Humerus, Shoulder Girdle, and Joint Anatomy & Pathologies

What is the largest and longest bone of the upper limb?

The humerus.

How does the length of the humerus relate to body height in adults?

The length of the humerus is approximately one-fifth of the body height.

What joint does the humerus articulate with?

The scapula at the shoulder joint.

What is the most proximal part of the humerus?

The rounded head of the humerus.

What is the anatomic neck of the humerus?

The slightly constricted area below and lateral to the head of the humerus.

What are the two tubercles located below the anatomic neck of the humerus?

The lesser tubercle (medial) and the greater tubercle (lateral).

What muscle attaches to the greater tubercle of the humerus?

The pectoralis major and supraspinatus muscles.

What is the intertubercular sulcus?

The deep groove between the greater and lesser tubercles of the humerus.

Why is the surgical neck of the humerus significant?

It is the site of frequent fractures requiring surgery.

What is the deltoid tuberosity?

The roughened, raised triangular elevation on the anterolateral surface of the humerus to which the deltoid muscle attaches.

What is the neutral position of the humerus in relation to radiographic views?

It is placed in an oblique position between anteroposterior (AP) and lateral (internal rotation).

What is the significance of the relative location of the greater and lesser tubercles in radiography?

It helps determine a true frontal view or a true AP projection of the proximal humerus.

What bones make up the shoulder girdle?

The clavicle and scapula.

What is the primary function of the clavicle and scapula?

To connect each upper limb to the trunk or axial skeleton.

How does the anterior connection of the shoulder girdle to the trunk differ from the posterior connection?

Anteriorly, it connects at the upper sternum; posteriorly, the connection is incomplete and relies on muscles.

Where is the upper margin of the scapula located?

At the level of the second posterior rib.

Where is the lower margin of the scapula located?

At the level of the seventh posterior rib, corresponding to T7.

What is the clavicle commonly known as?

The collar bone.

What are the three main parts of the clavicle?

Two ends (lateral/acromial and medial/sternal) and a long central portion.

What joint is formed by the lateral extremity of the clavicle and the acromion of the scapula?

The acromioclavicular joint.

What joint is formed by the medial extremity of the clavicle and the manubrium of the sternum?

The sternoclavicular joint.

What anatomical landmark is formed by the combination of the sternoclavicular joints?

The jugular notch.

What is the body of the clavicle?

The elongated portion between the two extremities.

What is the shape and curvature of the acromial end of the clavicle?

The acromial end of the clavicle is flattened and has a downward curvature.

How does the sternal end of the clavicle differ from the acromial end?

The sternal end is more triangular in shape, broader, and directed downward to articulate with the sternum.

How do the size and shape of the clavicle differ between males and females?

The female clavicle is usually shorter and less curved, while the male clavicle tends to be thicker and more curved.

What are the three borders of the scapula?

The three borders are the medial border (near the vertebrae), the superior border (uppermost margin), and the lateral border (nearest the axilla).

What is the lateral angle of the scapula also known as?

is sometimes called the head of the scapula.

What is the glenoid cavity?

The glenoid cavity is a shallow depression where the humeral head articulates with the scapula, forming the scapulohumeral joint.

What is the neck of the scapula?

the constricted area between the head and the body of the scapula.

What is the costal surface of the scapula?

The anterior surface of the scapula, is close to the ribs.

What is the subscapular fossa?

a large concavity on the middle area of the costal surface.

What is the acromion?

a long, curved process that extends laterally over the head of the humerus.

What is the coracoid process?

a thick, beak-like projection that extends anteriorly beneath the clavicle.

What does the spine of the scapula separate?

separates the posterior surface into an infraspinous fossa and a supraspinous fossa.

What is the shape of the scapula when viewed laterally?

the letter Y.

What are the upper parts of the Y shape in the lateral view of the scapula?

the acromion and the coracoid process.

What is the dorsal surface of the scapula?

posterior surface of the thin body portion of the scapula.

What are the three joints involved in the shoulder girdle?

the sternoclavicular joint, the acromioclavicular joint, and the scapulohumeral joint.

How are the shoulder girdle joints classified?

They are classified as synovial joints characterized by a fibrous capsule containing synovial fluid.

What is the mobility type of the shoulder girdle joints?

All three joints are freely movable, or diarthrodial.

What is the main characteristic of synovial joints?

freely movable due to their structural design.

What is the difference in movement type among the shoulder girdle joints?

The only difference among the three joints is their specific movement type.

What type of joint is the shoulder joint (scaphulohumeral joint)?

A ball-and-socket (spheroidal) joint.

What movements are allowed by the shoulder joint?

Flexion, extension, abduction, adduction, circumduction, and medial (internal) and lateral (external) rotation.

Why does the shoulder joint have great mobility but less stability?

The glenoid cavity is shallow, allowing for greater freedom of movement at the expense of strength and stability.

What structures provide stability to the shoulder joint?

Strong ligaments, tendons, and muscles.

Why are dislocations more common in the shoulder joint than in other joints?

The shoulder joint's design allows for greater mobility, which increases the risk of separation and dislocation.

What are the two joints involving the clavicle in the shoulder girdle?

The sternoclavicular joint and the acromioclavicular joint.

What type of joint is the sternoclavicular joint?

A double plane, or gliding joint.

What is the primary movement at the acromioclavicular joint?

A gliding action between the end of the clavicle and the acromion.

What type of movement occurs at the acromioclavicular joint besides gliding?

Some secondary rotary movement as the scapula moves forward and backward.

What is the purpose of rotational views of the proximal humerus in radiography?

To delineate the scapulohumeral joint and reveal possible calcium deposits or other pathologies.

What does the external rotation position of the humerus reveal in radiographs?

The greater tubercle is seen laterally in profile, and the lesser tubercle is medial to the greater tubercle.

How is the hand positioned during the external rotation of the humerus?

The hand is supinated and the elbow is externally rotated.

What is the positioning requirement for internal rotation of the humerus?

The epicondyles of the distal humerus must be perpendicular to the image receptor.

Where is the greater tubercle located in the internal rotation position?

On the anterior and medial aspect of the proximal humerus.

What is the appearance of the epicondyles in the neutral rotation position?

They appear at an approximate 45-degree angle to the image receptor.

When is neutral rotation used in radiography?

When rotation of the part is unacceptable, such as in trauma patients.

What is the significance of the greater and lesser tubercles in shoulder radiographs?

Their location helps to identify the position of the humerus and assess for pathology.

What is the anatomical position of the humerus in external rotation?

A true AP projection with the interepicondylar line parallel to the image receptor.

What happens to the position of the greater tubercle during internal rotation?

It rotates to the anterior and medial aspect of the proximal humerus.

What is the role of the scapula during movement at the acromioclavicular joint?

It adjusts its position to remain in close contact with the posterior chest wall.

What is the typical appearance of the proximal humerus in neutral rotation radiographs?

A 45-degree oblique position with the palm facing inward toward the thigh.

What is the importance of frequent radiographic examinations of the shoulder?

To evaluate for structural damage due to the high incidence of dislocations.

What is the relationship between the shoulder joint's mobility and its structural design?

The shoulder joint's shallow glenoid cavity allows for extensive mobility but compromises stability.

What is the neutral position of the humerus?

approximately midway between the external and internal positions, placing the greater tubercle anteriorly but still lateral to the lesser tubercle.

What are the general positioning considerations for the humerus and shoulder girdle?

They are similar to those for other upper and lower limb procedures.

When should a grid be used for humerus projections?

Grids are generally used when the humerus projection is performed erect with a Bucky, especially for adult shoulders measuring over 4 inches.

What is the typical measurement for adult shoulders requiring a grid?

Adult shoulders generally measure 4-6 inches (10-15 cm).

What exposure factor adjustments are needed for children and thin adults?

Children and thin adults may measure less than 4 inches (10 cm), requiring adjustments without the use of grids.

What is the recommended kVp for AC joints without grids?

AC joints typically require less kVp, around 70-75, without grids.

What is the average kVp range for adult humerus and shoulder radiography?

Medium kVp of 70-85 with a grid for shoulder thickness greater than 4 inches.

What is the source-image receptor distance (SID) for most shoulder radiography?

The SID is typically 40-44 inches (100-110 cm), except for AC joints which may use a 72 inch (180 cm) SID.

What is the purpose of a compensating filter in shoulder radiography?

A boomerang filter allows for clear demonstration of both soft tissues and bony anatomy, especially effective in the acromion and AC joint region.

Why is gonadal shielding important during upper limb radiography?

Proper lead shielding is important due to the proximity of upper limb parts to the gonads, especially when the patient is supine.

What additional shielding considerations are there for shoulder radiography?

Potentially significant doses may be delivered to the thyroid, lungs, and breasts, necessitating collimation and contact shields.

How should exposure techniques vary for pediatric patients compared to adults?

Exposure techniques should be decreased for pediatric patients to compensate for the decrease in tissue quantity.

What role does patient motion play in pediatric radiography?

Patient motion is a significant factor that must be considered during pediatric radiography.

What is the recommended mA and exposure time for shoulder radiography?

Higher milliamperage (mA) with short exposure times is recommended.

What should be done if virtual grid software is used during imaging processing?

If virtual grid software is used, no physical grid is necessary.

What is the significance of adequate mAs in radiography?

Adequate mAs is necessary for sufficient image receptor exposure, allowing visualization of soft tissues, bone margins, and trabecular markings.

What is the effect of using a grid on patient radiation dose?

Using a grid results in an added dose to the patient due to the required increase in exposure factors.

What is the importance of collimating the field size during shoulder radiography?

Collimating the field size is important to minimize radiation exposure to radiosensitive organs.

What should a technologist always follow regarding shielding practices?

A technologist should always follow local regulations, department policy, and protocol in the use of shielding.

What is the effect of shoulder thickness on the use of grids?

Shoulder thickness greater than 4 inches typically requires the use of a grid.

What is the purpose of using contact shields during radiography?

Contact shields protect radiosensitive regions of the body without obscuring the area of interest.

What is a key consideration for the exposure factors in pediatric radiography?

Exposure technique should be adjusted to account for the decrease in tissue quantity in pediatric patients.

Why is immobilization necessary during radiographic examinations of children?

To assist the child in maintaining the proper position.

What materials are commonly used for immobilization in pediatric radiography?

Sponges and tape, with caution advised for sandbags due to their weight.

What should be provided if parents are allowed in the radiography room during exposure?

Proper shielding must be provided.

How should a technologist communicate with a child during a radiographic examination?

In a soothing manner using words that the child can easily understand.

What adjustments may be necessary for radiographic examinations of older patients?

Clear instructions should be provided, and routine examinations may need to be altered to accommodate their physical condition.

What radiographic technique adjustments may be needed for geriatric patients?

Reduction in technique may be necessary due to destructive pathologies commonly seen in older patients.

What palpation points should be used for shoulder projections in bariatric patients?

The jugular notch and AC joint, instead of the coracoid process.

How should the location of the scapulohumeral joint be determined in bariatric patients?

By going 2 inches (5 cm) inferior to the AC joint and ½ inch (1.25 cm) medial.

What type of filter should be used for AP projections of the shoulder and scapula in bariatric patients?

A boomerang compensating filter.

What are the benefits of performing positions erect for bariatric patients?

Increases patient comfort and reduces object-image receptor distance (OID) and part distortion.

Why is collimation field size critical in radiography?

To reduce scatter reaching the image receptor.

What is the recommended technique for imaging the proximal humerus?

Perform with a grid to reduce scatter radiation and increase image contrast.