Diagram Of Bones In The Human Hand – The carpal bones are eight small bones that make up the joint (carpus) that connects the hand to the forearm. The terms “carpus” and “carpal” come 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 the highly mobile condyloid joint (i.e. the wrist joint),

To provide attachments for the tar and hypotar muscles, and to form part of the rigid carpal tunnel that allows the median nerve and tendons of the anterior muscles of the forearm to be transmitted to the hand and fingers.

Diagram Of Bones In The Human Hand

In tetrapods, the carpus is the only set of bones in the joint between the radius and the ulna and the metacarpus. The carpus bones do not belong to individual fingers (or toes in quadrupeds), while the metacarpal bones do. The corresponding part of the foot is the tarsus. The carpal bones allow the wrist to move and rotate vertically.

Pisiform Bone: Anatomical Structure And Function

When viewed as paired rows, each row forms an arch that is convex proximally and concave distally. On the palmar side, the carpus is concave and forms the carpal tunnel, which is covered by the flexor retinaculum.

The proximal row (consisting of the scaphoid, lunate, triquetrum, and psiform) articulates with the surfaces of the radius and distal carpal row and thus constantly adapts to these moving surfaces. Within the proximal row, each carpal bone has slight independent mobility. For example, the scaphoid contributes to the stability of the midcarpal joint by articulating distally with the trapezius and trapezium. In contrast, the distal row is more rigid because its transverse arch moves with the metacarpals.

In this context, the pisiform is considered a sesamoid bone embedded in the tendon of the flexor carpi ulnaris.

The ulnar column leaves a gap between the ulna and the triquetrum, and therefore only the radial or scaphoid and ctral or capitate columns articulate with the radius. The wrist is more stable in flexion than in extension, due more to the strength of the various capsules and ligaments than to the interconnected parts of the skeleton.

Figure 7.9, Bones Of The Human Wrist, Hand, And Fingers Anterior View Diagram

Almost all carpal joints (except the carpal joint) have six surfaces. Of these, the palmar or front and dorsal or back surfaces are rough, for ligament attachment; the dorsal surfaces are wider, except in the lunate.

The upper or proximal and lower or distal surfaces are articulated, the upper generally convex, the lower concave; the medial and lateral surfaces are also articulate where they contact adjacent bones, otherwise they are rough and tuberculated.

Occasionally, accessory bones are found in the carpus, but of the more than 20 bones so described, only four (ctral, styloid, secondary trapezoid, and secondary pistil) are considered accessory bones. Sometimes the scaphoid, triquetrum and pisiform bone are divided into two parts.

The carpal bones are ossified prechondrally (inside the cartilage), and the bone nodes appear only after birth.

Hand Anatomy Video

The formation of these cells roughly follows a chronological spiral pattern beginning in the head and hamate during the first year of life. The ulnar bones ossify before the radial bones, while the sesamoid pisiform is formed in the tone of the flexor carpi ulnaris after more than t years.

The onset of ossification for each bone occurs during the same period as other bones. This is useful for age estimation.

The hand is said to be in a flat position when the third finger passes over the top of the head and is in a straight line with the forearm. This should not be confused with the mean arm position corresponding to 12 degrees of ulnar deviation. From the right position, two pairs of hand movements are possible: abduction (movement towards the radius, so-called radial deviation or abduction) of 15 degrees and adduction (movement towards the ulna, so-called ulnar deviation or adduction) of 40 degrees when the hand is in strict supination and slightly larger in strict pronation.

Flexion (leaning towards the palm, so-called palmar flexion) and extension (leaning towards the back of the hand, so-called dorsiflexion) is possible with a total range of 170 degrees.

Human Left Hand Posterior Dorsal View Bones Anatomy Chart Medical Scientific Science Class Classroom Lab Doctor Office White Wood Framed Art Poster 20×14

During radial abduction, the scaphoid tilts toward the palmar side allowing the trapezius and trapezium to approach the radius. Because the trapezius is firmly attached to the second metacarpal bone to which the flexor carpi radialis and extsor carpi radialis are also attached, radial abduction effectively pulls this combined structure toward the radius. During radial abduction, the phalanx travels the longest of all the carpal bones.

Radial abduction is produced (in order of importance) by extsor carpi radialis longus, abductor pollicis longus, extsor pollicis longus, flexor carpi radialis and flexor pollicis longus.

Both radial abduction and ulnar adduction occur around a dorsopalmar axis that passes through the head of the capitate bone.

During palmar flexion, the proximal carpal bones move dorsally and palmarly during dorsiflexion. While flexion and extension consist of movements about a pair of transverse axes—passing through the lunate bone for the proximal row and through the glenoid bone for the distal row—palmar flexion occurs mainly at the radiocarpal joint and dorsal flexion at the midcarpal joint.

Human Hand Bones, Computer Illustration Stock Photo

Back flexion is produced (in order of importance) by extsor digitorum, extsor carpi radialis longus, extsor carpi radialis brevis, extsor indicis, extsor pollicis longus and extsor digiti minimi. Palmar flexion is produced (in order of importance) by flexor digitorum superficialis, flexor digitorum profundus, flexor carpi ulnaris, flexor pollicis longus, flexor carpi radialis and abductor pollicis longus.

Combined with elbow and shoulder joint movements, intermediate or combined joint movements approximate ball joint movements with some necessary limitations, such as maximum palmar flexion blocking abduction.

Anteroposterior sliding movements between adjacent carpal bones or along the mid-joint can be achieved by stabilizing one bone while moving another (ie, grasping the bone between the thumb and forefinger).

The structure of the carpus varies widely among different groups of tetrapods, even among those that retain the entire set of five digits. In primitive fossil amphibians, such as Eryop, the carpus consists of three rows of bones; a proximal row of three carpals, a second row of four bones, and a distal row of five bones. The proximal carpal joints are called the radial, intermediate, and ulnar, after their proximal articulations, and are homologous to the scaphoid, lunate, and triquetral. The remaining bones are simply numbered, as the first through fourth ctralia (singular: ctrale), and the first through fifth distal carpals. Primarily, each distal bone appears to be fused to a single metacarpal.

Infographic Diagram Of Human Skeleton Upper Limb Bone Anatomy System Or Arm Bone Anterior View 3d Human Anatomy Medical Diagram Educational And Human Body Concept Isolated On White Background Stock Photo, Picture

However, the vast majority of later vertebrates, including modern amphibians, suffered varying degrees of loss and fusion of these primitive bones, resulting in fewer carpals. Almost all mammals and reptiles, for example, have lost the fifth distal carpal and have only one ctral – and this is missing in humans. The leg bone is somewhat unusual in that it first appears in primitive reptiles and is never found in amphibians.

Since many tetrapods have less than five digits on the forelimb, increasing degrees of fusion are common and a huge range of different possible combinations can be found. The wing of a modern bird, for example, has only two remaining carpals; radiale (scaphoid in mammals) and the bone formed by the fusion of the four distal carpals.

In crustaceans, “carpus” is the scientific term for the claws or “pincers” found on some legs. (See Decapod Anatomy)

The Latin word “carpus” comes from the Greek καρπὁς meaning “wrist”. The root “carp-” translates to “plucking”, an action performed by the wrist. Home Quizzes & Games History & Society Science & Technology Biographies Animals & Nature Geography & Travel Arts & Culture Money Videos

Broken Bones In Human Hand Stock Vector. Illustration Of Body

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Hand, grasping organ at the end of the forelimb of certain vertebrates which shows great mobility and flexibility of the fingers and the whole organ. It consists of the articular joint, carpal bones, metacarpal bones and phalanges. The digits include the medial thumb (when viewed palm down), which contains two phalanges, and four fingers, each of which contains three phalanges.

The main function of the hand in all vertebrates except humans is locomotion; bipedal locomotion in humans frees the arms for a mainly manipulative function. In primates, the tips of the fingers are covered with nails – a specialization that improves manipulation. The palms and undersides of the fingers are marked with folds and covered with ridges called palm prints and finger prints, which serve to improve tactile sensitivity and grasp. The friction ridges are arranged in general patterns which

Hand & Wrist Anatomy

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