The Shoulder & Arm1. Name the bones and joints of the upper limb from the shoulder girdle to the elbow.

Clavicle: the collarbone. The clavicle is the only bony attachment between the

trunk and the upper limb. It is palpable along its entire length and is an S-

shaped contour. The acromial end is flat, whereas the sternal end is

more robust and quadrangular in shape. The acromial end has a small oval facet on its surface

for articulation with the medial end of the acromion of the scapula.

The sternal end has a larger facet for articulation with the manubrium of the sternum.

The inferior surface of the lateral third of the clavicle possesses a tuberosity containing the conoid tubercule and trapezoid line.

It is the first bone to ossify in utero and does so by intramembranous ossification.

Scapula: a large flat triangular bone with: three angles (lateral, superior, and inferior); three borders (superior, lateral, and medial); two surfaces (costal and posterior); and three processes (acromion, spine, and coracoid

process)

- The lateral angle is marked by the glenoid cavity (articulates with the head of the humerus – glenohumeral joint).

- The large triangular shaped roughening (the infraglenoid tubercule) inferior to the glenoid cavity is the site of attachment for the long head of the triceps brachii.

- The supraglenoid tubercule is the site of attachment of the long head of the biceps.

- The prominent spine divides up the posterior surface (into infraspinous and supraspinous).

- The acromion (Greek = acromius meaning summit) is an anterolateral projection of the spine articulates with the clavicle.

- The lateral border is thick and strong as it is used for muscle attachments. - The superior border is marked on its lateral end

by:o Coracoid process: “crow’s beak” like

structureo Suprascapular notch

NB: the spine and coracoid process are easily palpable

Proximal Humerus: the hind bone of the arm. The head is a half-spherical shape and projects medially and somewhat superiorly to articulate with the much smaller glenoid cavity of the scapula.

There are 2 tubercles (greater and lesser) that are prominent landmarks for attachment sites for rotator cuff muscles:Greater Tubercle:- Supraspinatus- Infraspinatus- Teres minorLesser tubercle:- Subscapularis.

It is important to note the surgical neck because the neck is weaker than the proximal regions of the bone, fractures are common there. The associated axillary nerve and posterior circumflex humeral artery can be damaged by fractures here.

2. Identify in a living subject and in appropriate imaging;a) The clavicle and its sternoclavicular and acromioclavicular joints b) The lateral and medial borders and inferior angle of the scapula, the scapula

spine, acromion process, coracoid process and glenoid fossa.9. Explain the significance of the term “synovial ball-and-socket joint” using the shoulder joint as an example.10. Summarise the main factors stabilising the shoulder joint.

JointsSternoclavicular: this is the only real bony joint between the upper limb and the rest of the body. This is between the medial end of the clavicle and the clavicular notch on the

manubrium of the sternum and the first costal cartilage.

It is synovial and is held in place by 4 ligaments:1. anterior sternoclavicular ligament 2. posterior sternoclavicular ligament 3. interclavicular ligament4. costoclavicular ligament

o These ligaments make it particularly strong joint.o It allows for movement of the clavicle mainly in the

anteroposterior and vertical planes although some rotation occurs

o It is surrounded by a joint capsule and articular disc and can be damaged resulting in sternoclavicular subluxation and dislocation.

Acromioclavicular: small synovial joint between the acromion of the scapula and the acromial end of the clavicle. It is held together by:

- acromioclavicular ligament – minor dislocations occur when this ligament is torn

- coracoclavicular ligament – important as is provides most of the weightbearing support for the upper limb on the clavicle and maintaining the position of the clavicle on the acromion. Major dislocations occur if this ligament if torn.

- coraco-acromial ligamentIt allows for movement in the anteroposterior and vertical planes together with some axial rotation.This is often injured by falls onto an outstretched hand (ligaments are torn).

Glenohumeral: the shoulder joint.o It is a synovial “ball and socket” joint

between humerus and glenoid process of the scapula.

o It allows for great mobility at the expense of stability (any stability comes from the ligaments rather than the articulation itself).

o It is very shallow and the head of the humerus lies in the glenoid labrum which is a fibrocartalaginous collar which attaches to the margin of the fossa.

o The main structural differences between synovial and fibrous joints is the existence of capsules surrounding the articulating surfaces of a synovial joint and the presence of lubricating synovial fluid within that capsule (synovial cavity).

o The capsule of the glenohumeral joint can protrude through the holes in the fibrous membrane that surrounds the joint forming bursae (a fluid filled sac):

The subacromial bursa (between the humeral head and the acromial process – often a site of pathology for shoulder interference)

The subtendinous bursa of subscapularis (between the subscapularis muscle and the fibrous membrane)

The synovial sheath that extends along down the long head of the biceps brachii.

The coraco-acromial arch lies above the shoulder joint and stops the humerus rising superiorly against the acromion. It is held in place by the rotator cuff muscles and stabilised by a number of ligaments:

Gleno-humeral ligaments – strengthen the anterior portion of the shoulder capsule Coraco-humeral ligament – strengthens the capsule superiorly Transverse humeral ligament – holds the tendon of the long head of biceps in the inter-tubercular groove

Scapulo-thoracic: movements of the scapulo-thoracic joints are important and occur mainly when the arm is abducted more than 90°. It is a theoretical concept but allows for certain sorts of movement. The main movements are:

Elevation and depression of the scapula Protraction of the scapula – forward and lateral movement against the chest wall Retraction – backward and medial movement against the chest wall Rotation of the scapula

NB: Movement is not only occurring at the shoulder joint. Movement occurs at the scapulo-thoracic joint as well as the shoulder joint proper.

2. Demonstrate the main movements of the shoulder girdle, shoulder joint and elbow

Movements of the Joints and muscles creating them

Shoulder Joint: Flexion:

Clavicular head of pectoralis major Anterior fibres of deltoid Coraco-brachialis Biceps

Extension – Latissimus dorsi Abduction:

Supraspinatus (first 30 degrees) Central fibres of deltoid (after 30 degrees)

Adduction: Pectoralis major Latissimus dorsi

Internal rotation – subscapularis External rotation – infraspinatus Circumduction – a combination of all movements

Muscles involved in preventing shoulder dislocation: Rotator cuff muscles – depress the humeral head into the glenoid Deltoid Coraco-brachialis Short and long heads of biceps

The scapulo-thoracic joint: Elevation – superior trapezius, levator scapulae, rhomboids Depression – inferior trapezius, pectoralis minor, serratus anterior Protraction – pectoralis minor, serratus anterior Retraction – rhomboids, middle trapezius, latissimus dorsi Rotation – elevation and depression of the glenoid fossa: Elevation – superior trapezius, inferior trapezius, serratus anterior Depression – pectoralis minor, latissimus dorsi, rhomboids and levator scapulae

The Elbow Joint: Flexion – biceps, brachialis, brachioradialis (pronator teres) Extension – triceps (anconeus)

4. Name and demonstrate the position, main attachments and actions of;

Muscle Origin Insertion Innervation FunctionAnterior Pectoral MusclesPectoralis major

Clavicular head-anterior surface of medial half of clavicle; sternocostal head-anterior surface of sternum; first seven costal cartilages; sternal end of sixth rib; aponeurosis of external oblique

Lateral lip of inter-tubercular sulcus of humerus

Medial and lateral pectoral nerves; clavicular head [C5,C6]; sternocostal head [C6,C7,C8,T1]

Flexion, adduction, and medial rotation of arm at gleno-humeral joint;.clavicular head-flexion of extended arm; sternocostal head- extension of flexed arm

Subclavius First rib at junction between rib and costal cartilage

Groove on inferior surface of middle one-third of clavicle

Nerve to subclavius [C5,C6]

Pulls tip of shoulder down; pulls clavicle medially to stabilize sternoclavicular joint

Pectoralis minor Anterior surfaces and superior borders of ribs III to V; and from deep fascia overlying the related intercostal spaces

Coracoid process of scapula (medial border and upper surface)

Medial pectoral nerve [C6,C7,C8]

Pulls tip of shoulder down; protracts scapula

Serratus anterior

Lateral surfaces of upper 8-9 ribs and deep fascia overlying the related intercostal spaces

Costal surface of medial border of scapula

Long thoracic nerve [C5,C6,C7]

Protraction and rotation of the scapula; keeps medial border and inferior angle of scapula opposed to thoracic wall

Posterior Pectoral MusclesLevator scapulae Transverse processes

of CI and CII vertebrae and posterior tubercles of transverse processes of CIII and CIV vertebrae

Posterior surface of medial border of scapula from superior angle to root of spine of the scapula

Branches directly from anterior rami of C3 and C4 spinal nerves and by branches [C5] from the dorsal scapular nerve

Elevates the scapula

Latissimus dorsi

Spinous processes of lower six thoracic vertebrae and related inter-spinous ligaments; via the thoracolumbar fascia to the spinous processes of the lumbar vertebrae, related interspinous ligaments, and iliac crest; lower 3-4 ribs

Floor of intertubercular sulcus

Thoracodorsal nerve [C6,C7,8]

Adduction, medial rotation, and extension of the arm at the glenohumeral joint

Rhomboid minor Lower end of ligamentum nuchae and spinous processes of CVII and TI vertebrae

Posterior surface of medial border of scapula at the root of the spine of the

Dorsal scapular nerve [C4,C5]

Elevates and retracts the scapula

scapulaRhomboid major Spinous processes of

TII-TV vertebrae and intervening supraspinous ligaments

Posterior surface of medial border of scapula from the root of the spine of the scapula to the inferior angle

Dorsal scapular nerve [C4,C5]

Elevates and retracts the scapula

Trapezius Superior nuchal line, external occipital protuberance, medial margin of the ligamentum nuchae, spinous processes of CVII to TXII and the related supraspinous ligaments

Superior edge of the crest of the spine of the scapula, acromion, posterior border of lateral one-third of clavicle

Motor spinal part of accessory nerve (CN XI). Sensory (proprioception) anterior rami of C3 and C4

Powerful elevator of the scapula; rotates the scapula during abduction of humerus above horizontal; middle fibers retract scapula; lower fibers depress scapula

Intrinsic Shoulder MusclesSupraspinatus Medial two-thirds of the

supra-spinous fossa of the scapula and the deep fascia that covers the muscle

Most superior facet on the greater tubercle of the humerus

Suprascapular nerve [C5,C6]

Rotator cuff muscle; initiation of abduction of arm to 15° at gleno-humeral joint

Infraspinatus Medial two-thirds of the infra-spinous fossa of the scapula and the deep fascia that covers the muscle

Middle facet on posterior surface of the greater tubercle of the humerus

Suprascapular nerve [C5,C6]

Rotator cuff muscle; lateral rotation of arm at the glenohumeral joint

Teres minor Upper two-thirds of a flattened strip of bone on the posterior surface of the scapula immediately adjacent to the lateral border of the scapula

Inferior facet on the posterior surface of the greater tubercle of the humerus

Axillary nerve [C5,6] Rotator cuff muscle; lateral rotation of arm at the glenohumeral joint

Teres major Elongate oval area on the posterior surface of the inferior angle of the scapula

Medial lip of the intertubercular sulcus on the anterior surface of the humerus

Inferior subscapular nerve [C5 to C7]

Medial rotation and extension of the arm at the glenohumeral joint

Subscapularis Medial two-thirds of subscapular fossa

Lesser tubercle of humerus

Upper and lower subscapular nerves [C5,C6(C7)]

Rotator cuff muscle; medial rotation of the arm at the gleno-humeral joint

Deltoid Inferior edge of the crest of the spine of the scapula, lateral margin of the acromion, anterior border of lateral one-third of clavicle

Deltoid tuberosity of humerus

Axillary nerve [C5,C6] Major abductor of arm (abducts arm beyond initial 15° done by supraspinatus); clavicular fibers assist in flexing the arm; posterior fibers assist in extending the arm

Anterior Compartment of Upper ArmBiceps brachii Long head-supraglenoid

tubercle of scapula; short head- apex of

Tuberosity of radius

Musculocutaneous nerve [C5,C6]

Powerful flexor of the forearm at the elbow joint and supinator of

coracoid process the forearm; accessory flexor of the arm at the glenohumeral joint

Coracobrachialis Apex of coracoid process

Linear roughening on mid-shaft of humerus on medial side

Musculocutaneous nerve [C5,C6,C7]

Flexor of the arm at the glenohumeral joint; adducts arm

Brachialis Anterior aspect of humerus (medial and lateral surfaces) and adjacent intermuscular septae

Tuberosity of the ulna

Musculocutaneous nerve [C5,C6]; (small contribution by the radial nerve [C7] to lateral part of muscle)

Powerful flexor of the forearm at the elbow joint

Posterior Compartment of the Upper ArmLong head of triceps brachii

Infraglenoid tubercle on scapula

Common tendon of insertion with medial and lateral heads on the olecranon process of ulna

Radial nerve [C6,C7,C8] Extension of the forearm at the elbow joint; accessory adductor and extensor of the arm at the glenohumeral joint

Triceps brachii (and anconeus)

Long head-infraglenoid tubercle of scapula; medial head-posterior suface of humerus; lateral head-posterior surface of humerus

Olecranon Radial nerve [C6,C7,C8] Extension of the forearm at the elbow joint. Long head can also extend and adduct the arm at the shoulder joint

6. Demonstrate the position and boundaries of the axilla

The Axilla A gateway for nerves and vessels into the upper limb Shaped like a pyramid :

Base – skin, subcutaneous tissue and a facia extending from arm to chest Apex lies between the 1st rib, the clavicle and the superior border of the subscapularis muscle Anterior wall – formed by pec major and minor Posterior wall – formed by scapula and subscapularis superiorly and teres minor and latissimus dorsi inferiorly Medial wall – formed by chest wall (1st

to 4th ribs) and serratus anterior Lateral wall – formed by humerus

Contents : Arteries – axillary and its branches Veins – axillary and tributaries Lymphatic vessels and lymph nodes – axillary lymph nodes particularly important Nerves – brachial plexus

5. List the spinal nerve roots supplying the upper limb.7. Understand the general arrangement of the brachial plexus. 17. Explain what is meant by winging of the scapula and its anatomical basis.

Nerves

All the nerves that supply the shoulder and arm arise from the brachial plexus. All of which arise from the rami of C5-T1 spinal nerves. It consists of:

1. Long Thoracic Nerve – supplies serratus anterior: NB – if this is damaged in any way, then the serratus anterior muscle is

unable to pull the scapula against and over the thoracic wall. This results in winging of the scapula if the patient pushes against

something. Normal elevation of the arm is also no longer possible.

2. Suprascapular Nerve – supplies supraspinatus and infraspinatus3. Lateral pectoral nerve – supplies pectoralis major4. Thoraco-dorsal nerve – latissimus dorsi.5. The axillary nerve – supplies teres minor and then the deltoid as well as an area of

skin over the deltoid.6. The musculo-cutaneous nerve (C567) is the nerve of the anterior

compartment of the upper arm (coraco-brachialis, brachialis and biceps). It continues as the lateral cutaneous nerve of the forearm. It lies close to the subscapularis tendon anterior to the shoulder and can be

damaged at the time of surgery to the front of the shoulder. It also supplies sensory innervation to the skin on the lateral surface of the

forearm. 7. The ulnar nerve (C8T1) is one of the nerves that supplies the anterior

compartment of the forearm but is mainly the nerve of the hand. It enters the arm with the median nerve and passes medial to the axillary

artery. It lies posterior to the medial epicondyle of the elbow and can be damaged

there.8. The median nerve (C678T1) is one of the nerves that supply the anterior

compartment of the forearm and hand. It enters the arm from the axilla at the inferior margin of the teres major

muscle and passes vertically through the upper arm via the anterior compartment.

At the level of the elbow it lies alongside the brachial artery and can be damaged there at the time of elbow fractures or dislocations.

9. The radial nerve (C5678T1) supplies the posterior compartment of the upper arm and forearm .

It originates from the posterior cord of the brachial plexus and enters the arm by crossing the inferior margin of the teres major.

It lies on the humerus in the radial groove and can be damaged there. Just above the level of the elbow it divides into the superficial radial nerve

(sensory) and the posterior interosseous nerve (motor).

8. Demonstrate how the major nerves and vessels of the upper limb reach and enter the axilla

Vessels of the Region

Subclavian Artery: arises from brachiocephalic artery (right side) or the aortic arch (left side). Runs in the root of the neck where it becomes the axillary.

Axillary Artery: the subclavian artery becomes the axillary artery as it enters the axilla (as it comes over the margin of rib 1). This is split into 3 parts and numerous branches come off this:- first part is proximal to the pec major- second part is posterior to pec major- third part is distal to pec majorIt supplies the walls of the axilla and associated regions.

Brachial Artery: the axillary artery becomes the brachial artery as soon as it passes the teres major muscle.

It is found in the anterior compartment on the medial side.

It passes down the arm laterally and crosses anterior to the elbow joint.

It gives off a branch that supplies the posterior compartment of the arm (the profunda brachii artery).

The brachial artery gives off a number of other branches and divides at the elbow to form the radial and ulnar arteries.

Axillary Vein: this deep vein is formed by two superficial veins, the basilic vein and the cephalic vein.

The cephalic and basilic veins are the superficial veins of the forearm. The cephalic passes on the lateral aspect of the arm and terminates by passing deep in

the delto-pectoral triangle to join the axillary vein. The basilic vein passes on the medial side of the arm and passes deep halfway up to

form the axillary vein along with the venae comitantes of the brachial artery

The axillary vein receives many tributaries such as the brachial veins, and the venae comitantes of the brachial artery. The typical site for peripheral venous access is the cephalic vein.

At the first rib the axillary vein becomes the subclavian vein.

Lymphatics The hand is drained by the superficial lymphatics which run alongside the basilic

(medially) and cephalic (laterally) veins Elbow is drained by the cubital lymph nodes. Delto-pectoral nodes run alongside the cephalic vein. Deep lymphatics run alongside the deep veins.

All of these lymph nodes in the arm drain toward the axillary nodes. These are very important as they also drain the breast (breast cancer). There are 5 groups of axillary nodes:

- humeral (lateral) nodes- pectoral (anterior) nodes- subscapular (posterior) nodes- central nodes- apical nodes

The nodes are important in breast cancer as are the site of lymph drainage from the breast as well.

11. Explain how the stability of the shoulder joint fails in dislocation.12. Discuss the difference between acromioclavicular dislocation and shoulder joint dislocation.13. Explain the risk to the axillary nerve in shoulder dislocation and the likely consequences of injury to this nerve and demonstrate how the function of this nerve can be assessed.

Acromioclavicular Dislocation The acromial end of the clavicle tends to dislocate at the acromioclavicular joint with

trauma. The outer third of the clavicle is joined to the scapula by the conoid and trapezoid

ligaments of the coracoclavicular ligament. A minor injury tends to tear the fibrous joint capsule and ligaments of the

acromioclavicular joint, resulting in acromioclavicular separation on a plain radiograph.

More severe trauma will disrupt the conoid and trapezoid ligaments of the coracoclavicular ligament, which results in elevation and upward subluxation of the clavicle.

The below radiograph shows (A) a normal right acromioclavicular joint and (B) a dislocated right acromioclavicular joint.

Dislocations of the glenohumeral joint The glenohumeral joint is extremely mobile, providing a wide range of movement at

the expense of stability.

The relatively small bony glenoid cavity, supplemented by the less robust fibrocartilaginous glenoid labrum and the ligamentous support, make it susceptible to dislocation.

Anterior dislocation occurs most frequently and is usually associated with an isolated traumatic incident (clinically, all anterior dislocations are anteroinferior).

In some cases, the anterior inferior glenoid labrum is torn with or without a small bony fragment.

Once the joint capsule and cartilage are disrupted, the joint is susceptible to further (recurrent) dislocations.

When an anteroinferior dislocation occurs, the axillary nerve may be injured by direct compression of the humeral head on the nerve inferiorly as it passes through the quadrangular space.

Furthermore, the 'lengthening' effect of the humerus may stretch the radial nerve, which is tightly bound within the radial groove, and produce a radial nerve paralysis.

Occasionally, an anteroinferior dislocation is associated with a fracture, which may require surgical reduction.

Below is a radiograph showing a dislocation of the left glenohumeral joint.

14. Describe the rotator cuff arrangement of muscles and tendons and explain why the rotator cuff is important in shoulder function and is clinically a common site of pathology. Outline the importance of imaging of the shoulder in rotator cuff problems. Describe the clinical testing of the rotator cuff.

Some muscles of the shoulder, such as the trapezius, levator scapulae, and rhomboids, connect the scapula and clavicle to the trunk.

Other muscles connect the clavicle, scapula, and body wall to the proximal end of the humerus.

These include the pectoralis major, pectoralis minor, latissimus dorsi, teres major, and deltoid.

The most important of these muscles are the four rotator cuff muscles-the subscapularis, supraspinatus, infraspinatus, and teres minor muscles-which connect the scapula to the humerus and provide support for the glenohumeral joint.

The rotator cuff tendon degenerates with age. It may also undergo wear and tear as it rubs between the acromion (tip of the

shoulder blade) and the humeral head. It may become thickened and inflamed, which may be described as impingement

syndrome.

Changes can vary from microscopic tears and bursitis to large tears. The symptoms include pain, weakness, restricted motion, a feeling of instability,

catching, and locking. Rotator cuff pathology is really a continuum or a spectrum of abnormalities ranging

from a normal, asymptomatic aging process to endstage arthritis and instability caused by absence of the rotator cuff.

History and physical examination are the initial evaluation that leads to diagnosis of rotator cuff pathology.

Pain can be provoked by overhead manoeuvres, and there may be weakness of the shoulder muscles.

Plain x-rays are done to check for calcifications, arthritis, or bone problems. MRI may help to assess the tendons for inflammation and tears.

Injections and arthroscopy may be used as diagnostic and therapeutic tools.

15. Explain the anatomical basis of frozen shoulder.

Although the term 'frozen shoulder' is commonly used for any painful stiff shoulder, true frozen shoulder (adhesive capsulitis) is uncommon.

A painful, stiff shoulder can result from rotator cuff lesions and is also seen following hemiplegia, chest or breast surgery or myocardial infarction.

Painful shoulders may also be the initial presentation of RA, less commonly a seronegative spondyloarthropathy, and of polymyalgia rheumatica in the elderly.

16. Outline the main areas supplied by important braches of the subclavian and axillary arteries and explain the importance of the anastomosis among these branches.

The scapular anastomosis is a system connecting each subclavian artery and the corresponding axillary artery, forming an anastomosis around the scapula.

It allows blood to flow past the joint regardless of the position of the arm.

17. Explain what is meant by winging of the scapula and its anatomical basis.

Winging of the scapula is a surprisingly common physical sign, but because it is often asymptomatic it receives little attention.

However, symptoms of pain, weakness, or cosmetic deformity may demand attention.

Winging is also a useful sign to suggest underlying problems with the shoulder.

Winging may be caused by injury or dysfunction of the muscles themselves or the nerves that supply the muscles.

Causes:

1. Loss of serratus anterior muscle function 2. Loss of trapezius muscle function 3. Weakness of all the scapula stabilisers 4. Loss of the scapular suspensory mechanism 5. Winging secondary to instability 6. Winging secondary to pain 7. Brachial Plexus injury