The
femur is also called the thigh bone and is the longest and strongest
bone of the body. It is composed of upper end, lower end and a shaft.
The
upper and bears a rounded head, whereas the lower end is widely
expanded to from two large condyles. The head is directed medially. The
cylindrical shaft is convex forwards.
Upper end of Femur
The upper end of the femur includes the head, the neck, the greater
trochanter, the lesser trochanter, the intertrochanteric line, and the
intertrochanteric crest.
Head of Femur
Head articulates with acetabulum to form a hip joint. It is more than
half a sphere, and is directed medially, upwards and slightly forwards.
Fovea is a roughened pit just below and behind the center of the head. Head, in its most part is covered by cartilage.
Neck of Femur
Neck is about is about 3-3.5 cms long and connects head with shaft.
The neck forms an angle with shaft, known as neck shaft angle and is
about 125 in adults [lesser in females]. The angle facilitates movements
of the hip joint. Femoral neck is strengthened by a thickening of bone
called the calcar femorale present along its concavity.
The neck has two borders and two surfaces
The upper border, concave and horizontal, meets the shaft at the
greater trochanter. The lower border, straight and oblique, meets the
shaft near the lesser trochanter.
The anterior surface is flat and meets the shaft at the
interochanteric line. Anterior surface of femoral neck is entirely
interacapsular. Upper part of this surface may be covered by articular
cartilage.
The posterior surface is convex from above downwards and concave from
side to side. It meets the shaft at the intertrochanteric crest. It is
not intracapsular in its lower
lateral part.
Antecersion is the angle formed between the transverse axis of the upper and lower ends of the femur. It is about 15 degrees.
Read more about anteversion
Greater Trochanter
Greater trochanter is a large quadrangular prominence located at the
upper part of the junction of the neck with shaft. The upper border of
the trochanter lies at the level of the center of the head.
The greater trochanter has an upper border with an apex, and 3 surfaces (anterior,
medial and
lateral). The apex is the inturned posterior part of the posterior border. The anterior surface is rough in its
lateral part. The
medial surface presents a rough impression, above and a deep trochanteric fossa, below. The
lateral surface is crossed by an oblique ridge directed downwards and forwards.
Lesser Trochanter
It is a conical eminence directed medially and backwards from the junction of the posterior part of the neck with the shaft.
Intertrochanteric Line
It marks the junction of neck with the femur. It is a roughened ridge
from anterosuperior angle of the greater trochanter (as a tubercle),
and is continuous below with the spiral line in front of the lesser
trochanter.
Spiral line is a
curved line with its superior end adjacent to
the lesser trochanter, nearly continuous with the intertrochanteric line, and converging inferiorly with the pectineal line to
form the medial lip of
the linea aspera.
It
forms the medial boundary of
the distal attachment of
the iliacus muscle.The spiral line winds round the shaft below the lesser trochanter to reach the posterior surface of the shaft.
Intertrochanteric Crest
It marks the junction of the posterior surface of the neck with the
shaft of the femur. It is smooth rounded ridge which begins above at
the posterior
superior
angle of the greater trochanter and ends at the lesser trochanter. The
rounded elevation, a little above its middle is called the quadrate
tubercle.
Shaft of Femur
The shaft is almost a cylindrical structure wide superiorly and
inferiorly and narrowest in the middle. It is convex forwards and is
directed obliquely downwards and medially.
Credit:Teach Me Anatomy
The shaft in middle one-third has three borders -
medial,
lateral and posterior. The
medial and
lateral
borders are rounded and ill- defined, but the posterior border is in
the form of a broad roughened ridge, called the linea aspera. Linea
aspera is an important landmark in orthopedics surgeries involving
reduction of femoral fractures.
The Linea aspera has distinct
medial and
lateral lips. The
medial and
lateral surfaces are directed more backwards than to sides.
The shaft possesses 3 surfaces as well – anterior,
medial and
lateral.
In upper on third of the shaft he two lips of the Linea aspera
diverge wide to form an additional posterior surface and four borders (
medial,
lateral, spiral line and the
lateral hip of the gluteal tuberosity) and 4 surfaces (anterior,
medial,
lateral and posterior).
The gluteal tuberosity is a broad roughened ridge on the
lateral part of the posterior surface.
Similarly, the two lips of the Linea aspera diverge in lower one
third and enclose an additional, popliteal surface. Thus this part of
the shaft has four border (
medial,
lateral, supracondylar line and
lateral supracondylar line) 4 surfaces (anterior,
medial,
lateral and popliteal). The
medial border and
medial supracondylar line meet inferiorly to obliterate the
medial surface.
Lower End of Femur
The lower end of the femur is wide and expanded. It has two large condyles –
medial and
lateral.
Anteriorly, the two condyles are united and are in a line with the
front of the shaft. Posteriorly, they are separated by a deep gap,
termed the interocondylar fossa or intercondylar notch, and project
backwards much beyond the plane of the popliteal surface.
The
lateral condyle is flat laterally, less prominent than
medial condyle and stouter than it. It has a prominence called the
lateral epicondyle. Below it lies the popliteal groove with deeper anterior part and a shallower posterior part.
Medial condyle is convex medially. It also bears a prominent point called the
medial
epicondyle. Adductor tubercle is a projection posterosuperior to the
epicondyle which serves as an important landmark. The epiphyseal line
for the lower end of the femur passes through it.
Interondylar fossa or notch separates the lower and posterior parts
of the two condyles. Intercondylar line separates notch from the
popliteal surface. Anteriorly, the notch is limited by patellar
articular surface.
The two condyles are partially covered by a large articular surface.
Anteriorly, the condyles articulate with patella and this articualtion
extends more on the
lateral condyle than on the
medial.Between
the two condyles, the surface is grooved vertically. Two faint grooves
separate the patellar articualtion surface from tibial surfaces. Tibial
articulation surface over the
lateral condyle is short and straight anteroposteriorly whereas the part over the
medial condyle is longer and is convex medially.
Attachments on the Femur
Head of Femur
The fovea on the head of the femur provides attachment to the ligament of the head (round ligament, or ligamentum teres).
Greater Trochanter
- The piriformis is inserted into the apex
- The gluteus minimus is inserted into the rough lateral part of the anterior surface
- The obturator internus and the two gemelli are inserted into the upper rough impression on the medial surface
- The obturator externus is inserted into the trochanteric fossa
- The gluteus medius is inserted into the ridge on the lateral surface.
- The trochanteric bursa of the gluteus medius lies in front of the ridge, and the trochanteric bursa of the gluteus maximus lies behind the ridge.
Lesser Trochanter
- The psoas major is inserted on the apex and medial part of the rough anterior surface.
- The iliacus is inserted on the anterior surface of the base of the trochanter, and on the area below.
- Gluteus minimus bursa lies deep to the upper horizontal fibrres of the adductor magnus.
Intertrochanteric Line
Following structures attach to intertrochanteric line
- Capsular ligament of the hip joint
- Iliofemoral ligament in its upper part
- Lower band of the iliofemoral ligament in its lower part
- Highest fibres of the vastus lateralis from the upper end
- Highest fibres of the vastus medialis from the lower end
- Quadratus femoris attached on quadrate tubercle
Shaft of Femur
- The medial and popliteal surfaces are bare [ Except for part of gastrocnemius origin on the popliteal surface]
- Vastus intermedius – upper three fourths of the anterior and lateral surfaces.
- Articularis genu – just below the vastus intermedius.
- Vastus lateralis – upper part of the intertrochanteric line, anterior and inferior borders of the greater trochanter, the lateral lip of the gluteal tuberosity, and the upper half of the lateral lip of the line aspera.
- Vastus medialis – Lower part of the intertrochanteric line, the spiral line, the medial lip of the linea aspera, and the upper one –fourth of the medial supracondylar line.
- Gluteal tubersosity receives insertion of deeper fibres of the lower half of the gluteus maximus
- Adductor longus – Medial lip of the linea aspera between the vastus medialis and the adductor brevis and magnus
- Adductor brevis is inserted into a line extending from the lesser
trochanter to the upper part of the linea aspera, behind the pectineus
and the upper part of the adductor longus.
- Adductor magnus is inserted into the medial margin of the gluteal tuberosity, the linea aspera, the medial superacondylar line, and the adductor tubercle
- Pectineus is inserted on a line extending from the lesser trochanter to the linea aspera.
- Short head of the biceps femoris arises from the lateral lip of the linea aspera between the vastus lateralis and the adductor magnus, and from the upper two – thirds of the lateral superacondylar line
- Medial and lateral
intermuscular septa are attached to the lips of the linea aspera and to
the supracondylar line. These septae separate the extensor muscles
from the adductor medially, and from the flexors laterally. The lower
end of the lateral supracondylar line gives origin to the plantaris above and the upper part of the lateral head of the gastrocnemius below.
- The popliteal surface is covered with fat and forms the floor of the popliteal fossa. Medial head of the gastrocnemius extends to the popliteal surface just above the medial condyle.
Lateral Condyle
- Fibular collateral ligament of the knee attaches to the lateral epicondyle.
- The popliteus aries from the deep anterior part of the popliteal
groove. When the knee is flexed the tendon of this muscle lies in the
shallow posterior part of the grove.
- The muscular impression near the lateral epicondyle gives origin to the lateral head of the gastrocnemius.
Medial Condyle
- Tibial collateral ligament of the knee – medial epicondyle
- Hamstring part of the adductor magnus – adductor tubercle
Intercondylar Notch
- Anterior cruciate ligament – posterior part of the medial surface of the lateral condyle.
- The intercondylar line provides attachment to the capsular ligament and laterally to the oblique popliteal ligamemt.
- The infrapatellar synovial fold is attached to the anterior border of the intercondylar fossa.
Following video summarizes the femoral bone
Ossification of Femur
One primary and four secondary centres.
The primary centre for the shaft appears in the 7 week of intrauterine life.
The secondary centres appear as follows
- Lower end of Femur – At end of the 9th month of intrauterine life
- Head – first six months of life
- Greater trochanter – 4 years
- Lesser trochanter – 12 years
The upper apiphyses (lesser trochanter, greater trouchanter and
head, in that order) fuse with the shaft at about 18 year. The lower
epiphysis fuses by the 20th year.
Blood supply of Femur
- The smaller, medial part of the head, near the fovea, is supplied by medial epiphyseal arteries derived from the posterior division of the obturator artery and from the ascending branch of the medial
circumflex femoral artery. These arterial twigs enter the acetabular
notch and then pass along the round ligament to reach the head.
- The larger, lateral part of the head is supplied by lateral epiphyseal arteries which are derived from the retinacular branches of the medial
circumflex femoral artery. This set constitutes the main supply and
damage to it results in necrosis of the head of the following fractures
of the neck of the femur. After epiphyseal fusion, the lateral epiphyseal arteries anastomose freely with the metaphyseal arteries.
- The intracapsular neck is supplied by the retinacular arteries derived chiefly from the trochanteric anastomosis. The vessels produce longitudinal grooves and formina directed towards the head, mainly on the anterior and posterior- superior surface. The extracapsular part of the neck is supplied by the ascending branch of the medial circumflex femoral artery.
- Nutrient artery to shaft of femur is derived from the second
perforating arteryThe nutrient foramen (or foramina) is located on the medial side on the linea aspera, and is directed upwards.
- Lower end is supplied by genicular arteries and anastomosis around the knee
Significance of Femur
- Femur is a common bone to be injured
- Ossification of the lower end of the femur is of medicolegal
importance. Presence of its centre in a newly born child found dead
indicates that the child was capable of independent existence.
- Coxa valga is a condition where the femoral neck shaft angle is more than normal. ( 135 degrees)
- Coxa vara is a condition where the neck shaft angle is less than normal (120 degrees)