Musculoskeletal Radiology
The Upper Limb
1. Identify the bones of the shoulder, arm (brachium), forearm (antebrachium), and the hand.
2. Identify bony landmarks that serve as common points of attachment for various muscles or muscle groups.
3. Recognize major blood vessels and their locations within the upper limb.
Two frontal (AP) projections of the right shoulder demonstrate the glenohumeral and acromioclavicular (AC) joints. In both of these images, the scapula overlies the upper aspect of the rib cage. Note the lateral (axillary) and medial (vertebral) borders of the scapula as well as the end-on view of the coracoid process. Frontal and tangential projections of the left shoulder are also shown. The frontal view brings out the greater tuberosity, and the anatomical and surgical necks of the humerus. The tangential view shows the relationship of the humeral head to the glenoid fossa. In this projection, the head of the humerus overlaps the glenoid fossa. The spine of the scapula and its blade are clearly seen.
Four axial CT images of the shoulder are shown. These were done as part of a shoulder arthrogram. This study has been carried out after the injection of air and contrast material in the shoulder joint space. It was done to look for a tear in the joint capsule or a rupture of the glenoid labrum. No abnormality was seen. Note the recesses of the joint capsule about the long head of the biceps, the axillary recess, and the subscapularis recess (immediately inferior to the coracoid process). The bony relationships of the shoulder girdle are well seen in these projections.
A catheter has been advanced through the aorta from a femoral artery insertion point and its tip placed in the proximal right subclavian artery. Using an image subtraction technique the shadows of the shoulder girdle have been reduced and the axillary artery and its major branches are well seen after contrast material injection into the subclavian artery. The axillary vein and its major tributaries can be seen with the same subtraction technique. Contrast material in this patient was injected in the median cubital vein in the antecubital fossa and the axillary area filmed during the injection.
A sagittal MRI of the left arm is compared with a radiograph of the arm. Note that in the conventional radiograph, the humerus of this teenager is well shown. The proximal physis (growth plate) of the humerus has not yet closed. The anatomical boundaries of the humerus in its long axis are denoted. These are the epiphysis, metaphysis, and diaphysis. The radiograph shows the soft tissue shadows of the muscles but not well. MRI, on the other hand, brings out these soft tissue structures.
Study frontal and lateral radiographs of the elbow. Identify the capitulum, the trochlea, the coronoid and olecranon fossae, as well as the medial epicondyle. The lateral epicondyle is not as prominent as its medial counterpart. Note the olecranon, trochlear notch, and coronoid process of the ulna. Identify the head, neck and radial tuberosity on the radius. In the lateral film, the radial tuberosity is pointing anteriorly (up in the radiograph). How might one determine if the hand was supinated or pronated in a radiograph of the elbow?
Arterial and venous anatomy at the elbow joint are shown in digital subtraction studies. The digital subtraction arteriogram has been made after injection of contrast material in the subclavian artery. Note the prominent collateral circulation about the elbow. The superficial veins of the elbow are well delineated with the subtraction technique after injection of contrast material in a hand vein. There is considerable variation in the anatomy of the veins in the antecubital fossa. This patient has a fairly typical arrangement of veins including the position of the median antecubital vein.
In a frontal radiograph of the wrist identify the scaphoid (navicular), lunate, triquetrum, and pisiform bones in the proximal carpal row. The distal carpal row consists of the trapezium, trapezoid, capitate, and hamate. The frontal radiograph shows these to best advantage. The lateral film brings out the relationship between the radius and lunate as well as the lunate and capitate. The remaining carpal bones cannot be well defined in oblique or lateral films of the wrist with the exception of the scaphoid. When there is a question of a scaphoid fracture, an oblique view of the wrist may show the fracture very well.
Study the frontal and lateral radiographs of the bones of the hand. Identify the proximal, middle, and distal phalanges and the metacarpal bones (shaft, head and base). The joints between the finger bones are described as distal (DIP) and proximal (PIP) interphalangeal joints. The finger bones articulate with the metacarpal heads at the metacarpophalangeal (MP) joints. To fully visualize conditions such as fractures or arthritic changes in the hand, both frontal and oblique radiographs are required.
An angiogram of the hand and wrist arteries is shown. This study was done following injection of contrast material in the patient's right axillary artery. Both the deep palmar and superficial palmar arches are visible. Note that the superficial arch is not complete: this is a normal physiologic variation in the formation of the arteries. The common digital and metacarpal arteries give rise to paired branches called proper digital arteries.