Biomechanics Review Flashcards
What is the plane of scaption?
35 degrees anterior to the ML axis.
What is the posterior inclination of the clavicle?
20 degrees posterior to the ML axis.
What is humeral head retroversion?
30 degrees retroverted to face the glenoid.
Describe the movement at the sternoclavicular joint during elevation.
- Longitudinally convex on concave
- Contralateral rolls and slides.
How does the acromioclavicular joint move with the scapula?
It coordinates movement with the scapula, primarily in upward and downward rotation.
What does the superior glenohumeral ligament check?
Adduction.
What does the middle glenohumeral ligament check?
- Anterior translation
- Especially with some abduction and external rotation.
What does the inferior glenohumeral ligament check?
- At 90 degrees abduction, the anterior band checks external rotation.
- The posterior band checks internal rotation, and the axillary pouch checks AP translation.
Describe the scapulohumeral rhythm during shoulder abduction.
- 120° GH joint abduction, and
- 60° scapulothoracic upward rotation.
What is the role of the clavicle during shoulder abduction?
The clavicle retracts and posteriorly rotates around its axis.
What muscles are primary upward rotators of the scapula?
- Serratus anterior
- Upper/lower fibers of the trapezius.
What muscle can become adaptively shortened with anteriorly tilted and internally rotated scapula?
Pectoralis minor.
What is a SLAP lesion and its causes?
A tear in the superior labrum due to large or repetitive forces within the biceps tendon.
What is subacromial impingement?
Decreased subacromial space due to improper biomechanics and repetitive loading.
What is GIRD?
Glenohumeral Internal Rotation Deficit, common in throwing athletes.
What causes scapular dyskinesis and winging?
Weakness in the muscles that move and stabilize the scapula.
What is thoracic outlet syndrome?
Compression of neuro-vasculature at the scalenes, clavicle, or pec minor, causing pain in the arm, shoulder, or neck.
Tennis elbow
- What is it ?
- Cause = ?
Lateral epicondylitis, caused by repetitive wrist extension movements.
What is golfer’s elbow?
Medial epicondylitis, often seen in adolescent male baseball pitchers.
What is carpal tunnel syndrome?
Compression of the median nerve within the carpal tunnel.
What joints are involved in elbow and forearm movements?
- Humeroulnar
- Humeroradial
- Proximal/distal radioulnar joints.
What is the primary function of the biceps brachii?
Supination and flexion of the elbow.
Describe the movement of the distal radioulnar joint in weight-bearing.
- Convex-on-concave movement
- Contralateral rolls and slides
What is ulnar nerve entrapment?
Irritation of the ulnar nerve, often at the cubital tunnel near the medial epicondyle or at the ulnar side of the wrist.