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FastObsidian6744

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Tufts University

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shoulder anatomy human anatomy medical science biological science

Summary

This document provides an overview of the shoulder complex, including bones, joints, and characteristics. It also details the functions and movements of the shoulder.

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4.1 Shoulder Complex Overview shoulder complex bones shoulder complex jts • sternum • clavicle sternoclavicular • • scapula acromioclavicular • • humerus (in glenoid fossa) scapulothoracic • • glenohumeral sternum • manubrium (clavicular notch attaches clavicle to manubrium) • b...

4.1 Shoulder Complex Overview shoulder complex bones shoulder complex jts • sternum • clavicle sternoclavicular • • scapula acromioclavicular • • humerus (in glenoid fossa) scapulothoracic • • glenohumeral sternum • manubrium (clavicular notch attaches clavicle to manubrium) • body • xiphoid process characteristics • broad/thick superior • narrow/thin inferior • clavicular facets for art clavicle • s shaped • “strut” allowing scapular movement, shldr mob sternoclavicular jt • concave when ex: reaching/climbing saddle jt • scapula • 3 angles (inferior, superior, lateral) • spine of scap - attachment for post deltoid, middle/lower trap • acromion - clavicle art • glenoid fossa - ant/lat • coracoid process - attachment for ligaments/muscles of shldr girld scapular plane (NOT IN FRONTAL PLANE) • • on post rib cage/conforms to upper thorax 30-45 degrees ant to frontal plane ex: scaption both convex/ sup roll/inf glide w/ abd • scap retract: post roll/post glide Humerus • lesser tubercle: attachment for subscap • greater tubercle: attachment for supraspinatus, infraspinatus, teres minor • intertubercular groove: LH of biceps brachii, latissimus attachment radial groove • post • separates med/lat prox attachment of triceps ex: pain w/ radial n they will point here angle of inclination & angle of torsion • humeral head med/sup • 135 degree angle of inclination w/ long axis of humeral shaft • 30 degree retroversion w/ relationship to elbow summary: shldr complex w/ multiple jts, all allow mobility and proximal stability prox end of clavicle: convex top to bottom, concave from front to back opp for manubrium (only rotates post from rest) post rotation in elevation, anterior rotation when returning to start 4.2 The Glenohumeral Joint Glenohumeral Joint referred to as the shoulder joint analogy: golf ball on a tee -made for mobility but is compromised by stability Fxn: Stability is compromised by increased mobility Stability is reliant on soft tissue structures Lesser tuberosity and greater tuberosity have a reference, the lesser is in the anterior position to the greater -would be an inferior postion in relationship to the coracoid process and the glenoid making this your left shoulder -the lunatics of the distal or the clavicle itself goes to the distal component, which then merges with the chromium, right, creating the AC joint Articulate cartilage and Joint Capsule -both the head of the humerus and glenoid fossa are lined with articulate cartilage -GH is surrounded with a fibrous joint capsule -a synovial membrane lines the inner wall of the joint capsule -extension of the synovial membrane encapsulated the tendon of the biceps brachii Glenoid labrum edge of the glenoid fossa -surrounds the rim of the glenoid fossa (~50%) -made of fibrocartilage -is a biceps tendon attachment -it helps to increase concavity of fossa for stability Coracoacromial Arch -formed by CAL-coracoacromial ligament -acts as the “roof” of the GH joint -space below ligament and above humeral heads is the subacromial space -space includes: supraspinatus muscle and tendon, subacromial bursa, long head of the biceps and part of superior capsule Bursa: Arm Elevation 1. Subacromialbursa 2. Protects supraspinatusmuscle and tendon from the acromion 3. Could occur as early as 22° abduction 4. Other: subdeltoid bursa Muscles: Rotator Cuff 4 muscles: 1. Supraspinatus 2. Infraspinatus 3. Subscapularis 4. Teres minor Dynamic stabilizers of the GH joint Muscles: Biceps Brachii 1. The long head of the biceps brachii descends into the groove 2. The tension produced assist compression of the humeral head in the glenoid 3. Helps prevent subluxation Muscles: Deltoid and Rotator Cuff 1. The deltoid assists shoulder abduction 2. The rotary component provides a resultant upward force on the humerus 3. The rotator cuff muscles assist in a downward and compression fashion 4.3 Glenohumeral Ligaments jt capsule w/ ligaments fxn • intrarticular pressure for stability • support ant/inf capsule • most attach to humerus, some to capsule ligament anatomy • superior GH lig: attach to ant LH biceps • Middle GH lig: blends w/ ant capsule & subscap • Inferior GH lig: attaches ant-inf glenoid fossa & labrum ligaments in response to motion superior GH lig: taut in full adduction • ex: restraint to inf & ant/post translation when across body for stability middle GH lig: ant restraint @ 45-60 degrees abduction • - limits er ex: ER arm w/ abduction, tightness on ant shldr • inferior GH lig: made up of 3 bands - ant: taut w/ 90 degrees abd, strongest/thickest (restrains ant translation/abd in neutral) - post: taut w/ 90 degrees abd - axillary pouch: tightens w/ abduction (resists inf/post translation of humeral head) ex: extremes stress in cocking phase on ant band and inf capsule coracohumeral lig: strengthen capasule loaction: lat border of coracoid going across to inferior side of tubercle • blends w/ capsule/supraspinatus tendon • resists adduction • restrains inf translation/ER of humeral head Summary: ligaments & tendons provide shldr jt stability, passive restraint is specific to shldr motion and direction 4.4 Glenohumeral Joint: Arthrokinematics Planes and Axes: GH joint review 1. Shoulder flexion and extension occur in the sagittal plane around a med/lateral axis 2. Shoulder abduction and adduction occur in the frontal plane around an ant/posterior axis 3. Shoulder external rotation and internal rotation occur in the horizontal plane around a longitudinal axis Shoulder Flexion/Extension -Spinning of the humeral head around the glenoid fossa -120-180° with accompanying scapular motion -Slight ant translation of the humeral head is possible at the end range of full flexion -Shoulder extension approx 65° with slight anterior tilt of the scapula and tightening of the capsular ligaments Arthrokinematics - Glenohumeral Flexion anterior/superior roll; posterior spin - Glenohumeral Extension posterior/superior roll; anterior spin Shoulder Abduction 0˚ to 120˚ of Abduction at the GH joint 1. Humeral head glides inferiorly, while rolling superiorly 2. External rotation occurs in order for the greater tubercle to pass posterior to the acromion process (avoid jamming the acromial space) 3. The axillary pouch stretches and acts as a sling or hammock supporting the head of the humerus 4. Dynamic musculature forces also stabilize the Synergistic Muscles: Shoulder Abduction Force couple of the GH joint with muscles of the rotator cuff and deltoid assisting with shoulder abduction Arthrokinematics: Abduction 1. Glenohumeral Abduction: lateral/superior roll; inferior glide (conjunct lateral rotation) 2. Glenohumeral Adduction: medial/superior roll; lateral glide Poor Arthrokinematics Superior migrating humeral head without conjunct inferior glide would compromise the contents of the subacromial space during abduction Arthrokinematics: IR/ER Glenohumeral IR: anterior roll; posterior glide Glenohumeral ER: posterior roll; anterior glide (picture) External/Internal Rotation External Rotation: Humeral head rolls posteriorly and slides anteriorly on the glenoid fossa Internal Rotation: Humeral head rolls anteriorly and slides posteriorly on the glenoid fossa -Some scapular retraction/protraction GH Joint: open/closed pack Closed Packed position: Full abduction/external rotation Open (Loose) packed position: 50° of abduction with slight horizontal adduction and external rotation 4.5 Sacpulothoracic Joint NOT A TRUE JOINT! • articulation of ant portion of scap on thoracic/ribcage • suspended by muscle & ant articulation w/ clavicle Scapulothoracic Functions • increase ROM for greater reach • maintain length tension relationships for deltoid to fxn over 90 degrees for more stability of GH jt • increased stability in GH w/OH reach • elevate body w/ crutch uses, seated pushups, transfers scapulohumeral motion “scapulohumeral rhythm” • first 30 degree primary GH jt mvmt • 2:1 ratio GHJ and scapulothoracic mvmt from 30 -180 degrees ex: every 2 degrees of GH motion, 1 degree scapulothoracic jt in upward rotation force couple: upward/downward scap rotation *rotary forces on scap* Muscles helping w/ upward rotation • upper trap • lower trap going down • serratus ant protraction/upward rot muscles helping w/ downward rotation • rhomboids • levator scapulae • pectoralis minor winging: serratus ant winging • scap fail protract during a reaching or forward motion causing it to go in a posterior direction ex: med border of scap comes off thoracic cage normal: protraction would slide along rib cage & go ant scap motions • elevation • depression • protraction • retraction • upward rotation • downward rotation osteokinematics <333 don’t forget to use our PT book • 1. not arthrokinematics bc not true jt Elevation 2. depression Ex: pt w/ rounded shldr or elevating upper traps tilting of scap: inf angle moves post/superior 1. Abd/ protraction 2. add/ retraction ex: reaching forward winging of scap = medial border moves posterior in transverse plane/ vertical scap overall osteokinematics 1. • upward rot = inf angle up & lat combo of elevation, protraction, & IR of scap 2. downward rot = inf angle down & med • combo of depression, retraction, & ER of scap why upward rot of scap • stable base of glenoid for humerus to sit in full elevation scapular tilting: defined by dir of superior aspect of scap moves ant tilt: sup border of scap tilts fwrd w/ inf angle moving away from thorax post tilt: sup border tilts backwards med/lat tilt: around vertical axis through AC jt summary • scapulohumeral rhythm during elevation 2:1 • force couples help w/ motions in shldr in synergistic way • imbalances in musculature timing = pathology 4.6 Acromioclavicular and Sternoclavicualr Joints Sternoclavicular articulates with the clavicle and manubrium of sternum Acromioclavicular clavicle meets the scapula AC- plane synovial joint -clavicle acts as a strut to allow any scapular movements and arm rotation (strut) allows for stability Articulate disc helps with mobility of joint begins thinning by age 20 -Acromion process sits over the GH joint to protect it from overhead forces applied down toward the shldr -lateral acromion end hooks slightly forward and superiorly to meet the clavicle Acromion Types Type 1: extends up slightly Type 2: curve slightly more on the acromion Type 3: has hook AC ligaments -conoid and trapezoid ligament (also known as the coracoclavicular ligament) located inferior provides significant stability for joint Motions of AC Joint -elevation and depression mostly occur in the frontal plane -protraction and retraction occur mostly in the sagittal plane -Ac joint makes small adjustments during scapular movement to allow the scapular to maintain position with the thorax Sternoclavicular joint 1. Saddle joint -concave anterior to posterior -convex vertically 2. 3 degrees of freedom -elevation & depression -protraction-retraction -rotation SC Capsule and Ligaments Capsule is strengthened by ligaments: 1. Anterior and posterior sternoclavicular ligaments Restrict anterior/posterior movement of clavicle 2. Interclavicular ligament Connects left and right clavicle Costoclavicular Ligament 1. Limits the extremes of all motion especially elevation 2. No effect on downward rotation due to the clavicle coming in contact with 1st rib articulation SC ARTHROKINEMATICS: Elevation 1. OKC - convex on concave 2. Superior roll/inferior slide SC ARTHROKINEMATICS: Depression 1. OKC - convex on concave 2. Inferior roll / superior slide SC ARTHROKINEMATICS: Elevation/Depression 1. Elevation: upward roll , DOWNWARD SLIDE 1. Depression: downward roll, UPWARD SLIDE SC Joint Elevation Mechanics During elevation of the scapula, the SC joint pivots upward. 1. Motion is permitted by ligamentous arrangement (anterior/posterior SC ligs) 2. Checked by costoclavicular ligaments SC Athrokinematics: Retraction OKC- Concave on convex Protraction: anterior roll/anterior slide Retraction: Posterior roll/posterior slide SC Protraction/Retraction Mechanics -occurs mostly between the disk and sternum -protraction occurs with shoulder horizontal adduction -retraction with shoulder horizontal abduction and shoulder extension SC ARTHROKINEMATICS: Rotation 1. Rotates posteriorly from resting position 2. Spin 3. When the arm is raised overhead in flexion the clavicle passively rotates in response to movement at the scapula Close Packed Position: 1. Full elevation of UE Loose Packed Position: 1. Mid position of scapula - anatomical position 4.7 Elbow Arthrokinematics Elbow importance: hygiene, eating, reaching elbow jt • 3 bones: humerus, ulna, radius • 4 jts • humero-ulnar & humeroradial form elbow: flex/ext • proximal & distal radio ulnar jts: sup/pro elbow degrees of freedom • 2 DOF • flex/ext normal: 0-150 functional: 30-130 • pro/sup • normal: 80 • functional: 30 hinge joint or modified hinge jt • humerus has trochlea & capitulum (radius art w/) • medial epi: bigger than lat, palpable, attachment for MCL, wrist flexors & forearm pronator cubital valgus • carrying ankle created by trochlea • trochlea causes ulna to deviate lat from humerus ex: average 13 degrees (+-6) women = larger for hips what stabilizes the elbow? • humeroulnar jt stab = trochlea & trochlear notch • humeroradial jt = radial head against capitulum & • coronoid process = ant stab capsuloligamentous structures ex: compromised in post dislocation • radial notch = art depression for radius how does THIS happen? combo of axial loading, sup/ER, valgus post/lat force • radius head art w/ capitulum @ dist • humerus (humeroradial jt) radial head art w/ ulna in radial • notch (prox radio-ulnar jt) ligaments • art capsule strengthened by lig • MCL: ant fibers strongest, resist valgus force (abd) • LCL: radial collateral lig, LUCL resist varus force muscle movements! • Felxion brachialis brachioradialis biceps brachii pronator teres • extensor triceps • pro/sup pronator teres biceps brachii supinator arthrokinematics: flexion flexion: concave on convex roll/slide: same superior/ant slide & roll extension concave/convex roll/slide: same post/inf roll/post/inf slide pronation/supination: proximal radio-ulnar jt • radius moves on relatively stationary ulna • axis of rotation = oblique (no spin) remember radius = moving bone! supination • proximal radioulnar jt • anteromedial glide of radius on ulna • convex/concave: medial glide/post roll pronation • proximal radioulnar jt • posterolateral glide of radius on ulna • convex/conccave: ant roll/post glide summary • flex/ext in open chain: roll/slide in same dir • proximal radioulnar jt: oblique axis for sup/pro • proximal radioulnar jt: convex/concave 4.8 Wrist Arthrokinematics Fxns of wrist: grasping manipulating objects gestures (sometimes) ADLS -position and stability of wrist define hand fxns ex: opening jar -wrist extended in order to improve force though finger flexion -does transfer of forces Wrist Joints 1. Radiocarpal tfcc takes 80% of load 2. Ulnocarpal tfcc takes 20% of load 3. Wrist load: pronation increases ulocarpal load Distal radioulnar joint distal and proximal radioulnar joint move in conjunction with each other concave on convex=role and slide in same direction pronation=radius rolling and slide-anterior supination=radius rolling and sliding-posterior Forearm Pronation & Supination Exercises 1. the radius rotates around the ulna 2. In pronation, the ulna ends up lateral relative to the radius 3. Motion occurs both proximal and distal at the RU joints -important to assess both proximal and distal RU joints TFCC (triangular fibrocartilage complex located on the ulnar side of the -primary stabilizer for RU joint -helps transfer compression forces ~20% -reinforced by palmar and dorsal ligaments Wrist: Proximal Carpal Row 1. Pisiform 2. Triquetrum 3. Lunate 4. Scaphoid Wrist: Distal Carpal Row 1. Trapezium 2. Trapezoid 3. Capitate 4. Hamate Dorsal Ligaments -Dorsal radiocarpal ligament -Reinforces posterior side of radiocarpal joint Palmar Ligaments -Palmar radiocarpal ligament -Stronger than the dorsal radiocarpal ligament -Becomes taut at wrist extension Intrinsic Ligaments Intrinsic ligaments can be injured/disrupted causing instability Proximal Row -Scapholunate ligament* -Lunotriquetral ligament Arthrokinematics: Extension & Flexion Proximal carpal row moving on radius Convex on concave -Roll and slide in opposite direction Extension: closed-pack position Ulnar Deviation & Radial Deviation Proximal carpal row moving on radius -convex on concave -roll and slide in opposite direction -Capitate moves as well RD: proximal row slightly flexes UD: proximal row slightly extends Wrist Motions 3 degrees of freedom 1. Flexion & Extension • Normal: 65-80° • Functional: 40° 2. Pronation & Supination 3. Radial & Ulnar Deviation • Normal: 10-20° RD 2-35° UD • Functional: 40° combined Summary - wrist joint has 3 degrees of freedom -wrist joint include the distal radioulnar joint, radiocarpal joint and ulnocarpal joint -radius is the primary mover for the distal RU joint -radiocarpal joint is convex on concave with roll and slide occurring in opposite 4.9 Hand Arthrokinematics Joints of hand Carpometacarpal Jt • ex: CMC metacarpophalangeal jt • ex: MCP (flexion/extension, abd, add) proximal & distal interphalangeal jt • ex: DIP (flexion/extension) PIP (flexion/extension) Hand fxn • grip • dexterity • sensation Carpometacarpal jt • digits 2-5 minimal movement • Thumb: flexion, extension, ab/adduction, opposition • Thumb doesn’t have DIP metacarpophalangeal & interphalangeal jt • convex proximal surface w/ concave distal surface hand arthrokinematics concave/convex 1. flexion - palmar glide 2. extension - dorsal glide thumb motion: CMC joint 1. Abduction - away from palm 2. Adduction - closer to palm 1. Flexion - thumb moves unlarly 2. Extension - thumb goes radially Arthrokinematics: Thumb (CMC joint) 1. Thumb (CMC) saddle jt 2. Metacarpal & Trapezium 3. Abduction & Adduction: saggital plane (convex/concave) 4. Flexion & extension: frontal plane (concave on convex) Arthrokinematics: Thumb Flexion & Extension 1. Flexion ex: metacarpal; roll/slide in ulnar direction (concave/convex) 2. Extension ex: metacarpal: roll/slide in radial dir (concave/convex) thumb abduction & adduction ABDuction • convex metacarpal on concave trapezium • metacarpal rolls & slides in opp direction ex: palmar roll / dorsal slide ADDuction • surfaces are same ex: dorsal roll / palmar slide summary: CMC thumb joint = saddle = convex/concave flexion: medial roll/slide extension: lat roll/slide abd: palmar roll/ dorsal slide add: dorsal roll / palmar slide

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