FEMUR: osteology,myology, ossification, clinical anatomy.

Bone: femur.


Features

• Longest and the strongest bone of the body .
• Extends from the hip to the knee.

• It is a long bone with a shaft ,an upper end and a lower end.

Side determination

• Upper end has a pounded head that is joined to the neck by an elongated neck.
• The head is directed medially .
• Shaft is convex forwards.
• Anterior aspect of the shaft is smooth and posterior aspect is marked by a prominent vertical ridge called the Linea aspera.

Osteology

Upper end

• The upper end consist of head,neck and two there projections called the greater and lesser trochanteric.

Head

• Directed medially, upwards and forwards.
• Round in shape (make more than half of a sphere).
• Near its centre there is a pit or fovea .

Neck

• Connects the head and the shaft.
• It is separated from the shaft by the intertrochanteric line in front and the intertrochanteric crest behind.

Greater trochanter

• Large quadrangular projection on the lateral aspect of the upper end .
• On the medial surface is a small depression called the trochanteric fossa.
• The greater trochanter also has an anterior,a lateral and a posterior surface .
• The projecting conical point of the upper part is called the tip of the trochanter.

Lesser trochanter

• Is a conical projection attached to the shaft where the lower border of the neck meets the shaft. It points medially and backwards.

Intertrochanteric crest

• The posterior part of the greater and lesser trochanter are joined together by a prominent ridge called the intertrochanteric crest.

Quadrate tubercle

• A little above its middle , the crest bears a rounded elevation called quadrate tubercle.

Intertrochanteric line

• The junction of the neck and the shaft is marked by a much less prominent intertrochanteric line.
• Below the lesser trochanter, the intertrochanteric line becomes continuous with the spiral line.

Shaft

• It is smooth anteriorly but it's posterior aspect is marked by a rough vertical ridge called the linea aspera.
• It has three borders (lateral,medial, posterior) and three surfaces  (anterior, lateral and medial).
• The lateral and medial border are rounded . The posterior border corresponds to the Linea aspera.
• The anterior surface is very smooth .
• The Linea aspera has distinct medial and lateral lips.
• When traced upward  to the upward 1/3rd of the shaft, the lips diverge. The medial lip become continues with the spiral line. The lateral lip becomes continuous with a broad rough area called the gluteal tuberosity.
• The area between the gluteal tuberosity and the spiral line constitute a fourth surface.
• The two lips of the Linea aspera diverge from each other over the lower 1/3rd of the shaft to become continues with the ridges called the medial and lateral supracondylar lines.
• Popliteal surface is an additional surface between medial and lateral supracondylar lines.

Lower end

• Consists of the two large condyles called the medial and lateral condyles.
• Anteriorly the two condyles are joined together and lie in the same plane as the lower part of the shaft.
• Posteriorly they project much beyond the plane of the shaft .
• Posteriorly they project much beyond the plane of the shaft and are separated by a deep intercondylar notch or fossa.
• Lateral condyles are more or less flat . A little behind the middle it is marked by a prominence called the lateral epicondyle.
• When viewed from the medial aspect , the medial condyle is seen to be convex. The most prominent point on it is the medial epicondyle.
• The uppermost part of the medial condyle is marked by a sharp prominence called the adductor tubercle.

Myology
Muscular insertion

Greater Trochanter

• Gluteus minimus: inserted into the anterior aspect of the greater trochanter.
• Gluteus medius: is inserted into the oblique strip running downwards and forwards  across the lateral surface of the greater trochanter.
• Piriformis: inserted into the upper border of the greater trochanter.
• Obturator internus and Gemelli: inserted into the anterior part of the medial surface of greater trochanter.
• Obturator externus: inserted into the trochanteric fossa on the medial surface of the greater trochanter.

Lesser trochanter 

• Psoas major : inserted into the medial part of the anterior surface of the lesser trochanter.
• Iliacus : inserted  into the medial side of the base of the lesser trochanter and into a smaller area below latter.
• Pectineus inserted along a line descending from the root of the upper end of the lineaaspera .

• Quadratus femoris: inserted into the quadrate tubercle.
• Gluteus maximus: inserted into gluteal tuberosity.
• Adductor brevis: inserted between the insertions of the pectineus and adductor Magnus. Lower part of the muscle inserted to the Linea aspera.
• Adductor longus: inserted into the middle 1/3rd of the Linea aspera.
• Adductor Magnus: inserted into the medial margin of the gluteal tuberosity, the Linea aspera and the medial supracondylar line.

Muscular origin

• Vastus lateralis: has long linear origin. The line begins at the upper end of the intertrochanteric line. It passes along the anterior and lower borders of the greater trochanter, the lateral margin of the gluteal tuberosity and the lateral lip of the Linea aspera.
• Vastus medialis: originates from the lower part of the intertrochanteric line , the spiral line ,the medial lip if the Linea aspera and the medial supracondylar line up to the adductor tubercle.
• Vastus inermedius : arises from small areas on the anterior surface of the shaft. 
• Articularis genu: arises from small areas on the anterior surface of the shaft below the origin of the vastus intermedius.
• Biceps femoris : (short head ) arise from the Linea aspera and from the upper part of the lateral supracondylar line.
• Popliteus : arises from the lower part of the lateral supracondyle.

Ossification

• Second long bone to start ossifying .
• The primary centres appears in the shaft during the 7th foetal week.
• The secondary centres appear at the upper end of the bone ; one each for the head , the greater trochanter and the lesser trochanter.
• Each of these centres fuses independently with the shaft in the reverse order of appearance.
• The lesser trochanter fuses at about 13 years.
• The greater trochanter fuses at about 14 years of age.
• The head fuses around 16 years of age.
• One secondary centre for the distal end appears before birth in the 9th  month of the foetal life. It fuses with the shaft between 16th and 18th year.

Clinical anatomy

• Congenital dislocation:occurs as a result of imperfectly formed bone ends.
• Avascular necrosis: caused due to insufficient blood supply to the to the head of the femur. The head collapses and the hip joint becomes disorganised.
• Arthroplasty : repairing of the joints using artificial components.