Generality
The fingers of the hand are the 5 anatomical projections of tapered shape, which, in the human body, represent the last stretch of each upper limb.
Known as the thumb, index, middle, ring and little fingers, the fingers of the hand include bones, joints, ligaments, tendons, blood vessels, nerves and, of course, the covering skin; the fingers of the hand, moreover, are provided with nails, at the ends of the dorsal face, and of the so-called dermatoglyphics, at the ends of the palmar face.
The fingers of the hand can be subject to various medical conditions, including: bone fractures, burns, skin wounds, synovial cysts, hand osteoarthritis, carpal tunnel syndrome, etc.
What are the fingers of the hand?
The fingers of the hand are the 5 mobile anatomical structures, of tapered shape, which, in the human body, constitute the last stretch of the distal end of each upper limb .
Brief review of the proximal-distal terms
" Proximal " means "closer to the center of the body" or "closer to the point of origin"; " distal ", instead, means "farther from the center of the body" or "farther from the point of origin.
Examples:
- The femur is proximal to the tibia, which is distal to the femur.
- In the femur, the extremity bordering the trunk is the proximal end, while the extremity bordering the knee is the distal end.
Anatomy
The fingers of the hand are anatomical segments, some centimeters long (in the adult human being) which include bones, joints, ligaments, tendons, blood vessels, nerves and, obviously, the covering skin .
Nomenclature and Position of the Finger
The 5 fingers of the hand are called thumb, forefinger, middle finger, ring finger and little finger .
Imagining to observe the palm of a person's hand with the upper limb stretched along the side,
- The thumb is the most lateral finger, while the little finger is the most medial finger;
- the index finger is the finger closest to the thumb, while the ring finger is the finger closest to the little finger;
- Finally, the middle is the finger located between the index and the ring finger.
Brief review of the medial-lateral terms
Recalling that the sagittal plane is the anteroposterior division of the human body from which two equal and symmetrical halves are derived, " medial " means "near" or "closer" to the sagittal plane, while " lateral " means "far" or " farther "from the sagittal plane.
Examples:
- The second toe is lateral to the big toe, but is medial to the third toe.
- The ulna is medial with respect to the radius, which is lateral to the ulna (this is true if we assume that the upper limb is extended along the side and with the palm facing towards the observer).
External Characteristics of the Hand Fingers
Although they all have a tapered shape, the fingers of the hand are slightly different from each other; indeed:
- The thumb is the shortest finger and the generally most voluminous finger;
- The middle finger is the longest finger, followed, in most individuals, by the ring finger, the index finger and the little finger;
- Index, middle and ring are more or less equivalent in terms of volume;
- The little finger is the second shortest finger, after the thumb, as well as the least bulky one.
On the dorsal face, all the fingers of the hand culminate with a fingernail, that is an epidermal formation rich in keratin with the function of protection, support, hold of the objects and sensitivity.
On the palmar face, on the other hand, all the fingers of the hand end with a very particular skin area, called a fingertip, in which the so-called dermatoglyphics are located, that is, the set of crests and furrows of the skin that make up a person's fingerprints .
Did you know that ...
The dermatoglyphs on the palmar face of the fingers are:
- Immutable . Since they formed (VIII month of fetal life), the dermatoglyphs maintain the same alternation of ridges and furrows for the rest of existence, even in the case of scratches or cuts on the fingertips (the skin grows back exactly as it was before the scratch or of the cut);
- Different from person to person . It seems that, in every human being, the structure of the dermatoglyphs is unique in its kind; this explains why fingerprints are used in the identification and recognition of a given individual.
Bones and Joints
The skeleton of the fingers of the hand includes 14 total bones, all cylindrical in shape, called phalanges ; belonging to the category of long bones, the phalanges are 3 for each finger, except one, the thumb, in which they are only 2.
In each finger of the hand, the phalanges present are arranged in series along the length, ie with longitudinal orientation.
For each finger of the hand, the phalangeal complex is connected to the skeleton of the center of the hand, a skeleton consisting of the 5 metacarpals (or metacarpal bones ).
Going into the details of how the phalanges are distributed in the various fingers, it is necessary to report the following observations:
- For each finger of the hand, there is a phalanx directly connected to a specific metacarpus; the phalanx which, in the fingers of the hand, is joined to the metacarpus takes the name of the first phalanx ;
- In the index, middle, annular and little finger, there are, for each one, a phalanx immediately after the first phalanx, called the second phalanx or middle phalanx, and a phalanx immediately following the just mentioned intermediate phalanx, called the third phalanx ;
- In the thumb, the phalanx count ends with the phalanx immediately following the first phalanx, then with the second phalanx.
JOINTS
Between each phalanx and between the first phalanx and the corresponding metacarpus there is a joint; this articulation serves not only to connect the various bone elements involved, but also to guarantee its characteristic mobility.
In all 14, the joints of the fingers of the hand are equipped with a joint capsule and a set of ligaments (including the cruciform ligaments and collateral ligaments), whose task is to contribute to the mobile union between the phalanges and between the phalanges and the pasterns .
- The articulation present between each first phalanx of a finger of the hand and the corresponding metacarpus is called metacarpophalangeal joint ;
- The joint which, in each finger of the hand, connects the first phalanx to the second phalanx is called the proximal interphalangeal joint ;
- The joint that, in each finger of the hand, joins the second phalanx to the third phalanx is better known as the distal interphalangeal joint .
Without the joints present between the various phalanges, the human being could not move the fingers of the hand and this would compromise any precision activity, the taking of objects, etc.
Tendons
A tendon is a band of fibrous connective tissue, with a certain flexibility and a high content of collagen, which combines a skeletal muscle with a bone.
The bones of the fingers of the hand guarantee the insertion to the tendon of the terminal head of numerous muscles of the hand .
More specifically, the phalanges welcome the tendon of the terminal head of the hand muscles known as:
- Common extender of fingers . This muscle ends its path, in part, on the second phalanges and, in part, on the third phalanges of the index, middle, annular and little finger;
- Extender of the index . This muscle concludes its path, in part, on the second phalanx and, in part, on the third phalanx of the index;
- Extender precisely of the minimum finger (or little finger) . This muscle is inserted, in part, on the second phalanx and, in part, on the third phalanx of the little finger;
- Short extender of the thumb . This muscle ends its course on the first phalanx of the thumb;
- Long thumb extender . This muscle concludes its path on the second phalanx of the thumb;
- Hand finger flexors . There are a total of 8 and they are subdivided into superficial and deep. The superficial ones terminate on the second phalanges of the fingers (excluding thumb); the deep ones, instead, end on the third phalanges of the fingers (excluding thumb);
- Muscles of the tenar eminence known as: short abductor of the thumb (first phalanx of the thumb), short flexor of the thumb (first phalanx of the thumb) and adductor of the thumb (first phalanx of the thumb);
- Hypenenar eminence muscles known as: abductor of the minimum finger (first phalanx of the little finger) and flexor of the minimum finger (first phalanx of the little finger);
- Voloss interosseous (or palmar) and dorsal muscles of the hand . Both these classes of muscles end their path on the first phalanx (clearly in distinct areas) of the index, middle and ring fingers.
Blood vessels
CIRCULATION OF ARTERIAL BLOOD
The flow of oxygenated blood along the fingers of the hand is due to a series of arterial branches, which originate from the so-called deep palmar arch and superficial palmar arch, and, still before, from the radial artery and from the ulnar artery ; these branches include: the main artery of the thumb, the digital palmar arteries and the digital dorsal arteries .
VENOUS BLOOD CIRCULATION
On the other hand, digitalis palmar veins, dorsal digital veins and intercapitular veins are concerned with the drainage of oxygen-poor blood from the fingers of the hand; constituting a very complex vascular network, these venous vessels discharge the blood which must return to the heart in the superficial palmar venous arch and in the dorsal venous arch, which arches communicate with the veins of the ulnar, cephalic and basilic arm .
innervation
The innervation of the fingers of the hand belongs to the sensory and motor branches of 3 important nerves originating from the so-called brachial plexus; specifically, these 3 important nerves are: the ulnar nerve, the median nerve and the radial nerve .
Functions
The fingers of the hand are fundamental to the hand itself, in order to perform its functions, which are:
- Grab the items . In this regard, it is worth re-examining the two types of gripping possible, namely precision gripping and power take-off .
- Accuracy is when an individual holds an object in his hand using his thumb and another or two other fingers; the thumb performs an abduction movement, while the other or other fingers involved perform a flexing movement. In the precision grip, the palmar surfaces of the fingers of the hand used "look at each other".
The power takeover, however, is when an individual grabs an object using all the fingers and the palm of the hand; the thumb, as well as the palm, serve above all to give stability to the handle. In the grip, there is almost total involvement of the hand muscles.
- Act as a tactile sense organ . The skin sensitivity with which the hand is equipped, especially fingers, makes it possible to establish whether an object is hot or cold; if it is rough or smooth; etc.
- Act as a communication tool . Thanks to the fingers of the hand, the human being can effectively translate the spoken language into signs and gestures. In this regard, think of the so-called "sign language", used for communication with the deaf-mutes: in these circumstances, the fingers of the hand and the hand in general become a real communicative tool.
- To guarantee stability to the human being, when, at an early age, he still walks on 4 legs .
diseases
The fingers of the hand may be subject to various medical conditions, including: skin wounds, fractures of one or more phalanges, burns, nail diseases, cutaneous warts, synovial cysts (or tendon cysts), carpal tunnel syndrome, the phenomenon Raynaud's disease, Dupuytren's disease, De Quervain's syndrome, hand osteoarthritis, rheumatoid arthritis, etc.
Cutaneous wounds to the fingers
The cutaneous wounds on the fingers of the hand are, generally, the result of cuts resulting from the improper use of a knife, scissors or some instrument aimed at the so-called "do-it-yourself jobs".
Phalangeal fracture
The fracture of one or more phalanges of the hand is usually the result of a strong trauma to the fingers.
People who play sports such as, for example, rugby, volleyball, basketball and American football, and those who carry out heavy work and work with their hands suffer the most from the fracture of the phalanges of the fingers. (ex: construction workers, porters, warehouse workers, etc.).
Burns borne by the fingers of the hand
Burns affecting the fingers of the hand are injuries whose severity varies according to the area of interest and the layers of skin involved in the triggering factor.
Burns on the fingers of the hand are common in the home.
Nail Diseases
Some examples of nail diseases are: onycholysis, onycho-cryptosis, onycho-dystrophy, onychophagia, paronychia, onimicosis and ononic acid.
Cutaneous warts on the fingers
The cutaneous warts are benign growths, with yellow-greyish shades and spherical or oval, which, as far as the fingers of the hand are concerned, is usually formed near the nails.
Synovial Cysts on the Fingers of the Hand
Also known as tendon cysts, synovial cysts are fluid-filled swellings, of more variable dimensions, which grow close to tendons (to be precise on so-called tendon sheaths) or synovial joints (to be precise at the level of the joint capsule of synovial joints).
Synovial cysts can affect any tendon or synovial joint in the human body, including tendons and synovial joints of the fingers of the hand.
Carpal Tunnel Syndrome
Carpal tunnel syndrome is the set of symptoms and signs that occurs after compression of the median nerve at the wrist, exactly where the so-called transverse carpal ligament is located.
Carpal tunnel syndrome causes pain, sometimes associated with soreness, affecting the thumb, forefinger, middle finger and part of the ring finger.
Raynaud's phenomenon
Raynaud's phenomenon is the particular vascular event, whereby, due to an excessive spasm of the peripheral blood vessels, there is a reduction in the blood supply to: fingers and toes, tip of the nose, ear lobes and tongue.
The appearance of Raynaud's phenomenon is associated with pain at the anatomical parts involved, a pain that can sometimes be very intense.
Dupuytren's disease
Dupuytren 's disease is a disease of the hand, which causes permanent flexion (or curvature) (in the absence of adequate care) of one or more fingers towards the palm.
Dupuytren's disease can affect one or both hands simultaneously and can affect any finger, including the thumb.
De Quervain syndrome
Also known as De Quervain's stenosing tenosynovitis, De Quervain syndrome is the painful condition, resulting from the irritation of the synovial sheath that wraps the tendons of the abductor muscles long and short extensor of the thumb.
Sufferers of De Quervain syndrome experience a characteristic pain at the base of the thumb.
Arthrosis of the Hands
Osteoarthritis of the hands is the chronic inflammation of the interphalangeal joint of the fingers, which appears following the irreversible degeneration of the so-called articular cartilage and the consequent rubbing between the adjacent phalanges involved.
Rheumatoid Arthritis in the Hand
Rheumatoid arthritis is the chronic inflammation of the joint capsule of the synovial joints, which, over time, also affects the other elements of the joint involved (ligaments, synovial bags, etc.).
Rheumatoid arthritis can affect any joint in the human body that has a joint capsule, and therefore also the joints of the fingers of the hand.
