UPPER EXTREMITY Flashcards
FUNCTIONAL ARTICULATIONS OF THE SHOULDER COMPLEX
Shoulder girdle has increased ROM with less compromise of stability
JOINTS OF THE SHOULDER
- Sterno-clavicular
- Acromio-clavicular
- Scapulo-thoracic
- Gleno-humeral (ball and socket)
- Supra-humeral/sub-acromial
- LH biceps and bicipital groove
ROLE OF LONG AND SHORT HEAD OF BICEP
Ant stability of GH, therefore failure of stabilisation of LHB can have damaging effects on GH and rotator cuff function
Achieved through compression of humeral head against glenoid fossa
Humeral head stability= compression of humeral head to glenoid fossa, doesn’t go into subacromial space
EVIDENCE THAT LONG HEAD BICEPS ENABLES GH STABILITY
LHB hypertrophies in pt with rotator cuff tears
FORCE COUPLING MECHANISM
Force coupling around a pivot point
2 opposing forces rotating around a pivot point
There are multiple forces at any given moment
These can be equal or unequal, depending on the function required and balance of moving elements such as muscles and balance of stabilising elements such as ligaments
SCAPULO-HUMERAL RHYTHM
Area at which scapula moves and relies on rate at which the humerus moves
Permits largest ROM of any complex in the body
The shoulder girdle increases ROM with less compromise of stability (scapula-humeral rhythm) (4 joints vs 1 joint)
Facilitate movements of the upper extremity by positioning the GH favourably
PHASE ONE OF ABDUCTION
30 humeral abduction
0-5 clavicle elevation
Minimal scapula movement medially
PHASE TWO OF ABDUCTION
Humerus 40 abduction (up to 90)
Scapula 20 lat rot
Clavicle 15 elevation
PHASE THREE OF ABDUCTION
Humerus 60 abduction + 90 lat rot
Scapula 30-40
Clavicle 30-50 post rot
15 elevation
COMBINED ROLL AND SLIDE PRINCIPLE
- Maintains joint congruity through range of movement
- GH is an example of convex on concave; where the moving bone (humerus) is convex and the stationary bone (scapular) is concave
- The humerus superior rolls, whilst the scapular slides inferiorly during abduction
- During flexion/extension, the head of the humerus spins along with accompanying upward rotation of the scapulothoracic joint. Assisted by rotation of the clavicle
ROLE OF THE CLAVICLE
- The clavicle is the only axial attachment for the entire upper extremity
- The clavicle elevates, depresses, rotates, protracts and retracts. All movements are passive accessory movements
- All clavicular movements are essential to position the scapular in the optimal position to accept the head of the humerus
- Essentially all movements of the glenohumeral joint involves some movement of the clavicle around the pivot point of the sternoclavicular joint
ROLE OF CAROCOID PROCESS
Ant anchor of scapula- e.g., pec minor, corocobrachialis, short head of bicep
ROLE OF THE LONG AND SHORT HEADS OF BICEPS IN HUMERAL HEAD STABILITY
- Provides anterior stability to the GH, therefore failure of the stabilisation of the long head biceps can have damaging effects on the GH and rotator cuff function
- Achieved through compression of the humeral head against glenoid fossa
- Observations that the tendon of long head of biceps atrophies in patients with rotator cuff tears confirms that it has a role in GH stability
IMPORTANCE OF SUB ACROMIAL SPACE
Location of bicep tendon, rotator cuff and bursa
Can become pinched during some shoulder movements
GH MOVERS
- Deltoid
- Supraspinatus
- Biceps brachii
- Brachioradialis
- Pectoralis major
GH STABILISING TISSUES
- Capsule
- Ligaments
- Articular disc (AC/SC joints)
GH STABILISING MUSCLES
- Subscapularis
- Serratus anterior
- Latissimus
- Coracobrachialis
- Pectoralis minor
IDENTIFY THE CAUSE OF PAINFUL AND WEAK SHOULDER
Rotator cuff related shoulder P
Subacromial impingement syndrome
SLAP lesion
IDENTIFY THE CAUSE OF PAINFUL AND STIFF SHOULDER
Adhesive capsulitis
OA (bony remodelling) of GH, AC
IDENTIFY THE CAUSE OF PAINFUL AND UNSTABLE SHOULDER
Dislocations
Repeated dislocations
ELBOW TORQUES
Flexion torques are 70% greater than extension torque
Torque forces needed for bicep curl are 70% greater than an ext push down
Flex torque with supination is 20% greater than with pronation
Brachioradialis in mid prone inc power of flexion
ELBOW LEVERS
3rd class lever- during flexion
Effort= muscle (at point of insertion)
Load= weight of body and additional resistance
Fulcrum= Jt itself
ELBOW ROLL AND GLIDE
Ulnar concave
Humerus convex- two shapes make Jt more congruent
Humerus passive in both flex and ext, driven by active movement of ulnar and radius
On elbow flexion- roll and slide move in same direction
WHAT IS THE PURPOSE OF THE INTEROSSEOUS MEMBRANE?
- The interosseous membrane is a fibrous connective tissue structure that runs between the ulna and radius bones in the forearm, connecting them together
- Its purpose is to provide stability and support to the forearm by distributing the forces from the humerus to the carpals
- It plays a critical role in allowing the forearm bones to rotate around each other, enabling the pronation and supination of the hand
WHAT IS SIGNIFICANT ABOUT THE STRUCTURE OF THE INTEROSSEOUS MEMBRANE?
- The interosseous membrane is significant because it plays an essential role in the stability and movement of the forearm and hand
- It provides stability and support for the radius and ulnar as well as helping to distribute the forces from the humerus to the carpals preventing damage and injury to these structures
MECHANICS OF GRIP
Lumbricals allow for L-shape grip
WRIST - ROLL AND SLIDE MECHANISM
- Ulnar and radial deviation
- The radius is the concave structure
- The proximal carpals are the convex structures
- Movement driven actively by carpals, and passively allowed by distal radius and ulnar
MOVERS
o Biceps brachii
o Brachialis
o Brachioradialis
o Triceps brachii
PRONATORS/SUPINATORS
o Supinator
o Pronator teres
o Pronator quadratus
STABILISING TISSUES
o Capsule
o Ligaments
o Interosseous membrane
WHAT IS SPECIAL ABOUT THE LUMBRICALS?
- The lumbrical muscles are a set of 4 small muscles located in the palm of the hand
- They originate from the tendons of the flexor digitorum profundus muscles in the forearm
- Control of finger movement – responsible for flexing the metacarpophalangeal (MCP) joints while extending the interphalangeal (IP) joints of the fingers which allows for precision gripping and grasping
EXAMPLES OF MECHANICAL PRINCIPLES IN THE ELBOW
Lever- 3rd class
Force- torque in pronation/supination
Roll/slide- proximal humerus-radius/ulnar roll- slide in same direction
Flexion force- 70% greater than ext, 3x bicep, 1x triceps
Stabiliser- interosseous membrane
90 pro/supination, 140-150 flex
EXAMPLES OF MECHANICAL PRINCIPLES OF THE WRIST
Ulnar/radial deviation ROM- 30-45, 15
Roll and slide mechanism in radial/ulnar deviation
Movement driven by carpals, radius is passive, carpals roll and slide in different directions around pivot point of capitate
Role of lumbricals- allow for L-shaped grip, inc stability
DESCRIBE KINEMATICS OF PRO/SUP OF THE FOREARM
COMMENT OF ROM, TYPES OF MOVEMENT, ROLL AND SLIDE CONCEPT
90 pro/sup
Torque force
Roll + slide mechanism- same direction- radial/ulnar/humeral
Roll + slide- radial/ulnar Jt
Stabilising effects of interosseous membrane
DESCRIBE KINEMATICS OF FLEXION OF THE ELBOW
COMMENT ON ROM, TYPE OF MOVEMENT, ROLL AND SLIDE CONCEPT, TYPE OF LEVER
3rd class
120-140 flex
Humerus convex, ulnar concave
Roll + slide in same direction
Flexibility of capsule allows flex/ext
