Download biomechanics of human upper extrimity

biomechanics
 Bio= life; Mechanics= physical actions
 We might think of biomechanics as the “physics of
human movement” : Biomechanics is the science of
movement of a living body, including how muscles,
bones, tendons and ligaments work together to
produce movement.
Structure of shoulder
 Most complex joint in human body
 Include 5 different articulations
1) Glenohumeral joint
2) Strenoclavicular joint
3) Acromioclavicular joint
4) Coracoclavicular joint
5) Scapulothoracic joint
1.Sternoclavicular joint
 Proximal end of clavical articulate the clavicular notch
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of manubrium of sternum and with the cartilage of 1st
rib
Fibro cartilagenious disc improve the fit of articulating
bone and act as shock absorber.
Characteristics
Modified ball and socket joint
Major axis of rotation for the movement of clavical and
scapula
Characteristics of sternoclavicular
joint
 Movement in frontal and transverse plane and
farward and backward saggital plane rotation
 Rotation occur during shrugging of shoulders,
Elevation of arms above head
 Close pack position of SC joint occur with max.
shoulder elevation
Sternoclavicular joint
Sternoclavicular joint
acromioclavicular joint
 Articulation of acromion process of scapula with distil
end of clavicle is known as acromioclavicular joint
 Characteristics
1) Irregular joint
2) Allow limited motion in three plane
3) Rotation occur at AC joint during arm elevation
Characteristics of AC joint
 Close pack position of AC joint occur when arm is
abducted at 90 degree
Acromioclavicular joint
Coracoclavicular joint
 This joint is a syndyesmosis ( joint surface is bound by
ligament)
 Coracoid process of scapula and inferior surface of
clavicle bound together by coracoclavicular ligament
 This joint permits little movement
Coracoclavicular ligament
Glenohumeral joint
 Ball and socket joint, head of humerus articulate with
glenoid fossa of scapula.
 Most freely moving joint in human body
 Hemispherical head of humerus has three to four time
the amount of surface area as the shallow glenoid
cavity
 Glenoid fossa is also less curved as compare to head of
humerus,
Movement in glenohumeral joint
 Flexion
 Extension
 Abduction
 Adduction
 Horizontal adduction, abduction
 Medial rotation and lateral rotation
 circumduction
Characteristics of glenohumeral
joint
Glenoid fossa composed of part of joint capsule, tendon
of long head of biceps , and glenohumeral ligament
located on the periphery of glenoid fossa deepen fossa
and add stability to glenohumeral joint
Ligaments :
 Superior, middle and inferior glenohumeral ligaments
on anterior side of joint
 Coracohumeral ligament on superior side of joint.
 Transverse humeral ligament
Ligaments of glenohumeral joint
Rotator cuff muscles and Jt.
stability
 Tendon of four muscles also join the joint capsule.
these are rotator cuff.
 The rotator cuff muscles are the group of muscles in
the upper arm and shoulder area that support the or
stabilize the shoulder area. The four muscles that
make up the rotator cuff are the supraspinatus,
infraspinatus, subscapularis, and the teres minor
muscles. Reffered to as SITS
Factors contributing to stability
 Supraspinatus, infraspinatus teres minor participate in
lateral rotation
 Subscapularis causes medial rotation
 Rotator cuff surround the shoulder from posterior,
superior and anterior side
 Contraction of theses muscles pulls the head of
humerus toward glenoid fossa contributing to joint
sability.
Factors contributing to stability
 Negative pressure within capsule of joint also helps to
stabilize the joint
 Joint is most stable in closed-pack position
 Abducted and laterally rotated
Rotator cuff
Scapulothoracic joint
 Region between anterior scapula and thoracic wall is
referred to scapulothoracic joint, as scapula can move
in both saggital and frontal plane.
Functions of muscles attaching to scapula
1) Either stabilize shoulder region
2) Or facilitate movement of upper extremity through
appropriate positioning of glenohumeral joint ex.
Rhomboids during overhead through