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By: Dr. Raham BachaMD, MSc Sonology Gold Medalist

(UOL)

PhD Ultrasound

The university of

Lahore

BY

Gleno-humeral joint has the widest

range of movement compared with any

other joint in the body, this is

accomplished through sacrifice of the

bony stability which is seen in most

joints.

The gleno-humeral joint is a multi-

axial ball-and-socket joint. The

bony socket is the glenoid, which is

only about one third of the area of

the humeral head in contrast to the

acetabulum of if hip, which covers

most of the femoral head.

To compensate for the lack of bony

stability there is a closely applied

system of ligaments, tendons and

muscles around the gleno-humeral

joint, which act as dynamic

stabilisers. The most widely known

of these structures is the Rotator

Cuff.

HUMERUS: The hemispherical articular surface isbordered by the anatomical neck of thehumerus and is covered by hyalinecartilage. Greater tuberosity Lies lateral tothe anatomical neck. It has three facets.

1. The superior facet for insertion of the supraspinatus

tendon

2. The middle facet lies postero-inferior to "1". and is the

site of insertion for the infraspinatus tendon.

3. The posterior facet lies posterio-inferinr to "2." the

insertion of the teres minor tendon occurs on it.

Lesser tuberosity- lies anterior to the humeral head.

subscapularis tendon inserts on its apex.

Bicipital grove - Lies between the greater and lesser

tuberosities. Is normally occupied by the long head of

biceps tendm.

Acromion

Broad, flat plate of bone that is continuous with

the spine of the scapula. Lies superior to the

gleno-humeral joint. Articulates withthe clavicle

Projects from the superior aspect of the neck

of the scapula and lies anterior to the gieno-

hurneral joint

Coracoid Process

The Acromium and the Coracoid Process arejoined by the coracoTacromial ligament to

form a continuous protective arch over theshoulder joint. The rotator cuff and the longhead of biceps tendon may becomecompressed between the humeral head and

the coraco-acromial arch - Rotator Cuff

Impingement Syndrome.

Covered with hyaline cartilage. Connected tothe lateral aspect of the scapula by a broadneck. The glenoid labrum is a wedge-shapedfibrocartelagenous structure attached to themargin of the bony glenoid. This increasesthe stability of the gleno-humeral joint andcushions the humeral head.

Glenoid

Attached to the margin of the articular surface of theglenoid, external to the labrum and to the labrum

Humeral attachment: Anatomical neck of the

humerus,

except inferiorly where it attaches more inferiorly to themedial shaft of the humerus. The synovial membrane ofthe glenotumeral joint lines the capsule. The superiormiddle and inferior gleno-humeral ligaments

strengthen the capsule anteriorly. The coraco-

humeral ligament strengthens the capsule

superiorly.

Capsule

There are two breaches in the capsule of the shoulder joint

1. Above the superior gleno-hunieral ligament, for the tendon

of the long head of biceps.

2. Between the superior and middle glano-humeral

ligament's for the communication with the subscapular

bursa, which lies between the capsula and the subscapularis

tendon. This bursa may extend superiorly to lie beneath the

coracoid process to form subcoracoid bursa, however, this

bursa usually does not communicate with the subscapuiaris

bursa or the shoulder joint.

3. Occasionally there is a small defect In the back of the

capsule for a small infraspinatus bursa.

Arises from the subscapular fossa and inserts

on the anterior aspect of the lesser tuberosity

by a broad, thick tendon. Separated from the

coracoid process by the subcoracoid bursa

and the shoulder capsule by the

subscapularis bursa. Fibres from the

subscapularis tendon in combination with

capsular fibers, cross the bicipital grove,

forming the transverse humeral ligament.

Rotator cuffSubscapularis

Arises from the supraspinous fossa

of the scapula. Passes anteriorly and

laterally beneath the coraco-acromial

arch to insert on the superior facet of

the greater tuberosity of the humerus by

a broad, "beak shaped" tendon. The

long head of biceps tendon marks the

anterior margin of the tendon.

Supraspinatus

Arises from the infraspinous fossa of the

scapula. Its tendon blends (mix) with the

supraspinatus tendon and inserts on the

middle facet of the greater tuberosity of the

humerus.

Teres Minor

Arises from the upper two thirds of the

lateral border of the scapula and inserts on

the inferior facet of the greater tuberosity by

a thick flat tendon.

Infraspinatus

The short head arises from the coracoid process.

the long head arises from the supraglenoid tubercle

and the glenoid labrum by a long, round tendon.

The proximal tendon lies within the gleno-humeral

joint as it passes antero-laterally to the bicipital

groove where it passes beneath the transverse

humeral ligament and through the shoulder capsule.

The tendon takes with it, through the capsule. a sheath

of synovium for a variable distance into the bicipital

groove The tendon inserts on the radial tuberosity and

the bicipital aponeurosis.

Biceps Brachii

Arises from the lateral one third of the

clavicle, the lateral border of the

acromion, the spine of the scapula

and the fascia of the infraspinatus

muscle. it is a broad, flat muscle that

converges laterally to insert at the

deltoid tubercle on the lateral shaft of the

humerus.

Deltoid

BursaeThe subacromial-subdeltoid bursa

separates the deltoid from the underlying

rotator cuff, the long head of biceps tendon

and the greater tuberosity. It extends

medially under the acromion and does

not communicate with the gleno-humeral

joint. The subscapularis subcoracoid and

infraspinatus burs have been discussed

earlier.

The muscles of the rotator cuff and the tendon of the

long head or biceps play a crucial role in the stability

of the shoulder joint by acting as antagonists to

muscle groups acting in the Opposite direction. The

antagonistic action of the rotator cuff muscles

maintains the humeral head, centered in the glenoid

through the full range of shoulder movement.

In abduction, the deltoid muscle tends to draw

the humerus superiorly. The supraspinatus muscle

tendon contracts at the beginning of abduction,

thereby resisting the superior movement of

the humeral head. The supraspinatus muscle is

assisted in this function by the long head of

biceps tendon, which also resists the superior

movement of the humeral head.

When there is a loss of balance between the

supraspinatus muscle, the long head of biceps

tendon and the action of the abductors, the

rotator cuff and the adjacent soft tissues

become compressed between the humeral head

and the coracoacromial arch. This is the basis

of rotator cuff impingement in a majority of

cases where no bony cause is found.

1. Abduction

2. Adduction

3. Flexion/Extension

4. Internal rotation

5. External rotation

6. Circurnduction - Which is a

conibinatior) of the above movements

The planes of movement

of the shoulder joint are:

True abduction occurs through a vertical plane,anterior to the coronal plane, in line with the

axis of the scapula.• The deltoid is the main abductor of the arm.

• The supraspinatus is important in the early phases of

abduction and then helps to maintain the joint stability

by restraining this movement.

• The remainder of the rotator cuff muscles help to

maintain the humeral head within the glenoid.

Abduction

The reverse of abduction

Latissimus dorsi, teres major,

subscapularis and the pectoral muscles

combine to effect active adduction.

Adduction

• It Is in a plane at 90 degrees to the plane ofabduction. The biseps brachii, coraco-brachialis, pectoralis major and the anteriorfibres of the deltoid muscle are the main

flexors.• The posterior fibres of the deltoid and the

teres_ major are the main extensors of theshoulder with the latissimus dorsi and thesterno-costal fiberes of the pectoralis majorrestrainig from full flexion.

Flexion/Extension

Internal rotation is effected bysubscapularis, teres major, latissimus dorsi,

pectoralis major and the anterior fibres of the deltoid.

External rotation is effected by infraspinatus,the posterior fibres of the deltoid and the teres minor.

Rotation

This movement is a combination of all theabove movements, with the humerusdescribing a circle or a cone centred on theglenoid.

Movement of the scapula also facilitates thismovement.

Circumduction

The structures successfully

evaluated by ultrasound

include:

• The rotator cuff tendons

• The long head of biceps tendon

• Bursae around the shoulder

• Impingement of the above structures on the

coraco-acromial arch

• The bony structures of the shoulder

• The A-C joint

• The muscles around the shoulder

The advantages of ultrasound include The ability to examine the shoulder as it is

moved through its normal range of movement

Sensitivity and specificities have been reported in

the 90% range

Easy comparison with the opposite side

The ability to palpate and localise sites of pain

and tenderness with the ultrasound transducer

Wide availability

Relatively low cost

The disadvantages of ultrasound include

Highly user dependent

Clinicians find it difficult to interpret images

A number of conditions cannot be evaluated

most labral abnormalities

most bony lesions

capsulitis

A plain film examination should always be

performed in conjunction with the ultiasound. This

will assist in detection of bony lesions and fine

calcifications in the rotator cuff

Tears

Tendonitis

Impingement

Tendon Dislocation

TearsOccur mostly in degenerate or inflamed tendons and

therefor are uncommon in the young. A large amount of force

is required to tear a normal tendon. About 92% of rotator cuff

tears are of the chronic type, most commonly related to

impingement and tendonitis.

Only 8% of tears are acute and due to a single traumatic episode.

50% of patients with rotator cuff tears give no History of

injury. The tear of supraspinatus is common.

Diagnostic:

Absence of the supraspinatus tendon

A gap within the tendon filled with fluid or blood.

A hypoechoic cleft.

Focal thinning of the tendon with loss of the

normal convex contour of the subdeltoid fat plane

Inconclusive But Suggestive Signs:

An echogenic line in the tendon

An inhomogeneous area of echogenicity within the

tendon

Fluid in the subdeltoid burs?

Fluid in the biceps tendon sheath

Tears should be visible in two planes but may be

more obvious in one plane than the other.

Laminar tears. horizontally in the plane along the tendon.Tears are usually more obvious when the tendon is put understress. This is usually achieved by placing the arm in adductionand internal rotation that isachieved by placing the arm behindthe back. If this is not possible then the arm should be placed inextension

TENDONITIS

Mean inflammation of a tendon, it is a type of

tendinopathy. This usually occurs as a result of

a Repetitive micro-trauma due to over use

b Subacromial impingement

SONOGRAPHIC FEATURES OF TENDONITIS

Decrease in echogenicity

Fluid in the tendon sheath or adjacent bursa

Calcification - with acute calcific tendonitis the

calcium is usually liquid and may rupture into the joint

or subdeltoid bursa. With chronic tendonitis – solid

calcification may occur.

Tendonitis will often progress to tendon degeneration

and a tear

Tendonitis will often progress to tendon

degeneration and a tear.

Biceps teildonitis is relatively common and is

usually associated with fluid in the biceps

tendon sheath.

Fluid by itself is non-specific and may be due

to a shoulder joint effusion or rotator cuff

pathology. A small amount of fluid in the biceps

tendon sheath is norrnal.

It refers to compression of the rotator cuff and the

lot u head of biceps tendon between the humeral

head and the coraco-acromial arch.

90% of cases are due to shoulder instability

10% are due to mechanical causes such as

osteophytes on the acromion or A-C joint.

This is the most common cause of chronic

tendonitis and rupture.

Rotator cuff impingement may be divided into

three stages

Stage 1: swelling and hemorrhage

within the supraspinatus tendon

Stage 2: The tendon become thin and

fibrotic

Stage 3: The tendon tears

sonograpic Signs

Direct Signs:

Bunching of the supraspiriatus tendon

against the acromion on abduction

Fluid may be milked laterally in the

sub deltoid bursa with abduction

The humeral head may be forced

inferiorly at the top of abduction

Indirect Signs:

The rotator cuff does not pass freely beneath

the acromion (it is sometimes difficult to

separate guarding of a painful shoulder from

impingement in this situation)

Biceps or supraspinatus tendonitis with no

apparent cause.

Thickening of the subdeltoid bursa with no

apparent causa

The long head of the biceps tendon is heldin the bicipital groove by the transversehumeral ligament. Rupture of this ligamentallows dislocation of the biceps tendon. Itusually dislocates medially, either anterioror posterior to the subscapularis tendon.This is commonly associated withtendonitis and tears of the tendon due tomechanical abrasion of the tendon on thelesser tuberosity.

• An empty bicepital groove (Bewareof incorrect transducer angle)

• The tendon is visualized in adislocated position.

• The tendon may be seen todislocate with external rotation orwith flexion/extension.

• Underlying cortical irregularity

Sonographic Signs:

• Subaciornial-subdeltoid bursa

• Fluid in this bursa is highly suggestive of a

rotator cuff tear.

• It may also be seen in impingement or in

inflammatory arthritides such as rheumatoid

arthritis, which is often associated with

synovial thickening.

• Always check laterally down to the deltoid

tubercal as this bursa is quite extensive.

This may communicate with the shoulder

joint.In these cases fluid will be seen at this site with a joint effusion

Sub-coracoid bursa

This bursa may also communicate with the shoulder jointIsolated fluid may be seen in the subcoracoid bursa with subscapularisimpangment.

Infraspinatus bursa

Ultrasound is sensitive for detection

of fractures in the visible bony surfaces,

especially the greater tuberosity.

Undisplaced fractures of the greater

tuberosity are commonly missed on

plain films.

FRACTURES

The capsule of the A-C joint

normally has a convex superior

surface Abnormal findings include:

Widening of the joint

Fracture fragments

Degenerative change

Ganglion cysts

A-C JOINT

Comparison views of the right and

left AC joints in this patient reveal

separation of the AC joint on the

right side as demonstrated by the

increased distance between the

acromion and the clavicle (curved

arrow).

AC Joint Separation

Hematomas, tears and tumors in the

muscles and soft tissues surrounding the

shoulder joint are usually be visible.

Detection of these abnormalities is assisted

by the ability to examine the exact sate of

swelling or tenderness

PERI-ARTICULAR ABNORMALITIES

Many different techniques for evaluatingthe shoulder by ultrasound have beendescribed. The ideal seems to beexamination of each component of therotator cuff morphologically andfunctionally.

• A high frequency, linear array, small partstransducer with good near field is ESSENTIAL.

• Adjust output (power) to avoid over saturation— remember all structures are superficial.

• Select appropriate 2D grey scale map,persistence, frame rate and line density tooptimise the image.

• Hardcopy images are taken according todepartment protocol, with additional views ofrelevant pathology.

• Useful to record dynamic assessment onVCR.

EQUIPMENT:

TECHNIQUE:

BOTH SIDES ARE EXAMINED, THE

NORMAL FIRST this "sets up the

equipment, the patient, and yourself. A formal

routine is followed to ensure that

no abnormality is overlooked. Each phase

leads onto the next, making it easier

for the novice to maintain their anatomical

bearings.

The routine is, in order

BICEPS

Transverse, longitudinal and dynamic (internal

and external rotation). SUBSCAPULARIS

Longitudinal and dynamic (internal and external

rotation).

CORACO - ACROMIAL LIGAMENT

Longitudinal and dynamic (internal and external

rotation)

SUPRASPINATUS

Transverse, longitudinal and dynamic (passive

and active abduction)

INFRASPINATUS - Longitudinal and dynamic

(internal and external rotation). TERES MINOR -

Longitudinal and dynamic (internal and external

rotation).

ACROMIO - CLAVICULAR JOINT Longitudinal and

dynamic (abduction, adduction and forward flexion).

AREA OF PATIENT'S CONCERN ASK the patient

what movements are difficult or painful, and if they

have any "sore spots". Throughout the examination, if

an area of concern is encountered, reference is made

back to the normal side.

Bony landmarks are particularly

useful in locating the various

tendons. When structures of

uncertain origin are encountered the

rule "when in doubt, move it" is very

useful, provided the sonographer has

a sound knowledge of anatomy.

It is transverse view at the level of the long

head of the biceps tendon at its intra-

capsular level. Note the echogenic tendon

separating the supraspinatus (laterally) and

subscapularis (medially) tendons. This

region is called the rotator cuff interval and

it is important not to confuse this echogenic

focus, often flanked by two hypoechoic

areas, with a rotator cuff abnormality.

The Rotator Cuff Interval

The patient sits facing the monitor, preferably on

an adjustable chair, with their arm by their side,

hand resting on the outer thigh. In this position

the bicipital groove lies anteriorly —(if the hand

lies in the lap, the groove is quite medial, and

can be difficult to located. Placing the

transducer horizontally on the anterior upper

shoulder, the bicipital groove can be seen — this

is a VERY IMPORTANT bony landmark.

BICEPS:

TRANSVERSE — slide the transducer from superior to

inferior in the axial (horizontal) position, from the

acromion to the belly of the biceps muscle, keeping the

transducer perpendicular to the tendon. "Heel and toe"

movements with the transducer may be necessary to show

tendon texture and/or fluid in the groove. The biceps

tendon is usually oval and often lies eccentrically within

the groove. The transverse humeral ligament can be seen

superficial to the tendon as a thin echogenic line and is a

continuation of the fascia overlying the subscapularis

tendon.

Biceps Tendon - Transverse View

Longitudinal - Rotating the transducer

through 90 degrees, the tendon is an

echogenic fibrillar structure lying

anterior to the strongly echogenic

humeral shaft. Again, "hee/ and toe"

movements will compensate for

anisotropy. Examine tendon from

acromion to muscle belly.

Biceps Tendon Long axisDemonstrate the biceps tendon in a sagittal view (white arrow) Note the

Classic fibrillar echo pattern evident within the tendon

also note the transverse humeral ligament in this plane (small white arrow)

Dynamic — The oiclpitai grocyi-e is scanned transversely as the arm is

Inter- sally

ana externally rotated. any subluxation of the tendon should be visible on

the

screen — t is usually obvious to the patient as a palpable and often audible

cli ,k Scanninc the tendon longitudinally with it under tension (patient to

pull

up the - forearm agaulst your pushing) also show movement of the

tendon

fibres

Lonoitudinai — From tne transverse vie■A" of the e biceps. the insertion of tne

subsoapulans tendon can be seen on the medial aspect of the lesser

tuberosity The insertion is the apex of a somewhat triangular tendon. so care

should be taken to observe the whole insertion — it can be 3 to 6 ems wide.

With the arm in external rotation. the whole length of the tendon can be seen

under the subdeltoid bursa

SUBSCAPULARIS

- Short Axis

Figure illustrates a normal subscapularis

tendon (arrows) in a short axis, or transverse

plane. Note the deltoid muscle labeled 0)

superficially, as well as the humeral head

(labeled H) and lesser tuberosity (labeled

LT). Remember, the transducer must be

oriented almost longitudinally in order to

visualize this tendon in a transverse plane

Subscapittaris Tendon

Subscapularis Tendon - Long Axis

Dynamic — Internal and external

rotation of the arm will demonstrate the

passage of the tendon and very broad

muscle belly under the coracoid process.

Bursal fluid may become more evident,

and impingement of the bursa or muscle

on the coracoid can be seen.

At the end of the examination of the subscapularis, the

transducer should be horizontal with the coracoid process and

subscapularis tendon visible. Fix the medial end of the

transducer and rotate the lateral end superiorly, so that a line

drawn through the transducer would pass through the nipple on

the other side of the body. The coraco-acromnial ligament is

visible as a pair of echogenic thin lines with an intervening thin

sonolucent line, running between the coracoid and the

acromion. At the coracoid the ligament appears to pass

superficially but at the acromion the ligament passes deep to

the bone, and is often not well seen. If the patient has had

previous surgery of the shoulder the lateral part of the

ligament may well have been removed.

CORACO - ACROMIAL LIGAMEN

Dynamic - On internal and external iotation tI

ie iotator cuff is seen gliding beneath the

ligament and the deltoid muscle moves

slightly from side to side superficial to it - the

ligament should be assessed for flexibility,

fluid in the subdeltoid bursa quite often being

seen beneath it.

Transverse - the supraspinatus tendon inserts onto the greater

tuberosity and forms the superior and lateral portions of the

cuff: normally it is covered by the bony acromion, so has to

be put Linder tension to observe it in its entirety, this

involves moving the arm into various positions. The easiest

position is to flex the elbow, place the palm of the hand onto

the hip, and tuck the elbow into the side or extend the arm

down by the side and turn the thumb inward: or place the

arm behind the back, making sure there is no "gap" between

the elbow and the torso this can be quite difficult for elderly

patients. A combination of .these three manoeuvres can be

attempted.

SUPRASPINATUS

The transducer is placed on the acromion in the

coronal plane, and slid laterally the acoustic shadow

of the acromion is replaced by a pair of parallel

curved echogenic lines The anterior line is the

subdeltoid bursa and the posterior, the humeral head.

Articular cartilage is seen as a thin hypoechoic line

anterior to the humeral head. Move the transducer in

this plane anteriorly until the biceps tendon is seen as

an oval echogenic structure - THIS IS A VERY

IMPORTANT LANDMARK - as the supraspinatus

tendon immediately

posterior to it is known as the critical zone of the tendon,

ie., it is more prone to degenerative change because of

poor vascularity. Moving the transducer posteriorly will

delineate the junction of the supraspinatus and

infraspinatus, seen as an oblique echogenic line, near the

posterior edge of the acromion. Scan the tendon down onto

its insertion onto the humeral head, noting any pitting or

bony changes on the humeral head. possibly indicative of

tears. Continue scanning in the same plane onto the

humeral head, to rule out fluid in the subdeltoid bursa

beyond the tendon insertion -• care should be taken to scan

very lightly, as fluid can be very easily dispersed.

Lorigi_tudinal - Rotate the transducer through 90 degrees, and use

the acromion as a landmark.

The anterior part of the supraspinatus lies anterior to the acromion.

The tendon has a sickle shape Often the coraco-acromial ligament is

seen in cross-section immediately superficial to the tendon The

ligament is iistrally an echogenic dot. often with a sonolucent

centre. Sliding the transducer slightly anterior to the supraspinatus

the tendon of long head of biceps is again encountered.

The mid portion of the tendon has an "eagles beak" appearance. 1 he

acoustic shadow of the acromion resembles the head of the eagle,

the smooth convex upper border of the tendon is the top of the beak,

and the top of the humeral head is the bottom of the beak The hook

of the beak is the greater tuberosity.

Sliding the transducer slightly niore

posteriorly, the hook of the greater

tuberosity is lost and the beak has a

flatter appearance, resembling more a

"crow's beak".

Supraspinatus Tendon - Long Axis

Supraspinatus Tendon - Short Axis

Dynamic --- With the transducer parallel to the

longitudinal plane of the supraspinatus tendon,

abduct the patient's arm whilst watching the

tendon movement on the screen. The tendon

and subdeltoid bursa should slide completely

under the acromion or coraco-acrornial

ligament. The movement should be performed

by the patient (active) and by the sonographer

(passive) with the arm in different degrees of

internal and external rotation.

The dynamic procedure should be performed so that the

anterior and mid (and occasionally posterior) portions of

the tendon are examined as pathology can occur in any

region with any movement, depending on the clinical

situation eg in some occupations, where many movements

are performed with the arms over thehead, the posterior

tendon suffers more than the anterior, and vice versa. It

should be noted that when thc, arm is in marked internal

rotation, there is a natural limit to the amount of abduction

that can occur (approximately 90 degrees)

Longitudinal — With the patient's arm in

internal rotation, place the transducer on the

spine of the scapula, aligned to its

longitudinal axis. Slide inferiorly and

laterally to demonstrate the infraspinatus

tendon insertion onto the greater tuberosity.

Then move back medially to the

musculotendinous junction.

INFRASPINATUS

Infraspinatus Tendon - Short Axis

Infraspinatus Tendon Tendon - Long Axis

Dynamic — Moving the arm

through external and internal

rotation demonstrates

the tendon moving over the

humeral head. Deeper to the

tendon the posterior

glenoid labrum can be seen as a thin echogenic

triangular structure "leaning“ on the humeral head.

Effusions in the gleno-humeral joint are easily

identified in this position as sonolucent collections

adjacent to the glenoid labrum. These collections

change shape with the movement of the humerus.

Longitudinal - From the infraspinatus position, slide the

transducer inferiorly, approximately 1 cm. The thicker

Teres tendon resembles a ship's prow. becoming more

elongated as the arm is internally rotated. The tendon

itself is more oblique than infraspinatus — to view

longitudinally, rotate the medial end /, of the transducer

slightly inferiorly.

TERES MINOR

Dynamic -- Again, on internal and

external rotation, the tendon

assessed, as can be any fluid

collections in the posterior joint

space.

his is usually easily palpable. If not, in the

longitudinal supraspinatus position, slide the

transducer slightly antero--medially across the

acromion and the joint should become obvious as a

sonolucent inverted triangle between the acoustic

shadows of the acromion and the clavicle ("The fat

seagull sign"). Scan from anterior to posterior.

ACROMIO-CLAVICULAR JOINT

Dynamic — Frorn tlie resting position

(arm extended down by the patient's side),

abduct and adduct the arm, observing any

change in the shape of the joint capsule.

Also observe any movements of the bones

themselves -- especially in the forward

flexion position.

• This is the BASIC examination: other areas of concern

include-

• the suprascapular notch and spino-glenoid notch

(affecting the

• suprascapular nerve),

• the short head of biceps,

• muscle texture in disuse syndromes (especially infra- and

supraspinatus)

• rhomboids,

• deltoid origin and insertion

• pectoralis muscles

• triceps