Scapulothoracic Protraction is one of several movments available to the Scapulothoracic Joint that involves lateral gliding of the Scapula with a compliment of Sternoclavicular Joint and Acromioclavicular Joint rotations in the horizontal plane. In layman’s terms this movement describes the process of reaching forwards with the arm.
Prime Movers
Accessory
Sternoclavicular Joint Capsule
Spiral Line - Pain ful
Superficial Back Arm Line - restricted
Deep Back Arm Line - restricted
Deep Front Arm Line - Pain ful
Lateral Line - restrcited
Protraction of the Scapulothoracic Joint occurs as the Scapula glides laterally, following the contour of the Ribs , to promote The Shoulder Girdle in a forwards position. While Protraction occurs as a composite of motion at multiple joints, it follows the Clavicle about the fixed point of the Sternoclavicular Joint where it translates posteriorly and tensions the articular disc (SOURCE-2+8). Simultaneously, Protraction of the Scapula promotes the Acromion beyond the Clavicular Facet (SOURCE-2). The Inferior Angle of Scapula typically translates further lateral than the Superior Angle which results in Scapulothoracic Joint - Upward Rotation which forms the basis for a common movement coupling (SOURCE-2+6).
Both Serratus Anterior and Pectoralis Major facilitate the lateral glide of the Scapula along the Thorax while the eccentrically contracting Rhomboids regulate the velocity and extent of Protraction (SOURCE-2). Contraction of the Pectoralis Major compliments Protraction by guiding the Clavicle and Humerus anteriorly via its attachments (SOURCE-3)The overlying and often attaching Latissimus Dorsi prevents the Inferior Angle of Scapula from excessive Scapular Winging (SOURCE-2).
Excessive Protraction at rest or through movement may result from altered tone of related musculature or restrictions in soft-tissue. Hypertonicity of the Pectoralis Major , Serratus Anterior , Pectoralis Minor or Latissimus Dorsi all have the capacity to increase Protraction (SOURCE-1+2+6). Further, increased Protraction is often indicative of weak Scapulothoracic Joint musculature (SOURCE-6). Excessive Protraction is also a common compensatory pattern associated with Glenohumeral Joint restriction, with the combination predisposing Subacromial Impingement during arm elevation (SOURCE-6+7). Restriction in the Posterior Glenohumeral Joint Capsule specifically, often results in a combined posture of excessive Protraction and Scapulothoracic Joint - Depression which predisposes Rotator Cuff pathology (SOURCE-6). Restricted GH Joint - Internal Rotation results in excessive Protraction and Anterior Scapular Tilting (SOURCE-6). A similar pattern of Winging and Protraction develops fromReverse Scapulohumeral Rhythm , where insufficiency from Scapula stabilisers drives the Rotator Cuff to favour stabilising the Scapulothoracic Joint rather than its normal stabilisation role at the Glenohumeral Joint (SOURCE-6).As engagment of the Protractors draws anteriorly on the Head of Humerus , this motion may be vulnerable in those with Anterior Glenohumeral Instability (SOURCE-6). A forceful stretch into Protraction with Horizontal GH Joint - Adduction may compromise the Suprascapular Nerve (SOURCE-6).
Normal Protraction is limited by several structures. At the Sternoclavicular Joint , posterior gliding of the medial Clavicle is limited by tension in the Sternoclavicular Ligaments and Posterior Lamina of the Costoclavicular Ligament (SOURCE-2+5). Protraction is also limited by the antagonistic Rhomboids and Trapezius and near the Acromioclavicular Joint , tension in the Trapezoid Ligament (SOURCE-5). Insufficient movement in the Acromioclavicular Joint or Sternoclavicular Joint joint can be, at least in part, compensated for by the other (SOURCE-8). Insufficient Protraction also faces its own sequelae. During throwing for example, reduced Protraction increases deceleration forces on The Shoulder Girdle , altering its safe-zone and predisposing Glenoid Labrum Tears (SOURCE-7).
Both excessive and insufficient Protraction are common forms of Scapular Dyskinesis of which there may be many causes. If persistent, dysfunctional Protraction often falls to an impingement or instability related cascade.
Excessive Protraction is a common compensatory pattern associated with limited Glenohumeral Joint movement, with the combination predisposing Subacromial Impingement during arm elevation (SOURCE-6+7). This limited Glenohumeral motion may be attributed to many factors, including simple Muscle tightness or fibrotic changes such as those seen in Adhesive Capsulitis . Restriction in the Posterior Glenohumeral Joint Capsule specifically, often results in a combined posture of excessive Protraction and Scapulothoracic Joint - Depression which predisposes Rotator Cuff pathology (SOURCE-6).
Glenohumeral Instability - typically results in decreased Scapulothoracic Joint - Upward Rotation and a reciprocal increase in Protraction (SOURCE-7). In these instances, Pain and other symptoms are often alleviated with Scapulothoracic Joint - Retraction (SOURCE-7). Conversely, insufficient Protraction of the Scapula may lead to instability during particular movements. Reduced Protraction during the acceleration/ deceleration phase of overhead throwing increases deceleration forces on The Shoulder Girdle which alters its safe-zone and predisposes Glenoid Labrum Tears (SOURCE-7).
Thoracic Outlet Syndrome - a posture of increased Protraction can decrease the diameter of theCervico-Axillary canalto predispose Thoracic Outlet Syndrom (SOURCE-7).
Vertebral Column Posture - both excessive Cervical Spine Lordosis and Thoracic Spine Kyphosis have been described to correspond with an increase in Protraction of the Scapula to predispose pathologies such as Subacromial Impingement or Scapular Dyskinesis (SOURCE-4+7).
At Rest - resting posture of slight Scapulothoracic Joint - Elevation and Scapulothoracic Joint - Retraction is considered an optimal position for The Shoulder Girdle as it leaves the Glenoid Fossa facing slightly upwards (SOURCE-8)
Scapulohumeral Rhythm - during this motion slight Protraction is considered normal (SOURCE-6)
Snapping Scapula - clicking/ snapping sensation associated with arc of motion between Protraction and Scapulothoracic Joint - Retraction caused by rubbing with underlying Ribs (SOURCE-6)
Excessive Protraction - at rest or through movement may indicate hypertonic Protractors, weak Scapulothoracic Joint Muscles or a restricted Glenohumeral Joint
Serratus Anterior Atrophy - may indicate Long Thoracic Nerve plasy/ entrapment
Protraction of the Scapula is often evaluated as a consequence of Serratus Anterior strength testing but as one of several composite motions available to The Shoulder Girdle , still forms a component of the Shoulder - Active Range of Motion and Shoulder - Passive Range of Motion assessment. Over the total arc of Protraction-to- Scapulothoracic Joint - Retraction , approximately 10-12cm of Scapula motion should be available (SOURCE-5).
To perform this movement bilaterally, the patient is instructed to bring their shoulders together anteriorly. Unilaterally, the patient is asked to punch their arm forward while it remains straight. To diminish the effect of gravity against Protraction, the patient should be kept upright (such as seated) and to better isolate the Serratus Anterior the patient should be evaluated in the supine position with arm in 90º GH Joint - Flexion (SOURCE-5). As the Medial Borders of the Scapula glide laterally from the Vertebral Column it is common that the Inferior Angle of the Scapula moves further than the Superior Angle, thus, some Scapulothoracic Joint - Upward Rotation should occur (SOURCE-2+6).
As the motion at one joint is often compensated for by the other, Range of Motion of the Glenohumeral Joint should be evaluated, particularly in the presence of excessive Protraction (SOURCE-6). Isometric Tests for Protraction are typically used to evaluate the Serratus Anterior in the supine position.
The following Shoulder - Special Tests may be relevant in the assessment of dysfunctional Protraction: Serratus Anterior
Punch Out Test - manual muscle test
Shoulder Flexion Resistance Test - sensitivity 1.0, specificity 1.0
Posterior Glenohumeral Joint Capsule Restriction
Anterior Glenohumeral Instability
The following tests may be conducted to rule in/out nerve contribution with C5 , C6 , C7 Nerve Roots relevant to Protraction: Cervical - Myotomes (active resisted)
Cervical - Dermatomes - evaluates sensory region
C5 - skin over the lateral shoulder/ Deltoid towards base of Thumb
C6 - skin over lateral arm from shoulder to Thumb and index Fingers
C7 - skin over posterior arm from shoulder to middle Fingers
Reflex - diminished reflex indicates potential lesion at corresponding Nerve Root
Upper Limb Nerve Tension Tests
The treatment of Scapulothoracic Joint Protraction dysfunction should be specific to the underlying cause. For rehabilitation of common underlying conditions such as Scapular Dyskinesis , Glenohumeral Joint Restriction, Subacromial Impingement or a hypertonic Protraction muscles, see their respective pages.
The following Stretching techniques may directly or indirectly improve Scapulothoracic Joint Protraction restriction:
Genie Stretch - rudimentary horizontal adduction stretch
Forward Elevation Stretch - rudimentary passive stretch with moderate GH Joint - Flexion range
Sleeper Stretch - greater emphasis on GH Joint - Internal Rotation
Sleeper Stretch MWM - internal rotation stretch combined with Humerus Mobilisation
Shoulder Dislocates - mobility exercise that emphasises the greatest circumduction range possible
Seated Thoracic Rotation with Breathing - large lateral flexion and rotation range coupled with breathing
Bent Over Lat Stretch - accessible active stretch with large GH Joint - Flexion or Horizontal GH Joint - Adduction range
As a specific training protocol relates to the underlying cause of Scapulothoracic Joint Protraction dysfunction, the following lists protraction-based Strength exercises in rough descending order from most rudimentary:
Cat-Cow - promotes Vertebral Column movement and retraction/ protraction
Isometric Chest Squeezes - isometric exercise that isolates Chest
Scapular Punches - isotonic exercise that emphasises Scapulothoracic Joint - Protraction
Chest Press Machine - rudimentary horizontal push machine
Push-Up - bodyweight isotonic horizontal push exercise
Push-Up Plus - push-up variation with additional Scapulothoracic Joint - Protraction
Bench Press - isotonic horizontal push exercise with capacity for high loads
Incline DB Bench Press - unilaterally loaded Bench variation on variable incline
Bottoms-Up Kettlebell Walk - isometric push/ stability exercise with or without perturbation
Pallof Press - low load horizontal push exercise that emphasises anti-rotation of Core
Dips - bodyweight isotonic push exercise with large GH Joint - Extension range
The following Mobilisation techniques may be relevant in the treatment of Scapulothoracic Joint Protraction: Joint Play
Acromioclavicular Joint - if subtle restrictions are present
Cervical Spine - for instances of Radiculopathy a PACVP , PAUVP or TVP may be applied to relevant Cervical segment(s) in addition to the following techniques:
Mobilisation with Movement - mobilisations applied with active movement
AC Joint - MWM 1 - GH Flexion or Horizontal Adduction
Sleeper Stretch MWM - self-guided Posterior Capsule release
Cervical Spine - for suspected Radiculopathy , the following techniques may be indicated:
SMWAM - Cervical mobilisations with arm movement
Neurodynamic SMWAM - Cervical mobilisations with neurodynamic arm movement
Cervical SNAGS - Cervical mobilisations with neck movement
NAGS - particularly useful for restriction or Pain associated with movement for C2-C7
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