Gordon Engle Tim Evans Tim Evans Sandra Thompson August 4, 1999

Dem Bones are Levers n Classes of levers n Radius and ulna are levers n Force is applied by muscles

Classes of levers –First class levers have the fulcrum between the weight and the force. –The ulna is a first class lever.

Classes of levers –Second class levers have the weight between the fulcrum and the force. –Where is an example of a second class lever in the body?

Classes of levers –Third class levers have the force between the fulcrum and the weight. –The radius is a third class lever.

The force is applied by muscles. n In the arm the biceps brachii and the triceps brachii work in opposition to each other to flex and extend the forearm.

Biceps brachii n The origin is the name for the attachment to the bone that doesnt move. –Long head is attached to the supraglenoid tubercle and glenohumeral labrum. –Short head is attached to the tip of the coracoid process of the scapula.

Biceps brachii n The insertion is the name for the attachment to the bone that does move. –Radial tuberosity –Bicipital aponeurosis

Triceps brachii n Origin –Long head attaches to the infraglenoid tubercle of the scapula. –Lateral head attaches to the upper half of the posterior surface of the shaft of the humerus, and the upper part of the lateral intermuscular septum. –Medial head attaches to the posterior shaft of the humerus and lateral intermuscular septum

Triceps brachii n Insertion –Posterior surface of the olecranon process of the ulna –Deep fascia of the antebrachium

Dem Bones are Levers n Classes of levers n Radius and ulna are levers n Force is applied by muscles