Shoulder Flashcards
(47 cards)
What are the four mechanically interrelated articulations of the shoulder complex?
- Sternoclavicular (SC) Joint
- Acromioclavicular (AC) Joint
- Scapulothoracic (ST) ‘Joint’
- Glenohumeral (GH) Joint
What is the primary design purpose of the shoulder complex?
Mobility
What type of joint is the sternoclavicular (SC) joint?
Synovial, saddle joint
What is the only structural attachment between the axial skeleton and the shoulder/upper extremity?
Sternoclavicular Joint
How many degrees of freedom does the SC joint have for rotational movements?
3
What are the three rotational degrees of freedom of the SC joint?
- Elevation/depression of clavicle
- Protraction/retraction of clavicle
- Anterior/posterior rotation of clavicle
What is the range of motion (ROM) for clavicular elevation at the SC joint?
Up to 48°
What role does the SC disc play in the SC joint?
Acts as a pivot point for medial end of clavicle during movements
What are the main components of the sternoclavicular capsule?
- Anterior & posterior sternoclavicular ligaments
- Bilaminar costoclavicular ligament
- Interclavicular ligament
What type of joint is the acromioclavicular (AC) joint?
Incongruent plane, synovial joint
What are the main functions of the acromioclavicular joint?
- Allows scapula to move in 3 dimensions during arm movement
- Increases upper extremity motion
- Positions glenoid beneath humeral head
- Helps maximize scapula contact with thorax
- Assists in force transmission from upper extremity to clavicle
True or False: The acromioclavicular joint is inherently stable.
False
What are the two portions of the coracoclavicular ligament?
- Conoid ligament
- Trapezoid ligament
What kinematic motions occur at the acromioclavicular joint?
- Internal/external rotation
- Anterior/posterior tilting
- Upward/downward rotation
What is the principal motion of the scapula during active elevation of the arm?
Upward rotation
What muscles are primarily responsible for scapular protraction?
- Serratus anterior
- Pectoralis major
- Pectoralis minor
What type of joint is the glenohumeral joint?
Ball & socket, synovial joint
What is the orientation of the glenoid fossa typically?
Slightly tilted upward
What is the consequence of reduced stability in the glenohumeral joint?
Increased susceptibility to instability, injury, and degenerative changes
What occurs during anterior tilting of the scapula?
Acromion moves forward & inferior angle moves posteriorly
What happens during posterior tilting of the scapula?
Acromion moves backward & inferior angle moves anteriorly
Fill in the blank: The scapulothoracic joint is not a true _______.
[anatomic joint]
What is retroversion in relation to the glenoid fossa?
Retroversion refers to the glenoid fossa facing slightly posterior.
Most commonly, the glenoid is in slight retroversion (6° - 7°).
What are the articular surfaces of the glenohumeral joint?
The articular surfaces include the humeral head, which forms 1/3 to 1/2 of a sphere and has a larger surface area than the glenoid.
When arms hang dependently at the side, there is little contact between these surfaces.