Anatomy - The Shoulder Joint Flashcards
Bones of the shoulder
Clavicle Acromion process Scapula Coracoid process Glenoid fossa Humerus
Clavicle
Provides bony articulation between entire upper limb and body
Articulates with sternum anteriorly and part of the scapula distally (acromion process)
Proximal convexity and distal concavity to withstand force through upper limb
Actromion process
Part of scapula and sits over gleno-humeral joint
Found lightly lower than clavicle
Continuous with spine of scapula
Medial border of scapula
Closes to spine
Lateral border of scapula
Closer to humerus
Supraspinous fossa
Above spine of scapula
Infraspinous fossa
Below spine of scapula
Subscapular fossa
Found anteriorly and is in contact with chest wall
Coracoid process
Bony protrusion lateral to clavicle, provides muscle and ligament attachment
Glenoid fossa
Has two tubercles, inferior and superior, to provide muscle attachment
Articlulates with head of humerus
Anatomical neck of humerus
Where articular cartilage is
Surgical neck
Where humerus begins to narrow
Greater tubercle of humerus
Sits laterally and provides muscle attachment from posterior and superior aspects
Lesser tubercle of humerus
Sits anteriorly
Intertubercular groove
Found in between greater and lesser tubercles
Movements at glena-humeral joint
Flexion - brings limb anteriorly
Extension - brings limp posteriorly
Abduction and adduction
Lateral (away from midline) and medial rotation (towards midline)
Movement at shoulder girdle
Elevation Depression Protraction Retraction Lateral and medial rotation
Elevation
Scapula moves up
Depression
Scapula moves down
Protraction
Scapula moves forward
Retraction
Scapula moves back towards spine
Rotation at scapula
Named after movement of inferior angle
Supporting the shoulder joint
Ball and socket adapted for mobility not stability so rotator cuff muscles provide stability
Why is the gleno-humeral joint lax inferiorly
Allow abduction
Rotator cuff muscles
Subscuplaris
Infraspinatus
Teres minor
Supraspinatus
Where does the supscaularis sit
Sits in the supcapsular fossa and attatches to lesser tubercle of humerus
Where does the supraspinatus pass
Passes the supraspinous fossa and attaches to superior portion of greater tubercle
Where does infraspinatus and teres minor sit
Infraspinous fossa and attach to greater tubercle posteriorly,
Function of rotator cuff muscles
Pull the head of the humorous towards the glenoid fossa to prevent dislocation - shunt action
Acromio-clavicular joint
Between acromion process and clavicle
Sterno-clavicular joint
Between sternum and clavicle
Coraco-clavicular ligaments
Attach coccoid process and clavicle, trapezoid
Coraco-acromial ligament
Attach corocoid process and acromion - helps prevent upward dislocation of head of humerus
Acromio-clavicular ligament
Between acromion process and clavicle
Sub-acromion bursa
In-between greater tubercle and acromion process to help reduce friction
Teres minor function
Involved in lateral rotation of the scapula w/ infraspinatus
Supraspinatus function
Abduction of shoulder joint (first 15 degrees)
Subscapularis function
Medial rotation of humerus
What happens initially when the glen-humeral joint sublaxes or dislocates
The humerus moves inferiorly initially as the joint is lax inferiorly and there is no rotator cuff muscle to reinforce or support the shoulder joint. These features allow for accommodation of the large head of humerus during abduction
Innervation of supraspinatus
Suprascapular nerve (C4,5,6)
Innervation of infrapsinatus
Suprascapular nerve (C4,5,6)
Innervation of sybscapularis
Subscapular nerve (C5,6,7)
Innervation of Teres minor
Axillary nerve
Function of infraspinatus
Lateral rotator of humerus
Function of Teres minor
Adductor of humerus
Innervation of trapezius
Accessory nerve
First 30 degrees of shoulder abduction
Initiation by suprapsinatus
Next 60 degrees of shoulder abduction
Abduction by deltoid
Rotation of scapula - serrates anterior, trapezius
Last 9- degrees of shoulder abduction
Scapula is stationary
Rotation at glenohumeral joint - rotator muscles
Adduction of humerus - pectoralis major