Chapter 5 the Shoulder Joint

Home , Greater tubercle, Lesser tubercle, Rotator cuff, Scapula, Shoulder, Shoulder girdle

• Shoulder joint is attached to axial skeleton via the clavicle at SC joint • Scapula movement usually occurs with movement of humerus Chapter 5 – Humeral flexion & abduction require scapula The Shoulder Joint elevation, rotation upward, & abduction – Humeral adduction & extension results in scapula depression, rotation downward, & adduction Manual of Structural Kinesiology – Scapula abduction occurs with humeral internal R.T. Floyd, EdD, ATC, CSCS rotation & horizontal adduction – Scapula adduction occurs with humeral external rotation & horizontal abduction

The Shoulder Joint Bones

• Wide range of motion of the shoulder joint in • Scapula, clavicle, & humerus serve as many different planes requires a significant attachments for shoulder joint muscles amount of laxity – Scapular landmarks • Common to have instability problems • supraspinatus fossa – Rotator cuff impingement • infraspinatus fossa – Subluxations & dislocations • subscapular fossa • spine of the scapula • The price of mobility is reduced stability • glenoid cavity • The more mobile a joint is, the less stable it • coracoid process is & the more stable it is, the less mobile • acromion process • inferior angle

© McGraw-Hill Higher Education. All rights reserved. 5-3 © McGraw-Hill Higher Education. All rights reserved. From Seeley RR, Stephens TD, Tate P: Anatomy and physiology , ed 7, 5-4 New York, 2006, McGraw-Hill

Bones Bones

• Scapula, clavicle, & humerus serve as • Key bony landmarks attachments for shoulder joint muscles – Acromion process – Humeral landmarks – Glenoid fossa • Head – Lateral border • Greater tubercle – Inferior angle • Lesser tubercle – Medial border • Intertubercular groove • Deltoid tuberosity – Superior angle – Spine of the scapula

1 Glenohumeral Joint Glenohumeral Joint

– Glenoid labrum • multiaxial ball- slightly &-socket enhances stability • enarthrodial

Glenohumeral Joint Glenohumeral Joint

– Glenohumeral – Ligaments are quite lax until extreme ligaments provide ranges of motion reached due to wide stability range of motion involved • especially – Stability is sacrificed to gain mobility anteriorly & inferiorly • inferior glenohumeral ligament

Glenohumeral Joint Glenohumeral Joint

• Determining – 90 to 95 degrees exact range of abduction each – 0 degrees adduction, movement is 75 degrees anterior difficult due to to trunk accompanying shoulder girdle movement

2 Glenohumeral Joint Glenohumeral Joint

– 40 to 60 degrees of – 70 to 90 degrees of internal & external extension rotation – 90 to 100 degrees of flexion

Glenohumeral Joint Glenohumeral Joint

– 45 degrees of • Frequently injured due to anatomical design horizontal – shallowness of glenoid fossa abduction – laxity of ligamentous structures – 135 degrees of – lack of strength & endurance in muscles horizontal adduction – anterior or anteroinferior glenohumeral subluxations & dislocations – common – posterior dislocations – rare – posterior instability problems somewhat common

Pairing of shoulder girdle & shoulder joint Glenohumeral Joint movements • Rotator cuff is frequently injured Shoulder joint Shoulder girdle Abduction Upward rotation – Subscapularis, supraspinatus, infraspinatus, & teres minor muscles Adduction Downward rotation – attach to the front, top, & rear of humeral head Flexion Elevation/upward rotation – point of insertion enables humeral rotation Extension Depression/downward rotation – vital in maintaining humeral head in correct Internal rotation Abduction (protraction) approximation within glenoid fossa while more External rotation Adduction (retraction) powerful muscles move humerus through its wide Horizontal abduction Adduction (retraction) range of motion Horizontal adduction Abduction (protraction)

3 Movements Movements

• Abduction • Flexion – upward lateral – movement movement of humerus of humerus out to the side, away straight from body anteriorly • Adduction • Extension – downward movement – movement of humerus medially of humerus toward body from straight abduction posteriorly

Movements Movements

• Horizontal adduction • External rotation (transverse flexion) – movement of – movement of humerus in a humerus laterally horizontal or transverse around its long axis plane toward & across chest away from midline • Horizontal abduction • Internal rotation (transverse extension) – movement of – movement of humerus in a humerus medially horizontal or transverse around its long axis plane away from chest toward midline

Movements Muscles

• Diagonal abduction • Intrinsic glenohumeral muscles – movement of humerus – Originate on scapula & clavicle in a diagonal plane – Deltoid, Coracobrachialis, Teres major away from midline of – Rotator cuff group body • subscapularis, supraspinatus, infraspinatus, & • Diagonal adduction teres minor – movement of humerus • Extrinsic glenohumeral muscles in a diagonal plane – latissimus dorsi & pectoralis major toward midline of body

4 Muscles Muscles

• Anterior • Superior – Pectoralis major – Deltoid – Coracobrachialis – Supraspinatus – Subscapularis • Posterior • Superior – Latissimus dorsi – Deltoid – Teres major – Supraspinatus – Infraspinatus – Teres minor From Shier D, Butler J, Lewis R: Hole’s essentials of human anatomy and physiology , ed 9, New York, 2006, McGraw-Hill.

From Shier D, Butler J, Lewis R: Hole’s essentials of human anatomy and physiology , ed 9, © McGraw-Hill Higher Education. All rights reserved. New York, 2006, McGraw-Hill. 5-25 © McGraw-Hill Higher Education. All rights reserved. 5-26

Nerves Nerves

• All shoulder joint muscles are innervated from • Axillary nerve branching the brachial plexus from C5 & C6 • Lateral pectoral nerve arising from C5, C6, & – Deltoid C7 – Teres minor – Pectoralis major (clavicular head) – Sensation to lateral patch of • Medial pectoral nerve arising from C8 & T1 skin over deltoid region of – Pectoralis major (sternal head) arm • Thoracodorsal nerve arising from C6, C7, & C8 • Upper subscapular nerves – Latissimus dorsi arising from C5 & C6 – Subscapularis

Nerves Nerves

• Lower subscapular nerve arising from • Musculotaneous nerve C5 & C6 branching from C5, C6, & – Subscapularis C7 – Teres major – Coracobrachialis • Suprascapula nerve originating from – Sensation to radial aspect C5 & C6 of forearm – Supraspinatus – Infraspinatus

5 Deltoid Muscle Pectoralis Major Muscle Upper fibers (clavicular head): Anterior fibers: Posterior fibers: internal rotation, horizontal abduction, flexion, abduction, extension, adduction, flexion, abduction (once horizontal adduction, horizontal abduction, arm is abducted 90 degrees, upper fibers assist in further abduction), & & internal rotation & external rotation adduction (with arm below 90 degrees of abduction) Middle fibers: Lower fibers (sternal abduction head): internal rotation, horizontal adduction, extension, & adduction

Latissimus Dorsi Muscle Coracobrachialis Muscle

Adduction

Extension Flexion Adduction Internal rotation Horizontal adduction Horizontal abduction

Rotator cuff muscles Rotator cuff muscles • Supraspinatus • not very large – attach to greater tubercle from above (Abduct) • must possess strength & muscular endurance • Infraspinatus • conducting repetitious overhead activities – attach to greater tubercle posteriorly (Ext. Rot.) (throwing, swimming, & pitching) with poor • Teres Minor technique, muscle fatigue, or inadequate warm- – attach to greater up & conditioning leads to failure of rotator cuff tubercle posteriorly muscle group in dynamically stabilizing humeral (Ext. Rot.) head in glenoid cavity S • ubscapularis • leads to further rotator cuff problems such as – attach to lesser tendinitis & rotator cuff impingement within tubercle anterior (Int. subacromial space Rot.)

6 Subscapularis Muscle Supraspinatus Muscle

Internal rotation Adduction Abduction Extension Stabilization of the Stabilization of the humeral head in humeral head in glenoid fossa glenoid fossa

Infraspinatus Muscle Teres Minor Muscle

External rotation External rotation

Horizontal abduction Horizontal abduction

Extension Extension

Stabilization of humeral Stabilization of humeral head in the glenoid fossa head in the glenoid fossa

Teres Major Muscle Glenohumeral Flexion

Extension, particularly from • Agonists the flexed position to the – Anterior Deltoid posteriorly extended position – Upper Pectoralis Major Internal rotation Adduction, particularly from the abducted position down to the side & toward midline of body

7 Glenohumeral Extension Glenohumeral Abduction

• Agonists • Agonists – Teres – Deltoid Major – Supraspinatus – Latissimus – Upper Pectoralis Dorsi Major – Lower Pectoralis Major

Glenohumeral Adduction Glenohumeral Internal Rotation

• EX. Lat. Pull - • Agonists pull down – Latissimus weights Dorsi • Agonists – Teres Major – Latissimus – Subscapularis Dorsi – Pectoralis – Teres Major Major – Lower Pectoralis • All attach Major anteromedially on humerus

Glenohumeral External Rotation Glenohumeral Horizontal Abduction

• Agonists • Agonists – Infraspinatus – Posterior – Teres Minor Deltoid • Both attach – Middle posteriorly on Deltoid greater tubercle – Infraspinatus – Teres Minor

8 Glenohumeral Horizontal Adduction Glenohumeral Diagonal Abduction

• Agonists • Agonists – Anterior Deltoid – Posterior Deltoid – Pectoralis Major – Infraspinatus – Coracobrachialis – Teres Minor – Triceps Brachii (Long Head)

Glenohumeral Diagonal Adduction Web Sites

Radiologic Anatomy Browser http://radlinux1.usuf1.usuhs.mil/rad/iong/index.html • Agonists - both – This site has numerous radiological views of the low & high musculoskeletal system. University of Arkansas Medical School Gross Anatomy for Medical – Anterior Deltoid Students http://anatomy.uams.edu/anatomyhtml/grossresources.html – Coracobrachialis – Dissections, anatomy tables, atlas images, links, etc. Loyola University Medical Center: Structure of the Human Body – Biceps Brachii www.meddean.luc.edu/lumen/MedEd/GrossAnatomy/GA.html (short head) – An excellent site with many slides, dissections, tutorials, etc., for the study of human anatomy – Pectoralis Major - Wheeless’ Textbook of Orthopaedics Upper & Lower www.wheelessonline.com/ – This site has an extensive index of links to the fractures, joints, muscles, nerves, trauma, medications, medical topics, lab tests, and links to orthopedic journals and other orthopedic and medical news. © McGraw-Hill Higher Education. All rights reserved. 5-51 © McGraw-Hill Higher Education. All rights reserved. 5-52

Web Sites Web Sites

Premiere Medical Search Engine Lecture Topics in Kinesiology http://www.medsite.com/Default.asp?bhcp=1 http://moon.ouhsc.edu/dthompso/namics/shoulder.htm – This site allows the reader to enter any medical condition and – Shoulder articulations, movements, and muscles that are it will search the net to find relevant articles. within the shoulder girdle Arthroscopy.Com The Physician and Sportsmedicine www.arthroscopy.com/sports.htm www.physsportsmed.com/issues/2003/0703/depalma.htm – Patient information on various musculoskeletal problems of – Detecting and Treating Shoulder Impingement Syndrome: The the upper and lower extremity Role of Scapulothoracic Dyskinesis Virtual Hospital Southern California Orthopedic Institute www.vh.org www.scoi.com/sholanat.htm – Numerous slides, patient information, etc. – Anatomy of the Shoulder Medical Multimedia Group FamilyDoctor.org www.healthpages.org/AHP/LIBRARY/HLTHTOP/CTD/ http://familydoctor.org/268.xml – A Patient's Guide to Cumulative Trauma Disorder (CTD) – Shoulder Pain Baseball Almanac www.baseball-almanac.com/chapters/cap-ch8.shtml – Coaching Adult Pitchers

9 Web Sites Web Sites

MedlinePlus Orthopaedic Research Institute www.nlm.nih.gov/medlineplus/tutorials/shoulderarthroscopy/htm/ http://www.ori.org.au/bonejoint/shoulder/contents.htm index.htm – Several web pages, text, and graphics on glenohumeral – Shoulder arthroscopy interactive tutorial instability MedlinePlus American Sports Medicine Institute www.nlm.nih.gov/medlineplus/tutorials/rotatorcuffinjuries/htm/ind www.asmi.org/asmiweb/mpresentations/mmp.htm ex.htm – Biomechanics of the Shoulder during Throwing – Rotator cuff injuries interactive tutorial American Sports Medicine Institute American Physical Therapy Association http://www.asmi.org/SportsMed/throwing/thrower10.html www.apta.org/AM/Template.cfm?Section=Home&TEMPLATE=/ – Throwers Ten Exercises CM/HTMLDisplay.cfm&CONTENTID=20448 Washington Musculoskeletal Tumor Center – Taking Care of Your Shoulder www.sarcoma.org/main.php?page=shoulder American Academy of Orthopaedic Surgeons – Shoulder girdle surgery http://orthoinfo.aaos.org/category.cfm?topcategory=Shoulder – Patient Education Library on the Shoulder