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Movement Science > Exam #2- Chapter 3 and 7 > Flashcards

Exam #2- Chapter 3 and 7 Flashcards

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1
Q

Sternoclavicular Joint

A
  • only structural attachment of the shoulder complex and UE to the axial skeletal
  • plane synovial joint with three rotary and three translators degrees of freedom
  • has synovial capsule, joint disc, and three major ligaments
  • at rest, SC joint space is wedge-shaped and open superiorly
  • superior portion of medial clavicle does not contact the manubrium– serves as the attachment for the SC joint disc and interclavicular ligament
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2
Q

Sternoclavicular disc

A
  • fibrocartilage, meniscus, increases congruence between articulating surfaces
  • upper portion is attached to the posterosuperior clavicle, lower portion to manubrium and first costal cartilage
  • divides the joint space diagnonally
  • acts as a hinge or pivot point for the medial end of clavicle -during elevation/depression of clavicle, the medial surface rolls and slides on stationary disc–considered part of manubrium
  • during protraction/retraction, disc and surface slides together–considered part of clavicle
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3
Q

Sternoclavicular Ligaments

A
  • anterior and posterior
  • reinforce capsule and function to check anterior and posterior translator movement of the medial end of clavicle (posterior capsule provides primary restraint to anterior and posterior translation)
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4
Q

Costoclavicular Ligament

A
  • anterior and posterior
  • anterior: fibers are directed laterally from the first rib to the clavicle
  • posterior: fibers directed medially from rib to clavicle- resist medial movement of clavicle
  • both: limit elevation of lateral end of clavicle, and when taut, may contribute to inferior gliding of the medial clavicle on manubrium that occurs with clavicular elevation
  • limits superiorly directed forces applied by SCM and sternohyoid muscles
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5
Q

Interclavicular Ligament

A
  • limits excessive depression and of superior gliding of the medial clavicle on manubrium
  • critical to protecting arteries and nerve that pass under clavicle
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6
Q

Motions at the SC joint

A
  • elevation/depression
  • protraction/retraction
  • anterior/posterior rotation
  • –described by the movements at the lateral end of clavicle
  • joint axis=lateral to joint at costoclavicular ligament–results in larger intra-articular motion of medial clavicle
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7
Q

Elevation/Depression of the clavicle

A
  • elevation=lateral clavicle rotates upward= 45 degrees

- depression=rotates downward= 15 degrees

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8
Q

Protraction/Retraction of clavicle

A
  • occur at the sternoclavicular joint
  • protraction=lateral clavicle moves anterior=15-20 degrees
  • retraction=lateral clavicle moves posterior= 30 degrees
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9
Q

Anterior/Posterior Rotation of clavicle

A
  • rotates primarily in one direction from resting position (posterior rotation)
  • inferior surface of clavicle faces anterior
  • also called backwards or upward rotation
  • 50 degrees
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10
Q

Acromioclavicular Joint

A
  • plane synovial joint
  • three rotational and three translational degrees of freedom
  • joint capsule, two major ligaments, and joint disc
  • disc start as fibrocartilage–develops to meniscoid fibrocartilage with use of UE
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11
Q

Acromioclavicular ligaments

A
  • capsule is weak and cannot maintain integrity of joint without the ligaments
  • superior and inferior
  • superior AC ligament: main ligament limiting movement caused by anterior forces applied to the distal clavicle- reinforced by trapezius and deltoid muscles (making superior joint support stronger than inferior)
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12
Q

Coracoclavicular ligament

A
  • medial portion=conoid- slightly posterior, more triangular and vertically oriented- primary restraint to translatory motion caused by superior directed forces applied to distal clavicle
  • lateral portion= trapezoid- quadrangular and horizontal in orientation- more restraint to translatory motion caused by posterior-directed forces applied to distal clavicle
  • two portions separated by adipose tissue and large bursa
  • limit upward rotation of scapula, prevents medial displacement of scapula on clavicle (primarily the horizontal trapezoid ligament)
  • most critical role= couple posterior rotation of clavicle to scapula rotation during arm elevation
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13
Q

Acromioclavicular motion

A

-internal/external rotation
-anterior/posterior tilting or tipping
upward/downward rotation
–occur around axes that are oriented around the plane of the scapula

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14
Q

internal/external rotation of AC joint

A
  • up to 60 degrees
  • approx. vertical axis through AC joint
  • brings the glenoid fossa of scapula anteromedially or posterolaterally
  • maintain contact of scapula with horizontal curvature as clavicle protracts/retracts
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15
Q

anterior/posterior tilting of AC joint

A
  • up to 60 degrees
  • anterior tilt= coronoid forward, inferior angle backward
  • occurs to maintain contact of scapula with contour of rib cage and to orient glenoid fossa
  • elevation of scapula results in anterior tilting
  • during normal flexion or abduction the scapula posteriorly tilts on thorax as scapula is upwardly rotating
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16
Q

upward and downward rotation of AC joint

A
  • ???? degrees
  • occurs around an oblique AP axis
  • upward rotation tilts glenoid fossa upward
  • amount of available passive motion is limited by attachment of coracoclavicular ligament
  • in order for upward rotation to occur at AC joint, coracoid process and superior border of scapula need to move inferior away from clavicle
  • posterior rotation of clavicle releases tension on the coracoclavicular ligaments and opens up the AC joint allowing for upward rotation
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17
Q

Stress on the AC and SC joints

A
  • AC joint is much more susceptible to both trauma and degenerative changes than SC joints
  • common during either contact or fall on shoulder with arm adducted
  • typically high inferior forces on the acromion
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18
Q

AC joint injury classifications

A

Type I- sprain of AC ligaments, no rupture
Type II- sprain of coracoclavicular joint, rupture AC- see step off, clavicle can not hold down
Type III- rupture of AC and CC- separation of joint surfaces, large step off
Type IV- rupture of AC and CC (type III) + posterior displacement of clavicle
Type V- just worse than IV–3 to 5 times greater coracoclavicular space than normal
Type VI- inferior displaced clavicle in relation to acromion, complete ligament rupture and displacement of distal clavicle into subacromial postion

–Type IV, V, VI–requires surgery

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19
Q

Scapulothoracic Joint

A
  • articulation of the scapula with the thorax depends on SC and AC joints
  • true closed chain joint
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20
Q

Resting position of the scapula:

A 
10-20 degree anterior tilt
30-45 IR
10-20 upward rotation from vertical 
about 5 cm from midline 
T2-T7 location on rib cage
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21
Q

what is the primary scapular motion? Secondary motions?

A
  • primary= upward/downward rotation
  • secondary= IR/ER, anterior/posterior tilting
  • scapula also has translator motions of elevation/depression and protraction/retraction; however, the linkage to AC and SC joints require motions to occur simultaneously
  • arm abduction= scapular upward rotation, ER, and posterior tilting
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22
Q

Upward/downward rotation of scapula

A
  • principal motion of scapula during active elevation of arm, significant role in overhead ROM
  • 60 degrees (30 from SC and 30 from AC)
  • produced by clavicular posterior rotation, SC elevation, and upward rotation at AC joint
  • average angle of SC IR is 58-68 degrees (2/3 of 90 degree AC IR)—> results in ST upward rotation of 2/3 from SC posterior rotation and 1/3 from clavicular elevation
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23
Q

elevation/depression of scapula

A
  • commonly described as translatory motions

- scapular elevation occurs through elevation of the clavicle at SC joint and rotations at AC joint

24
Q

protraction/retraction of scapula

A
  • should not be referred to as abduction/adduction of scapula–would mean that glenoid fossa faces laterally and only vertebral border would stay in contact with ribs
  • full scapular protraction=glenoid fossa faces anteriorly, scapula full contact with rib cage
  • occurs through SC joint protraction and retraction and follows the contour of the ribs by rotating internally and externally at AC joint
25
Q

internal/external rotation of scapula

A
  • too large amount of IR causing prominence of vertebral border and loss of contact with thorax (winging)
  • indicative of pathology or poor neuromuscular control of the ST muscles
26
Q

anterior/posterior tilting of scapula

A
  • occurs at the AC joint
  • can couple with elevation/depression of the clavicle at SC joint
  • excessive anterior tilting will result in inferior angle of the scapula lifting off thorax
27
Q

Glenohumeral joint

A
  • ball and socket synovial joint with three rotary and three translatory degrees of freedom
  • has capsule, supporting ligaments and bursae
  • sacrificed articular conguency to increase mobility of UE; therefore, susceptible to degenerative changes, instability, and derangement
  • # 1 dislocated joint in the body
  • most commonly, upward tilt of glenoid fossa, 6-7 degree retroversion
28
Q

Anatomical position of humeral head:

A
  • head faces medially, superiorly, and posteriorly
  • angle of inclination=130-150 degrees–formed by an axis through the shaft of the humerus in relation to longitudinal axis through shaft of humerus
  • angle of torsion= 30 retroversion– axis through humeral head and neck in relation to axis through humeral condyles
  • because of IR resting position of the scapula, normal retroversion of humeral head increase congruence of GH joint by orienting the head toward the surface of the fossa
  • if there is an increased humeral retroversion, will result in increased range of ER of humerus and reduced IR (seen in throwing athletes)
29
Q

Glenoid Labrum

A
  • enhances depth and concavity of the fossa by 50%
  • core is composed of densely packed fibrous CT covered by a fine superficial mesh consistent with cartilaginous tissue, with fibrocartilage at the attachment of the labrum to periphery of the fossa
  • attachment site for GH ligaments and tendon of long head of biceps
30
Q

GH capsule

A
  • with arm at side: taut superiorly, slack anteriorly and inferiorly
  • close-packed position= abducted and laterally rotated
  • relative laxity of the capsule is necessary for large excursions, but provides little stability without reinforcement of ligaments and muscles
  • reinforced by: superior, middle, and inferior GH ligaments and by the coracohumeral ligament. Also rotator cuff muscles and their tendons
  • particularly vulnerable to anterior dislocation
31
Q

GH ligaments

A
  • coracohumeral ligament= originates from base of coracoid process and has two bands: first band inserts on edge of supraspinatus and onto the greater tubercle, joining SGHL, second band inserts into the subscapularis and lesser tubercle –bands form tunnel for tendon of biceps long head–limits inferior humeral head translation, resists lateral rotation with arm adducted
  • superior GH ligament= from superior labrum to upper neck of humerus deep to the extra capsular coracohumeral ligament- contribute most to anterior and inferior joint stability by limiting anterior and inferior translations with arm at side (0 degrees abduction)
  • middle GH ligament= runs obliquely from superior anterior labrum to the anterior aspect of the proximal humerus below the superior GH attachment –absent in 30%- contributes primarily to anterior joint stability by limiting anterior humeral translation (arm at side and up to 60 degrees of abduction)
  • inferior GH ligament= three components– inferior GH ligament complex (IGHLC)–> anterior and posterior ligament bands and axillary pouch in between- with abduction beyond 45 degrees or with combined abduction and rotation, the IGHLC plays the primary role of stabilization.
  • If humeral head ER=anterior band of IGHLC fans out and provides anterior joint stability and resistance to anterior humeral head translation, if IR, posterior band fans out
32
Q

Rotator Interval capsule (RIC)

A
  • superior GH ligament, superior capsule, and the coracohumeral ligament
  • interconnected structures that bridge the space between the supraspinatus and subscapularis muscles tendons
33
Q

Coracoacromial arch

A
  • also called suprahumeral arch
  • formed by coracoid process, acromion, and coracoacromial ligament, inferior surface of AC joint
  • osteoligamentous vault over humeral head, called subacromial space
34
Q

subacromial space

A

= subacromial bursa, RCT, portion of long head biceps tendon—all protected by the coracoacromial arch

  • can cause impingement or abrasion (supraspinatus most at danger)
  • also referred to as suprahumeral space, supraspinatus outlet, acromiohumeral interval
  • 10 mm with arm at side, decreases by half during arm elevation
  • recent research suggests that normal decreases in acromiohumeral distance during arm elevation may not impact RC at elevation higher than 60 degrees
  • inadequate posterior tilting or upward rotation of scapula during arm elevation or excessive superior or anterior translation of humeral head on glenoid fossa are believed to increase risk of impingement (humeral head close in proximity to acromion process)
35
Q

GH bursa

A
  • most important = subacromial and sub deltoid bursa
  • separate the head of humerus and supraspinatus from the acromion, coracoid process, coracoacomial ligament and deltoid muscle
  • commonly continuous with each other=subacromial bursa
36
Q

GH motions

A
  • flexion/extension, abduction/adduction, medial/lateral rotation
  • IR/ER restricted with arm at side- greater and less tubercles create mechanical block
  • restriction of abduction with medial or neutral alignment of humeral head-must laterally rotate so that the greater tubercle can pass under or behind coracoacromial arch
  • available passive ROM for abduction in scapular plane may be slightly greater than abduction in frontal plane–capsule less twisted
  • humeral head still moves superiorly (translates upwardly) on fossa despite the inferior slide during arm elevation–humeral head also moves anterior/posterior and medial/lateral on fossa
  • humeral head center moves superior (1-2 mm) until 60 degrees of active elevation motion
37
Q

Role of the GH capsule

A
  • provide stability by limiting anterior, inferior, or posterior humeral head translation
  • the stabilizing function is minimal at less than 90 degrees of humeral elevation when only the superior segment is under any significant tension.
  • at lower angles, RC muscles and tendons actively stabilize , towards end range of humeral motions, the capsule becomes tight passively and tension restricts GH translation. At end range, the tension begins to produce rather than restrict humeral head center translations
38
Q

Mechanisms that provide static stabilization of the GH joint

A
  • gravity imparts a downward direct translatory force on the humerus
  • all muscles of shoulder complex (deltoid, supraspinatus, or long head biceps and triceps) are electrically silent in relaxed, unloaded limb
    1. structures of the rotator interval capsule (superior capsule, superior GH ligament, and coracohumeral ligament) are taut and passively oppose
  • the resultant vector formed creates a force that compresses the humeral head into lower portion of the fossa and prevents inferior humeral head translation
    2. negative intra-articular pressure in GH joint-creates a relative vacuum that resists the inferior translation (tear in labrum or venting of the air tight capsule can cause large increase in inferior translation)
    3. supraspinatus may be recruited to provide active assistance
39
Q

Deltoid and GH stabilization

A
  • prime mover for GH abduction and flexion (ant. delt)
  • with arm at the side, the result force of pull of the deltoids creates a large translatory component and small rotary–would cause the deltoid to produce more superior translation than rotation of the humerus
  • with arm at side, fossa is not in line with shaft of humerus-would create a shear force rather than stabilizing (compressive) effect
  • Fy rotory forces are not particularly effective until translatory forces are in equilibrium
  • deltoid cannot independently elevate the arm
40
Q

Rotary Cuff and GH stabilization

A
  • ITS muscles have similar lines of pull. Perpendicular component (Fy) compresses and rotates, parallel component (Fx) offsets the superior translatory pull of deltoid
  • supraspinatus has a superior directed rotory component and a perpendicular component that is more compressie than the other RC muscles and can independently abduct humerus
  • teres minor and infraspinatus muscles also contribute to abduction of the arm by providing lateral rotation that occurs during elevation
  • force couple= ITS vs deltoid– nearly equal and opposite superior/inferior forces
  • supraspinatus is located more superior to the GH joint axis than the ITS; larger MA allows for independent full ROM during abduction while still stabilizing joint
41
Q

Long head of biceps brachia and GH stabilization

A
  • tendon enters the GH capsule between the supraspinatus and subscapularis muscles, where it penetrates the capsule but not the synovium
  • tethered by the transverse humeral ligament that runs between the greater and lesser tubercles
  • tightens a relatively posse superior labrum and transmits increased tension to the superior and middle GH ligaments
42
Q

what is the painful arc?

A
  • between 60-120 degrees of humeral elevation, rotator cuff tendonopathy or tears typically produce pain
  • pain due to AC degeneration is similar area as pain from RC lesions; however, the AC degeneration pain is found when the arm is raised beyond the painful arc or adducted across the body (compressing the AC joint surfaces)
43
Q

predispositon to GH subluxation or dislocation:

A
  1. anterior tilting of glenoid fossa in relation to scapular plane
  2. excessive retroversion of humeral head
  3. weakened RC muscles
44
Q

Scapulohumeral Motion:

A
  1. distributes motion between the GH, AC, SC joints, permitting a large ROM with less compromise of stability than would occur if the same range occurred at one joint
  2. maintains the glenoid fossa in optimal position in relation to the head of the humerus, increasing joint congruency while decreasing shear forces
  3. permits muscles acting on the humerus to maintain a good length-tension relationship while minimizing or preventing active insufficiency of GH muscles
45
Q

scapulothoracic and glenohumeral contributions

A
  • scapula on thorax contributes to elevation of humerus by upwardly rotating the fossa 50-60 degrees from resting position
  • GH joint contributes 90-120 degrees of elevation
  • combination results in maximum range of 150-180
  • 2:1 overall ratio= scapohumeral rhythm
  • during flexion, average 51 degrees of lateral rotation reported
  • as the arm is elevated in flexion, scapular plane abduction, or frontal plane abduction, the scapula posteriorly tilts to allow the interior angle of the scapula to move anteriorly and stay in contact with the thorax as it rotates upwards and around the rib cage- also brings acromion up and back
  • at end ranges of elevation, the scapula is externally rotating on thorax; during early range, slight IR occurs to keep medial border in contact with thorax
46
Q

sternoclavicular and acromioclavicular contributions

A
  • initiation of scapulothoracic upward rotation appears to couple with clavicular posterior rotation and elevation at SC joint
  • scapulothoracic axis of rotation= oblique AP axis passing through costoclavicular ligament (SC joint motion) and projecting backward through the root of the scapular spine (ST motion) —as elevation progresses, the axis shifts laterally, reaching the AC joint in final range of scapular upward rotation
  • in order for upward rotation of scapula to occur at AC joint, the limitation of AC motion imposed by coracoclavicular ligament must be overcome
  • Tension in the coracoclavicular ligament (especially conoid) is produced as the coracoid process gets pulled downward with muscle forces attempting to upwardly rotate the scapula at the AC joint–tightened conoid ligament pulls its posterior inferior clavicular attachment forward and down as the coracoid process drops, causing clavicle to posteriorly rotate
47
Q

Upward rotators of the scapula

A
  • motions of the scapula are primarily produced by the balance of of forces between the trapezius and serratus anterior muscles
  • upper trapezius, attached to clavicle, contributes directly to initial elevation of clavicle as well as SC joint retraction that occurs during normal arm elevation
  • as axis of rotation shifts laterally towards AC joint, the middle trap has progressively smaller MA for scapulothoracic upward rotation
  • serratus anterior maintains a large moment arm for scapulothoracic upward rotation throughout entire range
  • scapular winging included IR and anterior tilting of the scapula, produced by the remaining muscles without the stabilizing ER and posterior tilting influence of the serratus
  • middle and lower trap can also contribute to ER torques of the scapula at the AC joint and upper trap to clavicular retraction at SC joint
48
Q

Glenohumeral Joint Hypomobility

A
  • total humerus ROM will be reduced
  • whatever portion of motion remains at GH joints will be accompanied by ST motion
  • GH limited to 60, can still combine with 60 of ST motion to provide total range of 120
  • evidence of increased ST upward rotation, or scapular substitutions
49
Q

Sternoclavicular Joint Hypomobility

A
  • SC fusion (no clavicular elevation, posterior rotation, or retraction) would eliminate both contributors to scapular upward rotation and result in ST IR
  • only GH joint elevation, with limited AC contribution- no posteriorly rotating clavicle to reduce coracoclavicular tightness
50
Q

Acromioclavicular Joint Hypomobility

A
  • if fused AC and fixed scapuloclavicular relationship, the clavicular protraction would bring the scapula into the thorax, and further motion would be limited
  • clavicular protraction and scapular IR at initiation of arm flexion are dependent on the ability of AC joint to allow the scapula to IR to orient the glenoid fossa anteriorly and accommodate curvature of the thorax
51
Q

Deltoid muscle function

A
  • as humerus elevates, translatory component of deltoid diminishes its superior dislocating influence as resultant force vector shifts increasingly towards the glenoid fossa- rotary component must counteract the increasing torque of gravity as arm moves to horizontal
  • MA gets larger as humerus elevates and torque of gravity diminishes once arm is above horizontal
  • short deltoid is not able to produce as much active tension, and passive tension is diminished- greater number of motor units must be recruited to maintain force output
  • multipennate structure and considerable cross-sectional area of deltoid compensates for its small MA, low mechanical advantage, and less than optimal length-tension relationship as elevation progresses
  • if serratus anterior and trapezius (scap upward rotators are absent) the delt will work on the lighter scapula causing it to downwardly rotate; net effect of attempted abduction in this position is 60-75 degrees
  • effective deltoid activity also depends on an intact rotator cuff- without, the contraction of deltoid results in shrug of shoulder (elevation at SC and upward translation of the humerus)
52
Q

Supraspinatus muscle function

A
  • abductor in all planes of humerus elevation
  • MA is constant throughout the ROM and is larger than that of the deltoid for the first 60 degrees of shoulder abduction
  • with the deltoid, the supraspinatus can bring the shoulder through most, if not all, GH motion, just weaker
  • compress the GH joint, act as a steerer for humeral head, and maintain the stability of dependent arm
  • not common to experience isolated supraspinatus tear/paralysis
53
Q

Infraspinatus, teres minor, subscapularis muscle function

A
  • rise in AP from 0-115 degrees, activity dropped between 115-180; total activity in flexion was greater than that of abduction
  • medial rotatory function of subscap muscle diminishes with abduction, instead steers the head of humerus horizontally and compress and stabilize joint
54
Q

Upper and Lower Trapezius and Serratus anterior muscle function

A
  • work in synergy to upward rotate scapula
  • activity in trapezius rises linearly to 180 abduction, serratus in 180 flexion
  • trapezius more active in abduction than flexion, may be related to increase ST and AC internal rotation noted in flexion compared to abduction
  • when serratus is damaged, and the scapular retraction component of trapezius is unopposed, the trap is unable to effectively upwardly rotate the scapula to allow for flexion
  • serratus anterior: simultaneous upward rotation, posterior tilting, and ER (all seen during elevation of arm); has largest MA of all ST muscles; primary stabilizer of inferior angle and medial border of scapula
  • trap and serratus maintain optimal muscle-length tension relationship with deltoid and permit it to carry its heavier distal lever through full ROM
  • both work as agonist to scapular movement and syngery with GH movement
55
Q

Rhomboid muscle function

A
  • work eccentrically to control the change of position of the scapula produced by trap and serratus anterior
  • paralysis disrupt normal SH rhythm and diminished ROM
  • act primarily to offset lateral translation of serratus muscle and help prevent excess IR of scapula at AC joint by stabilizing medial border to thorax
56
Q

Latissimus dorsi and pectoral muscle function

A

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Movement Science (3 decks)

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