HAND PHALANGES

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.

Each proximal phalanx consists of three parts:

• The base, which represents the expanded proximal part. It has a concave, oval-shaped articular facet that articulates with the metacarpal head to form the metacarpophalangeal (MCP) joint. The base also contains nonarticular tubercles for the attachment of various soft tissue structures.
• The body, which continues distally from the base. It tapers distally and has two surfaces: dorsal and palmar. The dorsal surface is round and smooth, appearing convex in the transverse plane. The palmar surface is flat and rough, especially on the sides where the flexor fibrous sheaths of digits attach. The surface appears flat in the transverse plane but concave in the sagittal plane.
• The head, which represents the expanded and rounded distal part. It has a pulley-shaped articular surface that articulates with the base of the middle phalanx to form the proximal interphalangeal (PIP) joint. The heads consist of smooth grooves, especially on the palmar aspects. These grooves represent the attachment points of the collateral interphalangeal ligaments of hand.

Various ligaments attach to the proximal phalanges. The most complex one is the digital fascial complex which attaches the surrounding subcutaneous tissue and neurovasculature to the bony phalanges. The collateral and palmar metacarpophalangeal ligaments attach to the bases of the proximal phalanges. They provide strength to the metacarpophalangeal joints. The collateral interphalangeal ligaments of hand attach to the heads, supporting the PIP joints. The proximal phalanges are also covered by the extensor expansion of hand on the dorsal aspect.

The proximal phalanges are very mobile at the MCP joints. They are mainly capable of flexion, extension, adduction and abduction. Circumduction and rotation are also possible, especially at the MCP joint of the thumb. These movements are enabled by the action of several muscles:

• Posterior (extensor) forearm muscles, such as extensor digitorum, extensor pollicis brevis, extensor digiti minimi and extensor indicis.
• Metacarpal muscles, such as the lumbricals, palmar interossei and dorsal interossei.
• Thenar muscles, for example flexor pollicis brevis and adductor pollicis.
• Hypothenar muscles like abductor digiti minimi and flexor digiti minimi.

These muscles carry out their functions via their direct attachments to the bases of the proximal phalanges. In addition, many extensors carry out the movements via the extensor expansion of hand which covers the phalanges

Middle phalanges

There are four middle (intermediate) phalanges in each hand because the thumb is missing one. They have a similar structure to the proximal ones, consisting of a base, body and head. The base of each middle phalanx has two concave-shaped articular facets and matches the head of the corresponding proximal phalanx. Their apposition forms the PIP joint. The heads of the middle phalanges have a pulley-like appearance. They articulate with the bases of the distal phalanges to form the distal interphalangeal (DIP) joints of hand.

The middle phalanges are reinforced by the same ligaments supporting the proximal ones, digital fascial complex, collateral interphalangeal ligaments and extensor expansion of hand. The collateral interphalangeal ligaments attach to the base and heads of the middle phalanges to reinforce the PIP and DIP joints.

The middle phalanges are less mobile compared to the proximal phalanges. They are only capable of flexion and extension at the PIP joints. Only the flexor digitorum superficialis muscle attaches directly to the sides of the middle phalanges, flexing them at the PIP joints. The remaining contributions are provided by the action of the previously mentioned muscles; the forearm extensors, metacarpal, thenar and hypothenar muscle groups. Flexion and extension are transferred to the middle phalanges from the direct action of these muscles on the proximal phalanges or via the extensor expansion of hand.

Distal phalanges

Each hand has five distal phalanges, which look shorter and slightly thicker compared to the previous two sets. Each distal phalanx has a base, body and head. The base has a double articular facet which matches the shape of the head of the middle phalanx. The distal phalanges have a smooth and round dorsal surface. In contrast, their palmar surface is wrinkled and irregular. The nonarticular heads contain an irregular, curved shaped distal tuberosity. It serves as an anchor point for the pulps of the digits.

The distal phalanges are stabilized by the digital fascial complex, collateral interphalangeal ligaments and extensor expansion of hand. The collateral interphalangeal ligaments attach to the base of the distal phalanges to reinforce the DIP joints.

The distal phalanges are capable of flexion and extension at the DIP joints. Two forearm extensors and one flexor muscle insert directly into the bases of the distal phalanges, permitting these actions. These include flexor digitorum profundus, flexor pollicis longus and extensor pollicis longus. The previously mentioned muscle groups acting on the proximal and middle phalanges also act indirectly on the distal ones via the extensor expansion of hand.

BLOOD SUPPLY

The hand phalanges are richly supplied with blood, lymphatics, and nerves, and their development involves a precise pattern of ossification. The blood supply to the phalanges comes primarily from the digital arteries, which are branches of the superficial and deep palmar arches derived from the radial and ulnar arteries. These arteries run alongside the phalanges, especially near the lateral aspects, where they give off perforating branches that penetrate the bone through nutrient foramina. Venous drainage mirrors the arterial supply, with the digital veins draining into the superficial and deep venous systems of the hand. The lymphatic drainage follows the venous pathways, with lymphatic vessels accompanying the digital veins. These vessels drain into the epitrochlear and axillary lymph nodes, playing a crucial role in immune surveillance and fluid balance in the hand.

NERVOUS SUPPLY

The nervous supply of the phalanges is derived from the median, ulnar, and radial nerves, which innervate the hand based on their anatomical distribution. The median nerve supplies the palmar side of the first three and a half fingers and their corresponding phalanges, while the ulnar nerve supplies the remaining fingers. The radial nerve provides sensation to the dorsal aspect of the phalanges, primarily for the proximal portions of the first three fingers. These nerves are responsible for transmitting sensory information, including pain, touch, and temperature, and they also play a critical role in motor function by innervating the muscles controlling finger movement.

OSSIFICATION

Ossification of the hand phalanges follows a well-defined sequence. Each phalanx typically ossifies from one primary ossification center, which appears during fetal development, generally between the 8th and 12th weeks of gestation. A secondary ossification center forms at the base of the phalanx during early childhood, usually between 2 and 4 years of age, depending on the specific phalanx and its position in the hand. The fusion of the primary and secondary ossification centers, marking skeletal maturity, occurs by 15–18 years of age. The ossification sequence begins with the proximal phalanges, followed by the middle and distal phalanges. This progression is vital for assessing growth and development in pediatric radiology and clinical evaluations.

Evolution of Human Anatomy

The human anatomy studies to explore it began from B.C. and it still continues to explore and discover more and more...

Over the years many inventions, discoveries where seen and studied but when all these started no proper tools, machines where there but yet we humans still did!

Let us being with whom and when the exploration begin...:

1. Greek Period (B.C.)

    a. Hippocrates of Cos (circa 400 B.C.), the 'Father of Medicine', is regarded as one of the founders of anatomy. 

He had two theories in his ancient school of Greek Medicine, first was Knidian which was also known as School of Medicine which mainly focused on diagnosis. The other was Koan that mainly applied general diagnosis and passive treatment, also it focused on patient care, prognosis and not on the diagnosis. 

    b. Herophilus of Chalcedon (circa 300 B.C.), is called 'Father of Anatomy'. He was a Greek physician and was one of the first to dissect the Human Body. He distinguished cerebrum from cerebellum, nerves from tendons, arteries from veins, motor from sensory nerves, described various parts of eye, meninges, torcular Herophili, fourth ventricle with calamus scriptorius, hyoid bone, duodenum, prostrate gland, etc. He was a successful teacher and wrote a book on anatomy, A special treatise of the eyes. 

2. Roman Period (A.D.)

Galen of Pergamum (Circa 130-200 A.D.) was also known as 'The Prince of Physicians', practised medicine at Rome. He wrote on many medical subjects like anatomy, physiology, pathology, symptomalogy and treatment. He wrote on anatomy "De anatomicis-administrationibus", his teachings were followed nearly 15 centuries 

3. Fourteenth Century:

Mundinus or Mondino d'Luzzi (1276-1326) alao known as the "restorer of anatomy", was an Italian anatomistand professor at University of Bologna. He wrote a book named as Anathomia, after his death, Mondino was regarded as a "divine master" to such an extent that anything differing from the descriptions in his book was regarded as anomalous or even monstrous.

4. Fifteenth Century:

Leonardo di Vinci of Italy (1452-1519) had originated the cross sectional anatomy, also was one of the greatest geniuses the world has ever known. He made the observations that humours were not located in cerebral spaces or ventricles. He documented that the humours were not contained in the heart or the liver, and that it was the heart that defined the circulatory system. He was the first to define atherosclerosis and liver cirrhosis. He created models of the cerebral ventricles with the use of melted wax and constructed a glass aorta to observe the circulation of blood through the aortic valve by using water and grass seed to watch flow patterns. The drawing of his where created by his observation on dissection named as Treatise on painting.

5. Sixteenth Century:

Vesalius (1514-1564), also known as 'Reformer of Anatomy', was a professor at Padua. He challenged traditional anatomy by applying empirical methods of cadaveric dissection to the study of the human body by Galen thus reviving anatomy after a deadlock of about 15 centuries. His anatomical treatise De Febricia Humani Corporis, written in 7 volumes, revolutionized the anatomy which remained for 2 centuries. 

6. Seventeenth Century:
William Harvey (1578-1657) was an English physician who discovered the blood circulation. His has wrote and published it as Anatomical Exercise on the Motion of the Heart and Blood in Animals, The Works of William Harvey & The Circulation of the Blood and other writings. 

7. Eighteenth Century: 

William Hunter (1718-1783) was a London anatomist and obstetrician. His greatest work was Anatomia uteri umani gravidi. He and his brother founded Hunterian Museum. 

8. Nineteenth Century:

Dissection was mandatory for medical students. Formalin was used as a fixative in 1890s.

Roentgen discovered X-rays in 1895.

Various types of Endoscopes were devised between 1819 and 1899.

Few remarkable anatomists during this century were Ashley Cooper (British Surgeon), Cuvier (French Naturalist), Meckel (German Anatomist) and Henry Gray (wrote Gray's Anatomy).

9. Twentieth Century:

Electron Microscope was invented and also its various modificationsof itswere also devised like transmission EM & SEM, etc.

Ultrasonography & echocardiography were discovered. 

CT - Scan and MRI were devised.

Tissue culture was developed. 

Infertility was discovered, which gave hopes to families Gamete Intrafallopian Transfer (GIFT) was started. 

10. Twenty First Century:

Foetal medicine and 'in-utero' treatments are emerging.

Many vaccines are researched for various diseases including COVID 19.

by Dr. Palak Shah