Editing Appendicular skeleton

{{short description|Part of the skeletal system}}
{{Infobox anatomy
| Name      = Appendicular skeleton
| Latin     = skeleton appendiculare
| Image     = Appendicular skeleton diagram.svg
| Caption   = Human appendicular skeleton
| Image2    =
| Caption2  =
| Precursor =
| System    =
| Artery    =
| Vein      =
| Nerve     =
| Lymph     =
}}
The '''appendicular skeleton''' is the portion of the [[vertebrate]] [[endoskeleton]] consisting of the [[bone]]s, [[cartilage]]s and [[ligament]]s that support the [[bilateral symmetry|paired]] [[appendage]]s ([[fish fin|fin]]s, [[flipper (anatomy)|flipper]]s or [[limb (anatomy)|limb]]s). In most [[terrestrial animal|terrestrial]] vertebrates (except [[snake]]s, [[legless lizard]]s and [[caecillian]]s), the appendicular skeleton and the associated [[skeletal muscle]]s are the predominant [[animal locomotion|locomotive]] structures.

There are 126 [[bone]]s in the [[human]] appendicular skeleton, includes the skeletal elements within the [[shoulder girdle|shoulder]] and [[pelvic girdle]]s, [[upper limb|upper]] and [[lower limb]]s, and [[hand]]s and [[feet]].<ref>[http://www.britannica.com/EBchecked/topic/547371/skeleton/41994/Amphibians-and-higher-vertebrates Skeleton] ''Encyclopædia Britannica''. Updated 24 August 2014.</ref> These bones have shared ancestry (are [[homology (biology)|homologous]]) to those in the [[forelimb]]s and [[hindlimb]]s of all other [[tetrapod]]s, which are in turn homologous to the pectoral and pelvic fins in [[fish]].

==Etymology==
The [[adjective]] "appendicular" comes from [[Latin]] ''appendicula'', meaning "small addition".<ref>{{citeweb|url=https://www.etymonline.com/word/appendicular#etymonline_v_26432|title=Appendicular (adj.)|publisher=[[Online Etymology Dictionary]]|accessdate=2024-02-06}}</ref> It is the [[diminutive]] of ''appendix'', which comes from the [[prefix]] ''ad-'' (meaning "to") + and the [[word root]] ''pendere'' (meaning "to hang", from [[PIE root]] ''*(s)pen-''  meaning "to draw, stretch, spin").<ref>{{citeweb|url=https://www.etymonline.com/word/appendix|title=Appendix (n.)|publisher=[[Online Etymology Dictionary]]|accessdate=2024-02-06}}</ref>

==The organization of the appendicular system==
Of the 206 bones in the [[human skeleton]], the appendicular skeleton comprises 126. Functionally, it is involved in [[terrestrial locomotion]] and [[weight-bearing]] ([[lower limb]]s), and [[grasping]] and [[object manipulation]] ([[upper limb]]s).

The appendicular skeleton forms during development from [[cartilage]], by the process of [[endochondral ossification]].

The appendicular skeleton is divided into six major regions:

* [[Shoulder girdle]] (4 bones) - Left and right [[clavicle]] (2) and [[scapula]] (2).
* [[Arm]]s and [[forearm]]s (6 bones) - Left and right [[humerus]] (2) (arm), [[ulna]] (2) and [[radius (bone)|radius]] (2) (forearm).
* [[Hand]]s and [[wrist]]s (54 bones) - Left and right [[carpals]] (16) (wrist), [[metacarpals]] (10) ([[palm (anatomy)|palm]]), [[proximal phalanges]] (10), [[intermediate phalanges]] (8) and [[distal phalanges]] (10) ([[finger]]).
* [[Human pelvis|Pelvis]] (2 bones) - left and right [[hip bone]]s (2), each of which is actually a fusion of three bones ([[ilium (bone)|ilium]], [[ischium]] and [[pubis (bone)|pubis]]).
* [[Thigh]]s and [[leg]]s (8 bones) - Left and right [[femur]] (2) (thigh), [[patella]] (2) (knee), [[tibia]] (2) and [[fibula]] (2) (leg).
* [[Feet]] and [[ankle]]s (52 bones) - Left and right [[Tarsus (skeleton)|tarsals]] (14) (ankle), [[Metatarsal bones|metatarsals]] (10) (foot), [[proximal phalanges]](10), [[intermediate phalanges]] (8) and [[distal phalanges]] (10) ([[toe]]).

Through [[anatomical variation]], the appendicular skeleton may have an [[accessory bone]]. Examples include [[sesamoid]]s in the hands and feet. Some occurrences are rarer than others.

The 126 bones of the appendicular skeleton and the 80 bones of the [[axial skeleton]] together form the complete skeleton of 206 bones in the human body. Unlike the axial skeleton, the appendicular skeleton is made up of significantly more [[long bone]]s and predominantly [[joint|articulate]]d via [[synovial joint]]s, which allow for a much greater [[range of motion]].

==See also==
* [[Axial skeleton]]
* [[Lepidotrichia]], bony spines in [[ray-finned fish]] that are functional [[analogy (biology)|analogue]]s of appendicular skeleton.

==References==
{{Reflist}}

{{Commons category|Appendicular skeleton}}

{{Bones of skeleton}}
{{Authority control}}

[[Category:Appendicular skeleton| ]]
[[Category:Skeletal system]]