910 213 week 2 1 910 213 week 2 2 HUMAN FUNCTIONAL ANATOMY THE SHOULDER COMPLEX 213 SHOULDER MOVEMENT MANY JOINTS INVOLVED GlenohumeralTHIS WEEKS LAB: AcromioclavicularShoulder and hip Joints Sternoclavicular ScapulothoracicIn this lecture CostovertebralThe shoulder complex Costotransverse Costochondral Scapulo-thoracic Sternocostal GlenohumeralThe ClavicleScapular movements and muscles Elevation – Depression Protraction – Retraction Upward and Downward RotationGlenohumeral movements and muscles Rotator Cuff Muscles Simultaneous movements of all these joints Flexion – Extension Hard to voluntarily move one joint Adduction – Abduction +ve can compensate for loss of range in one joint Medial and Lateral Rotation -ve one painful joint can upset movements of the whole complex.Combined movements Although there are many joints, we only normally referReadings to movements two joints. 1. Stern – Core concepts – sections 81 and 84 (plus Scapulothoracic or scapular movements appendices) Glenohumeral 2. Faiz and Moffat – Anatomy at a Glance – Sections 32 and 34 We will examine the movements of the two joints 3. Grants Method of Anatomy – shoulder in joints of separately – but be aware that the movements occur the upper limb together910 213 week 2 3 910 213 week 2 4 SCAPULAR MOVEMENTS SHOULDER MUSCLESThe scapular slides on the body wall and can move in Scapular musclesthree directions (and combinations of the those 3) Levator scapulae Serratus anterior 1. Elevation – Depression Rhomboids 2. Protraction – Retraction Pectoralis minor 3. Upward and Downward Rotation TrapeziusIn humans and other animals with clavicles themovements of the scapula is regulated by the clavicle. Glenohumeral musclesAnimals with clavicles and without clavicles: Supraspinatus Infraspinatus Teres minor Subscapularis Teres major Deltoid Triceps long head Biceps CoracobrachialisThe clavicle is important in the use of the hand forgrasping and manipulation.It acts as a strut that, with the muscles as “guy ropes”, Both Scapular and Glenohumeral (they don’t attach to the scapula)forms a secure basis for movements of the arm. Pectoralis major Latissimus dorsi
910 213 week 2 5 910 213 week 2 6 SCAPULAR MOVEMENTS SCAPULAR MOVEMENTS Elevation and Depression Protraction and RetractionElevation = Lifting the shoulders Protraction = shoulders forwardsAs is shrugging (where the scapula moves) Maybe an actual movement or stopping the shoulderOr carrying heavy objects (where the scapula stays still being pushed backwards.or may even go down!)Muscles involved: Muscles involved:Levator scapulae Serratus anteriorTrapezius (upper fibres) Pectoralis minorRhomboidsDepression = loweringthe shoulders Retraction = shoulders backMay be an actual lowering, or merely May be an actual movement or …preventing the scapula going up (as when yousupport yourself with your arms) Muscles involvedMuscles involved: RhomboidsTrapezius (lower fibres) Trapezius (middle part)Pectoralis major and minorLatissimus dorsi Rhomboids and serratus anterior form a couple thatGravity control the mediolateral position of the scapula910 213 week 2 7 910 213 week 2 8 SCAPULAR MOVEMENTS GLENOHUMERAL JOINT Upward and downward rotation The glenohumeral joint is a ball and socket joint.Upward rotation = makes the glenoid cavity face Glenohumeral movementsupwards Flexion – ExtensionMuscles involved Adduction – AbductionSerratus anterior (lower part) Medial and Lateral RotationTrapezius (upper and lower parts) Bones The bony socket is very shallow Deepened by the glenoid labrum The acromion, coracoid and coracoacromial ligament form a secondary socket that prevents upward dislocation. The ligaments are very loose to allow free movements, so the joint relies on muscles to maintain its stability The rotator cuff muscles 1. Act as dynamic ligaments to stabilise the joint in all positions. 2. They attach very close to the joint centre and so can not cause strong movements of the arm. 3. They assist other muscles (synergists) Subscapularis SupraspinatusDownward rotation = makes the glenoid cavity face Infraspinatusdownwards Teres minorMuscles involvedPectoralis majorLatissimus dorsiRhomboidsGravity
910 213 week 2 9 910 213 week 2 10 GLENOHUMERAL MOVEMENTS GLENOHUMERAL MOVEMENTS Flexion and extension Abduction and Adduction Sagittal plane movement Coronal plane movementFlexion is the forward movement of the arm. Abduction is moving the armIt may be an actual movement or just a stabilising action away from the bodyMuscles involved It may be an actual movement orPectoralis major just a stabilising action(clavicular part) Muscle InvolvedDeltoid (anterior part) Middle part of DeltoidBiceps and Rotator cuff muscles act as synergistscoracobrachialisExtension is the backwards movement of the armMuscles involvedPectoralis major(sternal part)Deltoid (posterior Adduction is bringing the arm to the bodypart) Muscles involvedLatissimus dorsi and Teres major, latissimus dorsiteres major Pectoralis majorTriceps (scapular Anterior and posterior deltoidhead) Gravity910 213 week 2 11 910 213 week 2 12 GLENOHUMERAL MOVEMENTS EXAMPLES OF ACTUAL Medial and lateral rotation MOVEMENTSMedial rotation is rotation around the long axis of the It is important to learn the movements and muscles ofhumerus that moves the anterior part medially. the scapular and glenohumeral components of theMay be the movement itself or a stabilising action like shoulder separately, and not to allow yourself towhen you carry something between two hands. confuse the two.Muscles involvedTeres major and latissimus dorsi But, in practice the movements that we do involvePectoralis major and anterior both components acting together.deltoid For example:Subscapularis Raising the arm laterally to the vertical position 1. Glenohumeral movement can only perform half of the movement. 2. The scapula must rotate laterally as well.Lateral rotation is rotating the humerus outwards Pushing forwards with the hand as in opening a heavyMuscles involved doorPosterior deltoidInfraspinatusTeres minor 1. Glenohumeral flexion (and elbow extension), performs most of the action - but. 2. The Scapula must protract as well. This pushes the whole shoulder forwards. a. In people with paralysis of serratus anterior, as they try to push forwards the scapula moves backwards.