Maximus Gage
The human hand is a complex network of bones, muscles, nerves, connective tissue, and blood vessels. There are 34 muscles in each hand, which can be categorised as intrinsic or extrinsic. 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. These muscles work together to give the hand its strength and dexterity. The hand's muscles are innervated by the radial, median, and ulnar nerves, which are connected to smaller nerves that spread out into the hand and wrist. Tendons connect the muscles to the bones, allowing movement, and ligaments help bind the joints together.
| Characteristics | Values |
|---|---|
| Number of muscles in each hand | 34 |
| Types of muscles | Intrinsic (located within the hand itself) and extrinsic (located near the outside of the hand and in the forearm) |
| Function of intrinsic muscles | Responsible for fine motor functions of the hand |
| Function of extrinsic muscles | Give strength and dexterity to the hand |
| Types of bones in the hand | Phalanges (14 bones in the fingers and toes), metacarpals (5 bones in the mid-hand), and carpals (8 bones in the wrist) |
| Types of tendons in the hand | Extensor tendons (help extend and straighten fingers, hand, and wrist) and flexor tendons (help flex and curl fingers, hand, and wrist) |
| Types of nerves in the hand | Radial nerve, median nerve, and ulnar nerve |
| Function of radial nerve | Innervates the finger extensors and the thumb abductor |
| Function of median nerve | Innervates the flexors of the wrist and digits, the abductors and opponens of the thumb, and the first and second lumbricals |
| Function of ulnar nerve | Innervates the remaining intrinsic muscles of the hand |
| Types of muscles in the thumb | One long flexor and a short flexor in the thenar muscle group |
| Function of the thenar muscle group | Moving the thumb in opposition, making grasping possible |
| Types of muscles in the fingers | Two long flexors located on the underside of the forearm |
| Function of the flexors | Allow for the actual bending of the fingers |
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What You'll Learn
- Intrinsic muscles are located within the hand and control fine motor functions
- Thenar muscles control the thumb and are located at its base
- Hypothenar muscles are located at the base of the pinkie finger
- Interossei muscles are between the metacarpal bones in the palm and help fingers move side-to-side
- Lumbrical muscles are at the base of the four non-thumb fingers and help with finger flexion
Intrinsic muscles are located within the hand and control fine motor functions
The human hand is a complex network of bones, muscles, nerves, connective tissue, and blood vessels. There are 34 muscles in each hand, which can be categorised into two groups: extrinsic and intrinsic muscles. The extrinsic muscles are located in the anterior and posterior compartments of the forearm and are responsible for crude movements and a forceful grip.
Intrinsic muscles, on the other hand, are located within the hand itself. They are responsible for the fine motor functions of the hand, such as pinch and grip strength. These muscles are smaller and are found within the various hand osseofascial compartments within the anatomic confines of the wrist (proximally) and phalanges (distally). The intrinsic muscles work with the extrinsic muscles to give the hand its strength and dexterity.
The intrinsic muscles of the hand include the thenar and hypothenar muscles. The thenar muscles are three short muscles located at the base of the thumb, responsible for its fine movements. The hypothenar muscles line the outer edges of the palm on the outside of the pinkie finger. Other intrinsic muscles include the interossei and lumbrical muscles. 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 responsible for allowing the fingers to straighten and assisting in bending the MCP joints at the knuckles.
The nerves of the intrinsic hand arise from the brachial plexus, specifically the median, radial, and ulnar nerves. The median nerve innervates the flexors of the wrist and digits, as well as the abductors and opponens of the thumb. The radial nerve innervates the finger extensors and thumb abductor, while the ulnar nerve innervates the remaining intrinsic muscles.
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Thenar muscles control the thumb and are located at its base
The human hand is a complex network of bones, muscles, nerves, tendons, and ligaments. There are 34 muscles in each hand, which work together to help you move your fingers and control objects. The muscles of the hand are innervated by the radial, median, and ulnar nerves.
The thenar muscles are a group of three short muscles located on the lateral (radial) aspect of the hand. They are the abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis. A fourth muscle, the adductor pollicis, is also located in this region but is not part of the thenar muscle group and is classified on its own as the muscle of the adductor compartment of the hand.
The thenar muscles form a fleshy prominence on the lateral (radial) aspect of the palm called the thenar eminence. They originate from different carpal bones and distally attach to the thumb. The thenar eminence can be easily identified by palpating the base of the thumb on the palm (volar) side of the hand. The abductor pollicis brevis, flexor pollicis brevis, and the opponens pollicis are located here and control the movements of the thumb.
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), allowing the thumb to move in opposition, making grasping possible. The opponens pollicis is the largest muscle in the thenar group and is located deep to the other muscles. Its prime function is to produce the opposition of the thumb in the first carpometacarpal joint. This is a complex movement in which flexion, adduction, and medial rotation occur together, allowing the tip of the thumb to contact the tips of the other digits on the same hand.
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Hypothenar muscles are located at the base of the pinkie finger
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 with the wrist to allow us to touch and control objects. These muscles are soft tissue made of stretchy fibres.
The hypothenar muscles are located at the base of the pinkie finger, forming a noticeable fleshy prominence on the medial side of the palm called the hypothenar eminence. They are the three short muscles of the medial (ulnar) palmar compartment of the hand. A fourth muscle, the palmaris brevis, is also located in this region, but it does not belong to the hypothenar muscle group.
The hypothenar muscles are similar to the thenar muscles in both name and organisation. 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 hypothenar muscles, on the other hand, control the little finger, allowing for flexion, abduction, lateral rotation, and opposition.
The three hypothenar muscles, from superficial to deep, are: abductor digiti minimi, flexor digiti minimi, and opponens digiti minimi muscles. The abductor digiti minimi muscle is a short muscle that originates from the palmar surface of the pisiform bone and the dorsal aponeurosis. It courses along the ulnar side of the metacarpal bone and inserts into the ulnar aspect of the base of the proximal phalanx of the little finger. The flexor digiti minimi brevis muscle 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 opponens digit minimi lies deep to the other hypothenar muscles. It originates from the hook of the hamate and associated flexor retinaculum and inserts into the medial margin of metacarpal V.
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Interossei muscles are between the metacarpal bones in the palm and help fingers move side-to-side
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 hand and fingers. These muscles are soft tissue made of stretchy fibres. Intrinsic muscles inside your hand work with extrinsic muscles near the outside of your hand and in your forearm to give your hand its strength and dexterity.
The interossei muscles are intrinsic hand muscles situated between the metacarpal bones in the palm. They help the fingers move side-to-side. There are four dorsal and three palmar interossei muscles. All interossei bend the MCP joints, but they have different functions. The dorsal interossei allow us to spread our fingers away from each other, while the palmar interossei pull our fingers together. The first dorsal interosseous muscle is the largest and originates from the first and second hand bones. It forms the contour between the thumb and index finger when looking at the top of the hand.
The interossei muscles are innervated by the deep branch of the ulnar nerve. Consequently, ulnar nerve injury may significantly impair intrinsic hand functions, particularly finger abduction and adduction. Understanding the anatomy and function of the interossei is essential in assessing ulnar nerve injuries, which often present with impaired finger abduction and adduction.
The hand has two groups of tendons: extensor tendons and flexor tendons. Extensor tendons help extend and straighten the fingers, hand, and wrist. Flexor tendons help flex and curl the fingers, hand, and wrist.
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Lumbrical muscles are at the base of the four non-thumb fingers and help with finger flexion
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 hand.
The lumbrical muscles are a group of four small, worm-like muscles on each hand. They are deep muscles that do not attach to bone, unlike most muscles. Instead, they attach proximally to the tendons of flexor digitorum profundus and distally to the extensor expansions. They are at the base of the four non-thumb fingers and help with finger flexion.
The primary function of the lumbrical muscles is to allow the fingers to straighten. They also help bend the MCP joints, which are at the knuckle. The name of this muscle is derived from the Greek word for earthworm.
The lumbricals are innervated by the median nerve. They are relevant in carpal tunnel syndrome, where damage to the median nerve results in the loss of the fundamental function of the human hand – the ability to bring the thumb away from the fingers to grasp objects.
The lumbrical muscles are also involved in sensory feedback, which is important for precision pinching. They contain many muscle spindles and have a large fibre length, which indicates their likely role in proprioception.
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Frequently asked questions
Intrinsic muscles are located within the hand itself and are responsible for the fine motor functions of the hand.
Thenar muscles are three short muscles located at the base of the thumb. They are responsible for the fine movements of the thumb.
Interossei muscles are located between the metacarpal bones in the palm of the hand. They help the fingers move side-to-side.
