The carpal bones are the eight small bones that make up the wrist (carpus) that connects the hand to the forearm. The terms "carpus" and "carpal" are derived from the Latin carpus and the Greek καρπός (karpós), meaning "wrist". In human anatomy, the main role of the carpal bones is to articulate with the radial and ulnar heads to form a highly mobile condyloid joint, to provide attachments for thenar and hypothenar muscles, and to form part of the rigid carpal tunnel which allows the median nerve and tendons of the anterior forearm muscles to be transmitted to the hand and fingers.
In human anatomy, the metacarpal bones or metacarpus, also known as the "palm bones", are the appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones, which articulate with the forearm. The metacarpal bones are homologous to the metatarsal bones in the foot.
The upper limbs or upper extremities are the forelimbs of an upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digits, including all the musculatures and ligaments involved with the shoulder, elbow, wrist and knuckle joints. In humans, each upper limb is divided into the shoulder, arm, elbow, forearm, wrist and hand, and is primarily used for climbing, lifting and manipulating objects. In anatomy, just as arm refers to the upper arm, leg refers to the lower leg.
The phalanges are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones.
The extensor digitorum muscle is a muscle of the posterior forearm present in humans and other animals. It extends the medial four digits of the hand. Extensor digitorum is innervated by the posterior interosseous nerve, which is a branch of the radial nerve.
In human anatomy, the extensor pollicis longus muscle (EPL) is a skeletal muscle located dorsally on the forearm. It is much larger than the extensor pollicis brevis, the origin of which it partly covers and acts to stretch the thumb together with this muscle.
In human anatomy, the palmar or volar interossei are four muscles, one on the thumb that is occasionally missing, and three small, unipennate, central muscles in the hand that lie between the metacarpal bones and are attached to the index, ring, and little fingers. They are smaller than the dorsal interossei of the hand.
The metacarpophalangeal joints (MCP) are situated between the metacarpal bones and the proximal phalanges of the fingers. These joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow cavities on the proximal ends of the proximal phalanges. Being condyloid, they allow the movements of flexion, extension, abduction, adduction and circumduction at the joint.
In human anatomy, the dorsal interossei (DI) are four muscles in the back of the hand that act to abduct (spread) the index, middle, and ring fingers away from the hand's midline and assist in flexion at the metacarpophalangeal joints and extension at the interphalangeal joints of the index, middle and ring fingers.
Boutonniere deformity is a deformed position of the fingers or toes, in which the joint nearest the knuckle is permanently bent toward the palm while the farthest joint is bent back away. Causes include injury, inflammatory conditions like rheumatoid arthritis, and genetic conditions like Ehlers-Danlos syndrome.
The interphalangeal joints of the foot are the joints between the phalanx bones of the toes in the feet.
An extensor expansion is the special connective attachments by which the extensor tendons insert into the phalanges.
Jammed finger is a common term used to describe various types of finger joint injuries. It happens from a forceful impact originating at the tip of the finger directed towards the base. This type of directional force is called axial loading. It occurs most often when the finger is fully extended. This kind of impact can stretch or strain the ligaments in the joint beyond their normal limits. The severity of damage to the finger increases with the amount of force on the fingertip. In severe cases, injury to bone may occur. When experiencing a jammed finger, the extent of injury is not always obvious and one should be evaluated by a medical professional. Toes may become jammed as well, with similar results.
In human anatomy, the radial (RCL) and ulnar (UCL) collateral ligaments of the metacarpophalangeal joints (MCP) of the hand are the primary stabilisers of the MCP joints. A collateral ligament flanks each MCP joint - one on either side. Each attaches proximally at the head of the metacarpal bone, and distally at the base of the phalynx. Each extends obliquely in a palmar direction from its proximal attachment to its distal attachment. The collateral ligaments allow spreading our the fingers with an open hand but not with the hand closed into a fist.
In the human hand, palmar or volar plates are found in the metacarpophalangeal (MCP) and interphalangeal (IP) joints, where they reinforce the joint capsules, enhance joint stability, and limit hyperextension. The plates of the MCP and IP joints are structurally and functionally similar, except that in the MCP joints they are interconnected by a deep transverse ligament. In the MCP joints, they also indirectly provide stability to the longitudinal palmar arches of the hand. The volar plate of the thumb MCP joint has a transverse longitudinal rectangular shape, shorter than those in the fingers.
In the human foot, the plantar or volar plates are fibrocartilaginous structures found in the metatarsophalangeal (MTP) and interphalangeal (IP) joints. The anatomy and composition of the plantar plates are similar to the palmar plates in the metacarpophalangeal (MCP) and interphalangeal joints in the hand; the proximal origin is thin but the distal insertion is stout. Due to the weight-bearing nature of the human foot, the plantar plates are exposed to extension forces not present in the human hand.
Swan neck deformity is a deformed position of the finger, in which the joint closest to the fingertip is permanently bent toward the palm while the nearest joint to the palm is bent away from it. It is commonly caused by injury, hypermobility or inflammatory conditions like rheumatoid arthritis or sometimes familial.
A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala are often described as having "hands" instead of paws on their front limbs. The raccoon is usually described as having "hands" though opposable thumbs are lacking.
The extrinsic extensor muscles of the hand are located in the back of the forearm and have long tendons connecting them to bones in the hand, where they exert their action. Extrinsic denotes their location outside the hand. Extensor denotes their action which is to extend, or open flat, joints in the hand. They include the extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), extensor digitorum (ED), extensor digiti minimi (EDM), extensor carpi ulnaris (ECU), abductor pollicis longus (APL), extensor pollicis brevis (EPB), extensor pollicis longus (EPL), and extensor indicis (EI).
Acquired hand deformity refers to the structural or functional abnormalities that develop in the hand. There are multiple varying causes of acquired hand deformity, triggering significant consequences and complications. Trauma, including blunt force, penetrating injuries, burns, and sports-related incidents, is a primary cause of acquired hand deformities. Inflammatory conditions such as rheumatoid arthritis, gouty arthritis, and systemic lupus erythematosus can also contribute to hand deformities by affecting the joints. Degenerative arthritis, specifically osteoarthritis, functions to evoke impaired hand function due to the gradual deterioration of cartilage. Neurological disorders like cerebral palsy can result in hand contractures due to increased muscle tone and stiffness. There are different types of acquired hand deformities, each with distinct characteristics and underlying causes, such as boutonnière deformity, Dupuytren's contracture, gamekeeper's thumb, hand osteoarthritis deformity, mallet finger, swan-neck deformity, ulnar claw hand, among many others.
