Shoulder Complex Chapter 5 PDF

Shoulder Complex Chapter 5 PTH516 Pathokinesiology Letrisha Stallard, DPT Introduction  bones of shoulder: Osteology clavicle scapula...

Shoulder Complex Chapter 5 PTH516 Pathokinesiology Letrisha Stallard, DPT Introduction  bones of shoulder: Osteology clavicle scapula humerus sternum rib Clavicle – Note that the long axis is positioned about 20 degrees posterior to the frontal plane. axis runs through bone *know these angles* Scapular plane, motion is called scaption which combines abduction and flexion  Osteology Humeral head is positioned ~30 degrees POSTERIORLY relative to the M-L axis through the elbow (retroversion) WHICH ACCOMMODATES THE SCAPULAR PLANE.  Arthrology (joints) not really a joint (not bone on bone and its actually the Sternoclavicular jt and Acromioclavicular jt that makes it move) Primary Movements of ST Joint A. Pure frontal plane, superior and inferior on thorax B. Medial scapular border slides anterior-laterally and posterior-medially C. Glenoid fossa tilts upward and downward, OR inferior angle of scapula rotates superior-laterally and inferior-medially.  Sternoclavicular Joint basilar joint (saddle, plane, modified ball and socket) Only structural attachment of clavicle, scapula, and UE to the axial skeleton Very stable joint – clavicular fx often occurs before SC joint dislocates  Sternoclavicular Joint Clavicle Joint surface convex longitudinal diameter, concave transverse diameter Sternum Joint surface concave longitudinal diameter, convex transverse diameter  Sternoclavicular Joint Articular disc Separates joint into medial and lateral cavities Functions Strengthens articulation Shock Ligaments absorption Anterior & posterior sternoclavicular Interclavicular Costoclavicular (anterior and posterior bundles) [run perpendicular to each other]  Sternoclavicular Joint Stabilizing muscles Sternocleidomastoid (anteriorly) Sternothyroid (posteriorly) Sternohyoid (posteriorly) Subclavius (inferiorly)  KINEMATICS Osteokinematics Arthrokinematics -Joint classification -Motion occurring between -Degrees of Freedom bony joint surfaces -Planes and Axes -Convex/concave rule -Description of motion (esp. if not cardinal planes) -Motion-specific stability -Amount of Motion (in provided by ligaments and degrees) capsule Sternoclavicular joint Degrees of Freedom: 3  SC Elevation Frontal plane A/P axis 35-45⁰ ROM Convex surface of clavicle rolls superiorly & slides inferiorly on concave sternum  SC Elevation Motion-limiting periarticular C.T. at end range Costoclavicular ligament Force of stretched ligament same direction as slide  SC Depression Frontal plane A/P axis 10⁰ ROM limited ROM due to ribs being there Convex surface of clavicle rolls inferiorly & slides superiorly on concave sternum  SC Depression Motion-limiting periarticular C.T. at end range Interclavicular ligament Capsule (superior portion)  SC Protraction Horizontal plane (nearly) Vertical axis 15 - 30⁰ ROM Concave surface of clavicle slides anteriorly on convex surface of sternum  SC Protraction Motion-limiting periarticular C.T. at end range Costoclavicular ligament (posterior bundle) Capsular ligament (posterior portion) Motion-limiting muscles Scapular retractors  SC Retraction Horizontal plane (nearly) Vertical axis 15 - 30⁰ ROM Concave surface of clavicle slides posteriorly on convex surface of sternum  SC Retraction Motion-limiting periarticular C.T. at end range Costoclavicular ligament (anterior bundle) Capsular ligament (anterior bundle) Sternoclavicular Axial Rotation Longitudinal axis through SC and AC joints (Fig. 5-13) (sagittal plane) 20 - 35⁰ ROM posterior rotation Spin of sternal end of clavicle on lateral surface of articular disc  Sternoclavicular Axial Rotation Motion-limiting periarticular C.T. at end range Costoclavicular ligament (anterior bundle) Capsular ligament (anterior bundle) Acromioclavicular Joint — Plane (gliding) joint (2 jts making one) Degrees of Freedom: 3 Articulation: Clavicle Scapula Acromioclavicular Joint Joint capsule directly reinforced by superior and inferior AC ligaments Ligaments Superior & inferior acromioclavicular Coracoclavicular Articular disc Stabilizing muscles Deltoid Trapezius Aponeurotic AC Upward rotation Scapular plane A-P axis Up to 30⁰ ROM Gliding arthrokinematics Close-packed position of AC joint is upward rotation AC Upward rotation Motion-limiting periarticular C.T. at end range Coracoclavicular ligament (both portions) Capsule (inferior portion) AC Downward rotation Scapular plane usually (motion occurs naturally during shoulder ext. or add.) A-P axis Motion-limiting periarticular C.T. at end range Capsule (superior portion) Horizontal plane rotational adjustments Vertical axis During internal rotation of AC joint, the medial border of the scapula pivots away from thorax During external rotation of AC joint, the medial border of the scapula pivots toward the thorax Up to 30 ROM Acromial joint surface spins on clavicle Motion-limiting periarticular C.T. at end range Not researched well Functional significance of motion Optimally- aligns scapula against the thorax Adds to total motion of scapula Sagittal plane rotational adjustments Medial-lateral axis (nearly) During anterior tilting (of glenoid fossa) the inferior angle of the scapula pivots away from posterior surface of the thorax During posterior tilting the inferior angle pivots toward the thorax 5-30⁰ ROM Motion-limiting periarticular C.T. at end range Not researched well AC Joint Dislocation Fall on shoulder or outstretched arm SC joint is stronger that AC joint Type I = partial damage to ligaments (sprain) Type II = complete tear of AC & partial tear of CC Type III dislocation = AC & CC torn, resulting in permanent bump Type IV = AC tear and avulsion of CC from clavicle] Scapulothoracic Joint —not a true joint Articulation: Point of contact between the anterior surface of the scapula and the posterior-lateral wall of the thorax. -> separated by muscle. Scapula position: Ribs 2-7, scapular plane, medial border 6 cm from spine Scapulothoracic Jointt Shock absorption (scapular muscles) protects the shoulder (fall on outstretched arm) Stabilizing muscles Rhomboids Trapezius Serratus anterior Primary movements of Scapulothoracic Jointt Degrees of freedom: 3 1. Elevation and depression (pure frontal plane, superior and inferior on thorax) 2. Protraction and retraction (medial scapular border slides anterior-laterally and posterior -medially) 3. Upward and downward rotation (Glenoid fossa tilts upward and downward, or inferior angle of scapula rotates superior- laterally and inferior -medially.) Movement of ST joint must result in movement of SC and/or AC joint movement emphasis Primary role is to assist GH joint motion, thus increasing the GH joint range of motion.  ST Joint Elevation/Depression Elevation (shoulder shrug) SC joint elevation AC joint downward rotation Depression occurs opposite to elevation  ST Joint Protraction/Retraction Protraction SC joint protraction AC joint internal rotation Retraction SC joint retraction AC joint external rotation ST Joint Upward/Downward Rotation Upward rotation Downward rotation 60⁰ from: 60⁰ from: ○ SC joint elevation (30⁰) ○ SC joint depression (30⁰) ○ AC joint upward rotation (30⁰) ○ AC joint downward rotation (30⁰)  Glenohumeral Joint Ball and Socket Articulation Glenoid fossa of scapula Humeral head 1. Glenoid fossa: anterior-lateral and slightly upward 4 degrees 2. Glenohumeral Capsular Ligaments  Superior GH Capsular Ligament Taut in full ER , then restrains inferior and anterior translations of the humeral head  Middle GH Capsular Ligament Taut with anterior translation of humeral head, especially with 45-90⁰ abduction. Taut at end range of external rotation.  Inferior GH Capsular Ligament Anterior band taut with combined 90⁰ abd. & full external rotation so will resist ant. translation of humeral head Posterior band taut with combined 90⁰ abduction and full internal rotation Axillary pouch (connects anterior & posterior bands) becomes taut in 90⁰ abduction Coracohumeral Ligament Blends with superior capsule and supraspinatus tendon Taut with humeral adduction so will restrain inferior translation and external rotation of the humeral head Stabilizing Muscles Subscapularis S Infraspinatus I rotator cuff muscles Teres minor T Supraspinatus S Long head biceps tendon Glenoid labrum Joint stabilization by increasing humeral head contact area  Scapulothoracic Posture At complete rest with arms hanging at side the humeral head is stable (static stability) Superior capsular structures Gravity Resultant force prevents inferior displacement of the humerus Inclined plane of glenoid  Scapulothoracic Posture Increased demand calls upon secondary muscular support Rotator cuff muscles Posterior deltoid  PATHOKINESIOLOGY Loss of upwardly rotated glenoid fossa may cause subluxation/dislocation of humeral head Could be caused by poor posture Coracoacromial Arch Formed by coracoacromial ligament and the acromion process Coracoacromial Arch Contents Supraspinatus muscle and tendon Subacromial bursa Long head of biceps tendon Superior capsule (portion)  Glenohumeral Kinematics Degrees of Freedom: 3 GH Abduction Frontal plane A-P axis 120⁰ Convex head rolls superiorly and slides inferiorly Close-packed position of is GH full abduction with full external rotation Motion-limiting periarticular C.T. Inferior GH capsular ligament (all portions) Middle GH capsular ligament (Norkin and White) Protective and Stabilizing structures Supraspinatus tendon GH Adduction Frontal plane A-P axis Return to neutral from raised position Convex head rolls inferiorly and slides superiorly No CT restriction GH Flexion Sagittal plane M-L axis 120⁰ ROM same as abd Spin of humeral head in glenoid fossa Motion-limiting periarticular C.T. at end range Inferior GH capsular ligament Posterior capsular ligament Coracohumeral ligament GH Extension Sagittal plane (near) M-L axis (near) ~65⁰ actively, 80⁰ passively Motion-limiting periarticular C.T. at end range Anterior GH capsular ligament Coracohumeral ligament GH Internal Rotation Vertical axis Horizontal plane 75-85⁰ ROM Convex head rolls anteriorly and slides posteriorly on concave glenoid fossa ○ Note: spin occurs if IR motion occurs in 90⁰ abducted position Motion-limiting periarticular C.T. at end range Posterior GH joint capsule Inferior GH ligament (posterior band) Coracohumeral ligament (posterior portion) Dynamic stabilization Anterior GH joint capsule due to active pull of subscapularis Post. GH jt. capsule due to passive pull of infraspinatus and teres minor Motion limiting periarticular CT Motion-limiting periarticular C.T. at end range Posterior GH joint capsule Inferior GH ligament (posterior band) Coracohumeral ligament (posterior portion) Dynamic stabilization Anterior GH joint capsule due to active pull of subscapularis Post. GH jt. capsule due to passive pull of infraspinatus and teres minor GH External Rotation spin Vertical axis Horizontal plane 60-70⁰ ROM Convex head rolls posteriorly and slides anteriorly on concave glenoid fossa ○ Note: spin occurs if ER motion occurs in 90⁰ abducted position Close-packed position of is full GH external rotation with abduction Motion-limiting periarticular C.T. at end range Anterior GH capsular ligaments ○ Superior GH, Middle GH, Inferior GH (anterior band). Dynamic stabilization Anterior GH ligament due to passive pull of subscapularis tendon attachment to capsule Posterior GH capsule due to active pull of infraspinatus and teres minor Motion limiting periarticular CT Motion-limiting periarticular C.T. at end range Anterior GH capsular ligaments ○ Superior GH, Middle GH, Inferior GH (anterior band). Dynamic stabilization Anterior GH ligament due to passive pull of subscapularis tendon attachment to capsule Posterior GH capsule due to active pull of infraspinatus and teres minor  Part 2 SC, AC, ST, GH Part 1: ○ Osteology ○ Arthrology ○ Kinematics Part 2: ○ Overall Kinematics of Shoulder Abd. ○ Muscle and Joint Interaction Overall Kinematics: Shoulder Abduction Principle 1 3,2,1 or 2:1 ratio For every 3⁰ shoulder abduction, 2⁰ occurs at GH joint; 1⁰ at ST joint’ 120⁰ GH joint 60⁰ ST upward rotation Overall Kinematics: Shoulder Abduction Principle 2 60⁰ combined ROM ○ 30⁰ SC joint elevation ○ 30⁰ AC joint upward rotation Overall Kinematics: Shoulder Abduction Principle 3 (Clavicular retraction) 20⁰ retraction posterior to the frontal plane or 15⁰ in scaption Retracting clavicle assists AC joint with optimal positioning of the scapular within the horizontal plane (p. 145) Overall Kinematics: Shoulder Abduction Principle 4 (Scapular rotation adjustments) Posterior tilt (sagittal plane) o Primarily AC joint External rotation (horizontal plane) o Net rotation at SC and AC joints Posterior Rotation of Clavicle Principle 5 Clavicular elevation stopped by strong coracoclavicular ligament As scapular upward rotators provide continued force, slack is taken up in the conoid ligament portion of the coracoclavicular ligament Tension in conoid ligament pulls on conoid tubercle of clavicle, posteriorly rotating clavicle Overall Kinematics: Shoulder Abduction Principle 6 (GH joint external rotation) GH external rotation 25-50⁰ with the majority occurring before 70-80 degrees of abduction Allows greater tubercle to pass posterior to the acromion o Potential impingement Scapulohumeral Rhythm Important components for smooth motion for abduction: 1. Superior roll and compression of humeral head 2. Scapula upward rotation 3. Humeral ER Shoulder Abduction with Muscular Interaction happens simulateously, all happens during shoulder abduction 1. Upper and lower trap and serratus anterior upwardly rotate scapula. 2. Supraspinatus superiorly rolls humerus and compress it 3. Deltoid elevates humerus 4. Infraspinatus, subscapularis and teres minor prevents excessive superior translation. 5. Infraspinatus and teres minor ER humerus Muscle and Joint Interaction need to have proximal stability in order to have distal mobility. The function of the shoulder muscles 1. Proximal stabilizers: origin on the spine, ribs and cranium and insert on clavicle or scapula 2. Distal mobilizers: origin on the scapula and clavicle and insert on the humerus or forearm  ST Elevators Counter the force of gravity acting on the UE to maintain UE and shoulder girdle posture Upper trapezius Levator scapulae Rhomboids ST Depressors Lower trapezius Latissimus dorsi (indirectly) Pectoralis minor Subclavius (indirectly) ST Protractor Serratus anterior o Force transferred across GH joint providing forward reach and push Serratus Anterior Weakness Serratus anterior gets stretched out and allows scapula to wing out ST Retractors Middle trapezius Rhomboids Lower trapezius The elevation force of the rhomboid is cancelled by the depressor force of the lower trapezius. ST Upward Rotators Serratus anterior Upper trapezius Lower trapezius ST Downward Rotators Rhomboid major and minor Levator scapula Pec minor Force Couple pg. 154 Muscles that Elevate the Arm at the GH GH Abductors Anterior deltoid Middle deltoid ○ With supraspinatus paralysis or tendon rupture, full abduction is difficult or impossible because of altered GH arthrokinematics Supraspinatus ○ With deltoid paralysis, full abduction usually achieved GH Flexors Anterior deltoid Coracobrachialis Biceps brachii ST Upward Rotators evolute- when the axis moves along a path A/P Axis location changes for scapular upward rotation Early phase- near the root (base) of the scapula spine Late phase- near acromion Serratus anterior Upper trapezius Lower trapezius Middle trapezius  Serratus Anterior Most effective upward rotator  Serratus Anterior Paralysis Long thoracic nerve., spinal cord, or cervical nerve root involvement Winging scap- Ant tilt and IR Subacromial impingement could occur Upper Trapezius pulls on spine, clavicle, and scapula elevates clavicle, which in turn does upward rotation of scapula  Trapezius Paralysis Moderate to marked difficulty elevating the arm overhead Lower Trapezius  Middle Trapezius o Since line of force is directed through the upward rotation axis, it cannot rotate the scapula o The middle trapezius is active as a stabilizing synergist with serratus anterior. o Note: Upward rotation of scapula occurs due to force coupling of these muscles.  Function of Rotator Cuff Muscles During Arm Elevation The Supraspinatus, Infraspinatus, Teres minor, and subscapularis- rotator cuff muscles 1. Dynamic stability 2. Active control Dynamic stability Provided by Rotator Cuff for the Arthrokinematics at the GH Joint  Example 1: GH External Rotation Infraspinatus and teres minor actively rotate humerus externally Increase active tension of posterior GH capsule via their capsular attachments Additionally, passive tension of anterior capsule enhanced by passive stretch of subscapularis Note: Both provide centralizing force to humeral head therefore stabilizes the joint.  Example 2: GH Internal Rotation Subscapularis rotate humerus internally 1. Increase active tension of anterior capsule via capsular attachment 2. Additionally, passive tension of posterior capsule is increased by passive stretch of teres minor and Infraspinatus Example 3: GH Abduction Supraspinatus Active Control Provided by Rotator Cuff for the Arthrokinematics at the GH Joint Abduction, External rotation, Internal rotation Active Control by RC for Abduction Supraspinatus facilitates superior roll Subscapularis, infraspinatus, teres minor: inferior glide of humeral head Infraspinatus and teres minor actively externally rotate clear greater tubercle from acromion process Active Control by RC for External Rotation Infraspinatus and teres minor assist posterior roll of humeral head Active Control by RC for Internal Rotation Subscapularis assists with anterior roll arthrokinematic of convex humeral head Muscles that Adduct/Extend the Shoulder Posterior deltoid Latissimus dorsi Teres major Triceps (long head) Pectoralis major (sternocostal head) Infraspinatus Teres minor  Stabilization by Rhomboids During resisted adduction, upward rotation and abduction forces are countered by rhomboids. Muscles that IR the Shoulder They importantly control high-velocity external rotation motions. Subscapularis Anterior deltoid Pectoralis major Latissimus dorsi Teres major  Muscles that ER the Shoulder Function to eccentrically control internal rotation Infraspinatus Teres minor Posterior deltoid Supraspinatus Glenoid Labrum Tears Shoulder Instability