Transcript Biomechanics of Human Upper Extremity

ENT 214
Biomechanics
Biomechanics
of Human
Upper
Extremity
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Picture retrieved from
http://thestar.com.my/archives/2006/12/9/sports/Sazali.jpg
Manubrium
Sternum
Retrieved from
http://en.wikipedia.org/wiki/Image:Human_arm_bones_diagram.svg
Structure of the Shoulder
 Sternoclavicular
joint
 Acromioclavicular joint
 Coracoclavicular joint
 Glenohumeral joint
 Scapulothoracic joint
Structure of the Shoulder
Interclavicular ligament
Clavicle
Clavicle
Sternoclavicular
ligament
Articular
disk
Costoclavicular
ligament
Costal
cartilage
(1st rib)
Sternum
Sternoclavicular joint: modified ball and
socket joint between the proximal clavicle
and the manubrium of the sternum
Structure of the Shoulder
Coracoclavicular
Clavicle ligament
Verterbal
border
Acromioclavicular Coracoclavicular
joint
ligament
Acromion process
Clavicle
Coracoacromial
ligament
Scapular
spine
Coracoid process
Vertebral
border
Glenoid fossa
Anterior view
Axillary border
Inferior
angle
Posterior view
Inferior angle
Acromioclavicular joint: irregular joint
between the acromion process of the
scapula and the distal clavicle
Structure of the Shoulder
Coracoclavicular
Clavicle ligament
Verterbal
border
Acromioclavicular Coracoclavicular
joint
ligament
Acromion process
Clavicle
Coracoacromial
ligament
Scapular
spine
Coracoid process
Vertebral
border
Glenoid fossa
Anterior view
Axillary border
Inferior
angle
Posterior view
Inferior angle
Coracoclavicular joint: syndesmosis with the
coracoid process of the scapula bound to the
inferior clavicle by the coracoclavicular ligament
Structure of the Shoulder
Coracoid process
Acromion process
Coracohumeral
ligament
Long head of biceps
Scapula
Humerus
Articular
capsule
Glenohumeral joint: ball and socket joint in
which the head of the humerus articulates
with the glenoid fossa of the scapula
Structure of the Shoulder
What is the scapulothoracic joint?
 articulation between the
anterior scapula and the thoracic
wall
Bursae
 A small
fluid-filled sac located
between movable parts of the
body especially at joints
 Reduce friction between layers
of collagenous tissue
Movements of the Shoulder
Complex
scapulohumeral
rhythm: a regular
pattern of scapular
rotation that
accompanies and
facilitates humeral
abduction
Movements of the Shoulder
Complex
First 30o humeral elevation, contribution of
scapula only 1/5 of glenohumeral joint
 Beyond 30o, scapula rotates 1o for every 2o
of humerus movement
 First 90o of arm elevation, clavicle elevated
35o to 45o of motion at sternoclavicular
joint.

Movements of the Shoulder
Complex
What muscles contribute to flexion at
the glenohumeral joint?
 anterior deltoid
 clavicular pectoralis major
 assisted by:
 coracobrachialis
 short head of biceps brachii
Retrieved from
http://upload.wikimedia.org/wikipedia/commons/d/de/Gray410.png
Movements of the Shoulder
Complex
What muscles contribute to extension at
the glenohumeral joint?
 sternal pectoralis major
 latissimus dorsi
 teres major
 assisted by:
 long head of triceps brachii
Retrieved from
http://upload.wikimedia.org/wikipedia/commons/d/d6/Deltoideus_posterior.PNG
Movements of the Shoulder
Complex
What muscles contribute to abduction at
the glenohumeral joint?
 middle deltoid
 supraspinatus
Retrieved from
http://upload.wikimedia.org/wikipedia/commons/8/8f/Gray412.png
Movements of the Shoulder
Complex
What muscles contribute to adduction at
the glenohumeral joint?
 latissimus dorsi
 teres major
 sternal pectoralis major
 assisted by:
 short head of biceps brachii
 long head of triceps brachii
Movements of the Shoulder
Complex
What muscles contribute to medial
rotation of the humerus?
 subscapularis
 teres major
 assisted by:
 pectoralis major
 anterior deltoid
 latissimus dorsi
 short head of biceps brachii
Retrieved from
http://upload.wikimedia.org/wikipedia/commons/f/f2/Gray411.png
Movements of the Shoulder
Complex
What muscles contribute to lateral
rotation of the humerus?
• infraspinatus
• teres minor
• assisted by:
• posterior deltoid
Movements of the Shoulder
Complex
What muscles contribute to horizontal
adduction of the humerus?
• pectoralis major
• anterior deltoid
• coracobrachialis
• assisted by:
• short head of biceps brachii
Movements of the Shoulder
Complex
What muscles contribute to horizontal
abduction of the humerus?
 infraspinatus
 middle and posterior deltoid
 teres minor
 assisted by:
 teres major
 latissimus dorsi
Torque at shoulder

Torque created by
weight of arm is the
product of arm weight
and perpendicular
distance between
arm’s COG and the
shoulder
Torque at shoulder
Sample Problem 1

wt


If the weight of the arm is 33 N,
moment arm for the total arm
segment is 30 cm, moment arm
for deltoid muscle (Fm) is 3 cm.
How much force must be
supplied by deltoid to maintain
the arm in this position?
What is the magnitude of the
joint reaction force (R)?
Common Injuries of Shoulder
Dislocation
 Rotator Cuff Damage




Rotator cuff - anatomical term given to the group
of muscles and their tendons that act to stabilize
the shoulder
Example – supraspinatus, infraspinatus, teres
minor, subscapularis muscles
Rotational Damage
Humeroulnar
Joint
Retrieved from
http://upload.wikimedia.org/wikipedia/commons/9/97/Gray329.png
Structure of the Elbow
What is the humeroulnar joint?
 hinge joint in which the humeral
trochlea articulates with the trochlear
fossa of the ulna
 considered to be the elbow joint
Structure of the Elbow
What is the humeroradial joint?
 gliding joint in which the capitellum
of the humerus articulates with the
proximal end of the radius
Structure of the Elbow
What are the radioulnar joints?
 the proximal and distal radioulnar
joints are pivot joints
 the middle radioulnar joint is a
syndesmosis
Movements at the Elbow
What muscles contribute to flexion at
the elbow?
 brachialis
 biceps brachii
 brachioradialis
Movements at the Elbow
What muscles contribute to extension
at the elbow?
 triceps brachii
 assisted by:
 anconeus
Retrieved from
http://upload.wikimedia.org/wikipedia/commons/7/79/Musculusanconeus2.png
biceps
be
fore
force?
Common Injuries of Elbow
Sprains
and dislocation
Epicondylitis
Inflammation
and sometimes
microrupting of collagenous
tissue at distal humerus
Wrist
Retrieved from
http://upload.wikimedia.org/wikipedia/commons/6/66/Gray334.png
Structure of the Wrist
What are the radiocarpal joints?
 condyloid articulations between the
radius and the three carpal bones
 these joints comprise the wrist
Structure of the Wrist
What is the function of the retinacula at
the wrist?
these fibrous bands of fascia form
protective passageways through which
tendons, nerves, and blood vessels
pass
Movements at the Wrist
What muscles contribute to flexion at
the wrist?
 flexor carpi radialis
 flexor carpi ulnaris
 palmaris longus
 assisted by:
 flexor digitorum superficialis
 flexor digitorum profundus
Retrieved from
http://upload.wikimedia.org/wikipedia/commons/5/5f/Gray418.png
Retrieved from
Movements at the Wrist
What muscles contribute to extension at
the wrist?
 extensor carpi radialis longus
 extensor carpi radialis brevis
 extensor carpi ulnaris
 assisted by:
 other wrist extensor muscles
F
I
N
G
E
R
Retrieved from
http://upload.wikimedia.org/wikipedia/commons/f/f7/X-ray_boy_hand.jpg
Structure of the Hand Joints
What are the carpometacarpal joints?
 the carpometacarpal joint of the
thumb is a saddle joint
 the other carpometacarpal joints are
gliding joints
Structure of the Hand Joints
What are the intermetacarpal joints?
irregular joints between the
metacarpals that share joint
capsules with the carpometacarpal
joints
Structure of the Hand Joints
What are the metacarpophalangeal joints?
 condyloid joints between the rounded
distal heads of the metacarpals and the
concave proximal ends of the phalanges
 these joints form the knuckles of the
hand
Structure of the Hand Joints
What are the interphalangeal joints?
the proximal and distal interphalangeal
joints of the fingers and the single
interphalangeal joint of the thumb are all
hinge joints
Movements of the Hand
What motions are permitted at
metacarpophalangeal joints 2-5?
 flexion
 extension
 abduction
 adduction
 circumduction
Movements of the Hand
What muscles are responsible for
motions of the hand?
 there are nine extrinsic muscles
with attachments both proximal and
distal to the wrist
 there are ten intrinsic muscles with
both attachments distal to the wrist
Common Injuries of Wrist & Hand
Fracture - boxers
 Injury - golfers
 Carpal tunnel syndrome

 Passageway
between carpal bone and
flexor retinaculum
 Symptom : pain, numbness along median
nerve, clumsiness of finger function,
atrophy of muscle
Summary
1.
2.
3.
4.
5.
Shoulder
– Structure
– Movement and muscle involve
– Common injuries
Elbow
Wrist
Hand
Force initiated and torque - calculation