Structure & Function of the Knee

One of the most complex “simple” structures in the human body.

The “middle child” of the lower extremity.

Osteology of the Knee

Distal femur

Right Femur

(ADDuctor tubercle)

Osteology of the Knee

The proximal tibia & fibula

The medial and lateral

condyles of the tibia form the

shallow articulations with the

distal femur

The intercondylar/intercondyloid

eminence

the attachment point for the

cruciate ligaments

Tibial

TuberosityFibular

Head

Interosseous

Membrane

Anatomy of the Knee: Anterior Aspect

• Femur

• Medial Condyle

• Articular Cartilage

• Quadriceps Tendon

• Tibia

• Tibial Plateau

• Tibial Tuberosity

• Patellar Tendon

• Fibula

• Medial Meniscus

• Lateral Meniscus

• Medial Collateral Ligament

• Lateral Collateral Ligament

Anatomy of the Knee: Posterior Aspect• Femur

• Medial condyle

• Lateral condyle

• ADDuctor Tubercle

• Tibia

• Tibial plateau

• Fibula

• Fibular Head

• Medial Meniscus

• Lateral Meniscus

• Posterior Cruciate Ligament

• Lateral Collateral Ligament

• Medial Collateral Ligament

• Popliteal space

Anatomy of the Knee

Cruciate Ligaments

Anterior: (ACL)

-resists anterior motion of the

tibia on a fixed femur

-resists extremes of knee

extension

Posterior: (PCL)

-resists posterior motion of

the tibia on a fixed femur

-resists extremes of knee

flexion

Anatomy of the Knee: Genu “what?”

Genu valgum refers to a

frontal deviation of the

position of the knee.

Commonly referred to as

“knock-knee” due to the

medial displacement of

the knee

Genu varum refers to a

frontal deviation of the

position of the knee.

Commonly referred to as

“bow-leg”

Anatomy of the Knee: Genu “what?”

Genurecurvatum:

Hyperextension of the tibiofemoral joint placing

excessive stress on the structures in the popliteal

space

Tibial nerve

Popliteal Vein

Popliteal Artery

Common Peroneal Nerve

Common Pathologies of the Knee

Chondromalacia of

the Patella

Osgood-Schlatter’s

Disease

Common Pathologies of the Knee

The menisci:

absorb shock and disperse large compressive forces

through the knee joint

They may not heal well:

inner 1/3: avascular (a)

middle 1/3: poor blood supply (b)

outer 1/3: good blood supply (c)

Myology of the Knee

Your subtopic goes hereRectus Femoris

Origin Anterior-inferior iliac spine

Insertion Tibial tuberosity via the quadriceps

tendon

Innervation Femoral n.

Action Hip flexion, knee extension

“tidbit” One of the heads of the “quads”

Myology of the Knee

Vastus Medialis

Origin Medial lip of the linea aspera

and the intertrochanterid line

of the femur

Insertion Tibial tuberosity via the

patellar tendon

Innervation Femoral n.

Action Knee extension

“tidbit” •One of the heads of the

“quad”

•“VMO” one of the first

muscles of the knee to atrophy

post-operatively,

• responsible for last 10-15o of

knee extension

Vastus

Medialis

Obliquus

Myology of the Knee

Vastus Lateralis

Origin Lateral lip of the linea aspera,

intertrochanteric line, lateral

region of the gluteal tuberosity

Insertion Tibial tuberosity via the

patellar tendon

Innervation Femoral n.

Action Knee extension

“tidbit” Part of the “quads”

Myology of the Knee

Vastus Intermedius

Origin Upper 2/3 of the anterior

femoral shaft

Insertion Tibial tuberosity via the patellar

tendon

Innervation Femoral n.

Action Knee extension

Q –Angle of the Knee

The line of force of the quadriceps can be described by

the Q-angle. It identifies patellofemoral tracking.

Females:

-greater angle

-greater incidence

of patellofemoral

joint pain

Q

Angle

Compression at the Patellofemoral Joint

The Patella:-also known as the knee cap, is a

thick, circular-triangular bone

which articulates with the femur

and covers and protects the

anterior articular surface of the

knee

Activity Force % Body

Weight

Pounds of

Force

Walking 850 N 1/2 x BW 100 lbs

Bike 850 N 1/2 x BW 100 lbs

Stair Ascend 1500 N 3.3 x BW 660 lbs

Stair Descend 4000 N 5 x BW 1000 lbs

Jogging 5000 N 7 x BW 1400 lbs

Squatting 5000 N 7 x BW 1400 lbs

Deep Squatting 15000 N 20 x BW 4000 lbs

To Squat or not to Squat?

Alignment is the key

Balance among the heads

of the quads is critical to

the health of your knees

Myology of the Knee

Your subtopic goes hereSemitendinosus

Origin Ischial tuberosity

Insertion Proximal-medial surface of the tibia

(pes anserinus)

Innervation Tibial portion of the sciatic n.

Action Hip extension, knee flexion,

“tidbit” One of the hamstrings

Myology of the Knee

Your subtopic goes hereBiceps Femoris

Origin Ischial tuberosity

Insertion Head of the fibula

Innervation Tibial portion of the sciatic n.

Action Hip extension, knee flexion

“tidbit” One of the hamstrings

A

A B C DBicep F Bicep F Semimem Semiten

Myology of the Knee

Your subtopic goes hereSemimembranosus

Origin Ischial tuberosity

Insertion Medial condyle of the tibia, posterior aspect

Innervation Tibial portion of the sciatic n.

Action Hip extension, knee flexion

“tidbit” One of the hamstrings

Myology of the Knee

Your subtopic goes hereSartorius

Origin ASIS

Insertion Proximal-medial surface of the tibia (via

the pes anserinus)

Innervation Femoral n.

Action Hip flexion, hip ABD, Hip ER, knee

flexion

“tidbit” Longest muscle in the body

Myology of the Knee

Your subtopic goes hereGracillis

Origin Body and inferior ramus of the

pubis

Insertion Proximal-medial aspect of the

tibia (pes anserinus)

Innervation Obturator n.

Action Hip ADD, hip flexion, knee

flexion

What is the Pes Anserinus?

The semitendinosus, sartorius and gracillis all attach to the proximal

medial tibia through a broad sheet of connective

tissue known as the pes anserinus.

The 3 muscles:

-originate from different

bones on the pelvis

-perform different actions

at the hip

-are innervated by different

nerves

The all perform the following at the knee:

-flexion

-medial stability

Myology of the Knee

Popliteus

Origin Posterior aspect of the

lateral femoral condyle

Insertion Posterior surface of the

proximal tibia

Innervation Tibial n.

Action Initiates knee flexion

Myology of the Knee

Gastrocnemius

Origin Medial head: posterior aspect of the

medial femoral condyle

Lateral head: posterior aspect of the

lateral femoral condyle

Insertion Calcaneal tuberosity via the Achilles

tendon

Innervation Tibial n.

Action Flexion of the knee, plantar flexion,

What can you identify? (in her knee)

Quadriceps

Vastus medialis

Vastus lateralis

Vastus intermedius?

Rectus femoris

Sartorius

Anything else?