Abduction: The movement of the fingers away from the middle finger to spread them apart. Controlled by the dorsal interossei muscles.
Adduction: The movement of the fingers toward the middle finger to bring them together. Controlled by the palmar interossei muscles.
Carpals: The eight small bones that make up the wrist. Includes the scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, and hamate bones. Form the wrist joint.
Carpal tunnel: The passageway on the palm side of the wrist surrounded by the carpal bones and transverse carpal ligament. Contains tendons and the median nerve.
Collateral ligaments: Fibrous bands on either side of the finger joints that connect adjacent bones and provide stability.
Dorsal interossei: Small muscles between the metacarpals on the back of the hand. Abduct the index, middle, and ring fingers away from the hand’s midline.
Extensor digitorum: A forearm muscle that extends the wrist, fingers, and hand. Assists in releasing a fist or grip.
Extension: The straightening or extending of the fingers or wrist, increasing the angle of the joints. Controlled by extensor muscles.
Extensor carpi radialis brevis: A forearm muscle that extends and abducts the wrist. Assists in lifting the hand.
Extensor digitorum: A forearm muscle that extends the fingers and hand. Enables releasing a grip and spreading the fingers.
Extrinsic muscles: The larger muscles of the forearm that control gross movements of the wrist, hand, and fingers. Includes flexors and extensors.
Flexion: The bending of the fingers or wrist toward the palm side, decreasing the angle of the joints.
Flexor digitorum profundus: A deep forearm muscle that flexes the distal phalanges of the fingers, allowing for gripping objects.
Flexor digitorum superficialis: A forearm muscle that flexes the middle phalanges of the fingers. Allows forming a fist.
Guyon’s canal: The tunnel at the wrist through which the ulnar nerve and artery pass into the hand.
Hypothenar hammer syndrome: Compression of the ulnar nerve and artery at the wrist, causing little finger symptoms.
Hypothenar muscles: Muscles at the base of the little finger that control its fine movements. Includes abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi.
Interphalangeal joints: The hinge joints between the phalanges of each finger and thumb. Allow fingers to flex and extend.
Interossei muscles: Small muscles between the metacarpals that control abduction and adduction of the fingers. Includes four dorsal and three palmar interossei.
Intrinsic muscles: Small muscles located entirely within the hand itself. Control fine movements of the fingers and thumb.
Lateral epicondylitis: Tennis elbow. Pain from tendon injury at the lateral epicondyle of the elbow.
Lumbricals: Four small muscles that originate from the flexor digitorum profundus tendons and insert into the fingers. Flex and extend the finger joints.
Metacarpals: The five long bones of the palm that connect the carpal bones to the proximal phalanges of each finger and thumb.
Metacarpophalangeal joints: The knuckle joints that connect the metacarpals to the proximal phalanges of each finger. Allow flexion, extension, abduction and adduction of the fingers.
Opponens pollicis: Thenar muscle that rotates the thumb across the palm for opposition. Enables pinching grip.
Opposition: The thumb’s ability to touch the tips of the other fingers, enabled by the thenar muscles. Allows pinching, grasping, and fine manipulation.
Palmar interossei: Three small muscles on the palm side between the metacarpals that adduct the fingers.
Phalanges: The digital bones of the fingers and thumb. Includes proximal, middle, and distal segments.
Radial nerve: Nerve that controls wrist, finger, and thumb extension. Also provides sensation to the back of the hand.
Retinaculum: Fibrous bands that hold tendons in place. Help prevent tendons from bowstringing away from bones during finger flexion.
Sesamoids: Small bones embedded in certain tendons that change the angle of pull of muscles. Two sesamoids are in the thumb flexor tendons.
Tenosynovitis: Inflammation of the lining of a tendon sheath. Causes pain, swelling, and limited motion.
Thenar eminence: Muscular ball at the base of the thumb that contains the thenar muscles.
Thenar muscles: Muscles at the base of the thumb that enable opposition and fine control of thumb movements. Includes abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis.
Ulnar nerve: Nerve that controls intricate finger movements and provides sensation to the little finger side of the hand. Can be compressed in cubital tunnel syndrome.
Volar plate: A thick fibrocartilage ligament on the palm side of the finger joints that prevents hyperextension.