Knee

In humans the knee refers to the joints between the femur, tibia and patella. In quadrupeds, particularly horses and ungulates the term is commonly used to refer to the carpus, probably because of its similar hinge or ginglymus action. The joints between the femur, tibia and patella are known as the stifle in quadrupeds. In insects and other animals the term knee is used widely to refer to any ginglymus joint.

a comparison beteween bony anatomy of the human pelvic gridle and leg with that of our closest living realtives, the african apes,reveals profound evolutionary changes related to the acquisition of bipedality more than 4 million years.

Fibula

The long thin bone

Beside (lateral)tibia
Articulate twice with tibia,once with the talus
The main part in forming the lateral border of the ankle joint
Little wieght

Blood Supply
The blood supply is important for planning free tissue transfer because the fibula is commonly used to reconstruct the mandible. The shaft is supplied in its middle third by a large nutrient vessel from the peroneal artery. It is also perfused from its periosteum which receives many small branches from the peroneal artery. The proximal head and the epiphysis are supplied by a branch of the anterior tibial artery. In harvesting the bone the middle third is always taken and the ends preserved (4cm proximally and 6cm distally)

The fibula is ossified from three centers, one for the shaft, and one for either end.
Ossification begins in the body about the eighth week of fetal life, and extends toward the extremities. At birth the ends are cartilaginous.
Ossification commences in the lower end in the second year, and in the upper about the fourth year. The lower epiphysis, the first to ossify, unites with the body about the twentieth year; the upper epiphysis joins about the twenty-fifth year.

the proximal and distal fibular ends are distinctive and are rarely confused with other bones.
fibular shafts are thin,straight and usually quatrilateral (sometimes rectangular) with sharp crests and corners.they are thus more irregular in cross section than either radial or ulnar shafts.

TIBIA

The major weight-bearing bone of the lower leg
tibia articulates:

proximal: distal femur
twice lateral: fibula ( one proximal/one distal)
distal: talus( is called: astragalus in other animalsplace between fibula and tibia)
tibia parts are:
tibia plateau
medial condyle
lateral //
intercondylar eminence
medial intercondylar tubercle
lateral // //
superior fibular articulate facet
tibial tuberosity
tibial shaft
soleal (popliteal)lines
nutrient foramen
anterior surface (anterior crest)
medial surface
interosseus surface
// crest
medial malleolus
fibular notch
inferior fibular articulate surface
malleolar groove

Tibia ossifies from three center
shaft and two each end of the bone

Tibia shaft is mauch larger than ulnar or radial shafts the proximal and distal ends could be mistaken with proximal articular surface for the body of vertebra but the tibia articular surface is much smoother and denser.

Patella

largest seamoid bone,articulated with the patellar surface of the distal femur(patellar notch). The patella rides in the Tendon the caudriceps femoris- the largest muscle of thigh and the primaay extensor of the knee. The patella functions to protect the knee joint, to lenghthen the lever arm of the quadricep, and to increase the area of contact between the patellar tendon and the femur.

Patella parts are:

Apex

Lateral articular facet

medial articular facet

the patella ossifies from a single center.

this bone might be mistaken for an os coxae fragment, but only in vary fragmentary state. The acetabulum of the os coxae is strongly hollowed, as opposed to the much flatter articular surface of the patella.

Patella is triangular in shape.its thin,pointed apex is distal, and the thicker, blunter end is proximal.

the lateral articular facet (articulates with the lateral condyle of the femur)= larger of the two facets.

Leg

Leg

Leg: Femur,Patella,Tibia,Fibula
The evolution of the leg mirrors is like arm.The single thight bone, the femur, is the serial homolog of the upper arm bone,the humerus. Likewise, the lower bones of the leg, the tibia and fibula,are serial homolgs of the radius and ulna. the largest sesamoid bone in the body, the patella,lies at the knee joint. The bipedal locomotor mode practiced by homonids has resulted in major specializations of leg bones.
Femur
is the longest,heaviest,and strongest bone in the body.it supports all of the body's weight during standing,walking and running.
because of its strength and density, it is frequently recovered in forensic, archaeological and paleontological contexts. The femur is valuable bone because of the information it can provide on the stature of an individual.
the femur articulates with the acetabulum of the os coxae. Distally, it articulates with the patella and proximal tibia. The leg's actions at the hip include medial and lateral rotation, abduction, flexion and extension. At knee, motion is far more restricted,confined mostly to flexion and extension. Although the main knee action is that of a sliding hinge, this joint is one of the most complex in the body.
femur parts are:
head
spiral line
pectinel line
femoral shaft
linea aspera
nutrient foramen
medial supracondylar line (ridge)
popliteal surface
lateral condyle
lateral epicondyle
popliteal groove
medial condyle
intercondylar fossa (notch)
patellar surface

the femur ossifies from 5 centers: one for shaft, head,distal end,each trochanter.

the femoral head has a fovea (fossa) and is more complete sphere than the humeral head
the femoral shaft is larger,has a thicker cortex and is rounder in cross section than any other shaft. It has only one sharp corner,the linea aspera.

For isolated femoral heads the fovea is medial and displaced posteriorly and inferiorly. The posterinferior head-neck junction is more deeply excavated than anterosuperior junction.