Shoulder Flashcards
What is the general function of the upper extremity?
It works as a position servomechanism (position, velocity, acceleration) to position the hand for function.
What parts are included in the upper extremity?
Shoulder
Elbow
Wrist
Hand
Fingers
What bone is considered the arm?
Humerus
What bones are considered the forearm?
Radius
Ulna
What are parts of the shoulder region?
Shoulder joint
Shoulder girdle
What bones are in the shoulder joint?
Scapula
Humerus
What bones are part of the shoulder girdle?
Scapula
Thorax (ribs & sternum)
Clavicle
What are the fossa’s of the scapula?
Supraspinous fossa
Infraspinous fossa
Subscapular fossa
Glenoid fossa
What are the 3 scapular borders?
Superior
Lateral
Medial
What are the angles of the scapula?
Superior angle
Inferior angle
What are the other anatomical scapular things?
Acromion process
Coracoid process
Glenoid cavity
Spine of scapula
Neck of scapula
What are the anatomical points of the humerus?
Head of humerus
Neck of humerus
Deltoid tuberosity
Greater tubercle
Lesser tubercle
Bicipital groove
What joint does all upper extremity loads go through?
SC joint
What is the SC joint?
It is where the clavicle and sternum/manubrium articulate
What is the AC joint?
It is where the acromion process of the scapula and the clavicle articulate
What is the glenhumeral joint?
It is where the humerus articulates with the Glenoid cavity
At what joint does primary motion of the scapula occur?
SC joint
What is the scapulothoracic articulation?
Where the scapula makes some contact with the ribs during movement
What is the suprahumeral (subacromial) space?
The space or cave where Supraspinatus, long head tendon of biceps, & the subdeltoid & acromial bursae sit
What 3 bursae are in the shoulder?
Subdeltoid
Subacromion
Subcoracoid
What movements occur at the shoulder joint?
Flexion/ Extension
Abduction/ Adduction
External/ Internal Rotation
Horizontal Abduction/ Adduction
What shoulder movements happen at the shoulder girdle?
Elevation/ Depression
Protraction/ Retraction
Upward/ Downward Rotation
Anterior/ Posterior Tilting
Why is the shoulder more reliant on muscle for stability?
It has increased mobility and decreased stability
What is normal shoulder ROM?
Flexion= 0-180 deg
Extension= 0-60 deg
Abduction=0-180 deg
ER=0-90 deg at 90 deg shoulder abduction
IR= 0-70 deg at 90 deg shoulder abduction
Which motions have tissue stretch for their end feel?
Flexion
Extension
Abduction
ER
IR
Which motions have tissue approximation as their end feel?
Adduction
What are the ligaments of the SC joint?
- anterior SC
- posterior SC
- costoclavicular
- interclavicular
Does the SC joint have an articulated disc?
Yes
When is the SC joint in close-pack position?
Max shoulder elevation
What is open pack position for the SC joint?
Anatomical position
What are the ligaments of the AC joint?
- acromioclavicular (synovial)
- coracoclavicular
• trapezoid
• conoid - coracoacromial (“arch”)
What does the clavicle look like?
It’s s-shaped
What does the clavicle do?
It acts as a strut between the shoulder & thorax preventing the shoulder from collapsing forward
Does the AC joint have a cartilaginous disk?
Yes, but it disappears between age 20-30
What is close pack position for the AC joint?
30 degrees of abduction
What is open pack position for the AC joint?
Anatomical position
What type of joint is the GH joint?
Diarthroidal (only 2 articulating surfaces that’s a multiaxial ball & socket joint)
What does a ball & socket joint allow for?
Global movement
What are the bones of the GH joint?
Glenoid fossa of scapula
Humeral head
What makes the GH joint unique?
- Only 25-33% of humerus contacts Glenoid fossa
- bone contribution to GH joint is minimal
What is close pack position for the GH joint?
Full abduction & ER
What is open pack position for the GH joint?
55 degrees abduction & 30 degrees of horizontal adduction
What are the osteokinematic movements of the GH joint?
- roll
- glide
- spin
Which osteokinematic movement is most important at the GH joint?
Spin
What are the characteristics of the anterior GH joint capsule?
12-8 position
Very strong
Forms the GH ligaments
What is the surface area of the capsule compared to the humeral head?
Twice the size of
What are the characteristics of the posterior GH joint capsule?
8-12 position
Very thin
Provides minimal strength to the GH joint
What are the ligaments of the GH joint?
Glenohumeral
- superior
- middle
- inferior
Coracohumeral
- suspension
Transverse humeral (not a true ligament)
When in anatomical position is the superior joint capsule lax or taut?
Taut
When in anatomical position is the inferior joint capsule lax or taut?
Lax
When in 180 degrees of abduction is the superior joint capsule lax or taut?
Lax
When in 180 degrees of abduction is the inferior joint capsule lax or taut?
Taut
When does the joint capsule primarily function?
In the end ROM
What is the primary stabilizer of the GH joint?
Muscle
What is the ceiling of the suprahumeral space?
Acromion process & CA ligament
What is the floor of the suprahumeral space?
Humeral head
In anatomical position, what are the landmarks where the scapula is even with the thoracic spine?
- Medial border of spine & T3
- Inferior angle & T7 or T8
How far anteriorly to the frontal plane does the scapula sit?
35-40 degrees
What plane does the scapula sit in and move in?
Scapular plane
What degree of tilt does the scapula have in anatomical position?
20 degrees of anterior tilt
Is the scapula pivotal with force/energy transmission to delivery in movement?
Yes
What muscles directly move the clavicle?
Subclavius
Sternocleidomastoid
What muscles directly move the humerus?
- Deltoids (all portions)
- Pectoralis major
- Latissimus Dorsi
- Biceps (both heads)
- Triceps (all heads)
- Rotator cuffs (supra- & Infraspinatus, teres minor, subscapularis)
- Coracobrachialis
What muscles directly move the scapula?
- Rhomboids
- Trapezius
- Serratus anterior
- Pectoralis minor
- Levator scapular
- Teres major
Where do the capsuloligamentous mechanoreceptors reside?
In the shoulders static structures
What do the capsuloligamentous mechanoreceptors do?
Relay sensory info regarding joint proprioception & kinesthesia via neural afferent pathways to the CNS
How does the brain help with joint stability at the GH joint?
The Glenoid labrum, joint capsule, & GH ligaments have mechanical & sensory functions that contribute to it
What structures help with the sensorimotor control system?
- Ruffini endings
- Pacinian corpuscles
- Golgi tendon organ-like
What slow adapting receptors continuously sense joint position?
Ruffini endings & GTO- like
What do the fast adapting receptors or Pacinian corpuscles do?
Provide info on joint motion & turn off shortly before being stimulated
What do the muscle spindles do?
Provide info about muscle length & changes in muscle length
What is the role of the tenomuscular mechanoreceptors?
They signal afferent info regarding the state of the muscle to the CNS to aid the dynamic restraint system
Where does shoulder abduction occur?
Scapular plane
What is the varying range of the scapulohumeral rhythm ratio?
1:1 to 1:4 ratio range
What is the scaoulohumeral rhythm dependent on?
- plane of movement
- velocity of movement
- resistance to arm
- type of muscle tension (concentric vs. eccentric)
- individual variance
What are arthrokinematics?
The movement of joint surfaces
What are osteokinematics?
Movement of bones around a joint
What movements of the scapula occurs during the first 20-30 degrees of abduction?
It oscillates medially & laterally with very little movement
What are the movements of the scapula beyond 20-30 degrees?
It upwardly rotates, elevates, retracts, & tilts posteriorly (following convexity of thorax)
What is scapular movement dependent on?
Muscles & movement at both the SC (1deg) & AC (2 deg) joints
What 7 things is scapular movement essential for maintaining during abduction?
- instant center of rotation
- length-tension relationship of deltoids
- relationship btwn humeral head/glenoid fossa
- protraction/retraction
- posterior tilting & elevation of the acromion
- distal to proximal link in the kinetic chain
- overall shoulder ROM
What is scapular dyskinesia?
An observable alteration in scapular position & motion pattern relative to the thorax
What is normal scapular motion?
Combo of upward rotation, posterior tilt, & retraction during full arm elevation (reversal during arm lowering)
What are scapular dyskinesia sub-types?
- winging
- dysrhythmia
What is normal winging of the scapula?
It wings at rest but doesn’t wing during motion
What is abnormal winging of the scapula?
It wings at rest & during motion
What occurs at the medial border during winging of the scapula?
Scapular protraction occurs during shoulder abduction when the scapula should be retracting
What occurs at the inferior angle during winging of the scapula?
The scapula tilts anteriorly when the scapula should be tilting posteriorly
What is scapular dysrhythmia?
- a lack of smooth scapulohumeral rhythm
- most common pattern is early/ excessive scapular elevation
Do winging & dysrhythmia often occur together?
Yes
During abduction, what kinematics does the clavicle generally follow?
- elevation
- retraction
- posterior rotation
(Follows scapula kinematics)
What is a force couple?
Parallel forces of equal magnitude applied to a structure of equal distance from the center of the mass, producing a resultant force
What is force couple for muscles?
A synergistic balance of agonist & antagonist muscles to stabilize a joint statically and/or dynamically
Do muscles work synergistically together to control movement or position of a joint
Yes
What does synergistic balance demonstrate?
-the high reliance on the dynamic restraint system for stability (shoulder)
What is the force couple for the GH joint with superior/inferior mvmt?
Stabilizing humeral head against superior/inferior movement
- deltoid & supraspinatus VS. infraspinatus & teres minor
What is the force couple at the GH joint for anterior/posterior mvmt?
Stabilizing humeral head against anterior/posterior movement
- subscapularis VS. infraspinatus & teres minor
What is the force couple for scapular upward rotation?
Lower trapezius & serratus anterior VS. upper trapezius
What is the force couple for scapular stabilization?
Upper portion of trapezius VS. lower portion of trapezius & rhomboids VS. serratus anterior
Why is the entire body used during the overhand throwing motion?
To maximize performance & minimize internal forces at the shoulder & elbow
What is the progression of energy through the body as throwing occurs?
Leg > hip > trunk > scapula > arm > forearm > hand > ball
Is neuromuscular control involved as energy is transferred from one unit to another during throwing?
Yes
What is the muscle activation & peak intensity progression?
Contralateral internal/external obliques & rectus abdominis muscles > scapular stabilizers > deltoids > rotator cuff
