Muscles of the Elbow Joint

• Muscles of the Elbow Joint

  these muscles cross the elbow joint to insert on the forearm bones, which they flex/extend

  walls of fascia divide the arm into 2 muscle compartments - the posterior extensors + anterior flexors
• Extension of the Elbow Joint

  the main forearm extensor = bulky triceps brachii

  = forms nearly the entire musculature of the posterior compartment
• Flexion of the Elbow Joint

  all anterior arm muscles flex the forearm (elbow)

  in order of decreasing strength:

  brachialis

  biceps brachii

  brachioradialis
• Chief Forearm (Elbow) Flexors

  the brachialis + biceps insert respectively into the ulna + radius + contract simultaneously during flexion

  = chief forearm flexors

  the brachialis, which lies deep to the biceps is equally important in flexing the elbow
• Brachioradialis


  cos the brachioradialis arises from the distal humerus + inserts on the distal forearm, it resides mainly in the forearm

  its force is exerted far from the fulcrum (elbow), so the brachioradialis is a weak forearm flexor
• Triceps Brachii - Description & Location

  large fleshy muscle

  the only muscle of posterior compartment of arm

  3-headed origin

  long + lateral heads lie superficial to medial head

  
• Triceps Brachii - Action

  powerful forearm extensor - prime mover = medial head

  antagonist of forearm flexors

  long + lateral heads mainly active in extending the forearm against resitance

  long head tendon may help stabilise shoulder joint + assist in arm adduction
• Anconeus - Description & Location

  short triangular muscles, partially belended w distal end of triceps on posterior humerus

  
• Anconceus - Action


  synergist of triceps brachii in elbow extension

  may control ulnar abduction during forearm pronation
• Biceps Brachii - Description & Action

  2-headed fusiform

  tendon of long head helps stabilise shoulder joint

  flexes + supinates forearm

  these actions usually occur at same time

  weak flexor of arm at shoulder

  
• Brachialis - Description, Location, Origin & Insertion

  storng muscle that is immediately deep to biceps brachii on distal humerus

  origin - anterior surface of distal humerus, embraces insertion of deltoid muscle

  insertion - coronoid process of ulna + capsule of elbow joint

  
• Brachialis - Action


  a major forearm flexor

  lifts ulna as biceps lifts the radius
• Brachioradialis - Description & Location

  superficial muscle of lateral forearm

  extends from distal humerus to distal forearm

  
• Brachioradialis - Action


  synergist in flexing forearm

  acts to best advantage when forearm is partially flexed + semipronated

  stabilises elbow during rapid flexion + extension