Phalanx bones
Encyclopedia
In anatomy
Anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...

, phalanx bone
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...

s (plural phalanges) are those that form the finger
Finger
A finger is a limb of the human body and a type of digit, an organ of manipulation and sensation found in the hands of humans and other primates....

s and toe
Toe
Toes are the digits of the foot of a tetrapod. Animal species such as cats that walk on their toes are described as being digitigrade. Humans, and other animals that walk on the soles of their feet, are described as being plantigrade; unguligrade animals are those that walk on hooves at the tips of...

s. In primate
Primate
A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...

s such as human
Human
Humans are the only living species in the Homo genus...

s and monkey
Monkey
A monkey is a primate, either an Old World monkey or a New World monkey. There are about 260 known living species of monkey. Many are arboreal, although there are species that live primarily on the ground, such as baboons. Monkeys are generally considered to be intelligent. Unlike apes, monkeys...

s, the thumb
Thumb
The thumb is the first digit of the hand. When a person is standing in the medical anatomical position , the thumb is the lateral-most digit...

 and big toe have two phalanges, while the other fingers and toes consist of three. Phalanges are classified as long bone
Long bone
The long bones are those that are longer than they are wide. They are one of five types of bones: long, short, flat, irregular and sesamoid. Long bones, especially the femur and tibia, are subjected to most of the load during daily activities and they are crucial for skeletal mobility. They grow...

s.

The phalanges do not have individual names. They are named for the digit they represent and their relative location from the center of the body (proximal or distal).
  • Proximal phalanges
    Proximal phalanges
    Proximal phalanges are bones found in the limbs of most vertebrates. In humans, they are the bones at the base of a toe or finger, the prominent, knobby ends of which are often called the knuckles....

     are closest to the main part of the hand
    Hand
    A hand is a prehensile, multi-fingered extremity located at the end of an arm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs...

     or foot
    Foot
    The foot is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made up of one or more segments or bones, generally including claws...

     and articulate with the metacarpals of the hand or metatarsals of the foot.
  • Middle or intermediate phalanges
    Intermediate phalanges
    Intermediate phalanges are bones found in the limbs of most vertebrates. In humans, they are the bones of the finger and toe which lie in the middle, between the two wrinkly joints. The thumb and big toe do not have intermediate phalanges...

     are between the distal and proximal. The thumb and big toe do not have middle phalanges.
  • Distal phalanges
    Distal phalanges
    The distal or terminal phalanges are the terminal limb bones located at the tip of the digits...

     are at the tips of the fingers and toes.


The term phalanx or phalanges refers to an ancient Greek army formation
Phalanx formation
The phalanx is a rectangular mass military formation, usually composed entirely of heavy infantry armed with spears, pikes, sarissas, or similar weapons...

 in which soldiers stand side by side, several rows deep, like an arrangement of fingers or toes.

Phalangeal formula

The number of phalanges in animals is often expressed as a "phalangeal formula" that indicates the numbers of phalanges in digits, beginning from the innermost (medial or proximal).

Most land mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s including humans have a 2-3-3-3-3 formula in both the hand
Hand
A hand is a prehensile, multi-fingered extremity located at the end of an arm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs...

s (or paw
Paw
A paw is the soft foot of a mammal, generally a quadruped, that has claws or nails. A hard foot is called a hoof. Paws are used to pad feet for walking and increase friction.- Common characteristics :...

s) and feet. Primitive reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...

s typically had the formula 2-3-4-4-5, and this pattern, with some modification, remained in many later reptiles and in the mammal-like reptiles. The phalangeal formula in the flippers
Flipper (anatomy)
A flipper is a typically flat limb evolved for movement through water. Various creatures have evolved flippers, for example penguins , cetaceans A flipper is a typically flat limb evolved for movement through water. Various creatures have evolved flippers, for example penguins (also called...

 of cetacea
Cetacea
The order Cetacea includes the marine mammals commonly known as whales, dolphins, and porpoises. Cetus is Latin and is used in biological names to mean "whale"; its original meaning, "large sea animal", was more general. It comes from Ancient Greek , meaning "whale" or "any huge fish or sea...

ns (marine mammals) is 2-12-8-1.
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