Supernumerary body parts are most commonly a

congenital disorder A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities ca ...

involving the growth of an additional part of the

body Body may refer to: In science * Physical body, an object in physics that represents a large amount, has mass or takes up space * Body (biology), the physical material of an organism * Body plan, the physical features shared by a group of anima ...

and a deviation from the

body plan A body plan, ( ), or ground plan is a set of morphological features common to many members of a phylum of animals. The vertebrates share one body plan, while invertebrates have many. This term, usually applied to animals, envisages a "blueprin ...

. Body parts may be easily visible or hidden away, such as

internal organ In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a f ...

s. Many additional body parts form by the same process as

conjoined twins Conjoined twins – sometimes popularly referred to as Siamese twins – are twins joined ''Uterus, in utero''. A very rare phenomenon, the occurrence is estimated to range from 1 in 49,000 births to 1 in 189,000 births, with a somewhat higher in ...

: the

zygote A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism. In multicell ...

begins to split but fails to completely separate. This condition may also be a symptom of repeated occurrences of continuous

inbreeding Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and o ...

in a genetic line.

Specific types of occurrence

Specific types of additional body parts include: *

Accessory breast Accessory breasts, also known as polymastia, supernumerary breasts, or ''mammae erraticae'', is the condition of having an additional breast. Extra breasts may appear with or without nipples or areolae. It is a condition and a form of atavism w ...

– one or more additional breastsOnline Mendelian Inheritance in Man.
Nipples, Supernumerary
. Accessed 10 July 2006. * Accessory spleen – one or more additional spleens *

Cervical rib A cervical rib in humans is an extra rib which arises from the seventh cervical vertebra. Their presence is a congenital abnormality located above the normal first rib. A cervical rib is estimated to occur in 0.2% to 0.5% (1 in 200 to 500) of th ...

– an additional rib *

Diphallia Diphallia, penile duplication (PD), diphallic terata, or diphallasparatus, is an extremely rare developmental abnormality in which a male is born with two penises. The first reported case was by Johannes Jacob Wecker in 1609. Its occurrence is 1 ...

– having two penes/penises *

Hermaphroditism In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have s ...

– having both male and female sex organs *

Hyperdontia Hyperdontia is the condition of having supernumerary teeth, or teeth that appear in addition to the regular number of teeth (32 in the average adult). They can appear in any area of the dental arch and can affect any dental organ. The opposite ...

– additional teeth * Pelvic digit – a bony growth in the soft tissue of the pelvic region *

Polycephaly Polycephaly is the condition of having more than one head. The term is derived from the Greek stems ''poly'' (Greek: "πολύ") meaning "many" and ''kephalē'' (Greek: "κεφαλή") meaning "head". A polycephalic organism may be thought o ...

– an extra head *

Polydactyly Polydactyly or polydactylism (), also known as hyperdactyly, is an anomaly in humans and animals resulting in supernumerary fingers and/or toes. Polydactyly is the opposite of oligodactyly (fewer fingers or toes). Signs and symptoms In human ...

– additional fingers or toesPenn State Milton S. Hershey Medical Center A-Z.
Polydactyly and Syndactyly
Accessed 10 July 2006. *

Polymelia Polymelia is a birth defect in which an affected individual has more than the usual number of limbs. It is a type of dysmelia. In humans and most land-dwelling vertebrates, this means having five or more limbs. The extra limb is most commonly shr ...

– an extra arm or leg * Polyorchidism – having three or more testicles * Supernumerary bones – these additional bones are fairly common, particularly in the feet, and are frequently mistaken for fractures on x-rays. * Supernumerary kidney – a third kidney * Supernumerary musculature – presence of extra muscles such as additional heads of the biceps brachii, or coracobrachialis muscle variants * Supernumerary nipples – an additional nipple * Supernumerary phantom limbs – where the brain acts as though a limb were there, but it is not *

Syndactyly Syndactyly is a condition wherein two or more digits are fused together. It occurs normally in some mammals, such as the siamang and diprotodontia, but is an unusual condition in humans. The term is from Greek σύν, ''syn'' 'together' and δά� ...

– webbing between the fingers or toes *

Uterus didelphys Uterus didelphys (sometimes also ''uterus didelphis'') represents a uterine malformation where the uterus is present as a paired organ when the embryogenetic fusion of the Müllerian ducts fails to occur. As a result, there is a double uterus wi ...

– two vaginal canals and/or uteri

Related conditions and concepts

Vestigial structures Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...

are anatomical structures of

organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...

s in a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

which are considered to have lost much or all of their original function through

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

. These body parts can be classed as additional to the required functioning of the body. In human anatomy the

vermiform appendix The appendix (or vermiform appendix; also cecal r caecalappendix; vermix; or vermiform process) is a finger-like, blind-ended tube connected to the cecum, from which it develops in the embryo. The cecum is a pouch-like structure of the large ...

is sometimes classed as a vestigial remnant. Prosthesis is an artificial extension that replaces a body part, and cybernetics is the study of computer technology in relation to organisms which can include replacement or additional body parts.

Body integrity identity disorder Body integrity dysphoria (BID, also referred to as body integrity identity disorder, amputee identity disorder and xenomelia, formerly called apotemnophilia) is a mental disorder characterized by a desire to have a sensory or physical disabil ...

(BIID) is a

psychiatric disorder A mental disorder, also referred to as a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitt ...

in which a person thinks that they have one or more additional

limb Limb may refer to: Science and technology *Limb (anatomy), an appendage of a human or animal *Limb, a large or main branch of a tree *Limb, in astronomy, the curved edge of the apparent disk of a celestial body, e.g. lunar limb *Limb, in botany, ...

s than they should, despite having two arms and two legs. People with this condition often wish to

amputate Amputation is the removal of a limb by trauma, medical illness, or surgery. As a surgical measure, it is used to control pain or a disease process in the affected limb, such as malignancy or gangrene. In some cases, it is carried out on indi ...

what they see as additional body parts. A

phantom limb A phantom limb is the sensation that an amputated or missing limb is still attached. Approximately 80 to 100% of individuals with an amputation experience sensations in their amputated limb. However, only a small percentage will experience pain ...

is the sensation that a missing limb is still attached to the body. A supernumerary phantom limb is the sensation of having an extra limb or body part despite no such limb actually existing. It is an uncommon syndrome, usually due to some kind of brain injuries in the

somatosensory cortex In physiology, the somatosensory system is the network of neural structures in the brain and body that produce the perception of touch ( haptic perception), as well as temperature (thermoception), body position (proprioception), and pain. It i ...

or in some parts of the right hemisphere of the brain, usually due to a stroke in the brain. A

chimera Chimera, Chimaera, or Chimaira (Greek for " she-goat") originally referred to: * Chimera (mythology), a fire-breathing monster of Ancient Lycia said to combine parts from multiple animals * Mount Chimaera, a fire-spewing region of Lycia or Cilici ...

is an

animal Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclu ...

that has two or more different populations of genetically distinct cells that originated in different

s that have merged; anatomical structures are typically mixed depending on which cells are prevalent in different body parts, for example plants can have two different types of flowers. A mosaic is a genetic anomaly similar in nature and effects to a chimera: genetically different populations of cells within one organism, originated from some propagated mutation of a single cell rather than from outside sources.

Mythology

In Hindu mythology, additional limbs and heads are considered a sign of power. In Greek mythology,

Artemis In ancient Greek mythology and religion, Artemis (; grc-gre, Ἄρτεμις) is the goddess of the hunt, the wilderness, wild animals, nature, vegetation, childbirth, care of children, and chastity. She was heavily identified wit ...

, the goddess of fertility, was sometimes represented as having numerous breasts. This was particularly notable in the cult of Artemis ( Diana) celebrated in the ancient city of Ephesus, in modern Turkey. In Japanese mythology, the god of the sea and storms, Susanoo, is sometimes depicted as having a third arm. In Hungarian mythology, having six fingers on a hand (

polydactyly Polydactyly or polydactylism (), also known as hyperdactyly, is an anomaly in humans and animals resulting in supernumerary fingers and/or toes. Polydactyly is the opposite of oligodactyly (fewer fingers or toes). Signs and symptoms In human ...

) is held to be the sign of innate supernatural power (see

táltos The táltos (; also "tátos") is a figure in Hungarian mythology, a person with supernatural power similar to a shaman. Description The most reliable account of the táltos is given by Roman Catholic priest Arnold Ipolyi in his collection of fo ...

). In Christian mythology, Goliath has brothers who have six fingers and six toes.

References

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External links

Supernumerary Bones of the Foot
*

Specific types of occurrence

Related conditions and concepts

Mythology

See also

References

External links