Osteology of the Elbow and Forearm Complex

Transcription

1 Osteology of the Elbow and Forearm Complex The ability to perform m any activities of daily living (ADL) d epends upon the elbow.

2 Activities of Daily Living (ADL) Can you think of anything that you do to take care of yourself that would not require you to flex your elbow?

3 Bone Markings Epicondyle Prominence above or on a condyle Condyle(rounded knucklelike projection) Head Rounded projection beyond a narrow, necklike portion of bone Fossa Hollow or depression Spine Long, thin projection Tubercle Small, rounded projection Tuberosity Large, rounded projection Process a projecting part

4 Elbow/Forearm Joints Elbow Humeroulnar Humeroradial Forearm Proximal radioulnar Distal radioulnar

5 Osteology of the Structures

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10 Osteology of the Proximal Structures of the Elbow & Forearm Ulna Radius

11 Osteology of the Distal Structures of the Forearm Ulna Radius

12 The Elbow Joint 2 articulations The humeroulnar /humeroradial joints Structural stability for the joint: trochlear notch Hinge joint Allows flexion (145 ) and extension (0 ) Hyperextension is common (5-10 degrees)

13 So how much elbow ROM do you need? Usually about 100 o for most ADLs, but it occurs between 30 and 130 degrees of flexion

14 Carrying Angle? (normal cubitus valgus) With the forearm supinated and elbow fully extended, the forearm projects laterally about o relative to the humerus. This is normal, but tends to be greater in females.

15 Supporting Structures of the Elbow Bony interlocking of humerus, ulna, and radius Coronoid process /fossa in flexion Olecranon process/fossa in extension Joint Capsule: Fairly lax, resists valgus and distraction forces Medial Collateral Ligament: Help provide stability in resisting valgus producing forces Most important soft tissue stabilizing structure Lateral Collateral Ligament: From the lateral epicondyle to the proximal forearm, resists varus Not an important stabilizing structure because varus forces are resisted mostly by bony constraints Interosseus Membrane

16 Medial Lateral

17 Interosseous Membrane

18 Arthrology of the Forearm Composed of proximal and distal radioulnar joints Acts as one uniaxial joint Supination and Pronation occur at humeroradial and in radioulnar joints

19 Osteology Note: The proximal radius rotates around the ulna which is stationary The distal radius is larger and broader than the distal ulna

20 Supination & Pronation Shoulder rotation can often be functionally substituted for each motion But not if the humerus is held tight against the thorax and the elbow is in 90 o of flexion

21 Colle s Fracture Fracture of the distal radius The weight of the body is transmitted through the hand and wrist, exceeding the strength of the radius The interosseous membrane dissipates some of the force

22 2007 McGraw-Hill Higher Education. All rights reserved. Movements Flexion movement of forearm to shoulder by bending the elbow to decrease its angle Extension movement of forearm away from shoulder by straightening the elbow to increase its angle 22

23 2007 McGraw-Hill Higher Education. All rights reserved. Movements Pronation 23 internal rotary movement of radius on ulna that results in hand moving from palmup to palm-down position Supination external rotary movement of radius on ulna that results in hand moving from palm-down to palm-up position

24 2007 McGraw-Hill Higher Education. All rights reserved. Muscles Elbow flexors Biceps brachii Brachialis Brachioradialis Weak assistance from Pronator teres Elbow extensor 24 Triceps brachii Anconeus provides assistance

25 2007 McGraw-Hill Higher Education. All rights reserved. Muscles 25 Radioulnar pronators Pronator teres Pronator quadratus Brachioradialis Radioulnar supinators Biceps brachii Supinator muscle Brachioradialis

26 2007 McGraw-Hill Higher Education. All rights reserved. Muscles 6-26 Anterior Primarily flexion & pronation Biceps brachii Brachialis Brachioradialis Pronator teres Pronator quadratus

27 2007 McGraw-Hill Higher Education. All rights reserved. Muscles 27 Posterior Primarily extension & supination Triceps brachii Anconeus Supinator

28 2007 McGraw-Hill Higher Education. All rights reserved. Nerves All elbow & radioulnar joints muscles are innervated from median, musculotaneous, & radial nerves of brachial plexus

29 Redundancy is a fact of life/function Innervation The musculocutaneous n. Supplies most of the elbow flexors.. EXCEPT the brachioradialis and pronator teres The radial n. Supplies the elbow extensors The median n. Supplies all the pronators of the forearm

30 Myology of the Elbow Biceps Brachii Origin Insertion Long Head: Supraglenoid tubercle of the scapula Short Head: Coracoid process of the scapula Bicipital tuberosity of the radius Innervation Musculocutaneous n. Action tidbit Elbow flexion, sh flexion and forearm supination corkscrew muscle Biceps Brachii Muscle Bellies Biceps Brachii Biceps Brachii Tendons

31 Myology of the Elbow Brachialis Origin Insertion Anterior aspect of the distal humerus Coronoid process of the ulna Innervation Musculocutaneous n. Action tidbit Elbow flexion workhorse for elbow flexion

32 Myology of the Elbow Brachioradialis Origin Insertion Innervation Radial n. Action Lateral supracondylar ridge of the humerus Near the styloid process of the distal radius Elbow flexion, Pronation or supination of the forearm to the neutral position

33 Myology of the Elbow Triceps Brachii Origin Insertion Innervation Radial n. Action Long Head: infraglenoid tubercle of the scapula Lateral Head: posterior aspect of the superior humerus, lateral to the radial groove Medial Head: posterior aspect of the superior humerus, medial to the radial groove Olecranon process of the ulna Elbow extension Sh extension: Long head only

34 Myology of the Elbow Anconeus Origin Insertion Innervation Radial n. Action tidbit Posterior aspect of the laterals epicondyle of the humerus Olecranon process of the ulna Elbow extension? Believed to clear the joint space of soft tissue to permit full elbow extension. Too small to create torque for elbow extension.

35 Myology of the Elbow Supinator Origin Insertion Innervatio n Action Lateral epicondyle of the humerus and supinator crest of the ulna Lateral surface of the proximal radius Radial n. Forearm supination,

36 Myology of the Forearm Pronator Teres Origin Insertion Innervation Median n. Action Humeral head; medial epicondyle of the humerus Lateral surface of the midshaft of the radius Forearm pronation, secondary elbow flexion

37 Myology of the Forearm Pronator Quadratus Origin Insertion Innervation Median n. Action Anterior surface of the distal ulna Anterior surface of the distal radius Forearm pronation