are located between the metacarpal bones and assist in the abduction and adduction of the fingers, as well as flexion at the MCP joints and extension at the IP joints.
The development of the intrinsic muscles of the hand begins during embryonic development. Around week 4, the upper extremity of the human embryo first appears as a lateral projection, or limb bud. By week 5, the arm buds enlarge and nerves, vasculature, chondrification, and muscles begin to develop. The muscles develop as myogenic progenitor cells divide into superficial and deep layers, with the deep layers contributing to the intrinsic muscles of the hand.
Healing Muscle Rupture: Rest, Rehab, and Recovery Techniques
You may want to see also
Explore related products
Thenar muscles
The hand and wrist are a complex network of bones, muscles, nerves, connective tissue, and blood vessels. There are 34 muscles in each hand, which work together to help you move your fingers and hand.
The thenar muscles are three short muscles located at the base of the thumb. They produce a bulge, known as the thenar eminence, and are responsible for the thumb's fine movements. The thenar muscles include the abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis. A fourth muscle, the adductor pollicis, is located in this region but is not part of the thenar muscle group. The adductor pollicis is chiefly responsible for rotation and opposition, and the opponens pollicis is the largest of the thenar muscles.
The thenar muscles are innervated by the median nerve (T1), except for the deep head of the flexor pollicis brevis, which, along with the adductor pollicis, is innervated by the ulnar nerve (C8, T1). The abductor pollicis brevis is the most superficial muscle of the thenar group and receives its innervation via the recurrent (thenar) branch of the median nerve. Its blood supply is provided mainly by the superficial palmar branch of the radial artery. The opponens pollicis receives its innervation from the same source as the abductor pollicis brevis and has a similar blood supply.
The prime function of the flexor pollicis brevis is to produce flexion of the thumb at the metacarpophalangeal and carpometacarpal joints, and it also contributes to the medial rotation of the thumb. The abductor pollicis brevis is responsible for the abduction of the thumb at the first carpometacarpal joint, along with flexion and opposition.
Building Muscle: Strategies for Filling Out Your Frame
You may want to see also
Explore related products
Hypothenar muscles
The hand and wrist are a complex network of bones, muscles, nerves, connective tissue, and blood vessels. There are 34 muscles in each hand, which can be categorised into groups. One of these groups is the hypothenar muscles, which are three short muscles of the medial (ulnar) palmar compartment of the hand. They form a noticeable fleshy prominence on the medial side of the palm, at the base of the little finger, known as the hypothenar eminence. The hypothenar eminence muscles, except for palmaris brevis, are innervated by the deep branch of the ulnar nerve (C8, T1). The palmaris brevis muscle is supplied by the superficial branch of the ulnar nerve (C8, T1). The blood supply for the hypothenar eminence comes mainly from the ulnar artery via the superficial palmar arch.
The three hypothenar muscles are the abductor digiti minimi, flexor digiti minimi, and opponens digiti minimi muscles. A fourth muscle, the palmaris brevis, is also located in this region, but it does not belong to the hypothenar muscle group. All four muscles are intrinsic muscles of the hand located within the medial side of the palm. They span between the medial aspect of the carpus and the carpal and metacarpal bones of the little finger.
The abductor digiti minimi muscle 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. Its function is to abduct 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 bone and medial aspect of the flexor retinaculum and inserts into the base of the proximal phalanx of the little finger. Its function is to flex the metacarpophalangeal joint of the little finger. The opponens digiti minimi lies deep to the other hypothenar muscles. It originates from the hook of hamate and associated flexor retinaculum and inserts into the medial margin of metacarpal V. Its function is to rotate the metacarpal of the little finger towards the palm, producing opposition.
Healing Your Iliopsoas: A Guide to Muscle Recovery
You may want to see also
Explore related products
Interossei muscles
The interossei muscles are located between the metacarpal bones in the palm of the hand. They are considered voluntary muscles. There are four dorsal and three palmar interossei muscles, with the first dorsal interosseous muscle being the largest and strongest of the dorsal interossei. The dorsal interossei muscles are short, bipennate intrinsic muscles of the hand. They occupy the space between the metacarpal bones, along with the palmar interossei muscles.
The dorsal interossei muscles consist of four short muscles that attach to the adjacent sides of metacarpals 1-4. Their function is to abduct the second, third and fourth digits, as well as to assist in flexion of these fingers at the metacarpophalangeal (MCP) joints and in extension at the interphalangeal (IP) joints. The palmar interossei, on the other hand, adduct the digits towards the third digit (towards the axial line) and are unipennate.
The interossei muscles help the fingers move side-to-side. While all interossei bend the MCP joints, the dorsal interossei allow us to spread our fingers away from each other. The palmar interossei pull our fingers together. The first dorsal interosseous muscle is often the first muscle to shrink in patients with severe cubital tunnel syndrome due to damage to the ulnar nerve.
GNC's Muscle Milk: A Comprehensive Overview
You may want to see also
Explore related products
Lumbrical 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 help you move your fingers and control objects.
One of these muscle groups is the lumbricals, which are intrinsic muscles of the hand. There are four lumbricals, each associated with one of the four non-thumb fingers. The name "lumbrical" comes from the Latin word for "worm", and they are indeed worm-like in appearance. These muscles are unusual in that they do not attach to bone but rather to the tendons of the flexor digitorum profundus.
The main function of the lumbrical muscles is to allow the fingers to straighten and flex at the metacarpophalangeal (MCP) joints, which are at the knuckle, while also extending the interphalangeal (IP) joints. This is crucial for finger movement, linking the extensor tendons to the flexor tendons. The lumbricals are used during an upstroke in writing, for example.
The lateral two lumbricals, associated with the index and middle fingers, are innervated by the median nerve. Meanwhile, the medial two lumbricals, associated with the little finger and ring finger, are innervated by the ulnar nerve.
The Levator Ani Muscle: Is It Straited or Not?
You may want to see also
Frequently asked questions
Muscles are groups of cells that can contract and relax, allowing movement of the bones in the hand. There are 34 muscles in each hand, which can be categorised as intrinsic or extrinsic muscles.
Intrinsic muscles are located within the hand itself and are responsible for the fine motor functions of the hand. They include the thenar, hypothenar, interossei, and lumbrical muscles.
Extrinsic muscles are located near the outside of the hand and in the forearm. They work with the intrinsic muscles to give the hand its strength and dexterity.
The hand muscles enable various movements, including flexing and extending the fingers, moving the wrist, and controlling the thumb and fingers to allow for grasping and pinching.
