Many anatomical terms descriptive of bone are defined in

anatomical terminology Anatomical terminology is a specialized system of terms used by anatomists, zoologists, and health professionals, such as doctors, surgeons, and pharmacists, to describe the structures and functions of the body. This terminology incorpor ...

, and are often derived from Greek and Latin.

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, ...

in the human body is categorized into

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 ...

short bone Short bones are designated as those bones that are more or less equal in length, width, and thickness. They include the Tarsus (skeleton), tarsals in the ankle and the Carpal bones, carpals in the wrist. They are one of five Bone#Types, types of ...

flat bone Flat bones are bones whose principal function is either extensive protection or the provision of broad surfaces for muscular attachment. These bones are expanded into broad, flat plates,'' Gray's Anatomy'' (1918). (See infobox) as in the cranium ...

irregular bone The irregular bones are bones which, from their peculiar form, cannot be grouped as long, short, flat or sesamoid bones. Irregular bones serve various purposes in the body, such as protection of nervous tissue (such as the vertebrae protect the ...

and

sesamoid bone In anatomy, a sesamoid bone () is a bone embedded within a tendon or a muscle. Its name is derived from the Greek word for 'sesame seed', indicating the small size of most sesamoids. Often, these bones form in response to strain, or can be presen ...

Types of bone

Long bones

A long bone is one that is cylindrical in shape, being longer than it is wide. However, the term describes the shape of a bone, not its size, which is relative. Long bones are found in the arms (

humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...

radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...

) and legs (

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 ...

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 ...

fibula The fibula (: fibulae or fibulas) or calf bone is a leg bone on the lateral side of the tibia, 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. ...

), as well as in the fingers (

metacarpals In human anatomy, the metacarpal bones or metacarpus, also known as the "palm bones", are the appendicular skeleton, appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones (wrist, wris ...

phalanges The phalanges (: phalanx ) are digit (anatomy), digital bones in the hands and foot, feet of most vertebrates. In primates, the Thumb, thumbs and Hallux, big toes have two phalanges while the other Digit (anatomy), digits have three phalanges. ...

) and toes ( metatarsals, phalanges). Long bones function as levers; they move when

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 contract.

Short bones

A short bone is one that is cube-like in shape, being approximately equal in length, width, and thickness. The only short bones in the human skeleton are in the carpals of the wrists and the tarsals of the ankles. Short bones provide stability and support as well as some limited motion.

Flat bones

The term “flat bone” is something of a misnomer because, although a flat bone is typically thin, it is also often curved. Examples include the cranial (skull) bones, the scapulae (shoulder blades), the sternum (breastbone), and the ribs. Flat bones serve as points of attachment for muscles and often protect internal organs. Flat bones do not have a medullary cavity because they are thin.

Irregular bones

An irregular bone is one that does not have an easily classified shape and defies description. These bones tend to have more complex shapes, like the

vertebrae Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...

that support the spinal cord and protect it from compressive forces. Many facial bones, particularly the ones containing sinuses, are classified as irregular bones.

Sesamoid bones

A sesamoid bone is a small, round bone that, as the name suggests, is shaped like a sesame seed. These bones form in tendons (the sheaths of tissue that connect bones to muscles) where a great deal of pressure is generated in a

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- ...

. The sesamoid bones protect tendons by helping them overcome compressive forces. Sesamoid bones vary in number and placement from person to person but are typically found in tendons associated with the feet, hands, and knees. The only type of sesamoid bone that is common to everybody is the

kneecap The patella (: patellae or patellas), also known as the kneecap, is a flat, rounded triangular bone which articulates with the femur (thigh bone) and covers and protects the anterior articular surface of the knee joint. The patella is found in m ...

(''patella'', pl. ''patellae'') which is also the largest of the sesamoid bones.

Protrusions

Rounded

A ''

condyle A condyle (;Entry "condyle"
in

'' is the round prominence at the end of a bone, most often part of a joint – an articulation with another bone. The ''

epicondyle An epicondyle () is a rounded eminence on a bone that lies upon a condyle ('' epi-'', "upon" + ''condyle'', from a root meaning "knuckle" or "rounded articular area"). There are various epicondyles in the human skeleton The human skeleton is ...

'' refers to a projection near a condyle, particularly the

medial epicondyle of the humerus The medial epicondyle of the humerus is an epicondyle of the humerus bone of the upper arm in humans. It is larger and more prominent than the Lateral epicondyle of the humerus, lateral epicondyle and is directed slightly more posteriorly in the ...

. These terms derive from

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

. An ''eminence'' refers to a relatively small projection or bump, particularly of bone, such as the medial eminence. A ''process'' refers to a relatively large projection or prominent bump, as does a ''promontory'' such as the

sacral promontory The sacrum (: sacra or sacrums), in human anatomy, is a triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part of the pelvic cavit ...

. Both ''tubercle'' and ''tuberosity'' refer to a projection or bump with a roughened surface, with a "tubercle" generally smaller than a "tuberosity". These terms are derived from ''

tuber Tubers are a type of enlarged structure that plants use as storage organs for nutrients, derived from stems or roots. Tubers help plants perennate (survive winter or dry months), provide energy and nutrients, and are a means of asexual reproduc ...

'' ()., as is also '' protuberance'', which occasionally is synonymous with "tuberosity". A ''ramus'' () refers to an extension of bone, such as the

ramus of 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 ...

in the

jaw The jaws are a pair of opposable articulated structures at the entrance of the mouth, typically used for grasping and manipulating food. The term ''jaws'' is also broadly applied to the whole of the structures constituting the vault of the mouth ...

superior pubic ramus In vertebrates, the pubis or pubic bone () forms the lower and anterior part of each side of the hip bone. The pubis is the most forward-facing (ventral and anterior) of the three bones that make up the hip bone. The left and right pubic bones ar ...

. Ramus may also be used to refer to nerves, such as the ramus communicans. A ''facet'' refers to a small, flattened articular surface.

Pointed

A ''line'' refers to a long, thin projection, often with a rough surface. ''Ridge'' and ''crest'' refer to a long, narrow line. Unlike many words used to describe anatomical terms, the word ''ridge'' is derived from

Old English Old English ( or , or ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the Early Middle Ages. It developed from the languages brought to Great Britain by Anglo-S ...

. A ''spine'', as well as referring to the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal c ...

, may be used to describe a relatively long, thin projection or bump.

Special

These terms are used to describe bony protuberances in specific parts of the body. The '' Malleolus'' () is the bony prominence on each side of the

ankle The ankle, the talocrural region or the jumping bone (informal) is the area where the foot and the leg meet. The ankle includes three joints: the ankle joint proper or talocrural joint, the subtalar joint, and the inferior tibiofibular joint. The ...

. These are known as the medial and lateral malleolus. Each leg is supported by two bones, the

on the inner side (medial) of the leg and the

on the outer side (lateral) of the leg. The ''medial malleolus'' is the prominence on the inner side of the ankle, formed by the lower end of the tibia. The ''lateral malleolus'' is the prominence on the outer side of the ankle, formed by the lower end of the fibula. The '' trochanters'' are parts of the femur, to which muscles attach. It may refer to the greater, lesser, or

third trochanter In human anatomy, the third trochanter is a bony projection occasionally present on the proximal femur near the superior border of the gluteal tuberosity. When present, it is oblong, rounded, or conical in shape and sometimes continuous with the ...

Cavities

Openings

The following terms are used to describe cavities that connect to other areas: A ''

foramen In anatomy and osteology, a foramen (; : foramina, or foramens ; ) is an opening or enclosed gap within the dense connective tissue (bones and deep fasciae) of extant and extinct amniote animals, typically to allow passage of nerves, artery, ...

'' is any opening, particularly referring to those in

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, ...

. Foramina inside 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 anim ...

humans Humans (''Homo sapiens'') or modern humans are the most common and widespread species of primate, and the last surviving species of the genus ''Homo''. They are Hominidae, great apes characterized by their Prehistory of nakedness and clothing ...

and other

animals Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia (). With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a ...

typically allow

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the Electrochemistry, electrochemical nerv ...

arteries An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...

vein Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...

s, or other structures to connect one part of the body with another. An example is the

foramen magnum The foramen magnum () is a large, oval-shaped opening in the occipital bone of the skull. It is one of the several oval or circular openings (foramina) in the base of the skull. The spinal cord, an extension of the medulla oblongata, passes thro ...

in occipital bone. A ''canal'' is a long, tunnel-like foramen, usually a passage for notable nerves or blood vessels. An example is the

auditory canal The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the auricle to the eardrum and is about in length and in diameter. Stru ...

Blind-ended

The following terms are used to describe cavities that do not connect to other areas: A '' fossa'' (from the Latin "''fossa''", ditch or trench) is a depression or hollow, usually in a bone, such as the

hypophyseal fossa The sella turcica (Latin for 'Turkish saddle') is a saddle-shaped depression in the body of the sphenoid bone of the human skull and of the skulls of other hominids including chimpanzees, gorillas and orangutans. It serves as a cephalometric la ...

, the depression in the

sphenoid bone The sphenoid bone is an unpaired bone of the neurocranium. It is situated in the middle of the skull towards the front, in front of the basilar part of occipital bone, basilar part of the occipital bone. The sphenoid bone is one of the seven bon ...

.Venieratos D, Anagnostopoulou S, Garidou A., A new morphometric method for the sella turcica and the hypophyseal fossa and its clinical relevance. Folia Morphol (Warsz). 2005 Nov; 64(4): 240–47. A ''

meatus In anatomy, a meatus (, , : meatus or meatuses)Entry "meatus" in Merriam-Webster Onlin ...

'' is a short canal that opens to another part of the body. An example is the

external auditory meatus The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the auricle to the eardrum and is about in length and in diameter. Str ...

. A '' fovea'' () is a small pit, usually on the head of a bone. An example of a ''fovea'' is the fovea capitis of the head of the femur.

Walls

The following terms are used to describe the walls of a cavity: A ''

labyrinth In Greek mythology, the Labyrinth () is an elaborate, confusing structure designed and built by the legendary artificer Daedalus for King Minos of Crete at Knossos. Its function was to hold the Minotaur, the monster eventually killed by the h ...

'' refers to the

bony labyrinth The bony labyrinth (also osseous labyrinth or otic capsule) is the rigid, bony outer wall of the inner ear in the temporal bone. It consists of three parts: the vestibule, semicircular canals, and cochlea. These are cavities hollowed out of the ...

and

membranous labyrinth The membranous labyrinth is a collection of fluid filled tubes and chambers in the inner ear The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for soun ...

, components of the inner ear, due to their fine and complex structure. A '' sinus'' refers to a bony cavity, usually within the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

Joints

A joint, or articulation is the region where adjacent bones contact each other, for example the

elbow The elbow is the region between the upper arm and the forearm that surrounds the elbow joint. The elbow includes prominent landmarks such as the olecranon, the cubital fossa (also called the chelidon, or the elbow pit), and the lateral and t ...

shoulder The human shoulder is made up of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone) as well as associated muscles, ligaments and tendons. The articulations between the bones of the shoulder m ...

, or

costovertebral joint The costovertebral joints are the joints that connect the ribs to the vertebral column. * The articulation of head of rib, articulation of the head of rib connects the rib, head of the rib and the Vertebra, bodies of thoracic vertebra, vertebrae. ...

. Terms that refer to joints include: * ''articular process'', referring to a projection that contacts an adjacent bone. * ''suture'', referring to an articulation between cranial bones.

Features of long bones

Gross features

Bones are commonly described with the terms ''head'', ''neck'', ''shaft'', ''body'' and ''base'' The ''head'' of a bone usually refers to the distal end of the bone. The shaft refers to the elongated sections of

, and the ''neck'' the segment between the head and shaft (or body). The end of the long bone opposite to the head is known as the ''base''.

Internal regions

Internal and external

The cortex of a bone is used to refer to its outer layers, and medulla used to refer to the inner surface of the bone. Red marrow, in which blood is formed is present in

spongy 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, and ...

as well as in the

medullary cavity The medullary cavity (''medulla'', innermost part) is the central cavity of bone shafts where red bone marrow and/or yellow bone marrow (adipose tissue) is stored; hence, the medullary cavity is also known as the marrow cavity. Located in the ma ...

, while the fatty yellow marrow is present primarily in the medullary cavity.

Notes

References

''This Wikipedia entry incorporates text from the freely licensed Connexion

edition of Anatomy & Physiolog

text-book by OpenStax College'' ;Books * {{cite book , editor = J. A. Simpson , title = The Oxford English dictionary. , url = https://archive.org/details/oxfordenglishdic12simp , url-access = registration , year = 1989 , publisher=Clarendon Press , location=Oxford , isbn=9780198611868 , ref={{harvid, OED, 1989 Bones Human anatomy Anatomical terminology