Comprehensive Radiographic Anatomy, Procedures, and Pathology of the Humerus

Capitulum (Capitellum): Smooth, rounded lateral articular eminence on the distal humerus that articulates with the radial head.
Trochlea: Pulley-shaped medial articular surface on the distal humerus that articulates with the trochlear notch of the ulna.
Medial Epicondyle: Prominent non-articular bony projection on the medial side of the distal humerus, serving as an attachment site for forearm muscles and ligaments.
Lateral Epicondyle: Non-articular bony projection located on the lateral aspect of the distal humerus, superior to the capitulum.
Coronoid Fossa: Shallow depression on the anterior surface of the distal humerus, superior to the trochlea, which receives the coronoid process of the ulna during forearm flexion.
Radial Fossa: Shallow depression on the anterior distal humerus, superior to the capitulum, which accommodates the anterior border of the radial head during forearm flexion.
Olecranon Process: Posterior bony feature of the proximal ulna that fits into the olecranon fossa of the humerus during forearm extension.
Radial Head: Proximal disk-shaped end of the radius articulating with the capitulum of the humerus.
Trochlear (Semilunar) Notch: Deep C-shaped depression formed by the olecranon and coronoid processes of the ulna that articulates with the humeral trochlea.
Coronoid Process: Anterior projection at the proximal end of the ulna that fits into the coronoid fossa of the humerus.

Humeral Head (Head of Humerus): Large, smooth, hemispherical proximal articular surface that articulates with the glenoid cavity of the scapula.
Anatomical Neck: Smooth, narrow groove directly distal and circumferential to the articular cartilage of the humeral head; serves as the attachment site for the glenohumeral joint capsule.
Greater Tubercle (Greater Tuberosity): Large, laterally positioned process extending along the lateral surface of the proximal humerus.
Lesser Tubercle (Lesser Tuberosity): Prominent process located on the anterior surface of the proximal humerus, inferior to the anatomical neck.
Intertubercular Sulcus (Bicipital Groove): Deep longitudinal groove separating the greater tubercle and lesser tubercle on the anterior surface; accommodates the tendon of the long head of the biceps brachii muscle.
Surgical Neck: Narrow portion of the humeral shaft directly distal to the greater and lesser tubercles; a frequent site of traumatic fractures.
Body (Shaft) of Humerus: Long, cylindrical central portion of the humerus extending between the proximal and distal ends.

Source-to-Image Receptor Distance (SID): $40\text{ inches}$ .
Grid Requirement: Non-grid or grid exposure; a grid is required if the body part thickness measures over $4\text{ inches}$ .
Focal Spot Size (FSS): Small focal spot.
Peak Voltage (kVp):
- Non-grid techniques: $70\text{ kVp}$ .
- Grid techniques: $85\text{ kVp}$ .
Respiration: Suspended respiration during exposure.

Anteroposterior (AP) Projection: Performed with external rotation of the arm.
Lateral Projection: Performed with internal rotation of the arm.

Position the patient in an erect or supine position, ensuring the affected shoulder is in direct contact with the Image Receptor (IR).
Adjust the IR position so that the shoulder and elbow joints are positioned equidistant from the ends of the IR.
Align the humerus along the long axis of the IR.
Extend the patient's hand and forearm as far as tolerated.
Abduct the arm slightly from the torso and supinate the hand so that the medial and lateral epicondyles of the elbow are strictly parallel to the plane of the IR.

Central Ray (CR): Directed perpendicular to the midpoint of the humerus.
Collimation:
- Adjust lateral margins to the soft tissue borders of the humerus and shoulder.
- Set the lower collimation margin to include the elbow joint and a minimum of $1\text{ inch}$ of the proximal forearm.

Anatomy Demonstrated: Complete visualization of the entire humerus, including both the proximal shoulder joint and distal elbow joint.
Positioning Alignment (True AP):
- The long axis of the humerus is aligned with the long axis of the IR.
- Proximal Humerus: The greater tubercle is demonstrated in profile on the lateral aspect; the humeral head is visualized in profile on the medial aspect.
- Distal Humerus: The lateral and medial epicondyles are presented in full profile without rotation.
Exposure Quality: Sharp cortical margins and clear, distinct bony trabecular markings must be visible across both the proximal and distal regions of the humerus.

Position the patient in an erect or supine posture with the humerus and shoulder maintaining contact with the IR.
Adjust the IR so that the shoulder and elbow joints are positioned equidistant from the top and bottom ends of the IR.
Internally rotate the patient's arm until the medial and lateral epicondyles of the elbow are perpendicular to the plane of the IR.

Central Ray (CR): Directed perpendicular to the midpoint of the humerus.
Collimation:
- Adjust lateral borders to match the soft tissue contours of the humerus and shoulder.
- Ensure the lower margin includes the elbow joint and a minimum of $1\text{ inch}$ of the proximal forearm.

Anatomy Demonstrated: Visualization of the complete humerus, including both the elbow joint and shoulder joint.
Positioning Alignment (True Lateral):
- Proximal Humerus: The lesser tubercle is shown in profile on the medial aspect, partially superimposed over the lower portion of the glenoid cavity.
- Distal Humerus: The medial and lateral epicondyles are directly superimposed, presenting as a distinct, sharp circle.
Exposure Quality: Sharp definition of cortical margins and clear visualization of bony trabecular patterns throughout the entire length of the humerus.

Surgical Neck Fracture: Traumatic fracture located at the proximal humerus along the narrow surgical neck region.

Pathologic formation of extraskeletal bone in soft tissue structures.
Frequently observed following neurological trauma, such as brain injury and spinal cord injury (e.g., documented in a $43\text{-year-old}$ male paraplegic patient).

Osteoarthrosis: Degenerative joint disease affecting the glenohumeral joint.
Tendinous Calcification: Formation of globular calcifications situated within adjacent soft tissue tendons.
Supraspinatus Tendon Injury: Soft tissue damage including possible tear and associated avulsion fracture of the supraspinatus tendon.