WRIST AND HAND

GENERAL INFORMATION

The muscles of the wrist and hands are responsible for intricate hand movements, wrist stability, and grip strength. These muscles allow flexion, extension, abduction, adduction, and fine motor control of the fingers and thumb, enabling complex tasks like gripping, writing, and lifting. They are divided into two main groups: extrinsic muscles, which originate in the forearm and control gross hand movements, and intrinsic muscles, which are located within the hand and control fine motor functions.

ORIGIN

• Flexor Carpi Radialis: Medial epicondyle of the humerus.
• Flexor Digitorum Superficialis: Medial epicondyle of the humerus, coronoid process of the ulna, and shaft of the radius.
• Extensor Carpi Ulnaris: Lateral epicondyle of the humerus and posterior border of the ulna.
• Lumbricals: Tendons of the flexor digitorum profundus.
• Opponens Pollicis: Trapezium and flexor retinaculum.

INSERTION POINT

• Flexor Carpi Radialis: Bases of the second and third metacarpals.
• Flexor Digitorum Superficialis: Middle phalanges of the four fingers (digits 2–5).
• Extensor Carpi Ulnaris: Base of the fifth metacarpal.
• Lumbricals: Extensor expansions of digits 2–5.
• Opponens Pollicis: Lateral side of the first metacarpal (thumb).

MAJOR ARTERIES

• Radial Artery: Supplies the lateral aspect of the forearm, wrist, and hand.
• Ulnar Artery: Supplies the medial aspect of the forearm, wrist, and hand.
• Superficial and Deep Palmar Arches: Provide blood to the hand and fingers.

NEURAL INNERVATION

• Flexor Carpi Radialis: Median nerve (C6-C7).
• Flexor Digitorum Superficialis: Median nerve (C7-T1).
• Extensor Carpi Ulnaris: Radial nerve (C7-C8).
• Lumbricals: Median nerve (lateral two) and ulnar nerve (medial two).
• Opponens Pollicis: Median nerve (C8-T1).

TRIGGER POINT

Trigger points in the wrist and hand muscles, especially in the flexor carpi radialis and lumbricals, can cause pain in the hand, wrist, and forearm. These points are often caused by repetitive tasks like typing or gripping, leading to muscle fatigue, weakness, and discomfort, affecting hand functionality.

CONCENTRIC FUNCTION

• Flexor Carpi Radialis: Flexes and abducts the wrist, which is essential for gripping and wrist control during various tasks.
• Flexor Digitorum Superficialis: Flexes the middle phalanges of the fingers, essential for gripping and holding objects.
• Extensor Carpi Ulnaris: Extends and adducts the wrist, providing stability during wrist extension and control during movements like lifting.
• Lumbricals: Flex the metacarpophalangeal joints and extend the interphalangeal joints, helping with finger dexterity and fine motor control.
• Opponens Pollicis: Opposes the thumb, allowing the thumb to touch the tips of other fingers, which is essential for grasping objects.

ECCENTRIC FUNCTION

• Flexor Carpi Radialis: Controls wrist extension, providing resistance during release or lowering movements.
• Flexor Digitorum Superficialis: Controls finger extension, allowing for smooth release of objects after gripping.
• Extensor Carpi Ulnaris: Controls wrist flexion and stabilises the wrist during downward movements.
• Lumbricals: Control finger extension, preventing hyperextension during finger movement.
• Opponens Pollicis: Controls thumb repositioning after opposition, ensuring smooth and coordinated thumb movements.

ISOMETRIC FUNCTION

The muscles of the wrist and hands stabilise the wrist and fingers during static positions, such as gripping an object or maintaining a fist. The flexor carpi radialis and extensor carpi ulnaris work together to stabilise the wrist, while the lumbricals and opponens pollicis maintain tension in the fingers and thumb during static grips or fine motor tasks.

RELATED MUSCLE – SCIENTIFIC NAMES

• Flexor Digitorum Profundus: Assists in finger flexion, particularly the distal phalanges.
• Extensor Digitorum: Extends the fingers and helps with wrist extension.
• Palmaris Longus: Assists in wrist flexion and tenses the palmar fascia.
• Abductor Pollicis Brevis: Abducts the thumb and helps in thumb opposition.
• Flexor Pollicis Longus: Flexes the thumb, contributing to grasping and fine motor control.

ANTAGONIST

• Extensor Carpi Radialis Longus: Opposes the flexor carpi radialis by extending the wrist while the latter flexes it.
• Extensor Digitorum: Opposes the flexor digitorum superficialis by extending the fingers while the latter flexes them.
• Flexor Carpi Ulnaris: Opposes the extensor carpi ulnaris by flexing the wrist while the latter extends it.
• Extensor Pollicis Longus: Opposes the opponens pollicis by extending the thumb while the latter opposes it.
• Extensor Indicis: Opposes the lumbricals by extending the index finger while the lumbricals flex it.

COMMON INJURIES

• Carpal Tunnel Syndrome: Compression of the median nerve at the wrist, causing numbness, tingling, and weakness in the hand, often due to repetitive flexion and poor ergonomics.
• De Quervain’s Tenosynovitis: Inflammation of the tendons of the thumb, causing pain along the radial side of the wrist during thumb or wrist movements.
• Trigger Finger: Thickening of the flexor tendons, causing fingers to catch or lock in a bent position, often caused by overuse or repetitive gripping.
• Wrist Tendonitis: Inflammation of the tendons around the wrist, often from overuse, leading to pain and difficulty in wrist flexion and extension.
• Flexor Tenosynovitis: Inflammation of the tendon sheath in the fingers, causing pain and swelling, commonly due to overuse or repetitive hand movements.

EXERCISES

• Wrist Curls: Hold a light dumbbell with your palm facing upwards, and curl the wrist to strengthen the flexor muscles and improve grip strength.
• Reverse Wrist Curls: Hold a light dumbbell with your palm facing down, extend the wrist upwards to target the extensor muscles and enhance wrist stability.
• Finger Squeezes: Use a stress ball or grip strengthener, squeezing to engage the flexor muscles and build finger and hand strength.
• Thumb Opposition with Resistance Band: Wrap a resistance band around the thumb and move it towards the little finger, strengthening the opponens pollicis and improving thumb mobility.
• Lumbrical Pushdowns: Press down on a soft surface with your fingertips, engaging the lumbricals and improving finger flexion and dexterity.

STRETCHES

• Wrist Flexor Stretch: Extend your arm forward, palm up, and gently pull the fingers back with the opposite hand to stretch the flexor muscles.
• Wrist Extensor Stretch: Extend the arm forward, palm down, and gently press the back of the hand to stretch the extensor muscles.
• Thumb Stretch: Extend the thumb across the palm and gently pull it with the opposite hand to stretch the muscles around the thumb.
• Finger Spread Stretch: Spread your fingers wide apart and hold to stretch the muscles of the hand and improve flexibility.
• Forearm Stretch: Extend the arm and rotate the wrist while gently pulling the hand to stretch both the flexor and extensor muscles.