Gordon EngleGordon Engle

Tim EvansTim Evans

Sandra ThompsonSandra Thompson

August 4, 1999August 4, 1999

““Dem Bones” are LeversDem Bones” are Levers

Classes of leversClasses of levers Radius and ulna are leversRadius and ulna are levers Force is applied by musclesForce is applied by muscles

Classes of leversClasses of levers

– First class levers have the fulcrum First class levers have the fulcrum between the weight and the force.between the weight and the force.

– The ulna is a first class lever.The ulna is a first class lever.

Classes of leversClasses of levers

– Second class levers have the weight Second class levers have the weight between the fulcrum and the force.between the fulcrum and the force.

– Where is an example of a second Where is an example of a second class lever in the body?class lever in the body?

Classes of leversClasses of levers

– Third class levers have the force Third class levers have the force between the fulcrum and the weight.between the fulcrum and the weight.

– The radius is a third class lever.The radius is a third class lever.

The force is applied by The force is applied by muscles.muscles.

In the arm the biceps brachii and In the arm the biceps brachii and the triceps brachii work in the triceps brachii work in opposition to each other to flex opposition to each other to flex and extend the forearm.and extend the forearm.

Biceps brachiiBiceps brachii

The origin is the name for the The origin is the name for the attachment to the bone that attachment to the bone that doesn’t move.doesn’t move.– Long head is attached to the Long head is attached to the

supraglenoid tubercle and supraglenoid tubercle and glenohumeral labrum.glenohumeral labrum.

– Short head is attached to the tip of Short head is attached to the tip of the coracoid process of the scapula.the coracoid process of the scapula.

Biceps brachiiBiceps brachii

The insertion is the name for the The insertion is the name for the attachment to the bone that does attachment to the bone that does move.move.– Radial tuberosityRadial tuberosity– Bicipital aponeurosisBicipital aponeurosis

Triceps brachiiTriceps brachii

OriginOrigin– Long head attaches to the infraglenoid Long head attaches to the infraglenoid

tubercle of the scapula.tubercle of the scapula.– Lateral head attaches to the upper half of Lateral head attaches to the upper half of

the posterior surface of the shaft of the the posterior surface of the shaft of the humerus, and the upper part of the lateral humerus, and the upper part of the lateral intermuscular septum.intermuscular septum.

– Medial head attaches to the posterior shaft Medial head attaches to the posterior shaft of the humerus and lateral intermuscular of the humerus and lateral intermuscular septumseptum

Triceps brachiiTriceps brachii

InsertionInsertion– Posterior surface of the olecranon Posterior surface of the olecranon

process of the ulnaprocess of the ulna– Deep fascia of the antebrachiumDeep fascia of the antebrachium

““Dem Bones” are LeversDem Bones” are Levers

Classes of leversClasses of levers Radius and ulna are leversRadius and ulna are levers Force is applied by musclesForce is applied by muscles