Shoulder Flashcards
Shoulder Joint
- Ball and Socket, Synovial joint
- Moves in 3 degrees/planes, and is Triaxial
- Flexion, Extension, Abduction, Adduction, Internal Rotation, External Rotation, Horizontal ABduction, Horizontal Adduction
- Greatest ROM of all joints
- Shoulder can compensate for loss of elbow/wrist motion
- If it gets injured, ADLs abilities are affected
Shoulder Complex
The four joints of the shoulder:
1) Glenohumeral Joint (GH): head of humerus, glenoid fossa of scapula
2) Sternoclavicular Joint
3) Acromioclavicular Joint
4) Scapular Thoracic Gliding Mechanism
Shoulder Girdle
Connects upper limb to axial skeleton; the clavicle and scapula; AKA “pectoral girdle”
• Contains 5 different true and false joints
• 2 primary support functions:
- Stabilizing shoulder during static contractions
- Providing strong base of support for shoulder movements
Scapulohumeral Rhythm
Motion of the clavicle, scapula and humerus together to achieve full elevation of arm. Exists between the scapula in shoulder girdle and the GH joint.
• 2 purposes:
- Scapular upward rotation; allows GH muscles to maintain length/tension
- Simultaneous movement of humerus/scapula; prevents impingement betw greater tubercle of humerus and acromion process
• First 30˚ GH flexion/abd is “Setting Phase”
• 2nd phase betw 30-90˚; scapula upward rotates 1˚ for every 2˚ of GH flex/abd (1:2 ratio)
• 2:1 ratio not consistent after 90˚
Strength/Stability of Shoulder
- Greatest strength produced in aDduction
- Extension stronger than flexion
- Internal rotation is stronger than external
- Remember: strongest going INTO body
- Weakest muscles are rotators
- Shoulder very mobile, therefore LESS stable
- Most frequently dislocated joint
- Most common dislocation position is 90˚ aBd and external rotation (climbing, kayaking, throwing, monkey bars)
Subluxation vs. Dislocation
Can be used interchangeably, but technically SUBLUXATION is when arm pops back in place, and true DISLOCATION is permanent (needs intervention).
Nerves Innervating Shoulder
Innervated primarily by Brachial Plexus (with exception of long thoracic nerve and spinal accessory nerve, not part of plexus).
Nerves of Brachial Plexus
- Axillary Nerve (C5-C6): Delts, Teres Minor
- Musculocutaneous Nerve (C5-C7): Coracobrachialis, Biceps
- Suprascapular Nerve (C5, C6): Supraspinatus, Infraspinatus
- Upper Subscapular Nerve (C5, C6): Upper Subscapularis
- Lower Subscapular Nerve (C5, C6): Lower Subscapularis, Teres Major
- Thoracodorsal Nerve (C6-C8): Lats
- Lateral Pectoral Nerve (C5-C7): Pecs Major
- Radial Nerve* (C5, C6): Triceps brachii (*easily damaged)
What adds stability to shoulder?
- Ligaments
- Rotator Cuff
- Joint Capsule
- Labrum
Shoulder Ligaments
- 2: Glenohumeral and Coracohumeral ligaments (don’t need to remember names)
- Hold head of humerus in place with glenoid fossa to provide stability (in addition to rotator cuff’s 4 tendons)
Labrum
Ring of fibrocartilage surrounding and deepening the socket and increasing articulation with the humeral head.
• Increases stability of GH joint.
• Glenoid fossa deepened by glenoid labrum, joint capsule, GH ligaments, and long head of biceps
• These structures increase surface contact area of humeral head in glenoid fossa
Rotator Cuff
4 muscle tendon insertions that stabilize the humerus in the glenoid fossa when arm is in motion.
• Head of humerus allowed to rotate internally/externally via rotator cuff
• Remember “SITS”: Supraspinatus, Infraspinatus, Teres minor, Subscapularis
Muscles of Shoulder (GH Joint)
Most of larger/powerful muscles are superior, while smaller/weaker rotator cuff muscles are deeper.
• Flexion: Pecs Major, Ant Deltoid, Biceps
• Extension: Lats
• ABduction: Mid Deltoid, Supraspinatus
• ADduction: Pecs Major, Lats, Teres Major
• Internal Rotation: Pecs Major, Ant Deltoid, Lats, Teres Major, Subscapularis
• External Rotation: Post Deltoid, Teres Minor, Infraspinatus
• Horizontal ABduction: Post Deltoid
• Horizontal ADduction: Pecs Major, Ant Deltoid
Muscles of Shoulder Girdle (Scapula)
- Protraction: Rhomboids, Trapezius, Serratus Anterior, Pecs Minor
- Retraction: Rhomboids, Trapezius
- Elevation: Levator Scapula, Trapezius
- Depression: Pecs Minor, Trapezius
- Upward Rotation: Trapezius, Serratus Ant.
- Downward Rotation: Pecs Minor
Frozen Shoulder
Clinically known as “adhesive capsulitis.”
• Only occurs in shoulder
• Starts with inflammatory response to secondary injury
• Joint capsule contracts, joint becomes stiff (loss of ROM)
• Mostly in women age 40-50
• Usually resolves spontaneously
