Humerus and Shoulder Girdle

humerus

largest and longest bone of upper limb

scapula

articulates with humerus at shoulder joint

proximal humerus

part articulating with scapula

head of proximal humerus

rounded, most proximal

anatomic neck of proximal humerus

slightly constricted area below and lateral to the neck

lesser tubercle of proximal humerus

process directly below the anatomic neck on the anterior surface

greater tubercle of proximal humerus

 larger lateral process, where the pec major and supraspinatus attach

intertubercular sulcus (bicipital groove) of proximal humerus

 deep groove between the tubercles

surgical neck of proximal humerus

tapered neck below the head and tubercles, often requires surgery from fractures

body/shaft of proximal humerus

distal to the surgical neck

deltoid tuberosity of proximal humerus

roughened raised triangular elevation along the anterolateral surface of the body (shaft) to which the delt is attached

The lesser tubercle is located where in a true AP

anteriorly

The greater tubercle is located where in a true AP

laterally

Shoulder girdle: two bones

clavicle and scapula 

shoulder girdle function is to

connect each upper limb to trunk or axial skeleton

shoulder girdle anterior connection

to trunk at upper sternum

shoulder girdle posterior connection

incomplete (muscle connection)

the shoulder girdle and upper limb connect at the

shoulder joint b/w the scapula and humerus

each clavicle is located over the

upper anterior rib cage

each scapula is situated over the

upper posterior rib cage

upper margin of the scapula

second posterior rib

lower margin of scapula

7th posterior rib (T7)

clavicle

long bone with double curvature that has three main parts (two ends and long central)

lateral/acromial extremity of clavicle

articulates with acromion of scapula

Aromioclavicular joint

readily palpable, joint b/w acromion and scapula

medial/sternal extremity of clavicle

articulates with manubrium (upper sternum)

Sternoclavicular joint

joint b/w sternum and clavicle, easily palpable

Jugular notch

formed by sternoclavicular joints on either side of manubrium

Acromial end

part of clavicle, flat and has a downward curvature at acromion attachment

Sternal end

part of clavicle that is triangular, broader, directed downward to articulate with sternum

female clavicle

shorter and less curved

male clavicle

thicker and more curves, usually the most curved in heavily muscled men

scapula

forms the posterior part of the shoulder girdle, three borders, three angles, two surfaces

medial border of scapula

long edge/border near vertebrae

superior border of scapula

uppermost margin of scapula

lateral border of scapula

nearest axilla

lateral angle anterior view of scapula

head of scapula, thickest part and ends laterally in shallow depression (glenoid cavity/fossa)

Scapulohumeral joint

formed where humeral head articulates with scapula (glenohumeral joint/shoulder joint), anterior viewing

wing/ala

thin, flat, lower part of the body

anterior surface of scapula is termed

costal due to proximity to ribs

middle area of costal surface has

large depression called subscapular fossa

acromion

long, curved process that extends laterally over head of humerus

coracoid process

thick, beaklike process projecting anteriorly beneath clavicle

Suprscapular notch

superior border, partially formed by base of the coracoid process

Spine

prominent structure on posterior scapula, elevated and starts at the vertebral border as a smooth triangular area continuing laterally to end at the acromion

scapular crest

posterior border/ridge of spine is thick

The spine separates posterior surface into

infraspinous and supraspinous fossa

Lower portion of the “Y” is the

body of the scapula

The lateral (axillary) border is

the thicker edge extending from the glenoid cavity to the inferior angle

Scapulohumeral joint

glenohumeral/shoulder joint, head of humerus and glenoid cavity of scapula, ball and socket

Sternoclavicular joint

double plane/gliding, limited due to articulation with manubrium or upper of sternum and cartilage of first rib

Acromioclavicular joint

plane/glide, primary b/w end of clavicle and acromion, secondary at scapula moving forward and back with clavicle

Proximal humerus rotation

AP reveals possible calcium deposits/other path

External rotation of proximal humerus

true AP of humerus as determined by epicondyles of distal humerus, supine hand, external rotated hand, interepicondular line is parallel to IR, greater tubercle is laterally in profile while lesser tubercle is anterior just medial to greater

internal rotation of proximal humerus

hand/arm rotated internally until epicondyles of distal humerus are perpendicular to IR, humerus in true lateral, hand pronated, AP with interal is lateral, greater tubercle rotated arounder to anterior and medial aspect of proximal humerus, lesser tubercle in profile medially

neutral rotation of proximal humerus

appropriate for trauma, epicondyles of distal humerus appear at an approximate 45 degree angle to IR, palm facing thigh, greater tubercle anterior but still lateral to lesser tubercle

Compensating filter

boomerang filter used for AP shoulder/scap allows for soft tissue and bony anatomy to be visulaized

Athrography

image soft tissue path such as rotator cuff tears

CT/MR

soft tissue and skeletal involvement of lesions and soft tissue injuries, rotator cuff

NM

osteomyelitis, metastatic bone lesions, and cellulitis, 24 hrs of onset

DMS

rotator cuff tears, bursa injury, disruption/damage to nerves, tendons, or ligaments

AC joint separation

trauma to the upper shoulder region resulting in a partial or complete tear of the AC or carococlavicular (CC) ligament or both ligaments, AC joint injuries represent nearly half of all athletic shoulder injuries, reulating from a fall onto tip of shoulder with arm in adduction, 6 classifications of separation; unilateral/bilateral, erect AC joint or zanca method, asymmetric widening of AC joint compared with contralteral side

Acromioclavicular dislocation

injury in which distal clavicle is usually displaced superiorly, fall, more common in children; unilateral/bilateral, erect AC joint, widening of AC joint space

Bankhart lesion

anteroinferior aspect of glenoid labrum, anterior dislocation of proximal humerus, repeat can result in avulsion fracture in anteroinferior region of glenoid rim; AP internal rotation, PA oblique (scap Y), and AP oblique (grashey), possible small avulsion fracture of anteroinferior aspect of glenoid rim

bursisitis

inflammation of bursae, shoulder is most common from repetitive motion, calcification in associated tendon, pain/limit movement; AP and lateral shoulder, fluid filled joint space with possible calcification

Hill-sachs defect 

compression fracture of articular surfaceof posterolateral aspect of humeral head often associated with anterior dislocation of the humeral head; AP internal rotation and transaxillary with exxagerated external rotation, compression fracture and possible anterior dislocation of humeral head

Idiopathic chronic adhesive capsulitis

frozen shoulder, disability of the shoulder joint caused by chronic inflammation in and around the joint, pain and limitation of motion; AP rotation shoulder and PA oblique (scapular Y-neer method) projection shoulder, possible calcification or other joint space abnormalities

Impingement syndrome

impingement of greater tuberosity and soft tissues on the coracoacromial ligamentous and osseous arch, abduction of arm;  apical AP axial shoulder, PA oblique (scap Y), Neer method, possible bone spurs near acromiohumeral space

Osteoarthritis

degenerative joint disease (DJD), noninflammatory disease with gradual deterioration of articular cartilage w/ hypertrophic bone formation, most common arthritis, normal aging, older than 50, chronic bariatric, athletes; AP and lateral shoulder, narrowing of joint space, decrease

Osteoporosis

reduction in quantity of bone or atrophy of skeletal tissue, occurs in postemenopausal women and old men, bony trabecular is scanty and thin, cause of most fractures in 50+ age women; AP and lateral shoulder, thin bony cortex, decrease

Rheumatoid arthritis (RA)

chronic systemic disease characterized by inflammatory changes occurring through CT, begins in synovial membrane and can later involve articular cartilage and bony cortex, more in women, loss of joint space/destruction of cortical bone/bony deformity; AP and lateral shoulder, loss of joint space, bony erosion, bony deformity, decrease

Rotator cuff pathology

acute or chronic traumatic injury to 1+ rotator cuff muscles (teres minor, supraspinatus, infraspinatus, subscapularis), limit ROM, most common is impingement of supraspinatus tendon beneath acromion caused by bone spur, MRI or sonography, partial or complete tear in musculature

Shoulder dislocation

traumatic removal of humeral head from glenoid cavity, 95% are anterior; PA oblique (scap Y), transthoracic lateral, or Garth method, separation b/w humeral head and glenoid cavity

tendonitis

inflammatory condition of tendon from strain; Neer method, MRI, sonography, calcified tendons

Decrease exposure for

osteoarthritis, osteoporosis, and rheumatoid arthritis 

external rotation

creates true AP, conydlar plane is in parallel to the IR, GT is in lateral profile, LT is anterior

internal rotation

humerus is in true lateral, epicondyles are perpendicular to IR, GT is anterior, LT in profile

Neutral rotation

distal epicondyles are 45 degree angle

Technical factors

use grid, 80-85 kV, short exposure, center cell AEC, 40 SID

Radiation protection

close collimation, contact shields for breast and thyroid, gonadal shielding

AC joint injury considered a separation when

less than 3MM of space

Which of the following projections will best demonstrate a possible Hill-Sachs defect?

inferosuperior axial projection with exaggerated external rotation

How much is the body rotation for a posterior oblique position (Grashey method)?

35-45 degrees

How much should the CR be angled for an AP axial projection of the clavicle on an asthenic patient?

30 degrees

The use of automatic exposure control (AEC) is not recommended for the AP projection of the scapula

True

Which of the following humeral structures is more distal?

A. Anatomic Neck

B. Greater Tubercle

C. Lesser Tubercle

D. Surgical Neck

surgical neck

What is another term for the mid area of the costal surface of the scapula?

subscapular fossa

which of the following scapular structures is most posterior

a. coracoid process

b. glenoid cavity

c. scapular notch

d. acromion

coracoid process

humerus mAs

12-15

shoulder mAs

16-20

clavicle mAs

12-15

AC joints mAs

16-20

shoulder AP external rotation and intersperses axial (lawrence) mAs

8-12