
The fibula (: fibulae or fibulas) or calf bone is a
leg
A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element cap ...
bone
A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...
on the
lateral
Lateral is a geometric term of location which may also refer to:
Biology and healthcare
* Lateral (anatomy), a term of location meaning "towards the side"
* Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx
* Lateral release ( ...
side of the
tibia
The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...
, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. Its upper extremity is small, placed toward the back of the
head of the tibia, below the
knee joint
In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the ...
and excluded from the formation of this joint. Its lower extremity inclines a little forward, so as to be on a plane anterior to that of the upper end; it projects below the tibia and forms the lateral part of the
ankle joint.
Structure
The bone has the following components:
*
Lateral malleolus
*
Interosseous membrane connecting the fibula to the tibia, forming a
syndesmosis
A syndesmosis (“fastened with a band”) is a type of fibrous joint in which two bones are united to each other by fibrous connective tissue. The gap between the bones may be narrow, with the bones joined by ligaments, or the gap may be wide a ...
joint
* The
superior tibiofibular articulation is an
arthrodial joint
A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...
between the
lateral condyle of the tibia and the head of the fibula.
* The
inferior tibiofibular articulation (tibiofibular syndesmosis) is formed by the rough, convex surface of the medial side of the lower end of the fibula, and a rough concave surface on the lateral side of the tibia.
Blood supply
The blood supply is important for planning
free tissue transfer because the fibula is commonly used to reconstruct the
mandible
In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla).
The jawbone i ...
. The shaft is supplied in its middle third by a large nutrient vessel from the
fibular artery. It is also perfused from its
periosteum
The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces (i.e. the parts within a joint space) of long bones. (At the joints of long bones the bone's outer surface is lined with "articular cartila ...
which receives many small branches from the fibular artery. The proximal head and the
epiphysis
An epiphysis (; : epiphyses) is one of the rounded ends or tips of a long bone that ossify from one or more secondary centers of ossification. Between the epiphysis and diaphysis (the long midsection of the long bone) lies the metaphysis, inc ...
are supplied by a branch of the anterior tibial artery. In harvesting the bone the middle third is always taken and the ends preserved (4 cm proximally and 6 cm distally)
Development
The fibula is
ossified
Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in t ...
from ''three'' centers, one for the shaft, and one for either end. Ossification begins in the body about the eighth week of
fetal life, and extends toward the extremities. At birth the ends are
cartilaginous.
Ossification commences in the lower end in the second year, and in the upper about the fourth year. The lower
epiphysis
An epiphysis (; : epiphyses) is one of the rounded ends or tips of a long bone that ossify from one or more secondary centers of ossification. Between the epiphysis and diaphysis (the long midsection of the long bone) lies the metaphysis, inc ...
, the first to ossify, unites with the body about the twentieth year; the upper epiphysis joins about the twenty-fifth year.
Head
The upper extremity or head of the fibula is of an irregular quadrate form, presenting above a flattened articular surface, directed upward, forward, and medialward, for articulation with a corresponding surface on the
lateral condyle of the tibia.
On the lateral side is a thick and rough prominence continued behind into a pointed eminence, the apex (''styloid
process
A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic.
Things called a process include:
Business and management
* Business process, activities that produce a specific s ...
''), which projects upward from the posterior part of the head.
The prominence, at its upper and lateral part, gives attachment to the
tendon
A tendon or sinew is a tough band of fibrous connective tissue, dense fibrous connective tissue that connects skeletal muscle, muscle to bone. It sends the mechanical forces of muscle contraction to the skeletal system, while withstanding tensi ...
of the
biceps femoris and to the fibular collateral ligament of the knee-joint, the
ligament
A ligament is a type of fibrous connective tissue in the body that connects bones to other bones. It also connects flight feathers to bones, in dinosaurs and birds. All 30,000 species of amniotes (land animals with internal bones) have liga ...
dividing the tendon into two parts.
The remaining part of the circumference of the head is rough, for the attachment of
muscle
Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...
s and ligaments.
It presents in front a
tubercle for the origin of the upper and anterior fibers of the
peroneus longus, and a surface for the attachment of the anterior ligament of the head; and behind, another tubercle, for the attachment of the posterior ligament of the head and the origin of the upper fibers of the
soleus.
Body
The body of the fibula presents four borders - the antero-lateral, the antero-medial, the postero-lateral, and the postero-medial; and four surfaces - anterior, posterior, medial, and lateral.
;Borders
The antero-lateral border begins above in front of the head, runs vertically downward to a little below the middle of the bone, and then curving somewhat lateralward, bifurcates so as to embrace a triangular subcutaneous surface immediately above the lateral malleolus. This border gives attachment to an intermuscular septum, which separates the extensor muscles on the anterior surface of the leg from the peronaei longus and brevis on the lateral surface.
The antero-medial border, or interosseous crest, is situated close to the medial side of the preceding, and runs nearly parallel with it in the upper third of its extent, but diverges from it in the lower two-thirds. It begins above just beneath the head of the bone (sometimes it is quite indistinct for about 2.5 cm. below the head), and ends at the apex of a rough triangular surface immediately above the articular facet of the lateral malleolus. It serves for the attachment of the
interosseous membrane, which separates the extensor muscles in front from the flexor muscles behind.
The postero-lateral border is prominent; it begins above at the apex, and ends below in the posterior border of the lateral malleolus. It is directed lateralward above, backward in the middle of its course, backward, and a little medialward below, and gives attachment to an aponeurosis which separates the peronaei on the lateral surface from the flexor muscles on the posterior surface.
The postero-medial border, sometimes called the oblique line, begins above at the medial side of the head, and ends by becoming continuous with the interosseous crest at the lower fourth of the bone. It is well-marked and prominent at the upper and middle parts of the bone. It gives attachment to an aponeurosis which separates the tibialis posterior from the soleus and flexor hallucis longus.
;Surfaces
The anterior surface is the interval between the antero-lateral and antero-medial borders. It is extremely narrow and flat in the upper third of its extent; broader and grooved longitudinally in its lower third; it serves for the origin of three muscles: the
extensor digitorum longus,
extensor hallucis longus, and
peroneus tertius.
The posterior surface is the space included between the postero-lateral and the postero-medial borders; it is continuous below with the triangular area above the articular surface of the lateral malleolus; it is directed backward above, backward and medialward at its middle, directly medialward below. Its upper third is rough, for the origin of the soleus; its lower part presents a triangular surface, connected to the tibia by a strong interosseous ligament; the intervening part of the surface is covered by the fibers of origin of the flexor hallucis longus. Near the middle of this surface is the nutrient foramen, which is directed downward.
The medial surface is the interval included between the antero-medial and the postero-medial borders. It is grooved for the origin of the tibialis posterior.
The lateral surface is the space between the antero-lateral and postero-lateral borders. It is broad, and often deeply grooved; it is directed lateralward in the upper two-thirds of its course, backward in the lower third, where it is continuous with the posterior border of the lateral malleolus. This surface gives origin to the peronaei longus and brevis.
File:Fibula - animation.gif, Position of fibula (shown in red)
File:Human fibula.stl, 3D image
File:Right fibula - close-up - animation.gif, Shape of fibula (right)
File:Gray263.png, Diagram which depicts ossification
Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in t ...
of human fibula.
File:Gray262.png, Lower extremity of right fibula. Medial aspect.
File:Slide5CEC4.JPG, Ankle joint. Deep dissection.
File:Slide1besa.JPG, Knee and tibiofibular joint. Deep dissection. Anterior view.
File:Fibula Anatomy by Jason Christian.webm, Fibula anatomy
Function
The fibula does not carry any significant load (weight) of the body. It extends past the lower end of the tibia and forms the outer part of the ankle providing stability to this joint. It has a groove (a depression) for certain ligaments which gives them leverage and multiplies the muscle force. It provides attachment points for the following muscles:
Clinical significance
As much of the fibula can be removed without it impacting an individual's ability to walk, the fibula is utilised as a source of bone material in fibular
free flap surgeries.
Fractures
The most common type of fibula fracture is located at the distal end of the bone, and is classified as
ankle fracture. In the
Danis–Weber classification it has three categories:
*Type A: Fracture of the
lateral malleolus,
distal to the syndesmosis (the connection between the distal ends of the tibia and fibula).
*Type B: Fracture of the fibula at the level of the syndesmosis
*Type C: Fracture of the fibula
proximal to the syndesmosis.
A
Maisonneuve fracture
The Maisonneuve fracture is a spiral fracture of the proximal third of the fibula associated with a tear of the distal Inferior tibiofibular joint, tibiofibular syndesmosis and the interosseous membrane of the leg, interosseous membrane. There is ...
is a
spiral fracture of the proximal third of the fibula associated with a tear of the distal
tibiofibular syndesmosis and the
interosseous membrane. There is an associated fracture of the medial
malleolus or rupture of the deep
deltoid ligament.
An
avulsion fracture of the
head of the fibula refers to the
fracture
Fracture is the appearance of a crack or complete separation of an object or material into two or more pieces under the action of stress (mechanics), stress. The fracture of a solid usually occurs due to the development of certain displacemen ...
of the fibular head because of a sudden contraction of the
biceps femoris muscle that pulls its site of attachment on the bone. The attachment of the biceps femoris tendon on the fibular head is closely related to the
lateral collateral ligament of the knee. Therefore, this ligament is prone to injury in this type of avulsion fracture.
History
Etymology
The word ''
fibula'' can be dated back to c. 1670. It derives from Latin ''fībula'', which describes a clasp or brooch – see
fibula (brooch)
A fibula (, : fibulae ) is a brooch or pin for fastening garments, typically at the right shoulder. The fibula developed in a variety of shapes, but all were based on the safety-pin principle. Unlike most modern brooches, fibulae were not o ...
– and was first used in English for the smaller bone in the lower leg c. 1706. The bone was so called because it resembles a clasp like a modern safety pin.
etymonline.com
/ref>
The adjective peroneal referring to the fibula bone or its surrounding structures derives from : perónē, the Ancient Greek word for a clasp.
Other animals
Because the fibula bears relatively little weight in comparison with the tibia, it is typically narrower in all but the most primitive tetrapods
A tetrapod (; from Ancient Greek τετρα- ''(tetra-)'' 'four' and πούς ''(poús)'' 'foot') is any four- limbed vertebrate animal of the clade Tetrapoda (). Tetrapods include all extant and extinct amphibians and amniotes, with the lat ...
. In many animals, it still articulates with the posterior part of the lower extremity of the femur
The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg.
The Femo ...
, but this feature is frequently lost (as it is in humans). In some animals, the reduction of the fibula has proceeded even further than it has in humans, with the loss of the tarsal articulation, and, in extreme cases (such as the horse
The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 mi ...
), partial fusion with the tibia.
See also
* Fibular hemimelia — congenital absence or shortening of the fibula
* Peroneal
References
External links
*
{{Authority control
Bones of the lower limb
Long bones