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Orthopedic Treatment 400 - Shoulder BioM
Terms in this set (50)
How many ways is the GH stabilized and what are they?
1. Passive/Inert Stability
2. Active/Dynamic Stability
How many structures are involved in Passive/Inert Stability? What are they?
1. Inf lip of GH fossa
(GH naturally faces upward creating a shelf for head of humerus)
2. Coracohumeral ligament & superior jt. capsule
(the superior joint capsule and coracohumeral ligament are usually taut creating an opposing force to the vertical weight of humerus. pulls the head of the humerus into GH cavity)
How many structures are involved in Active/Dynamic Stability? What are they?
When the shoulder is raised in any plane away from the side of the body, the superior joint capsule becomes lax. Therefore it is the responsibility of the dynamic ligaments - the rotator cuff muscles - to maintain congruency and stablization.
Rotator Cuff SITS muscles
"blend" togeather, wrap and hold humerus tight into GH cavity
3. Teres Minor
The Rotator Cuff muscles (SITS), when referring to dynamic stability are also called:
When does Active vs. Passive stability take over?
Any time the the shoulder is raised in any plane away from the side of the body (ABduction)
excessive curvature of the upper back, leading to a stooped forward posture
Thoracic Kyphosis/ Hyperkyphosis
Why is Thoracic Kyphosis/ Hyperkyphosis harmful to the shoulder?
- situates the scapula in a downward rotation taking away the stabilizing 'lip' of the glenoid fossa
- places the humerus into a
in reference to the newly positioned scapula.
-The normally taut superior joint capsule and coracoacromial ligaments become lax.
What takes over stabilization during hyperkyposis/loss of passive stabilization?
-Dynamic ligaments (rotator cuff) with ACTIVE stabliization.
-May lead to impingement syndrome because constant, increased tone in the rotator cuff group.
-ABduction where arm is
no longer at midline
coracohumeral ligament is no longer checking gravity
passive/inert stabilization is lost
Means partial mm paralysis
What happens with Paresis of RC mm?
-Weakness or imbalance may cause the scapular muscles to orient the scapula in the same forward rotation as thoracic kyphosis.
-Depending on the severity of muscle paresis, inferior dislocation or subluxation may occur if the rotator cuff muscles are affected.
-Decrease of Active/Dynamic Stability
= increase in Passive/Inert Stability
Overloaded coracohumeral ligament
What influence does the GH joint capsule have on the shoulder during movement?
The fibers of the GH joint capsule face anteriorly and medially. As the arm abducts this twist in the joint capsule increases and pulls the head of the humerus into the glenoid cavity. This increasing tension furthers abduction because the medial fibres become taut. This causes the capsule to pull the humerus into external rotation ("untwisting" of the joint capsule). This also allows for further abduciton because the external rotation helps to prevent the greater tubercle from colliding with the acromial arch.
I.e. The middle GH ligament is twisted. At 90 degrees the greater tubercle would butt against the acromial arch, so the ligament untwists and rotates the arm into external rotation to allow the arm to come up past 90 degrees.
-Mvmt of humerus away from body in the scapular plane.
-Glenohumeral abduction in a plane halfway b/w sagittal and frontal plane.
At what point does the twist in the Middle GH ligament reach max tautness?
90° of ABduction
(Same point at which max (P) is felt with NEER Impingement Test)
What other purpose does the twist in the anterior fibres allow?
-causes capsule to pull humerus into
-untwisting of joint capsule allows for further abduction by rotating greater tubercle posteriorly
-external rotation also helps to prevent greater tubercle from colliding with acromial arch
Muscles w/ different lines of pull (i.e. flex/ext, ABd/ADd) when exerting equal force, will create movement in same direction.
-When muscles act in opposite directions to create movement in the same range (e.g. hip flexors pull down in the front and back extensors pull up in the back. Same RANGE because both are pulling pelvis in the same direction i.e. forwards)
What is the force couple relationship between the deltoid and rotator cuff muscles during elevation?
The strong multi-pennate fibres of the deltoid act below the centre of rotation causing an upward and outward force on the humerus. The rotator cuff muscles act above the centre of rotation causing an inward, downward force on the humerus which helps maintain the congruency of the humeral head in the glenoid cavity. These muscles oppose each other and create a force coupling necessary for shoulder elevation.
The axis of rotation ("centre" of rotation) for deltoids/rotator cuffs
The axis of rotation is above the delts and below the sits.
What is the force couple relationship during elevation of shoulder?
create upward & outward force
2nd: RC (SITS) mm
create downward & inward force
Term which describes the force couple relationship of the Scapula:
What is the force couple relationship of the Scapulothoracic Mechanism during
rotation of scapula
pulls in & up
pulls in & down
i.e. the upward rotation of the glenoid fossa means the scapula needs to track superiorly, anteriorly and laterally.
Together, these muscles contribute to abduction via scapular rotation.
Different from force coupling as it only involves a single mm and not multiple:
Describe the Biceps Pulley System
The biceps contribute to stabilization at the GH joint. The long head of the biceps attaches to the superior lip of the glenoid fossa. It helps pull and keeps the humeral head in a depressed position during abduction.
"The long head of the biceps helps to depress the head of the humerus with abduction of the arm in external rotation because of the pully system created by the bicipital groove."
What is the significance of the Biceps Pulley System?
-w/ frequent overhead movements biceps gets abused
-if weak RC mm, biceps must help to stabilize shoulder
-overload = injury (tendonitis, etc)
Defined as the ratio of movement of humerus to scapula:
How many phases are there with Scapulohumeral Rhythm
Phase 1 - 3
Describe Phase 1
Phase 1 =
NO RHYTHM OCCURS
0 - 30°
°* ABduction occurs at GH, Humerus only mvmt
• Scapula stabilized by
• Scapula "sets" = very slight shift
• 0 - 5° clavicle elevation
Describe Phase 2
Phase 2 =
• +15° clav elev (total 20°)
Describe Phase 3
Phase 3 =
90 - 180°
• +15° clav elev (35° total)
At what point during Scapulohumeral Rhythm does the
begin to rotate?
* (Phase 3) => +91°
Describe what happens during the last 10-20° (160-180°) of ABduction in the shoulder?
Phase 3 (subcategory)
• last 170-180° of mvmt spine becomes involved
• Ipsi SB + rot manubrum => Inf glide R1 & R2
• Ipsi SB + Rot & Ext T1 & T2
• T10-12 contra SB + Rot & Ext to counteract T1/T2
(The above is for unilateral abduction. Bilateral abduction causes extension. Fixed spinal deformities cannot perform full elevation).
Phase 3 (subcategory) --> osseus structure invovmement
How do you achieve "True" extension of the spine during ABduction?
Bilateral full ABduction = true extension of spine
Shoulder related History questions:
■ Does pain spread below elbow?
■ Can patient lie on affected shoulder at night? (T&B = (P) lying on affected, AdH Cap = (P) at night any position)
■ Is it difficult to perform ADLs: brushing hair, pulling off shirt, fastening bra, eating?
■ Difficulty performing any activities requiring reaching above shoulder level? (Impingement)
1. What might ant. brachial pain indicate?
2. What might lat. brachial pain indicate?
3. What might superior/lateral pain indicate?
1. Bicipital tendonitis
2. Supraspinatus tendonitis, bursitis, or adhesive capsulitis
3. AC sprain
-Holding pattern arm/shoulder girdle (protecting affected side? holding arm close to side, across chest?)
-Functionality/Use of limb
-Abnormalities in Ribs
-Common cause of Step Deformity
-Clav overrides acromion
At distal end of clavicle
-Common cause of
-Head of humerus drops and deltoids flatten out
A "sagging" / "flattening" below the acromion process where a rounded deltoid muscle would be.
-When medial border of scapula moves away (lifts off) from the post chest wall
-Dynamic = serratus anterior injury or compromised
nerve, possible muscle imbalance or strain to rhomboids or upper trapezius
-Static = structural deformity of the scapula, clavicle, spine, or ribs
Superior or Inferior angle of scapula lifting away from chest wall:
-Indicative of weakness and instability
-M/C: inferior border tilts away from chest wall, may indicate weak muscles
lower trapezius, latissimus dorsi, serratus anterior
or a tight
pulling or tilting it forward from above.
Bunching of biceps brachii long head tendon into belly of mm
-What grade of tear/strain is this?
Important to know when performing movement testing:
-All movement should be observed with most
painful movements performed last.
(Except chronic stage of dislocation, MOI direction can be tested first for Appreh.)
-Test unaffected side first and watch/check for Appreh
-Observe Scapulohumeral Rhythm during func test
-Watch for signs of "cheating" (movements should be purely performed by shoulder girdle)
-Watch for painful arch
-Perform RROM in neutral position
-When scapula moves more than the humerus w/ ABd
-Pt tends to hike shoulder upward to achieve movement
Reverse Scapulohumeral Rhythm
-Normal is Humerus:Scapula = 0:0 (0-30°) & 2:1 (31-180°)
-Abnormal = 1:1 &/or 1:2
What is Reverse Scapulohumeral Rhythm indicative of?
(Pain at AC/SC jt. = AC Painful Arc)
-Term used for pain occurring with ABd when structures become pinched under Acromial Arch
-Usually subacromial bursitis, calcium deposits, or tendinitis of the rotator cuff muscles.
At what point does pain commonly occur w/ glenohumeral painful arc?
45°/60 - 120°
Max pain = 90°
* (Greater tubercle collides with acromial arch)
At what point does pain commonly occur w/ acromioclavicular painful arc?
The last 10-20° of abduction indicating possible impingement (general pain) or AC/SC joint involvement (specific pain)
Shoulder and referred pain:
-Pain associated with shoulder is usually non-specific and is generally felt over lateral brachial region (with exception to AC joint lesions).
-Take note if pain goes past elbows and into hands.
To rule out neurological involvement (spinal nerve root involvment)
-Dermatome, myotome (C4, C5, C6)
-Reflex testing: C5-Biceps, C6-Brachioradialis, C7-Triceps
Referred pain with shoulder is usually non-specific and generally felt over the lateral brachial region (with the exception of AC joint lesions). Take note if px goes past elbows and into hands.
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