Muscles and Joints

What are Muscles?

Units are bundled together with various connective tissues

Myofibril consists of bands of actin and myosin filaments.

Muscle Fascicle Muscle fiber Myofibril

Muscles and MovementOn a cellular level:

ACh released by the axon ending signals a release of Ca2+

Ca2+ removes complex over the actin fibril.

Myosin head attaches to actin groove and contracts

ATP is hydrolyzed to move myosin head back to the starting position.

Muscles and MovementOn a systemic level:

ContractionRelaxation

Most muscles work in muscle pairs:

Contracting Agonist

“Relaxing” Antagonist

But muscles do not produce systemic motion

by themselves!

Joints

Consist of:

Bone*Cartilage*Muscle*

Ligaments*Tendons*

Synovium*NervesGlands

Blood Vessels

JointsSynovial Joints:

Majority of the joints in your body

Contain a synovial cavity or sheath between the

contact points

Synovial cavity with fluid allows joints to glide

across each other

Joints

Motion Classification:

HingeBall and Socket

PivotEllipsoidal

And many more

Each joint has a certain Range of Motion (ROM)

associated with it.

Knee

Knee

Hinge JointSynovial Joint

ROM:Extension and Flexion:

-5 to 143 degrees (women) -6 to 140 degrees (men)

Studies of the range of knee motion show that -• 93 degrees is required for rising from a seated position • 106 degrees is required for shoelace tying• 135 degrees is required to take a bath

Knee Ligaments

Lateral Collateral Ligament (LCL)

Located:

Outer (or Lateral) side of the knee.

Function:

Mediolateral Stability

Knee Ligaments

Medial Collateral Ligament (MCL)

Located:

Inner (or Medial) side of the knee.

Function:

Mediolateral Stability

Covers major glands and nerves of the knee

Knee Ligaments

Anterior Cruciate Ligament (ACL)

Located:

Inside the knee joint, under the patella, near the front (anterior)

Function:

Resists anterior translation and medial rotation of the tibia

Knee Ligaments

Posterior Cruciate Ligament (PCL)Located:

Inside the knee joint, under the patella, near the back (posterior)

Function:

Prevent the femur from sliding anterior to the tibia and tibia from displacing posterior to the femur

Chicken Leg

The chicken’s knee is analogous to the human knee!! Let’s look for those ligaments!

Measuring the Effects of Injury and Illness

Injury and IllnessStress/Strain related:

Arthritis: Fracture:

Current treatment

Drug Therapy

Partial Joint Replacement

Total Joint Replacement

Reattachment

Hopes for the Future

Degradable Metal Scaffolding

Ability to Align Growing Fibrils

Stem Cell Therapy

Knee

Knee (Revisited)

Hinge JointSynovial Joint

ROM:Extension and Flexion:

-5 to 143 degrees (women) -6 to 140 degrees (men)

Studies of the range of knee motion show that -• 93 degrees is required for rising from a seated position • 106 degrees is required for shoelace tying• 135 degrees is required to take a bath

A loss of anything more than 3 degrees of motion can lead to serious problems and pain.

Why???

The Screw Home Mechanism

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Any questions?