Femur | Gross Anatomy | Anjani Mishra

 GROSS STUDY OF FEMUR (THIGH)    

Written By Anjani Mishra             

FEMUR

   It is largest and most massive bone in the body.

Shape: cylindrical above and prismatic below.

Direction: It extends obliquely downward and forward.

Location: This bone is distal to hipbone.

Artilation: Articulates with acetabulum above forming a hip joint and tibia & patella below forming a femero-tibial and femero-patellar joint.

Composition: It presents 1 shaft & 2 extremities.

Shaft:

• It is cylindrical above and prismatic below.
• It consists of 4 surfaces & 2 borders.     

Surfaces:

The anterior, lateral and medial surfaces:

• They are smooth, convex and continuous with each other and remain covered by quadriceps femoris muscle.

Posterior surface: 

• It is rough, narrow in middle but wider at the extremities.

Borders:

Medial Border:

• It bears trochanter minor at the middleao upper-third, which advance to the posterior surface.
• Trochantor minor presents medially a rough elongated depression, which gives attachment to the common tendon of iliacus and psoas major muscle.
• Dorsally it gives attachment to quadratus femoris. Immediately below and external to the trochantor minor, linear rough markings intended for the insertion of pectinious muscle. 
• Below the trochantor minor, there is wide vascular groove running obliquely downward and outward.
• The distal-third of the medial border, there is small rough obtuse eminence, the medial supracondoyloid crest, which attaches medial head of the gastrocnenemius muscles. 

Lateral border:

• At the level of supracondyloid crest, there is an elongated supracondyloid fossa, the other margin of which bears the lateral supracondyloid crest. 

Extremities:

Proximal Extremity:

•  It is very wide and is composed of a head, neck and trochantor major.
• Head is placed medially and is directed inwards to articulate with the acetabulum of pelvic bone. 
• There is small sulcus/fovea capitis at the center of head which attaches round ligament.
•   Below the head there is constriction, the neck, which is well marked.
• The tronchantor major is placed laterally and is very massive. Its lateral surface is convex, rough and is covered by tendons of middle & deep gluteus muscles. 
• The medial surface is concave and forms the lateral boundary of trochanteric fossa.
• Continuous with the tronchantor major posteriorly and connecting it to the trochantor minor is the trochanteric ridge.
• Medial to this ridge, is deep trochanteric fossa, in which the common tendon of obturator internus, obturatur externus and gamelli muscles are attached. 

Distal Extremity:

• It is large and composed of trochlea in front and two condyles behind.
•   The trochlea, which articulates with the patella, is slightly oblique and is composed of two ridges or lips separated by a groove called trochlear ridge.
• The medial ridge is much larger, more prominent and extends higher than the lateral.
• The rim around the trochlea gives attachment to the capsular ligament of the femuro-tibial articulation.
• The condyles are medial and lateral, which are separated by deep intercondyloid fossa. 
• The intercondyloid fossa receives the tibial spine and the cruciate ligament of the femuro-tibial articulation.
• The lateral condyle is more convex than the medial.
• Between the lateral condyle and external ridge of the trochlea, there is rough depression called extensor fossa, that gives origin to the peroneous tertius, medial digital extensor and common digital extensor. 
• Just behind the extensor fossa there is depression marking for the origin of popliteus muscle.
• The medial condyle presents a tubercle for the attachment of a ligament of femoro-tibial articulation.

Comparison with:

A) Femur of Horse:

• The bone is more massive and posterior surface is wider.
• On the dorsal third of the lateral border, there is an extra prominence, called trochanter tertius ( Third trochanter), for insertion of superficial gluteus muscle.
• The trochantor minor is in the form of thick, rough ridge.
• The supra condyloid crest is better marked and the supra condyloid fossa is deeper.
• The trochanter major is more massive and is divided into crest, convexity and summit.
• The head is large and hemispherical. (Shape as half of the earth.)
• Fovea capitis is deep and notched.
• Trochanteric ridge is vertical.   

 

B) Femur of Dog:

• Bone is comparatively larger and the shaft is more curved.
• The posterior surface is narrow and presents two crest.
• The trochanter tertius and supracondyloid fossa is absent.
• There are two supra condyloid crest, the lateral of which is larger.
• The trochanter minor is like a tuberosity.
• The tronchanter major is undivided and is lower in level than the head.
• The head is neatly spherical.
• The trochanteric fossa is deep and rounded.
• The trochlear ridges are nearly similar.
• Each condyle presents at its upper area posteriorly, a small, circular,  slightly concave or nearly flat facet of fabella. 
• Fabella is small bone and plays the part of sesamoid for the head of the gastrocnemius muscle.

 

C) Femur of Pig:

•  Femur is relatively wide and having massive shaft.
• Supracondyloid fossa and third trochanter is absent.
• The head is strongly covered and is marked towards the medial side.
• Neck is distinct.
• The trochanter major although massive, doesn't extend above the level of head.
• Trochlear ridge are of similar size.

D) Femur of Goat:

• The shaft of femur is slightly curved and the convexity being anterior.
• A distinct line separates the lateral and posterior surface.
• The supracondyloid fossa is very shallow.
• The head has shallow fovea capitis and neck is distinct.
• The trochanter major is little higher than the head.
• The ridges of the trochlea are similar and parallel but slightly oblique.

E) Femur of Fowl:

• Femur is short and somewhat bent.
• The head is smaller than the acetabulum.
• The distal extremity has a deep pulley-like articular area for articulation with the tibia and fibula.

  THE PATELLA

It is small, irregularly triangular sesamoid bone. It corresponds to the knee cap of the human.

It is also considered as a largest sesamoid bone. 

Shape: Roughly triangular shape.

Location: Bone is placed in front of the femoral trochlea.

Direction: Nearly straight from above downwards.

Articulation: It articulates with the femoral trochlea below forming a femero-patellar joint.

Relation: It is attached to the tibia by three extremely strong ligamentous bands(medial, middle & lateral) and placed in front of the femoral trochlea.

Composition: It consists of 2 surfaces, 3 borders, 3 angles; a base and an apex.

Surfaces:

Posterior /articular Surface:

• Smooth and is divided by a vertical ridge into two areas which articulates with corresponding groove of trochlea.

Anterior Surface:

• It is irregularly convex and rough for muscular and ligamentous attachment.

Borders:

• They are medial & lateral, which converge below, to form the apex, which points downward.
• The dorsal border is somewhat rough and tuberous for the attachment of three patellar ligaments.

Angles:

Lateral Angle:

• It is formed by the union of base and the lateral border.

Medial Angle: 

• Formed by the union of the base and the medial border and gives attachment to the fibro-cartilage of the patella.

Ventral Angle:

•   It is formed by the union of medial and lateral border.

Base:

• It is dorsal looks upward and backward and is irregularly convex and rough.

 Apex:

• Apex is somewhat pointed and is formed by the medial & lateral border, which converge below, pointing downward.

Comparison with:

A) Patella of Horse

• Patella is wider and longer.
• Shape is not as triangular as ox due to blunt apex.
• Both medial and lateral borders join at base at greater angle.  

B) Patella of Dog:

• Patella is long and narrow, nearly oval in outline.
• Apex is rounded and base is very narrow.
• Anterior surface is more convex.

C) Patella of Pig:

• Patella is much more compressed transversely and presents three surfaces. 

D) Patella of Goat:

• Smaller in size, relatively longer and narrower than that of ox. 

E) Patella of Fowl:

• Patella is wide and thin.

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