Sternum osteology
jugular notch, manubrium, sternal angle, body of sternum, xiphoid process
Clavicle
2 ends; round end is sternal end and acromial end is flattened end
Scapula - smooth surface
costal surface (other surface is posterior surface)
Scapula bony landmarks (posterior view)
spine of scapula, acromion process, supraspinous fossa, infraspinous ross, medial/vertebral border, lateral/axillary border, suprascapular notch
Scapula bony landmarks (lateral view)
Coracoid, supragelnoid tubercle, acromion, dorsal surface, ventral surface, infragelnoid tubercle, glenoid cavity
Humerus bony landmarks (anterior view)
humeral head, greater tubercle, lesser tubercle, inter tubercular groove, deltoid tuberosity, anatomical neck, surgical neck
Four joints of pectoral region and shoulder
Glenohumeral joint; acromioclavicular joint (AC); scapulothoracic articulation; sternoclavicular joint
Sternoclavicular joint: articular components
Sternal end of the clavicle and manubrium of sternum
Sternoclavicular joint: joint type
Modified saddle type synovial joint
Sternoclavicular joint: associated structures
Fibrocartilage disc; ligaments include sternoclavicular, interclavicular, and costoclavicular ligaments
Sternoclavicular joint: movements
Elevation/depression; protraction/retraction
Acromioclavicular joint: articular components
Acromial end of the clavicle and acromion process of scapula
Acromioclavicular joint: joint type
plane type synovial joint
Acromioclavicular joint: associated structures
Fibrocartilage disc; ligaments include acromioclavicular and coracoclavicular ligament
Acromioclavicular joint: movements
rotation (Scapula on clavicle)
Glenohumeral joint: articular components
humeral head and glenoid fossa
Glenohumeral joint: joint type
ball and socket type synovial joint
Glenohumeral joint: movement
flexion/extension; abduction/adduction; internal and external rotation
Glenohumeral joint: Features
Glenoid fossa is 1/3 size of humeral head; both non contractile and contractile structures enhance GH stability
Non contractile components of GH
corocoacromial ligament, coracoclavicular ligament, glenohumeral ligaments, transverse humeral ligament, glenoid labrium
Contractile components of GH
muscles of rotator cuff
Coracoacromial arch
� The coracoacromial arch is formed by the smooth inferior aspect of the acromion and the coracoid process of the scapula, with the coracoacromial ligament spanning between them
� This osseoligamentous structure forms a protective arch that overlies the h
Subacromial/Subdeltoid Bursa
� The subacromial /sub deltoid bursa is located between the coracoacromial arch and the supraspinatus tendon (also extends deep to the deltoid muscle)
- A bursa is a flattened sac containing synovial fluid.
- The inner walls of the bursa glide on one anot
Ligamentous/non-contractile stability of glenohumeral joint
coracoclavicular ligament, superior/middle/inferior glenohumeral ligaments, transverse humeral ligament
Additional non-contractile structures contributing to GH stability
Glenoid Labrum; fibrocartilaginous ring, attaches to margin of glenoid fossa, deepens glenoid cavity
Scapulothoracic joint
The scapulothoracic (ST) joint is a physiological joint in which
movement occurs between musculoskeletal structures (between the scapula and associated muscles and the thoracic wall), rather than an anatomical joint, in which movement occurs between direc
Shoulder arthrokinematics
flexion/extension; medial/lateral rotation; abduction/adduction
Shoulder abduction
Subacromial space is so limited that during full abudction of the arm we have to laterally rotate our humerus to move the greater tuberosity out of the way
Scapulothoracic joint motions
elevation/depression; adduction/abduction; upward/downward rotation
Scapulohumeral Rhythm
Motion available to the glenohumeral joint alone would not account for full range of motion observed at humerus; remainder of motion is contributed by the scapulothoracic joint (via SC and AC joint); each joint makes its contributions in a specific and co
Scapulohumeral rhythm; GH mobility and ST mobility
� Kinesiological studies have revealed that in the overall movement of fully
abducting the arm, the movement occurs at both the GH and ST joints.
� 0-30 � abduction at glenohumeral (GH) joint only
� 30-180� 2:1 GH/ scapulothoracic (ST) movement
Extrinsic muscles of shoulder: posterior superficial/deep
Posterior superficial: trapezius, latissimus dorsi
Posterior deep: levator scapulae, rhomboid major, rhomboid minor
Trapezius: attachments
� Attachments:
- superior nuchal line, external
occipital protuberance, nuchal ligament, spinous processes of C7-T12
- scapula spine, acromion, lateral 1/3 clavicle
Trapezius: action
� Action:
- upper: elevates and upwardly
rotates scapula
- middle: adducts scapula
- lower: depresses and
upwardly rotates scapula
Trapezius: Innervations
CNXI, C3, C4
Latissimus dorsi muscle: attachments
- spinous process T7-T12,
iliac crest, thoracolumbar fascia, iliac crest, ribs 9- 12
- floor of intertubercular groove of humerus
Latissimus dorsi muscle: action
Shoulder extension, adduction and internal rotation (IR)
Latissimus dorsi muscle: Innervation
Thoracodorsal nerver
Levator scapulae muscle: attachments
- transverse processes of C1-C4
- superior medial border of scapula
Levator scapulae muscle: Action
elevates and downwardly rotates scapula
Levator scapulae muscle: innervation
dorsal scapular nerve (C5) and ventral rami of C3, C4
Rhomboid minor: attachments
- spinous processes C7 and T1
- medial scapular border at the level of root of scapular spine
Rhomboid major: attachments
- spinous processes T2 - T5
- medial scapular border from level of spine to inferior angle
Rhomboid: action
adducts/retracts and downwardly rotates scapula
Rhomboid: innervation
dorsal scapular nerve
Triangle of Auscultation
The site on the back where great sounds may be most easily heard through a stethoscope; boundaries = latissimus dorsi, trapezius, medial border of scapula
Pectoralis major: attachments
-Clavicular head: Medial half of
clavicle
-Sternocostal head: anterior sternum, upper six costal cartilages
-Intertubercular groove of humerus
Pectoralis major: action
adducts and medially rotates humerus
Pectoralis major: innervation
medial and lateral pectoral nerves
Pectoralis minor: attachments
Ribs 3-5, corocoid process of scapula
Pectoralis minor: action
stabilizes scapula
Pectoralis minor: innervation
medial pectoral nerve
Serratus anterior: attachments
- External surfaces of lateral parts of ribs 1-8
- Anterior surface of medial border of scapula
Serratus anterior: action
protracts and upwardly rotates scapula, hold scapula against thoracic wall
Serratus anterior: innervation
long thoracic nerve
Subclavius: attachments
Junction of first rib and costal cartilage; inferior surface of medial third of clavicle
Subclavius: action
anchors and depresses clavicle
Subclavius: innervation
nerve to subclavius
Intrinsic Muscles of Shoulder
coracobrachialis, deltoid, teres major, teres minor, supraspinatus, infrapsinatus, subscapularis
Coracobrachialis: attachments
tip of coracoid process; medial, middle 1/3 of humerus
coracobrachialis: action
flex and adducts shoulder
coracobrachialis: innervation
musculocutaneous nerve
Deltoid: attachments
- scapula spine, acromion,
lateral 1/3 clavicle
- deltoid tuberosity of humerus
Deltoid: action
- anterior: shoulder flexion
- middle: shoulder abduction
- poster: shoulder extension
Deltoid: innervation
Axillary nerve
Teres major: attachments
- inferior lateral aspect of
posterior surface of scapula - medial lip of
intertubercular groove of humerus
Teres major: action
Shoulder medial/internal rotatoin (IR)
Teres major: innervation
lower subscapular nerve
Intrinsic muscles of shoulder: rotator cuff muscles
supraspinatus, infrapsinatus, teres minor, subscapularis
Supraspinatus: attachments
Supraspinous fossa; greater tubercles
Infrapsinatus: attachments
infraspinous fossa; greater tubercle
Teres minor: attachments
Middle part of lateral border of scapula; greater tubercle
Subscapularis: attachments
Subscapular fossa; lesser tubercle
Supraspinatus: action and innervation
Action: shoulder abduction
Innervation: suprascapular nerve
Infraspinatus: action and innervation
Action: shoulder lateral/external rotation (ER)
Innervation: suprascapular nerve
Teres minor: action and innervation
Action: shoulder lateral/external rotation (ER)
Innervation: axillary nerve
Subscapularis muscle: action and innervation
Action: shoulder medial/internal rotation (IR)
Innervation: upper subscapular nerve and lower sub scapular nerve
Quadrangular space boundaries
- Superior: teres minor
- Inferior: teres major
- Medial: long head of triceps brachii
- Lateral: surgical neck of humerus
� The axillary nerve and posterior humeral circumflex artery are transmitted to the posterior aspect of the shoulder via quadrangula
Dynamic stability of GH joint: muscles of rotator cuff
The tendons of the 4 rotator cuff muscles blend with the fibrous capsule forming a cuff which reinforces the joint capsule and provides active GH stability
Combined function of rotator cuffs
� All four muscles provide compressive forces across the GH joint, and thereby provide dynamic stability to the GH joint.
� Theses muscles are extremely important in maintaining the humerus centered within the glenoid fossa.
3 of the 4 rotator cuff muscles...
� The infraspinatus, teres minor and subscapularis depress the head of the humerus during shoulder elevation.
� This is important to avoid impingement of the rotator cuff under the coracoacromial arch.
Rotator cuff/injury
�Repetitive use of the rotator cuff muscles when using the upper limb above the horizontal( e.g., during throwing and swimming) may allow the humeral head and rotator cuff to impinge under the coracoacromial arch
�This may produce irritation of the arch a