Editing Phalanx bone (section)

==Structure==
[[File:Hand-bones.jpg|thumbnail|The phalanges in a human hand]]
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Toe bones or phalanges of the foot. Note the big toe has no middle phalanx. {{break}}People vary; sometimes the smallest toe also has none (not shown).<ref name="eval&manage">{{cite journal |last1=Hatch |first1=RL |last2=Hacking |first2=S |title=Evaluation and management of toe fractures. |journal=American Family Physician |date=15 December 2003 |volume=68 |issue=12 |pages=2413–8 |pmid=14705761 |url=https://www.aafp.org/afp/2003/1215/p2413.html}}</ref>
{{legend|red|[[Distal phalanges]] of the foot}}
{{legend|yellow|[[Middle phalanges]] of the foot}}
{{legend|lime|[[Proximal phalanges]] of the foot}}
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The phalanges are the bones that make up the fingers of the hand and the toes of the foot. There are 56 phalanges in the human body, with fourteen on each hand and foot. Three phalanges are present on each finger and toe, with the exception of the [[thumb]] and [[hallux|big toe]], which possess only two. The middle and far phalanges of the {{citation needed span|fourth and|date=November 2021}} fifth toes are often fused together (symphalangism).<ref name="eval&manage"/><ref>{{cite journal |last1=Moulton |first1=Lawrence Stephen |last2=Prasad |first2=Seema |last3=Lamb |first3=Robert G. |last4=Sirikonda |first4=Siva P. |title=How many joints does the 5th toe have? A review of 606 patients of 655 foot radiographs |journal=Foot and Ankle Surgery|date=December 2012 |volume=18 |issue=4 |pages=263–265 |doi=10.1016/j.fas.2012.04.003 |pmid=23093121 |url=https://pubmed.ncbi.nlm.nih.gov/23093121/ |issn=1460-9584}}</ref> The phalanges of the [[hand]] are commonly known as the finger bones. The phalanges of the foot differ from the hand in that they are often shorter and more compressed, especially in the proximal phalanges, those closest to the torso.<ref name=White2011>{{Cite book|last1=White|first1=Tim|last2=Black|first2=Michael|last3=Folkens|first3=Pieter|url=https://www.elsevier.com/books/human-osteology/white/978-0-08-092085-6|title=Human Osteology|publisher=[[Academic Press]]|year=2011|isbn=978-0-080-92085-6|edition=3|page=292|language=en|chapter=13 - Foot: Tarsals, Metatarsals, and Phalanges}}</ref>

A phalanx is named according to whether it is [[Anatomical terms of location#Proximal|proximal]], middle, or [[anatomical terms of location#distal|distal]] and its associated finger or toe. The proximal phalanges are those that are closest to the hand or foot. In the hand, the prominent, knobby ends of the phalanges are known as [[knuckle]]s. The proximal phalanges join with the [[metacarpal]]s of the hand or [[metatarsal]]s of the foot at the [[metacarpophalangeal joint]] or [[metatarsophalangeal joint]]. The intermediate phalanx is not only intermediate in location, but usually also in size. The thumb and large toe do not possess a middle phalanx. The distal phalanges are the bones at the tips of the fingers or toes. The proximal, intermediate, and distal phalanges articulate with one another through [[interphalangeal joints of hand]] and [[interphalangeal joints of the foot]].<ref name=GRAYS2005>{{cite book |last1=Drake |first1=Richard L. |last2=Vogl |first2=Wayne |last3=Tibbitts |first3=Adam W. M. |others=Illustrations by Richard Mitchell and Paul Richardson |year=2005 |title=Gray's Anatomy for Students |publisher=Elsevier/Churchill Livingstone |location=Philadelphia |isbn=978-0-8089-2306-0}}</ref>{{rp|708–711}}{{rp|708–711}}

===Bone anatomy===
Each phalanx consists of a central part, called the ''body'', and two extremities.<ref name=Rollins2022>{{Cite book|last1=Rollins|first1=Jeannean|last2=Long|first2=Bruce|last3=Curtis|first3=Tammy|url=https://www.elsevier.com/books/merrill%27s-atlas-of-radiographic-positioning-and-procedures---3-volume-set/rollins/978-0-323-83279-3|title=Merrill's Atlas of Radiographic Positioning and Procedures - 3-Volume Set|publisher=[[Mosby (imprint)|Mosby]]|year=2022|isbn=978-0-323-83323-3|edition=15|page=147|language=en}}</ref>
* The ''body'' is flat on either side, concave on the palmar surface, and convex on the dorsal surface.<ref name=Singh2014>{{Cite book|last=Singh|first=Vishram|title=Textbook of Anatomy Upper Limb and Thorax; Volume 1|publisher=[[Elsevier Health Sciences]]|year=2014|isbn=978-8-131-23625-3|edition=2|page=32|language=en}}</ref> Its sides are marked with rough areas giving attachment to fibrous sheaths of flexor tendons. It tapers from above downwards.<ref name=Gray's2008>{{Cite book|last=Gray|first=Henry|url=https://www.abebooks.com/Grays-Anatomy-Carter-Henry-Arcturus-Publishing/31017006929/bd|title=Gray's Anatomy|publisher=Arcturus Publishing|year=2008|isbn=978-1-841-93958-2|pages=192–193|language=en}}</ref>
* The ''proximal extremities'' of the bones of the first row present oval, concave articular surfaces, broader from side to side than from front to back. The proximal extremity of each of the bones of the second and third rows presents a double concavity separated by a median ridge.<ref name=Gray's2008/>
* The ''distal extremities'' are smaller than the proximal, and each ends in two [[Condyle (anatomy)|condyles]] (knuckles) separated by a shallow groove; the articular surface extends farther on the palmar than on the dorsal surface, a condition best marked in the bones of the first row.<ref name=Gray's2008/>

In the foot, the proximal phalanges have a body that is compressed from side to side, convex above, and concave below. The base is concave, and the head presents a trochlear surface for articulation with the second phalanx.<ref name=Palastanga2013>{{Cite book|last1=Palastanga|first1=Nigel|last2=Field|first2=Derek |last3=Soames|first3=Roger|title=Anatomy and Human Movement: Structure and Function|publisher=[[Butterworth-Heinemann]]|year=2013|isbn=978-1-483-19274-1|page=336|language=en}}</ref> The middle are remarkably small and short, but rather broader than the proximal. The distal phalanges, as compared with the distal phalanges of the finger, are smaller and are flattened from above downward; each presents a broad base for articulation with the corresponding bone of the second row, and an expanded distal extremity for the support of the nail and end of the toe.<ref name=Iannotti2013>{{Cite book|last1=Iannotti|first1=Joseph|last2=Parker|first2=Richard|url=https://www.elsevier.com/books/the-netter-collection-of-medical-illustrations-musculoskeletal-system-volume-6-part-ii---spine-and-lower-limb/978-1-4160-6382-7|title=The Netter Collection of Medical Illustrations: Musculoskeletal System, Volume 6, Part II - Spine and Lower Limb|publisher=[[Elsevier Health Sciences]]|year=2013|isbn=978-1-416-06382-7|edition=2|page=206|language=en}}</ref>

====Distal phalanx====
In the hand, the distal phalanges are flat on their palmar surface, small, and with a roughened, elevated surface of horseshoe form on the palmar surface, supporting the finger pulp.<ref name=GRAYS1918>{{cite book |last=Gray |first=Henry |title=Anatomy of the Human Body |year=1918 |url=https://archive.org/details/anatomyofhumanbo1985gray |isbn=0-8121-0644-X |url-access=registration }}</ref>{{rp|6b. 3. The Phalanges of the Hand}} The flat, wide expansions found at the tips of the distal phalanges are called "apical tufts". They support the fingertip pads and nails.<ref name="CARTA">{{cite web |title=Apical Phalangeal Tufts |publisher=Center for Academic Research & Training in Anthropogeny |url=http://carta.anthropogeny.org/moca/topics/apical-phalangeal-tufts |access-date=January 28, 2017 |quote=The tufts support the fleshy volar pad (also known as the distal pulp) on the palmar (volar) surface of the finger, as well as the nail on the dorsal surface.}}</ref> The phalanx of the thumb has a pronounced insertion for the [[Flexor pollicis longus muscle|flexor pollicis longus]] (asymmetric towards the radial side), an ungual fossa, and a pair of unequal ungual spines (the ulnar being more prominent). This asymmetry is necessary to ensure that the thumb pulp is always facing the pulps of the other digits, an osteological configuration which provides the maximum contact surface with held objects.<ref name="PLOS-2010" />

In the foot, the distal phalanges are flat on their dorsal surface. It is largest proximally and tapers to the distal end. The proximal part of the phalanx presents a broad base for articulation with the middle phalanx, and an expanded distal extremity for the support of the nail and end of the toe.<ref name=GRAYS1918 />{{rp|6b. 3. The Phalanges of the Foot}} The phalanx ends in a crescent-shaped rough cap of bone [[epiphysis]]&nbsp;— the apical tuft (or ungual tuberosity/process) which covers a larger portion of the phalanx on the volar side than on the dorsal side. Two lateral ungual spines project proximally from the apical tuft. Near the base of the shaft are two lateral tubercles. Between these a V-shaped ridge extending proximally serves for the insertion of the [[Flexor pollicis longus muscle|flexor pollicis longus]]. Another ridge at the base serves for the insertion of the extensor [[aponeurosis]].<ref name="Shrewsbury-Johnson-1975">{{harvnb|Shrewsbury|Johnson|1975| p=784}}</ref> The flexor insertion is sided by two [[Fossa (anatomy)|fossa]]e&nbsp;— the ungual fossa distally and the proximopalmar fossa proximally.

===Development===
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. For example, humans have a 2-3-3-3-3 formula for the [[hand]], meaning that the thumb has two phalanges, whilst the other fingers each have three.

In the distal phalanges of the hand the centres for the bodies appear at the distal extremities of the phalanges, instead of at the middle of the bodies, as in the other phalanges. Moreover, of all the bones of the hand, the distal phalanges are the first to ossify.<ref name=GRAYS1918 />{{rp|6b. 3. The Phalanges of the Hand}}