Shoulder Review Flashcards
The shoulder girdle has only ____ boney attachment to the axial skeleton. The ______ articulates with the sternum.
> 1 boney attachment
>The clavicle articulates with the sternum
4 joints of the shoulder girdle
Synovial Joints:
1. GHJ, ACJ, SCJ
Functional Articulations:
1. Scapulothoracic
GHJ
incongruous, ball & socket triaxial joint w/a lax capsule. Supported by tendons of the rotator cuff, the glenohumeral ligaments, and the coracohumeral ligament.
Arthrokinematics of GHJ
Convex humeral head roll/slide opposite of concave glenoid fossa
Anatomical location of the glenoid fossa
Anterior, lateral, & upward
purpose: provide some stability to GHJ
Anatomical purpose of the glenoid labrum
Deepen the glenoid fossa to provide greater congruity and to serve as an attachment site for the capsule
GHJ Arthrokinematics: Flexion
Spin
GHJ Arthrokinematics: Extensin
Spin
GHJ Arthrokinematics: Horizontal ADD
Convex humeral head rolls Anterior/ Slide Posterior
GHJ Arthrokinematics: Horizontal ABD
Convex humeral head rolls Posterior/ Slide Anterior
GHJ Arthrokinematics: IR @ 0 degrees ABD
Convex humeral head rolls Anterior/ Slide Posterior
GHJ Arthrokinematics: ER @ 0 degrees ABD
Convex humeral head rolls Posterior/ Slide Anterior
GHJ Arthrokinematics: ADD
Convex humeral head rolls Inferior/ Slide Superior
GHJ Arthrokinematics: ABD
Convex humeral head rolls Superior/ Slide Inferior
Static Stability of GHJ
The structural relationship between boney anatomy, ligaments, and glenoid labrum
Dynamic Stability of GHJ
The tendons of the RTC blend with the ligaments and glenoid labrum at their sites of attachment > when muscles contract they provide stability by tightening the static restraints.
In addition, the ______ and the ______ reinforce the capsule with their attachments and provide superior and inferior shoulder joint support respectively.
- Long head of the bicep
2. Triceps Brachii
The long head of the bicep
Provides stabilization against humeral elevation & contributes to anterior stability of the GHJ by resisting torsional forces when the shoulder is ABD and ER.
Static Stabilizers of the Scapula
- Cohesive forces of the subscapular bursa
- SC and AC joint ligaments
- Scapulothoracic Fascia
Dynamic Stabilizers of the Scapula
- Upper, middle, and lower traps
- Serratus Anterior
- Levator Scap
- Rhomboids
Static Stabilizers of the GHJ (with arm in dependent position)
- Super capsule, superior GH ligament, & Coracohumeral ligament
- Adhesive properties of synovial fluid & negative joint pressure
- Slight upward inclination of glenoid improves congruence
Dynamic Stabilizers of the GHJ
- RTC
- Deltoid
- Long head of biceps brachii
- Pectoralis major
- Lats
- Teres major
The weak capsule of hte ACJ is reinforced with _____ and ______.
- Superior and inferior AC ligaments
Stability of the ACJ
The AC ligaments are supported by strong coracoclavicular ligament
No muscles directly cross the joint for dynamic support
Arthrokinematics for ACJ Retraction
Clavicle Rolls Posterior & slides Anterior
Arthrokinematics for ACJ Protraction
Clavicle rolls anterior & slides posterior
SCJ
Incongruent, triaxial, saddle-shaped joint with a disk.
Stability of SCJ
Supported by anterior & posterior SC ligaments & the interclavicular/costoclavicular ligaments. No muscles directly cross the joint for dynamic stability.
True or False
Rotation of the clavicle occurs as an accessory motion when the humerus is elevated above the horizontal position & the scapula has to rotate; it cannot occur in an isolated voluntary motion.
True
SCJ Arthrokinematics: Protraction
Concave clavicle rolls and slides anterior
SCJ Arthrokinematics: Retraction
Concave clavicle rolls and slides posterior
SCJ Arthrokinematics: Elevation
Convex clavicle rolls superior/medial & slides inferior/lateral
SCJ Arthrokinematics: Depression
Convex clavicle rolls inferior/lateral & slides superior/medial
Upward & downward rotation of the STA
Upward rotation, posterior tilting, & ER of the scapula are component motions that must occur with full shoulder elevation
IR/ER of the scapula
When the medial border of the scapula lifts away from (wings) or approximates the rib cage.
Anterior tilting of the scapula
Occurs in conjunction with internal rotation and extension of the humerus when reaching the hand behind the back
Postural Relationship
In a dependent position, the scapula is stabilized through a balance of forces. The weight of the humerus creates a downward rotation, contraction, and forward tilting moment on the scapula. These moments are balanced by the support of the upper traps, serratus anterior, rhomboids, and middle traps.
Subacromial Space
Made up of the coracoacromial arch, overlies the subacromial/subdeltoid bursa, the supraspinatus tendon, and a portion of the muscle.
Function of subacromial space
Allow for & participated in normal shoulder function
Compromise of subacromial space
It could be caused by faulty muscle function, postural relationships, faulty joint mechanics, injury to the soft tissue in the region, or structural anomalies of the acromion that can lead to impingement syndromes.
Scapulohumeral Rhythm
2:1 (glenohumeral motion: Scapular rotation)
The function of scapulohumeral rhythm
Research shows that during humeral elevation, the synchronous motion of the scapula allows the muscles to move the humerus to maintain an effective length-tension relationship throughout the activity and helps maintain congruence between the humeral head and fossa while decreasing shear forces.
Clavicular elevation & rotation with humeral motion
The first 30 degrees of upward rotation of the scapula occurs with elevation of the clavicle in the SCJ. As the coracoclavicular ligament becomes taut, the clavicle rotates 38 degrees to 55 degrees about its longitudinal axis, which creates an elevation @ the acromial end. This allows for an extra 30 degrees @ the ACJ.
External Rotation of the humerus with elevation
During elevation of the arm, the humerus ER; this allows for the greater tubercle of the humerus to clear the coracoacromial arch. A weak infraspinatus and/or trees minor could result in an impingement of the soft tissues in the subacromial space leading to pain, inflammation and eventually loss of motion.
Deltoid/Supraspinatus vs. Infraspinatus/Teres minor/subscap
- The deltoid works to cause an upward translation of the humerus.
- The supraspinatus is significant in stabilizing, compressing and a slight upward translation effect on the humerus during arm elevation working with the deltoid during humeral elevation.
- The infraspinatus, teres minor, and subscap produce a stabilizing compression and downward translation of the humerus in the glenoid.
The combined motions of all 5 muscles produce a balance in forces that elevate the humerus and control the humeral head. Interruption of the coordinated function of these mechanisms may lead to tissue microtrauma and shoulder complex dysfunction.
Nerve Disorders in the Shoulder: Brachial Plexus in TOS
Common sites for compression:
- Scalene triangle
- Costoclavicular space
- Under the Coracoid Process
- Pectoralis minor muscle
Nerve Disorders in the Shoulder: Suprascapular nerve in Suprascapular notch
This injury occurs from direct compression or from nerve stretch, such as when carrying heavy book bags over the shoulder.
Nerve Disorders in the Shoulder: Radial Nerve in the Axilla
Compression occurs from continual pressure, such as when leaning on axillary crutches.
