Adductor pollicis muscle[edit | edit code]
Adductor pollicis muscle
Adductor pollicis muscle
(
m. adductor pollicis
), brings the thumb to the palm, participates in its opposition, as well as pressing the tip of the thumb to the index finger.
Home[edit | edit code]
- Oblique head: capitate bone (third carpal bone), bases of the second and third metacarpal bones, intercarpal ligaments
- Transverse head: proximal two-thirds of the palmar surface of the third metacarpal
Attachment[edit | edit code]
- Ulnar sesamoid bone at the carpometacarpal joint of the thumb
Innervation[edit | edit code]
- Ulnar nerve, deep branch, C8-T1
Functions[edit | edit code]
| Synergists | Antagonists |
| Carpometacarpal joint 1 | |
| Bringing | |
| m. interosseus dorsalis 1 m. opponens pollicis m. extensor pollicis longus m. flexor pollicis brevis (deep head) | m. abductor pollicis brevis m. abductor pollicis longus m. flexor pollicis brevis (superficial head) m. extensor pollicis brevis |
| Opposition | |
| m. opponens pollicis m. flexor pollicis longus m. flexor pollicis brevis | m. extensor pollicis longus m. extensor pollicis brevis m. abductor pollicis longus |
Adduction of the first carpometacarpal joint. Functional muscle tests[edit | edit code]
Issues and comments
- Abduction and adduction are only possible at the carpometacarpal joint (base of the thumb).
Other animals[edit]
The adductor pollicis evolved from the contrahens I muscles as the human body ancestors of the thumbs and thumbs became opposable. It may also contain an element of the interosseous muscle of the thumb.[4]
In the Pan-Homo LCA, the oblique head of the adductor pollicis likely had a relatively small physiological cross-sectional area (PCSA), and both heads likely acted as extensors and adductors at the carpometacarpal joint. In humans, the PCSA of the oblique capitis is relatively enlarged, and both capitis act as flexors at this joint.[5]
Read also[edit | edit code]
- Extensor digitorum
- Extensor index finger
- Extensor of the little finger
- Extensor pollicis brevis
- Extensor pollicis longus
- Vermiform muscles of the hand
- Flexor digitorum superficialis
- Flexor digitorum profundus
- Flexor of the little finger of the hand
- Flexor pollicis brevis
- Flexor pollicis longus
- Abductor pollicis longus muscle
- Abductor pollicis brevis muscle
- Muscle that abducts the little finger
- Dorsal interosseous muscles of the hand
- Palmar interosseous muscles of the hand
- Oppons pollicis muscle
- Opponus little finger muscle
- Palmaris brevis
Hand bones
The hand has three sections: wrist, metacarpus and fingers.
Carpal bones
The eight small bones of the wrist have an irregular shape. They are located in two rows.
The proximal row consists of the following bones, if you go from the thumb to the fifth finger: scaphoid, lunate, triquetrum and pisiform. The distal row also consists of four bones: polygonal, trapezoid, capitate and hamate, which with its hook faces the palmar side of the hand. The proximal row of carpal bones forms an articular surface convex towards the radius. The distal row is connected to the proximal row using an irregularly shaped joint. The bones of the wrist lie in different planes and form a groove (carpal groove) on the palmar surface and a bulge on the back. The groove of the wrist contains the tendons of the finger flexor muscles. Its inner edge is limited by the pisiform bone and the hook of the hamate bone, which are easily palpable; the outer edge is composed of two bones - the scaphoid and the polygonal.
Metacarpal bones
The metacarpus consists of five tubular metacarpal bones.
The metacarpal bone of the first finger is shorter than the others, but is distinguished by its massiveness. The longest is the second metacarpal bone. The following bones towards the ulnar edge of the hand decrease in length. Each metacarpal bone has a base, a body and a head. The bases of the metacarpal bones articulate with the bones of the wrist. The bases of the first and fifth metacarpal bones have saddle-shaped articular surfaces, and the rest have flat articular surfaces. The heads of the metacarpal bones have a hemispherical articular surface and articulate with the proximal phalanges of the fingers. Bones of the fingers
Each finger consists of three phalanges: proximal, middle and distal. The exception is the first finger, which has only two phalanges - proximal and distal. The proximal phalanges are the longest, the distal ones are the shortest. Each phalanx has a middle part - a body and two ends - proximal and distal. At the proximal end is the base of the phalanx, and at the distal end is the head of the phalanx. At each end of the phalanx there are articular surfaces for articulation with adjacent bones.
Sesamoid bones of the hand
In addition to these bones, the hand also has sesamoid bones, which are located in the thickness of the tendons between the metacarpal bone of the thumb and its proximal phalanx. There are also unstable sesamoid bones between the metacarpal bone and the proximal phalanx of the second and fifth fingers. Sesamoid bones are usually located on the palmar surface, but are occasionally found on the dorsal surface. The sesamoid bones also include the pisiform bone. All sesamoid bones, as well as all processes of bones, increase the leverage of the muscles that are attached to them.
Ligamentous apparatus of the hand
Wrist joint
The formation of this joint involves the radius and bones of the proximal row of the wrist: scaphoid, lunate and triquetrum. The ulna does not reach the surface of the radiocarpal joint (it is “supplemented” by the articular disc). Thus, in the formation of the elbow joint, the ulna plays the largest role of the two bones of the forearm, and the radius plays the largest role in the formation of the radiocarpal joint. In the radiocarpal joint, which has an elliptical shape, flexion and extension, adduction and abduction of the hand are possible. Pronation and supination of the hand occur together with the same movements of the bones of the forearm. A small passive rotational movement is also possible in the radiocarpal joint (10-12°), but this occurs due to the elasticity of the articular cartilage. The position of the gap of the radiocarpal joint is determined from the dorsal surface, where it is easily detected through the soft tissues; in addition, its position is determined from the radial and ulnar sides. On the radial side, in the area of the inferior radial fossa, you can palpate the gap between the lateral styloid process and the scaphoid bone. On the ulnar side, a depression is felt between the head of the ulna and the triquetral bone, corresponding to the ulnar portion of the cavity of the radiocarpal joint. Movements in the radiocarpal joint are closely related to movements in the midcarpal joint, which is located between the proximal and distal rows of carpal bones. This joint has a complex, irregularly shaped surface. The total range of mobility when flexing the wrist reaches 85°, and when extending it is also approximately 85°. Adduction of the hand in these joints is possible by 40°, and abduction by 20°. In addition, circular movement (circumduction) is possible in the radiocarpal joint. The radiocarpal and midcarpal joints are strengthened by numerous ligaments. The ligamentous apparatus of the hand is very complex. The ligaments are located on the palmar, dorsal, medial and lateral surfaces of the wrist, as well as between the individual bones of the wrist. The most important collateral ligaments of the wrist are the radial and ulnar ligaments. The first goes from the lateral styloid process to the scaphoid bone, the second - from the medial styloid process to the triquetral bone. Between the bony elevations on the radial and ulnar sides of the palmar surface of the hand there is a ligament, the flexor retinaculum. It is not directly related to the joints of the hand, but is, in fact, a thickening of the fascia. Throwing over the carpal groove, it turns it into the carpal tunnel, where the flexor tendons of the fingers and the median nerve pass.
Carpometacarpal joints of the hand
They are connections of the distal row of carpal bones with the bases of the metacarpal bones. These joints, with the exception of the carpometacarpal joint of the thumb, are flat and inactive. The range of movements in them does not exceed 5-10°. Mobility in these joints, as well as between the bones of the wrist, is sharply limited by well-developed ligaments. The ligaments located on the palmar surface of the hand make up a strong palmar ligamentous apparatus. It connects the carpal bones to each other, as well as to the metacarpal bones. On the hand you can distinguish ligaments that run arcuate, radial and transverse. The central bone of the ligamentous apparatus is the capitate, to which more ligaments are attached than to any other bone of the wrist. The dorsal ligaments of the hand are much less developed than the palmar ligaments. They connect the bones of the wrist to each other, making up thickening capsules covering the joints between these bones. In addition to the palmar and dorsal ligaments, the second row of carpal bones also has interosseous ligaments. Due to the fact that the bones of the distal row of the wrist and the four (II-V) bones of the metacarpus are inactive relative to each other and are firmly connected into a single formation that makes up the central bone core of the hand, they are designated as the solid base of the hand. The carpometacarpal joint of the thumb is formed by the polygonal bone and the base of the first metacarpal bone. The articular surfaces are saddle-shaped. The following movements are possible in the joint: adduction and abduction, opposition (opposition) and reverse movement (reposition), as well as circular movement (circumduction). Due to the opposition of the thumb to all other fingers, the scope of grasping movements of the hand increases significantly. The amount of mobility in the carpometacarpal joint of the thumb is 45-60° during abduction and adduction and 35-40° during opposition and reverse movement.
Metacarpophalangeal joints of the hand
Formed by the heads of the metacarpal bones and the bases of the proximal phalanges of the fingers. All these joints have a spherical shape and, accordingly, three mutually perpendicular axes of rotation, around which flexion and extension, adduction and abduction, as well as circular movement (circumduction) occur. Flexion and extension are possible at 90-100°, abduction and adduction - at 45-50°. The metacarpophalangeal joints are strengthened by collateral ligaments located on the sides of them. On the palmar side, the capsules of these joints have additional ligaments called palmar ligaments. Their fibers are intertwined with the fibers of the deep transverse metacarpal ligament, which prevents the heads of the metacarpal bones from diverging to the sides.
Interphalangeal joints of the hand
They have a block-like shape, their axes of rotation run transversely. Flexion and extension are possible around these axes. Their volume in the proximal interphalangeal joints is 110-120°, while in the distal ones it is 80-90°. All interphalangeal joints are strengthened by well-defined collateral ligaments.
Fibrous and synovial sheaths of the tendons of the fingers
The flexor retinaculum and extensor retinaculum ligaments are of great importance for strengthening the position of the muscle tendons passing under them, especially when flexing and extending the hand: the tendons rest on the named ligaments from their inner surface, and the ligaments prevent the tendons from moving away from the bones and withstand significant pressure during strong muscle contractions . The sliding of the tendons of the muscles passing from the forearm to the hand and the reduction of friction are facilitated by special tendon sheaths, which are fibrous or osteo-fibrous canals, inside of which there are synovial sheaths, in some places extending beyond these canals. The largest number of synovial sheaths (6-7) is located under the extensor retinaculum. The formation of the canals involves the ulna and radius bones, which have grooves corresponding to the passage of the muscle tendons, and fibrous bridges that separate one canal from the other, which go from the extensor retinaculum to the bones. The palmar synovial sheaths belong to the flexor tendons of the hand and fingers running in the carpal canal. The tendons of the superficial and deep flexor fingers lie in a common synovial sheath, which extends to the middle of the palm, reaching the distal phalanx of only the fifth finger, and the tendon of the flexor pollicis longus is located in a separate synovial sheath, which passes along with the tendon onto the finger. In the palm area, the tendons of the muscles going to the second, third and fourth fingers are deprived of synovial sheaths for some distance and receive them again on the fingers. Only the tendons leading to the fifth finger have a synovial sheath, which is a continuation of the common synovial sheath for the flexor tendons of the fingers.
Muscles of the hand
On the hand, the muscles are located only on the palmar side. Here they form three groups: the middle one (in the middle section of the palmar surface), the thumb muscle group and the small finger muscle group. The large number of short muscles on the hand is due to the fine differentiation of finger movements.
Middle hand muscle group
Consists of lumbrical muscles that originate from the tendons of the deep flexor digitorum and are attached to the base of the proximal phalanges of the second to fifth fingers; palmar and dorsal interosseous muscles, which are located in the interosseous spaces between the metacarpal bones and are attached to the base of the proximal phalanges of the second to fifth fingers. The function of the muscles of the middle group is that they are involved in flexing the proximal phalanges of these fingers. In addition, the palmar interosseous muscles bring the fingers of the hand towards the middle finger, and the dorsal interosseous muscles spread them apart.
Thumb muscle group
Forms the so-called eminence of the thumb on the hand. They begin on the nearby bones of the wrist and metacarpus. Among them are distinguished: the short muscle that abducts the pollicis, which is attached to its proximal phalanx; flexor pollicis brevis, which attaches to the external sesamoid bone located at the base of the proximal phalanx of the thumb; the opponus pollicis muscle, which goes to the first metacarpal bone; and the adductor pollicis muscle, which attaches to the internal sesamoid bone located at the base of the proximal phalanx of the thumb. The function of these muscles is indicated in the name of each muscle.
Small finger muscle group
Forms an elevation on the inside of the palm. This group includes: palmaris brevis; abductor digiti minimi muscle; flexor little finger brevis and oppons little finger muscle. They arise from the nearby carpal bones and attach to the base of the proximal phalanx of the fifth finger and the fifth metacarpal bone. Their function is determined by the name of the muscles themselves.
Materials used in the article: sportmedicine.ru
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Additional images[edit]
- Muscles of the thumb. (Adductor pollicis transversus is the red stripe below, and adductor pollicis obliquus is the red stripe directly above it.)
- Adductor pollicis muscle
- Transverse section of the wrist and fingers.
- Muscles of the left arm. Palmar surface.
- Radial and ulnar arteries.
- Superficial palmar nerves.
- Deep palmar nerves.
- Anterior part of the left forearm. Deep muscles. (The adductor pollicis is visible in the lower center.)
- Adductor pollicis muscle
- Adductor pollicis muscle
- Adductor pollicis muscle
- Adductor pollicis muscle
- Adductor pollicis muscle