Chapter 5 Functional Anatomy of the Upper Extremity

Review of Anatomical Structures Shoulder girdle An incomplete bony ring in the upper extremity formed by the two scapulae and clavicles Scapula Flat, triangular bone on the upper posterior thorax Clavicle “S”-shaped bone articulating with scapula and sternum “Collar bone” Glenoid fossa Depression in lateral superior scapula Socket for shoulder joint Glenoid labrum Ring of fibrocartilage around rim of glenoid fossa Deepens socket for shoulder joint

Review of Anatomical Structures (cont.) Bursa Fibrous, fluid-filled sac that reduces friction Located between bones, tendons, and other structures Subacromial bursa Bursa between acromion process and insertion of supraspinatus muscle Coracoid process Curved process arising from upper neck of scapula Overhangs shoulder joint

The Shoulder Complex Sternoclavicular joint Articulation between sternum and clavicle Acromioclavicular joint Articulation between acromion process of scapula and lateral end of clavicle Scapulothoracic joint Physiological joint between the scapula and thorax Glenohumeral joint Articulation between the head of the humerus and the glenoid fossa of the scapula

Movements of the Shoulder Complex Dislocation Rotation Elevation and Depression Protraction and Retraction Horizontal Flexion and Extension

Scapular Movements

Shoulder Joint Range of Motion

Shoulder Joint Movement Characteristics Large range of motion (ROM) at shoulder Extreme ROM required by many activities Swimming, throwing, gymnastics Ligaments and muscles provide stability Scapular and clavicular movements accompany any arm movement Scapulohumeral rhythm Movement relationship between humerus and scapula during arm raising movements

Muscular Actions Review Figure 5-9 on page 148 17 muscles that contribute to scapula and shoulder joint movements are listed Major muscles Deltoid, trapezius, rhomboids, pectoralis major, latissimus dorsi, serratus anterior Rotator cuff (4 muscles surrounding shoulder joint) Infraspinatus, supraspinatus, teres minor, subscapularis

Arm Abduction and Flexion

Muscle Action on the Shoulder Girdle

Shoulder Muscle Strength Generate greatest strength in adduction Abduction used frequently in daily living Weakest movements are internal and external rotation Muscles generate high forces within joint Almost 90% of body weight at 90° abduction Implications?

Shoulder Strength & Conditioning Shoulder muscles easy to stretch and strengthen Stretching Active and passive Strength training Weight training, limb/body weight exercises Rotator cuff strength and flexibility important Stabilization of joint Widely used in daily living

Stretching & Strengthening Exercises Review Figure 5-14 on pages 152 and 153.

Injury Sprain Rupture of fibers of ligament Subluxation Partial dislocation Fracture Break in bone, often clavicle Ectopic calcification Hardening of organic tissue through deposit of calcium salts in areas away from the normal sites Degeneration Deterioration of tissue

Injury (cont.) Bursitis Inflammation of bursa Impingement syndrome Irritation of structures above shoulder joint Due to repeated compression between greater tuberosity and acromion process Subacromial bursitis Common from impingement syndrome Bicipital tendinitis Inflammation of the tendon of the biceps brachii

Elbow and Radioulnar Joints Radiohumeral joint Articulation between radius and humerus Capitulum Eminence on distal end of lateral epicondyle Articulates with head of radius at elbow Ulnar-humeral joint “Elbow” Articulation between ulna and humerus Medial and lateral epicondyles Carrying angle Angle between ulna and humerus with elbow extended 10–20°

Carrying Angle

Elbow and Radioulnar Joints (cont.) Articulations between ulna and radius Proximal and distal Pronation, supination Interosseous membrane Thin layer of tissue running between ulna and radius Medial and lateral epicondyles

Elbow Movement Characteristics and Muscular Actions All 3 joints never close packed at same time Movements limited by several factors Soft tissue, ligaments, joint capsule, muscles 24 muscles cross elbow Most of these muscles capable of multiple movements Muscles better at some movements than others

Elbow Flexor Moment Arms

Biceps Brachii Action

Forearm Strength and Conditioning Flexor group nearly twice as strong as extensor Effectiveness of strengthening/stretching exercises Depends on position of arm Length-tension relationship Numerous exercises

Stretching and Strengthening Exercises Review Figure 5-21 on page 162.

Injury to Forearm Overuse injuries more common than trauma Throwing, tennis serve Ectopic bone Bone formation away from normal site Rupture Torn or disrupted tissue Muscle Olecranon bursitis Irritation of the olecranon bursae Commonly caused by falling on elbow

Injury to Forearm (cont.) Medial tension syndrome “Pitcher’s elbow” Medial elbow pain from excessive valgus forces May include ligament sprain, medial epicondylitis, tendinitis, avulsion fracture Osteochondritis dissecans Inflammation of bone and cartilage resulting in splitting pieces of cartilage into the joint

Wrist & Fingers Manipulation activities Very fine movements Many stable, yet mobile, segments

Joints of the Wrist Radiocarpal “Wrist” Ellipsoid joint Flexion/extension, radial/ulnar flexion Distal radioulnar Ulna makes NO contact with carpals Does NOT participate in wrist movements Midcarpal Articulation between two rows of carpals Intercarpal Articulation between a pair of carpals

Joints of the Wrist (cont.) Carpometacarpal Articulations between carpals and metacarpals Metacarpophalangeal Articulations between metacarpals and phalanges Interphalangeal Articulations between phalanges

Muscular Actions Most originate outside hand region Thenar eminence Mound on radial side of palm formed by intrinsic muscles acting on thumb Hypothenar eminence Mound on ulnar side of palm created by intrinsic muscles acting on little finger

Muscular Actions (cont.) Hand flexion/extension Hand radial/ulnar flexion Finger flexion/extension Finger abduction/adduction Thumb flexion/extension Thumb abduction/adduction Thumb opposition

Conditioning Why condition hand region? Improve grip strength Enhance wrist action for throwing, striking Prevent injury Exercises Wrist curls Gripping exercises Stretching

Contributions of the Wrist & Hand Power grip Powerful hand position Maximally flexing fingers around object Precision grip Fine-movement hand position Minimally flexing fingers around object Examples: Eating with fork Throwing softball Spiking volleyball Dribbling basketball Changing channel with remote control

Grip

Injury of the Wrist & Hand Bennett’s fracture Longitudinal fracture of base of first metacarpal Mallet finger Avulsion of finger extensor tendons at distal phalanx Result of forced flexion Boutonniere deformity Stiff proximal interphalangeal articulation Caused by injury to finger extensor mechanism

Injury of the Wrist & Hand (cont.) Jersey finger Avulsion of finger flexor Result of forced hyperextension Trigger finger Snapping during flexion and extension of fingers Created by nodules on tendons

Injury of the Wrist & Hand (cont.) Tenosynovitis Inflammation of sheath surrounding tendon Carpal tunnel syndrome Pressure and constriction of median nerve Caused by repetitive actions at wrist

Carpal Tunnel

Stretching and Strengthening Exercises Review Figure 5-27 on page 172.

Contribution of Upper Extremity Musculature to Sports Skills or Movements Upper extremity is obviously important in: Everyday activities Pushing up out of a chair Carrying, lifting Sporting/leisure activities Swimming, throwing, striking (golf, volleyball)

Overhand Throwing

The Golf Swing

Summary Questions What do the upper extremities enable us to do? What stabilizes the structures of the upper extremities? What are potential injuries to the upper extremities? What causes these injuries? How can injuries be prevented? What are some exercises for stretching and strengthening the upper extremities?