the shoulder and joints of the pectoral girdle

What is the classification of the scapulothoracic joint?

The scapulothoracic joint is classified as a functional joint and is held in place purely by muscles. Depends on movement of AC and/or SC joints.

What are the features of the scapulothoracic joint?

• articulation between the chest wall and body of scapula/subscapularis

• serratus anterior acts as a disc

• space between subscapularis and serratus anterior filled with loose connective tissue and bursae

How does the scapula move in relation to the thorax?

• elevation/depression

• protraction/retraction

• upward/downward rotation

It increases overall shoulder movement (by keeping the humeral head in contact with the glenoid fossa)

Scapulothoracic movements are named according to the direction of which feature of the scapula?

The glenoid fossa orientation

What is the normal position of the scapula on the chest wall?

• Tilted anteriorly 10-20 degrees.

• Upwardly rotated 10-20 degrees.

• Tilted posteriorly in coronal plane 30-45 degrees (internal rotation)

What anatomical landmarks indicate the "normal" position of the scapula?

• medial border about 6cm lateral to spine

• rests approximately 2 inches from midline between T2-7

• inferior angle= T7

• Medial part of spine of scapular= T3

What are the attachments of trapezius?

Origin: superior nuchal line, external occipital protuberance, nuchal ligament and spinous processes of C7-T12

Insertion: spine of scapula, medial acromion and posterior margin of lateral clavicle

What are the attachments of levator scapulae?

Origin: transverse processes of C1-4

Insertion: medial border of scapula

What are the attachments of rhomboid major?

Origin: spinous processes of T2-5 and supraspinous ligament

Insertion: medial border of scapula

What are the attachments of rhomboid minor?

Origin: nuchal ligament and spinous process of C7-11

Insertion: medial border of scapula

What are the attachments of pectoralis minor?

Origin: anterior surfaces of costal cartilage of ribs 3-5 (3 small heads)

Insertion: medial border and coracoid process of scapula (fused into single muscle body)

What are the attachments of serratus anterior?

Origin: outer surface of ribs 1-8 (or 1-9) (tendinous, finger like digitations

Insertion: anterior surface of the scapula at the superior angle, medial border and inferior angle

What are the attachments of subclavius?

Origin: sternal end of first rib

Insertion: anteroinferior surface of middle third of clavicle

What is the innervation of trapezius?

Accessory nerve (CN XI) and cervical spinal nerves from C3-4

What is the innervation of levator scapulae?

Anterior rami of C3-4 and dorsal scapular nerve

What is the innervation of rhomboids major and minor?

Dorsal scapular nerve (C4-5)

What is the innervation of pectoralis minor?

medial and lateral pectoral nerves (C6-T1)

What is the innervation of serratus anterior?

long thoracic nerve (C5-7)

What is the innervation of subclavius?

subclavian nerve (C5-6)

What muscles attach the scapula to the vertebral column?

1. trapezius

2. levator scapulae

3. rhomboids major and minor

What muscles attach the scapula to the chest wall?

1. pectoralis minor

2. serratus anterior

3. subclavius

What is the action of trapezius?

Upper fibres: elevate and upwardly rotate scapula, laterally flex neck ipsilaterally, rotate neck contralaterally and when both working together extend the head

Middle fibres: retract the scapula

Lower fibres: depress and upwardly rotate the scapula

What is the action of levator scapulae?

Elevates and downwardly rotates the scapula, laterally flexes and rotates the head and neck ipsilaterally and assists to extend the head and neck.

What is the action of rhomboids major and minor?

Adducts the scapula to stabilise the scapula and fasten it to the ribcage

What is the action of pectoralis minor?

depresses, abducts and downwardly rotates the scapula

What is the action of serratus anterior?

protracts and upwardly rotates the scapula, stabilizing it by holding the medial border against the thoracic wall (known as boxers muscle)

What is the action of subclavius?

stabilises the clavicle with upper limb movement, depresses the clavicle and elevates the 1st rib during respiration

What are the implications of an injury to the long thoracic nerve?

Can lead to winging of the scapula, impairing shoulder stability and function. It may also affect the ability to perform overhead activities due to weakness in serra

Which muscles control scapular movement during upward rotation?

Trapezius and serratus anterior

Which muscles control scapular movement during downward rotation?

rhomboids major/minor, levator scapulae and pectoralis minor (balancing synergy)

Which muscles control scapular movement during retraction?

Rhomboids major/minor and trapezius (balancing synergy)

What is the classification of the glenohumeral joint?

Ball and socket synovial joint

What are the articulating surfaces of the glenohumeral joint?

head of humerus and glenoid fossa of scapula

What are the movements of the glenohumeral joint?

• flexion/extension

• adduction/abduction

• medial/lateral rotation

• circumduction

What degree of upper limb elevation does the scapulothoracic joint contribute?

first 60

What rule explains the innervation of joints?

The Hilton's Law states that the nerves supplying a joint also supply the muscles that move the joint and the skin overlying them.

What degree of upper limb elevation does the glenohumeral joint contribute?

last 120

What are the main supporting ligaments of the glenohumeral joint?

glenohumeral (superior, middle, inferior), transverse humeral, coracohumeral and coracoacromial

What are the intrinsic ligaments of the glenohumeral joint?

Superior, middle and inferior glenohumeral and transverse humeral

What are the accessory ligaments of the glenohumeral joint?

coracoacromial

What are the extrinsic ligaments of the glenohumeral joint?

coracohumeral

What are the special structures of the glenohumeral joint?

glenoid labrum and long head of biceps tendon

What reinforces the fibrous capsule of the glenohumeral joint?

distal attachment of the rotator cuff tendons which act as dynamic ligaments

Where are the deficiencies of the fibrous capsule of the glenohumeral joint?

top of bicipital groove and inferior to coracoid process

What nerves supply the glenohumeral joint?

suprascapular, axillary, subscapular, lateral pectoral, musculocutaneous

What arteries supply the glenohumeral joint?

Anterior circumflex humeral, posterior circumflex humeral, suprascapular

What are the borders of the quadrangular space?

Superior: teres minor

Inferior: teres major

Lateral: surgical neck of humerus

Medial: long head of triceps.

What are the borders of the triangular space?

Superior: teres minor Inferior: teres major
Lateral: long head of triceps

What are the contents of the triangular space?

circumflex scapular artery

What are the contents of the quadrangular space?

axillary nerve, posterior circumflex humeral artery

What movement of the glenohumeral joint does the inferior glenohumeral ligament limit?

external rotation and internal rotation

What movement of the glenohumeral joint does the coracohumeral ligament limit?

external rotation

What movement of the glenohumeral joint do the glenohumeral ligaments limit?

all= external rotation

middle and inferior= abduction

superior= adduction

What tissue is the glenoid labrum made of?

fibrocartilage

What role does the glenoid labrum play?

It deepens the glenoid cavity and stabilizes the shoulder joint.

What are the common injuries of the glenoid labrum?

SLAP lesions: repetitive overhead motion or trauma

Bankart lesions: shoulder dislocations

What are the attachments of deltoid?

Origin: clavicula region= anterior third of clavicle, acromial region= lateral margin of acromion process, scapular region= inferior crest of spine of scapular

Insertion: deltoid tuberosity on lateral humerus (3 regions converge)

What are the attachments of supraspinatus?

Origin: supraspinous fossa of scapula

Insertion: greater tubercle of humerus

What are the attachments of infraspinatus?

Origin: infraspinous fossa of the scapular

Insertion: greater tubercle of the humerus

What are the attachments of teres minor?

Origin: lateral border of scapula

Insertion: greater tubercle of humerus

What are the attachments of subscapularis?

Origin: subscapular fossa of scapula

Insertion: lesser tubercle of humerus

What are the attachments of teres major?

Origin: inferior angle of scapula

Insertion: medial lip of bicipital groove

What are the attachments of coracobrachialis?

Origin: coracoid process of scapula

Insertion: anteromedial surface of humerus between triceps brachii and brachialis

What are the attachments of pectoralis major?

Origin: clavicular head= medial anterior clavicle, sternocostal head= anterior sternum, first 6 costal cartilages, aponeurosis of external oblique on abdominal wall

Insertion: lateral lip of bicipital groove of humerus (heads converge)

What are the attachments of latissimus dorsi?

Origin: spinous processes of T6-S5, posterior iliac crest, lower 3/4 ribs and inferior angle of scapula

Insertion: floor of intertubercular sulcus (bicipital groove) of humerus

What is the action of the deltoids?

Major abductors of the arm beyond 15 degrees (anterior region also flexion, posterior region also extension)

What is the action of supraspinatus?

initiates arm abduction up to 15 degrees and stabilizes the humeral head within the glenoid cavity

What is the action of infraspinatus?

externally rotates the shoulder and stabilises the humeral head within the glenoid cavity

What is the action of teres minor?

externally rotates and adducts the shoulder and stabilises the humeral head within the glenoid cavity

What is the action of subscapularis?

Internally rotates the shoulder and stabilises the humeral head within the glenoid cavity

What is the action of teres major?

acts synergistically with latissimus dorsi, it extends, adducts and internally rotates the shoulder whilst providing stabilisation for the head of humerus

What is the action of coracobrachialis?

flexion and adduction of the arm at the GH joint

What is the action of pectoralis major?

adduction and internal rotation of the arm and assists with elevating the thorax during forced inhalation

What is the action of latissimus dorsi?

adducts, medially rotates and extends the arm at the GH joint

What is the innervation of deltoid?

axillary nerve (C5-6)

What is the innervation of supraspinatus?

suprascapular nerve (C5-6)

What is the innervation of infraspinatus?

suprascapular nerve (C5-6)

What is the innervation of teres minor?

posterior branch of axillary nerve (C5-6)

What is the innervation of subscapularis?

upper and lower subscapular nerves (C5-6)

What is the innervation of teres major?

lower subscapular nerve (C5-7)

What is the innervation of coracobrachialis?

musculocutaneous nerve (C5-7)

What is the innervation of pectoralis major?

lateral and medial pectoral nerves (C5-6 clavicular head C7-T1 sternocostal head)

What is the innervation of latissimus dorsi?

thoracodorsal nerve (C6-8)

What muscles attach to the humerus?

1. deltoid

2. supraspinatus

3. infraspinatus

4. teres minor

5. subscapularis

6. teres major

7. corachobrachialis

8. pectoralis major

9. latissimus dorsi

What muscles attach the humerus to the scapula?

1. deltoid

2. rotator cuff (supraspinatus, infraspinatus, teres minor, subscapularis)

What muscles attach the humerus to the chest wall?

pectoralis major

What muscles attach the humerus to the vertebral column?

latissimus dorsi

What muscles attach into the bicipital groove?

Teres major, latissimus dorsi and pectoralis major (medial to lateral)

What bones make up the pectoral girdle?

clavicle x2, sternum, scapula x2, humerus x2

What are the components of the sternum?

manubrium (with jugular notch x2 and clavicular notches x2), body (with 4x sternebrae separated by 3x transverse ridges), xiphoid process

How is the sternal end of the clavicle distinguished?

shaped like a trumpet

What is the shape of the clavicle?

S-shaped (convex medial 2/3, concave lateral 1/3)

What are the features of the inferior surface of the clavicle?

conoid tubercle and trapezoid line (for the coracoclavicular ligament), subclavian groove and impression for costoclavicular ligament

What is the function of the clavicle?

Acts as a strut for the upper limp, holds the scapula away to increase ROM and stability

What is the classification of the sternoclavicular joint?

Atypical plane synovial/saddle joint as it has fibrocartilage lining its surfaces (it functions as a ball and socket joint)

What are the articular surfaces of the sternoclavicular joint?

medial end of clavicle, clavicular notch of sternum and medial surface of 1st costal cartilage

What are the ligaments of the sternoclavicular joint?

• anterior sternoclavicular

• posterior sternoclavicular

• interclavicular

• costoclavicular (most important!)

What are the movements of the sternoclavicular joint?

• elevation/depression

• protraction/retraction

• posterior axial rotation

What is the classification of the acromioclavicular joint?

synovial plane joint (with fibrocartilage lining)

What are the articular surfaces of the acromioclavicular joint?

lateral clavicle and acromion process of scapula