The femur (; : femurs or femora ), or thigh bone is the only

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

thigh In anatomy, the thigh is the area between the hip (pelvis) and the knee. Anatomically, it is part of the lower limb. The single bone in the thigh is called the femur. This bone is very thick and strong (due to the high proportion of bone tissu ...

— the region of the lower limb between the

hip In vertebrate anatomy, the hip, or coxaLatin ''coxa'' was used by Celsus in the sense "hip", but by Pliny the Elder in the sense "hip bone" (Diab, p 77) (: ''coxae'') in medical terminology, refers to either an anatomical region or a joint on t ...

and the

knee 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 hu ...

. In many four-legged animals the femur is the upper bone of the hindleg. The top of the femur fits into a socket in the pelvis called the hip joint, and the bottom of the femur connects to the shinbone (

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 ...

) and kneecap (

patella 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 ...

) to form the knee. In humans the femur is the largest and thickest bone in the body.

Structure

The femur is the only bone in the upper

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 ...

. The two femurs converge medially toward the

s, where they articulate with the

proximal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

ends of the

e. The angle at which the femora converge is an important factor in determining the femoral-tibial angle. In females, thicker

pelvic bone The hip bone (os coxae, innominate bone, pelvic bone or coxal bone) is a large flat bone, constricted in the center and expanded above and below. In some vertebrates (including humans before puberty) it is composed of three parts: the ilium, isch ...

s cause the femora to converge more than in males. In the condition ''genu valgum'' (knock knee), the femurs converge so much that the knees touch. The opposite condition, ''genu varum'' (bow-leggedness), occurs when the femurs diverge. In the general population without these conditions, the femoral-tibial angle is about 175 degrees. The femur is the largest and thickest bone in the human body. It is considered the strongest bone by some measures, though other studies suggest the

temporal bone The temporal bone is a paired bone situated at the sides and base of the skull, lateral to the temporal lobe of the cerebral cortex. The temporal bones are overlaid by the sides of the head known as the temples where four of the cranial bone ...

may be stronger. On average, the femur length accounts for 26.74% of a person's height, a ratio found in both men and women across most

ethnic group An ethnicity or ethnic group is a group of people with shared attributes, which they collectively believe to have, and long-term endogamy. Ethnicities share attributes like language, culture, common sets of ancestry, traditions, society, re ...

s with minimal variation. This ratio is useful in

anthropology Anthropology is the scientific study of humanity, concerned with human behavior, human biology, cultures, society, societies, and linguistics, in both the present and past, including archaic humans. Social anthropology studies patterns of behav ...

, as it provides a reliable estimate of a person's height from an incomplete

skeleton A skeleton is the structural frame that supports the body of most animals. There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal fra ...

. The femur is classified as a

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 ...

, consisting of

diaphysis The diaphysis (: diaphyses) is the main or midsection (shaft) of a long bone. It is made up of cortical bone and usually contains bone marrow and adipose tissue (fat). It is a middle tubular part composed of compact bone which surrounds a centr ...

(shaft or

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 ...

) and two

epiphyses 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 ...

(extremities) that articulate with the hip and knee bones.

Upper part

The upper or proximal extremity (close to the

torso The torso or trunk is an anatomical terminology, anatomical term for the central part, or the core (anatomy), core, of the body (biology), body of many animals (including human beings), from which the head, neck, limb (anatomy), limbs, tail an ...

) contains the

head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple ani ...

neck The neck is the part of the body in many vertebrates that connects the head to the torso. It supports the weight of the head and protects the nerves that transmit sensory and motor information between the brain and the rest of the body. Addition ...

, the two trochanters and adjacent structures. The upper extremity is the thinnest femoral extremity, the lower extremity is the thickest femoral extremity. The head of the femur, which articulates with the

acetabulum The acetabulum (; : acetabula), also called the cotyloid cavity, is a wikt:concave, concave surface of the pelvis. The femur head, head of the femur meets with the pelvis at the acetabulum, forming the Hip#Articulation, hip joint. Structure The ...

of the

, comprises two-thirds of a

sphere A sphere (from Ancient Greek, Greek , ) is a surface (mathematics), surface analogous to the circle, a curve. In solid geometry, a sphere is the Locus (mathematics), set of points that are all at the same distance from a given point in three ...

. It has a small groove, or fovea, connected through the round ligament to the sides of the

acetabular notch The acetabular notch is a deep notch in the inferior portion of the rim of the acetabulum The acetabulum (; : acetabula), also called the cotyloid cavity, is a wikt:concave, concave surface of the pelvis. The femur head, head of the femur mee ...

. The head of the femur is connected to the shaft through the

or ''collum''. The neck is 4–5 cm. long and the diameter is smallest front to back and compressed at its middle. The collum forms an angle with the shaft in about 130 degrees. This angle is highly variant. In the

infant In common terminology, a baby is the very young offspring of adult human beings, while infant (from the Latin word ''infans'', meaning 'baby' or 'child') is a formal or specialised synonym. The terms may also be used to refer to juveniles of ...

, it is about 150 degrees and in

old age Old age is the range of ages for people nearing and surpassing life expectancy. People who are of old age are also referred to as: old people, elderly, elders, senior citizens, seniors or older adults. Old age is not a definite biological sta ...

reduced to 120 degrees on average. An abnormal increase in the angle is known as

coxa valga Coxa valga is a deformity of the hip where the angle formed between the head and neck of the femur and its shaft is increased, usually above 135 degrees. The deformity may develop in children with neuromuscular disorders (i.e. cerebral palsy, spi ...

and an abnormal reduction is called

coxa vara Coxa vara is a deformity of the hip, whereby the angle between the head and the shaft of the femur is reduced to less than 120 degrees. This results in the leg being shortened and the development of a limp. It may be congenital and is commonly ...

. Both the head and neck of the femur is vastly embedded in the hip musculature and can not be directly

palpated Palpation is the process of using one's hands to check the body, especially while perceiving/diagnosing a disease or illness. Usually performed by a health care practitioner, it is the process of feeling an object in or on the body to determine ...

. In skinny people with the

laterally rotated, the head of the femur can be felt deep as a resistance

profound {{Short pages monitor