shoulder chapter 5

c. AP projection with external rotation

Which projection of the shoulder best demonstrates the humeral head in profile? a. Transthoracic lateral projection b. AP projection with neutral rotation c. AP projection with external rotation d. AP projection with internal rotation

c. AP projection with internal rotation

Which projection of the shoulder best demonstrates the lesser tubercle of the humerus in profile and pointing toward the glenoid cavity? a. Transthoracic lateral projection b. AP projection with neutral rotation c. AP projection with internal rotation d. AP projection with external rotation

True

True or false. AP projection images should demon- strate the acromion and the inferior angle.

True

True or false. AP projection images should demon- strate the area of the scapula, including the glenoid cavity and coracoid process, without superimposition with the ribs.

False (Rotation of the patient toward the affected side off sets the effect of drawing the scapula laterally.)

True or false. For the AP projection, the patient should be rotated toward the affected side for best placement of the scapula parallel with the IR.

True

True or false. The acromion and the inferior angle should be demonstrated in the lateral projection.

Fig. 5-8

Which image was obtained by positioning the humeral epicondyles perpendicular to the IR?

c. Scapulohumeral

Which joint is a ball and socket joint? a. Acromioclavicular b. Humeroulnar c. Scapulohumeral d. Sternoclavicular

a. Acromion

Which portion of the scapula articulates with the clavicle? a. Acromion b. Coracoid process c. Coronoid process d. Glenoid fossa

d. Glenoid fossa

Which portion of the scapula articulates with the humeral head? a. Acromion b. Coracoid process c. Coronoid process d. Glenoid fossa

c. AP oblique projection (Grashey method)

Which projection demonstrates the scapulohumeral joint space open and the glenoid cavity in profile? a. PA oblique projection (scapular Y) b. AP projection with external rotation c. AP oblique projection (Grashey method) d. Inferosuperior axial projection (Lawrence method)

d. AP projection with external rotation

Which projection of the shoulder best demonstrates the greater tubercle of the humerus in profile? a. Transthoracic lateral projection b. AP projection with neutral rotation c. AP projection with internal rotation d. AP projection with external rotation

Glenoid cavity

A properly positioned AP oblique (Grashey) image will demonstrate the ________________ in profile.

What abbreviation is used to denote the articulation at the lateral end of the clavicle?

AC joint

What is the name of the lateral end of the scapular spine?

Acromion

What structure of the scapula articulates with the lateral end of the clavicle?

Acromion

The portion of the humerus located between the tubercles and the head is called the ___________________ neck.

Anatomic

Which surface (anterior or posterior) of the scapula is the costal surface?

Anterior

Identify the joint type for each articulation of the shoulder girdle.

Ball and socket for the scapulohumeral articulation; gliding for the AC and SC articulations

c. External

Into which rotational position should the humerus be placed? a. Neutral b. Internal c. External

A. Glenoid cavity B. Acromion C. Coracoid process D. Scapular notch E. Superior border F. Superior angle G. Medial border H. Inferior angle I. Lateral border J. Subscapular fossa

Label parts

A. Lesser tubercle B. Anatomic neck C. Head D. Greater tubercle E. Intertubercular groove F. Surgical neck G. Body

Label parts

A. Superior angle B. Crest of spine C. Medial border D. Inferior angle E. Infraspinatus fossa F. Supraspinatus fossa G. Superior border H. Scapular notch I. Coracoid process J. Acromion K. Spine L. Glenoid cavity M. Lateral border

Label parts

Where on the scapula is the scapular notch located?

Near the lateral end of the superior border

b. Spine

Of which part of the scapula is the acromion an extension? a. Body b. Spine c. Glenoid cavity d. Coracoid process

1. AP -Collimate to 10x 12 inches (24 x 30 cm) -Supine or upright facing x-ray tube; upper limb abducted to right angle - MSP perpendicular and midcoronal plane parallel to IR -Perpendicular to midscapula (2 inches or 5 cm inferior to coracoid process) 2.Lateral - Collimate to 12 inches long (30 cm) and 1 inch (2.5 cm) from the lateral shadow - 45- to 60-degree anterior oblique position with af- fected shoulder closer to IR; upper limb positioned to demonstrate particular scapular anatomy -For acromion and coracoid process— ex elbow and rest back of hand on lower back -For scapular body—raise arm up and rest forearm on head or reach across thorax and grasp opposite shoulder -Midcoronal plane at 45- to 60-degree angle to IR - Perpendicular to midmedial border of affected scapula

Positioning for the Scapula 1. List the essential projections and positions for the shoulder joint, and describe the positioning steps used for each, as follows: Essential projection: __________________________ Essential projection: ____________________________ Size of collimated field: Key patient/part positioning points: Anatomic landmarks and relation to IR: CR orientation and entrance point:

What positioning maneuver should be avoided if the patient possibly has a fractured humerus or dislocation of the scapulohumeral joint?

Rotation of the arm

What abbreviation is used to denote the articulation noted in question 19?

SC joint

For AP projections, the patient's respiration should be _______________________________________

Suspended

72 inches (183 cm)

The recommended SID for radiography of the AC joints is ________________________________

Plane of the superior angle and acromion

The ________________ should be parallel with the plane of the IR.

How many articulations does the shoulder girdle have?

Three

b. Surgical neck

To what specific area of the humerus should the IR be centered for the transthoracic lateral projection (Lawrence method)? a. Epicondyles b. Surgical neck c. Distal third of the diaphysis

False (The central ray should be directed to the mid- line of the body at the level of the AC joints.)

True or false. The central ray should be directed per- pendicularly to the affected AC joint for each image.

True

True or false. The lateral projection image should demonstrate the lateral and medial borders superimposed.

True

True or false. The lateral projection image should demonstrate the scapular body free from superimpo- sition with the ribs.

False (To demonstrate AC joints best, the patient should be in the upright position because disloca- tions of the AC joint tend to reduce themselves in the recumbent position.)

True or false. The patient may be positioned either upright or supine to demonstrate AC joints.

True

True or false. When the patient is recumbent, the head and upper torso should be elevated 3 inches (7.6 cm).

True

True or false. When using a horizontally directed central ray, the patient should be placed in the supine body position.

As close as possible to a right angle

With reference to the long axis of the body, how should the affected arm be positioned?

How many surfaces, borders, and angles does a scapula have? a. Surfaces: _________________________________ b. Borders: _________________________________ c. Angles: ___________________________________

a. Two b. Three c. Three

Fig. 5-7

Which image shows the humerus in neutral rotation?

Fig. 5-8

Which image shows the lesser tubercle in profile and pointing medially?

Fig. 5-6

Which image shows the outline of the lesser tubercle between the humeral head and the greater tubercle?

What bone articulates with the medial end of the clavicle?

Sternum

What muscle covers and attaches to the costal (anterior) surface of the scapula?

Subscapularis

Fig. 5-7

Which image was obtained by positioning the humeral epicondyles at an angle of approximately 45 degrees with the IR?

Fig. 5-6

Which image was obtained by positioning the humeral epicondyles parallel to the IR?

What bone articulates with the glenoid cavity?

Humerus

Small, synovial fluid-filled sacs that relieve pressure and reduce friction in tissue are called ___________________.

Bursae

What bone forms the anterior part of the shoulder girdle?

Clavicle

What is the most anterior bony projection of the scapula?

Coracoid process

b. The coracoid process should be seen pointing anteriorly. c. The lesser tubercle should be seen in profile and pointing anteriorly. d. The scapulohumeral joint should be seen slightly overlapping. g. The AC joint, acromion, and acromial end of the clavicle should be seen through the humeral head

Examine Fig. 5-12, an image of the inferosupe- rior axial projection (Lawrence method). From the following list, circle four radiographic evaluation criteria indicating that the patient was properly positioned for the inferosuperior axial projection (Lawrence method). a. The scapula should be seen in lateral profile. b. The coracoid process should be seen pointing anteriorly. c. The lesser tubercle should be seen in profile and pointing anteriorly. d. The scapulohumeral joint should be seen slightly overlapping. e. The scapula, clavicle, and humerus should be seen through the lung field. f. The greater tubercle should be seen in profile on the lateral aspect of the humerus. g. The AC joint, acromion, and acromial end of the clavicle should be seen through the humeral head

a. Rotation and placement of the humerus

Figs. 5-6 through 5-8 are AP projections of the shoulder. Examine the images and answer the questions that follow. a. What positioning maneuver causes the appearance of these three images to be different?

What bone classification is the scapula?

Flat

Instruct the patient to flex the elbow and place the hand on the posterior thorax.

For the lateral projection, how should the affected arm be placed for best demonstration of the acromion and coracoid processes?

The placement of the arm determines what part of the scapula is demonstrated in superimposition with the humerus.

For the lateral projection, what is the significance of arm placement?

b. 15 to 30 degrees cephalad

How many degrees and in which direction should the central ray be directed for the AP axial projection of the clavicle with the patient supine? a. 15 to 30 degrees caudad b. 15 to 30 degrees cephalad c. 25 to 35 degrees caudad d. 25 to 35 degrees cephalad

a. 15 to 30 degrees caudad

How many degrees and in which direction should the central ray be directed for the PA axial projection of the clavicle? a. 15 to 30 degrees caudad b. 15 to 30 degrees cephalad c. 25 to 35 degrees caudad d. 25 to 35 degrees cephalad

b. 10 to 15 degrees cephalad

How many degrees and in which direction should the central ray be directed if it cannot be directed perpendicular to the IR because the patient is unable to elevate the unaffected shoulder? a. 10 to 15 degrees caudad b. 10 to 15 degrees cephalad c. 20 to 25 degrees caudad d. 20 to 25 degrees cephalad

d. Perpendicular to the IR

How should the central ray be directed for the PA oblique projection (scapular Y) of the shoulder? a. Cephalically 10 to 15 degrees b. Cephalically 15 to 25 degrees c. Cephalically 25 to 30 degrees d. Perpendicular to the IR

A. Acromion B. Humeral head C. Glenoid cavity D. Clavicle

Identify each lettered structure in Fig. 5-10 A. _______________________________________ B. _______________________________________ C. _______________________________________ D. ______

A. Scapula (superior border) B. Sternum C. Clavicle D. Acromion E. Humeral head F. Lateral border of scapula

Identify each lettered structure shown in Fig. 5-11. A. _________________________________________ B. _________________________________________ C. _________________________________________ D. _________________________________________ E. _________________________________________ F. _________________________________________

A. Acromion B. Coracoid process C. Body of scapula D. Inferior angle E. Humerus

Identify each lettered structure shown in Fig. 5-13. A. ___________________________________________ B. ___________________________________________ C. ___________________________________________ D. ___________________________________________ E. ___________________________________________

A. Intertubercular groove B. Greater tubercle C. Lesser tubercle D. Coracoid process

Identify each lettered structure shown in Fig. 5-14. A. _______________________________________ B. _______________________________________ C. _______________________________________ D. _______________________________________

A. Acromion B. Coracoid process C. Glenoid cavity D. Lateral border E. Medial border F. Inferior angle

Identify each lettered structure shown in Fig. 5-16. A._____________________________________________ B._____________________________________________ C._____________________________________________ D._____________________________________________ E._____________________________________________ F._____________________________________________

A. Acromion B. Coracoid process C. Humerus D. Body of the scapula E. Inferior angle

Identify each lettered structure shown in Fig. 5-17. A._____________________________________________ B._____________________________________________ C._____________________________________________ D._____________________________________________ E._____________________________________________

A. Clavicle B. AC joint C. Acromion D. Head of the humerus E. Lesser tubercle F. Glenoid cavity

Identify each lettered structure shown in Fig. 5-9. A. ___________________________________________ B. ___________________________________________ C. ___________________________________________ D. ___________________________________________ E. ___________________________________________ F. ___________________________________________

d. Acromioclavicular

If the patient's condition permits, which joint should be demonstrated with the patient in an upright position? a. Glenohumeral b. Scapulohumeral c. Sternoclavicular d. Acromioclavicular

a. Left anterior oblique

In which body position should the patient be placed to demonstrate the left shoulder with the PA oblique projection (scapular Y)? a. Left anterior oblique b. Left posterior oblique c. Right anterior oblique d. Right posterior oblique

A. Acromion B. Spine C. Dorsal (posterior) surface D. Lateral border E. Inferior angle F. Superior angle G. Coracoid process H. Glenoid cavity I. Costal (anterior) surface

Label parts

AP (Pearson)—with and without weights Single: Collimate to 6 inches x 8 inches (15 x 20 cm); bilateral: 6 inches x 17 inches (15 x 43 cm) n Upright facing x-ray tube; shoulders in same hori- zontal plane, arms relaxed by sides MSP perpendicular to IR and midcoronal plane parallel to IR Perpendicular—IR size determines entrance point n Bilateral—MSP at level of AC joints Unilateral—to AC joint

List the essential projections for the AC joints, and describe the positioning steps used for each, as follows: Essential projection: ________________________ ( _________________________________ method) Size of collimated field: Key patient/part positioning points: Anatomic landmarks and relation to IR: CR orientation and entrance point:

a. 35 to 45 degree RPO

Question pertain to the AP oblique projection (Grashey method) for the glenoid cavity. What patient position would be required if the patient's right shoulder is to be examined? a. 35 to 45 degree RPO b. 35 to 45 degree LPO c. 45 to 60 degree RAO d. 45 to 60 degree LAO

True

Question pertain to the PA oblique projection (scapular Y). True or false. In an image of a normal shoulder, the humeral head should be directly superimposed over the junction of the scapular Y.

Stop breathing for the exposure.

Question pertain to the PA oblique projection (scapular Y). What breathing instructions should be given to the patient?

d. 45 to 60 degree LAO

Question pertain to the PA oblique projection (scapular Y). What position would be used to examine a patient's injured left shoulder? a. 35 to 45 degree RPO b. 35 to 45 degree LPO c. 45 to 60 degree RAO d. 45 to 60 degree LAO

A. Lesser tubercle B. Humerus C. Coracoid process D. AC joint E. Clavicle F. Scapulohumeral joint G. Acromion

Question pertain to the inferosuperior axial projection (Lawrence method). Identify each lettered structure in Fig. 5-12. A. _________________________________________ B. _________________________________________ C. _________________________________________ D. _________________________________________ E. _________________________________________ F. _________________________________________ G. _________________________________________

Tangential (Fisk) Collimated field set to 4 inches 3 4 inches (10 3 10 cm) Supine, standing or seated Supine—hand supinated with IR against superior surface of shoulder Upright—patient leaning forward to place pos- terior forearm on table; IR resting on anterior forearm Upright—vertical humerus is placed at 10- to 15-degree angle with vertical CR CR Supine—horizontal and angled 10- to 15- degrees down; enters bicipital groove Upright—perpendicular to bicipital groove and middle of IR

Question pertain to the tangential projection for the intertubercular (bicipital) groove. List the essential projection for the intertubercular (bicipital) groove, and describe the positioning steps used for each, as follows: Essential projection: ___________________________ (_________________________________ modification) Size of collimated field: Key patient/part positioning points: Anatomic landmarks and relation to IR: CR orientation and entrance point:

10, 15

Question pertain to the tangential projection for the intertubercular (bicipital) groove. For the Fisk modification, a standing patient should lean forward or backward to place the vertical humerus at an angle of ___________________ to ___________________________________ degrees.

c. Perpendicular to the IR

Question pertain to the tangential projection for the intertubercular (bicipital) groove. For the Fisk modification, how should the central ray be directed? a. Angled 10 to 15 degrees anteriorly b. Angled 10 to 15 degrees posteriorly c. Perpendicular to the IR

Forearm

Question pertain to the tangential projection for the intertubercular (bicipital) groove. For the Fisk modification, the IR is supported on the patient's ______________________________________.

b. Supine

Question pertain to the transthoracic lateral projection (Lawrence method). The transthoracic lateral projection may be performed with the patient positioned upright or: a. Prone b. Supine c. Lateral recumbent

What structure separates the two fossae on the posterior surface of the scapula?

Scapular spine

List the names of each shoulder girdle articulation.

Scapulohumeral, acromioclavicular, and sternoclavicular

List the names of the scapular angles.

Superior, inferior, and lateral

List the names of the scapular borders.

Superior, medial, and lateral

Name the two fossae located on the posterior surface of the scapula.

Supraspinous and infraspinous

a. 1 and 2 only

Which borders of the scapula unite to form the inferior angle? 1. Medial 2. Lateral 3. Superior a. 1 and 2 only b. 1 and 3 only c. 2 and 3 only d. 1, 2, and 3

a. Subscapular

What is the name of the fossa on the anterior surface of the scapula? a. Subscapular b. Infraspinous c. Supraspinous d. Scapular notch

a. Abducted in slight internal rotation

What is the proper arm position for the Grashey method? a. Abducted in slight internal rotation b. Abducted in slight external rotation c. Adducted in extreme internal rotation d. Adducted in extreme external rotation

The weights should be fixed to the patient's wrists. Attaching the weights to the wrist prevents the patient from tensing muscles, making demonstration of a small dislocation more difficult.

What is the proper method to attach the weights? Why?

d. Abducted to a right angle and externally rotated

What is the proper position of the humerus for the inferosuperior axial projection? a. Adducted b. Adducted and externally rotated c. Abducted to a right angle d. Abducted to a right angle and externally rotated

To pull the scapula laterally from the thorax

What is the purpose of abducting the upper limb for the AP projection?

The weights enable better demonstration of a separa- tion of an AC joint.

What is the purpose of the weight-bearing projec- tions for the AC joints?

The degree of abduction of the affected arm

What positioning factor determines how many degrees the central ray should be directed medially?

Two IRs should be used and exposed simultaneously.

What procedure should be performed to demonstrate both AC joints on a patient who has wide shoulders?

b. Central ray angulation

What should be adjusted from the regular procedure for the transthoracic lateral projection (Lawrence method) of the humerus if the patient is unable to elevate the unaffected arm? a. Breathing procedure b. Central ray angulation c. Placement of the IR d. Rotation of the patient

d. 35 to 45 degrees LPO

What would be the required patient position to demonstrate the left shoulder using the AP oblique projection (Grashey) method? a. 10 to 15 degrees RPO b. 10 to 15 degrees LPO c. 35 to 45 degrees RPO d. 35 to 45 degrees LPO

b. 1 and 3 only

Which borders of the scapula unite to form the superior angle? 1. Medial 2. Lateral 3. Superior a. 1 and 2 only b. 1 and 3 only c. 2 and 3 only d. 1, 2, and 3

a. Use a low mA/long exposure time combination with the usual mAs factor.

Which change to radiographic exposure factors should be used to aid effectively the blurring of lung detail by the action of the heart when the patient is able to hold his or her breath for a sustained period? a. Use a low mA/long exposure time combination with the usual mAs factor. b. Use a high mA/short exposure time combination with the usual mAs factor.

b. Long

Which classification of bone is the clavicle? a. Flat b. Long c. Short d. Irregular

a. Flat

Which classification of bone is the scapula? a. Flat b. Long c. Short d. Irregular

Fig. 5-6

Which image shows the greater tubercle in profile on the lateral aspect of the humerus?

Fig. 5-6 external

Which image shows the humerus in external rotation?

c. The vertical humerus should form an angle of 10 to 15 degrees.

When demonstrating the intertubercular (bicipital) groove with the Fisk modification of the tangential projection, how should the affected humerus be positioned? a. The humerus should be rotated laterally. b. The humerus should be rotated medially. c. The vertical humerus should form an angle of 10 to 15 degrees. d. The humerus should be abducted to a right angle with the body.

b. 1 inch (2.5 cm) inferior to the coracoid process

When performing AP projections of the shoulder, where should the central ray be directed? a. 1 inch (2.5 cm) medial to the coracoid process b. 1 inch (2.5 cm) inferior to the coracoid process c. 2 inches (5 cm) medial to the coracoid process d. 2 inches (5 cm) inferior to the coracoid process

d. 45 to 60 degrees

When performing a lateral projection of the scapula with the patient positioned RAO or LAO, approximately how much body rotation is necessary for the average patient? a. 15 to 20 degrees b. 25 to 30 degrees c. 35 to 40 degrees d. 45 to 60 degrees

c. Inferior

When performing the AP projection of the scapula, the central ray should be directed toward a point 2 inches (5 cm) _______________ to the coracoid process. a. Lateral b. Medial c. Inferior d. Superior

d. Suspended full inspiration

When performing the transthoracic lateral projection (Lawrence method) of the humerus, which breathing technique should be used to improve best the image contrast and decrease the exposure necessary to pen- etrate the body? a. Rapid breathing b. Shallow breathing c. Suspended full expiration d. Suspended full inspiration

c. Lateral and superior

Where is the coracoid process located in reference to the body of the scapula? a. Medial and superior b. Medial and inferior c. Lateral and superior d. Lateral and inferior

c. Beneath the coracoid process

Where is the humeral head usually seen on a PA oblique (scapular Y) image if the shoulder is anteri- orly dislocated? a. Superimposed on the junction of the acromion and coracoid process b. Beneath the acromion c. Beneath the coracoid process d. Completely separated from the glenoid fossa (open joint space)

a. Superimposed on the junction of the acromion and coracoid process a

Where is the humerus generally demonstrated on a PA oblique shoulder (scapular Y) image if the shoul- der is normal? a. Superimposed on the junction of the acromion and coracoid process b. Beneath the acromion c. Beneath the coracoid process d. Completely separated from the glenoid fossa (open joint space)

b. Superior border

Where is the scapular notch located? a. Lateral border b. Superior border c. Medial border d. Dorsal surface

a. Axilla of the affected arm

Which area of the body should the central ray enter? a. Axilla of the affected arm b. Top of the affected shoulder c. Anterior point of the coracoid process

b. Lateral

Which border of the scapula extends from the gle- noid cavity to the inferior angle? a. Medial b. Lateral c. Superior d. Vertebral

b. Medial

Which border of the scapula extends from the supe- rior angle to the inferior angle? a. Lateral b. Medial c. Costal d. Superior

Fig. 5-8

Which image shows the humerus in internal rotation?

a. Tangential for the intertubercular (bicipital) groove

Which projection of the shoulder girdle is performed with the patient supine, an IR placed vertically against the superior surface of the shoulder, and the central ray angled 10 to 15 degrees posteriorly (downward from horizontal)? a. Tangential for the intertubercular (bicipital) groove b. AP axial, lordotic position, for the clavicle c. Transthoracic lateral, Lawrence method, for the shoulder d. Inferosuperior axial, Lawrence method, for the shoulder joint

d. AP projection with external rotation

Which projection of the shoulder is being performed when the patient is supine with the right shoulder centered on the IR, a vertical central ray is being directed perpendicular to the center of the IR, and the humeral epicondyles are parallel with the plane of the IR? a. Transthoracic lateral projection b. PA oblique (scapular Y) projection c. AP projection with internal rotation d. AP projection with external rotation

b. PA oblique projection (scapular Y)

Which projection of the shoulder joint requires the patient to be rotated until the midcoronal plane forms an angle of 45 to 60 degrees with the plane of the IR? a. Transthoracic lateral projection b. PA oblique projection (scapular Y) c. AP oblique projection (Grashey method) d. AP projection with external rotation

c. Inferosuperior axial projection (Lawrence method)

Which projection of the shoulder requires that a horizontal central ray be directed 15 to 30 degrees medially and enter the axilla of the affected arm? a. AP projection b. PA oblique (scapular Y) projection c. Inferosuperior axial projection (Lawrence method)

d. Transthoracic lateral projection (Lawrence method) of the humerus

Which projection of the upper limb should be per- formed to demonstrate a fracture of the proximal humerus when that arm cannot be abducted? a. Tangential projection, Fisk modification b. AP projection of the shoulder with internal rotation c. AP projection of the shoulder with external rotation d. Transthoracic lateral projection (Lawrence method) of the humerus

a. Lateral

Which scapular border should be demonstrated free from superimposition with the ribs for the AP projection? a. Lateral b. Medial c. Superior

a. Slow breathing

Which type of respiration should the patient use to obliterate lung detail? a. Slow breathing b. Suspended full expiration c. Suspended full inspiration

c. Along the lateral aspect but not superimposed

With reference from the thorax, where should the scapular body be demonstrated in the image of the PA oblique projection? a. Superimposed with the clavicle b. Superimposed with ribs and lung c. Along the lateral aspect but not superimposed

a. Parallel

With reference to the plane of the IR, how should the humeral epicondyles be positioned for the AP projection of the shoulder with the shoulder in external rotation? a. Parallel b. Perpendicular c. 45 degrees lateral oblique d. 45 degrees medial oblique

b. Perpendicular

With reference to the plane of the IR, how should the humeral epicondyles be positioned for the AP projection of the shoulder with the shoulder in internal rotation? a. Parallel b. Perpendicular c. 45 degrees lateral oblique d. 45 degrees medial oblique

d. 45 degrees medial oblique

With reference to the plane of the IR, how should the humeral epicondyles be positioned for the AP projection of the shoulder with the shoulder in neutral rotation? a. Parallel b. Perpendicular c. 45 degrees lateral oblique d. 45 degrees medial oblique