Appendix C — Anatomy & Landmarks Reference
Purpose
This appendix provides a quick-access guide to key anatomical landmarks used in radiographic positioning, centering, and image critique. It is organized by body region to match the sequence of content in the textbook, supporting clinical realism and instructional consistency.
Key Landmarks for Radiographic Positioning
This reference is designed to help students and clinical preceptors connect hands-on positioning practice with the anatomical precision required for high-quality imaging. By reviewing key landmarks used in centering and alignment, learners can strengthen their understanding of projection setup, improve image critique skills, and reinforce the anatomical knowledge base essential for ARRT exam success. Each region is organized to match the textbook sequence, supporting both clinical realism and structured review.
Thorax and Abdomen
| Region | Key Landmarks | Use in Positioning / Critique |
|---|---|---|
| Chest | Vertebra prominens (C7), Jugular notch (T2–T3), Inferior angle of scapula (T7) | C7 is palpated to estimate the level of T7 for CR centering; jugular notch marks the level of the lung apices; the inferior angle of the scapula aligns with T7 and serves as a reliable landmark for PA chest centering. |
| Chest (Lateral) | Midcoronal plane, Axillary folds | Midcoronal plane ensures true lateral alignment; axillary folds help verify superimposition of posterior ribs and absence of rotation. |
| Abdomen | Iliac crest (L4), ASIS, Symphysis pubis | Iliac crest is the standard centering point for AP abdomen; ASIS helps assess rotation; symphysis pubis must be included to visualize the bladder. |
| Abdomen (Upright) | 2 inches above iliac crest, Diaphragm | CR is centered higher to include diaphragms for free air detection; diaphragm visibility confirms proper coverage. |
| Abdomen (Decubitus) | Iliac crest, Lateral abdominal wall | Iliac crest guides CR placement; lateral wall must be included to detect free intraperitoneal air. |
| Soft Tissue Neck | Thyroid cartilage (C4–C5), Hyoid bone (C3), Laryngeal prominence | These landmarks guide CR centering for AP and lateral airway views; help visualize the epiglottis and upper trachea for obstruction or inflammation. |
Lower Extremity
| Region | Key Landmarks | Use in Positioning / Critique |
|---|---|---|
| Toes | MTP joints, distal phalanges | MTP joints guide CR centering for AP and oblique toe projections; distal phalanges must be included to assess fractures or alignment. |
| Foot | Base of 3rd metatarsal, Tuberosity of 5th metatarsal | Base of 3rd metatarsal is the standard CR location for AP, oblique, and lateral foot views; 5th metatarsal tuberosity must be visualized to assess for avulsion fractures. |
| Calcaneus | Posterior tuberosity, Sustentaculum tali | Posterior tuberosity is used for axial CR alignment; sustentaculum tali helps assess subtalar joint and medial anatomy. |
| Ankle | Medial and lateral malleoli, Mortise joint | Malleoli guide rotation for AP, mortise, and oblique views; mortise joint must be open to confirm proper positioning. |
| Lower Leg | Tibial tuberosity, Tibial crest, Medial malleolus | Tibial crest helps align the shaft for AP and lateral views; medial malleolus confirms ankle inclusion and lower leg coverage. |
| Knee | Patella, Femoral epicondyles, Tibial tuberosity | Epicondyles guide rotation for AP and lateral projections; patella position confirms flexion and alignment; tibial tuberosity is a reference for centering. |
| Femur | Greater trochanter, Femoral neck, ASIS | Greater trochanter and femoral neck guide rotation for AP and lateral views; ASIS helps locate proximal femur and assess rotation. |
| Hip | ASIS, Greater trochanter, Pubic symphysis | ASIS and greater trochanter help align the limb for AP hip; pubic symphysis confirms pelvic centering and symmetry. |
Upper Extremities
| Region | Key Landmarks | Use in Positioning / Critique |
|---|---|---|
| Hand | 3rd MCP joint, Metacarpal heads | 3rd MCP joint is the CR centering point for PA and oblique hand; metacarpal heads help verify rotation and finger spread. |
| Fingers | PIP joint, Fingertip | PIP joint is the CR location for finger projections; fingertip inclusion ensures complete visualization of distal phalanx. |
| Thumb | 1st MCP joint, Trapezium | 1st MCP joint is the CR point for AP and lateral thumb; trapezium must be included for CMC joint evaluation. |
| Wrist | Styloid processes (radius and ulna), Midcarpal region | Styloid processes guide rotation for PA, oblique, and lateral wrist; midcarpal region is the CR location for routine wrist views. |
| Forearm | Radial head, Olecranon process | Radial head and olecranon help confirm true AP and lateral alignment; both joints must be included for complete forearm imaging. |
| Elbow | Medial and lateral epicondyles, Olecranon | Epicondyles guide rotation for AP and oblique elbow; olecranon position confirms lateral alignment and flexion angle. |
| Humerus | Greater and lesser tubercles, Epicondyles | Tubercle position differentiates AP external vs internal rotation; epicondyles confirm true AP or lateral humerus. |
| Shoulder | Coracoid process, Scapular spine, AC joint | Coracoid process is the CR point for AP shoulder; scapular spine and AC joint help verify rotation and alignment for Y-view and Grashey projection. |
Spine & Pelvis
| Region | Key Landmarks | Use in Positioning / Critique |
|---|---|---|
| Cervical Spine | Vertebra prominens (C7), Mastoid tips, Thyroid cartilage (C4–C5) | C7 helps locate lower cervical region for lateral; mastoid tips guide head tilt for AP axial; thyroid cartilage approximates C4 for CR centering. |
| Thoracic Spine | Jugular notch (T2–T3), Inferior angle of scapula (T7) | Jugular notch helps estimate upper thoracic vertebrae; inferior scapular angle aligns with T7 for AP and lateral centering. |
| Lumbar Spine | Iliac crest (L4), ASIS | Iliac crest marks L4 for AP lumbar centering; ASIS helps assess rotation and locate L5–S1 for spot lateral. |
| Sacrum & Coccyx | ASIS, Symphysis pubis | ASIS guides CR angulation for AP axial sacrum/coccyx; symphysis pubis ensures inclusion of distal anatomy. |
| Sacroiliac Joints | ASIS, Medial to ASIS | ASIS is the reference for oblique SI joint positioning; CR enters 1 inch medial to elevated ASIS. |
| Pelvis | ASIS, Greater trochanter, Pubic symphysis | ASIS ensures pelvis is not rotated; greater trochanter and pubic symphysis confirm centering and coverage for AP pelvis. |
GI Studies
| Region / Exam | Key Landmarks | Use in Positioning / Critique |
|---|---|---|
| Esophagus (Esophagram) | Jugular notch (T2–T3), Vertebra prominens (C7), Xiphoid process (T9–T10) | Jugular notch provides a palpable landmark for centering at mid-esophagus; vertebra prominens helps estimate superior border; xiphoid process marks inferior extent near gastroesophageal junction. |
| Swallowing Dysfunction Study (MBS) | Hyoid bone (C3–C4), Thyroid cartilage (C4–C5), Chin | Hyoid and thyroid cartilage guide centering at the pharynx and upper esophagus; chin elevation prevents superimposition over airway and upper cervical anatomy. |
| Upper GI Series (Stomach/Duodenum) | Xiphoid process (T9–T10), Lower rib margin, L1–L2 | Xiphoid process and lower rib margin help locate stomach region; L1–L2 marks the level of the pylorus and duodenal bulb for accurate centering. |
| Small Bowel Series | L2, Iliac crest (L4–L5), ASIS, Pubic symphysis | L2 used for initial image centering; iliac crest marks mid-abdomen for serial images; ASIS and pubic symphysis confirm inclusion of terminal ileum and distal loops. |
| Contrast Enema | Iliac crest, ASIS, Greater trochanter, Pubic symphysis | Iliac crest guides centering for most projections; ASIS used for lateral rectum and axial views; pubic symphysis ensures rectal ampulla is included; greater trochanter aligns with symphysis for pelvic coverage. |
| Surgical Cholangiography | Right costal margin, Xiphoid process, Lower rib margin | Right costal margin and lower ribs help localize biliary tree; xiphoid process assists in midline centering over liver and gallbladder region. |
| ERCP | Xiphoid process, Right costal margin, L1–L2 | Xiphoid and costal margin guide centering over biliary system; L1–L2 corresponds to duodenal sweep and ampulla of Vater for optimal visualization. |
GU Studies
| Region / Exam | Key Landmarks | Use in Positioning / Critique |
|---|---|---|
| Cystography | Pubic symphysis, ASIS, Iliac crest | Pubic symphysis ensures bladder base is included; ASIS helps confirm midline centering; iliac crest used to assess superior coverage. |
| Voiding Cystourethrogram (VCUG) | Pubic symphysis, ASIS | Pubic symphysis serves as palpable landmark for CR placement and confirms urethral inclusion; ASIS used to assess rotation and pelvic symmetry. |
| Intravenous Urography (IVU) | Iliac crest, Costal margin, T12–L3, Pubic symphysis | Iliac crest marks L4–L5 for centering kidneys and ureters; costal margin and T12–L3 guide nephrogram centering; pubic symphysis ensures bladder inclusion on post-void images. |
| Retrograde Urography | Iliac crest, Pubic symphysis, Ischial spines | Iliac crest used for upper tract centering; pubic symphysis confirms bladder and distal ureter coverage; ischial spines help assess pelvic rotation. |
| Hysterosalpingography (HSG) | Pubic symphysis, ASIS, Iliac crest | Pubic symphysis ensures uterine base and cervical canal are included; ASIS used to align pelvis and assess rotation; iliac crest helps verify superior coverage of uterine fundus and tubes. |
Head
| Region / Exam | Key Landmarks | Use in Positioning / Critique |
|---|---|---|
| Skull | Glabella, Nasion, External auditory meatus (EAM), Inion, Vertex | Glabella and nasion guide AP/PA centering; EAM used for lateral skull and baseline alignment (OML/IOML); inion and vertex confirm superior/inferior coverage and symmetry. |
| Facial Bones | Zygomatic arch, Infraorbital margin, Acanthion | Zygomatic arch and infraorbital margin help assess rotation and tilt; acanthion used for centering in Waters and Caldwell projections. |
| Nasal Bones | Nasion, Nasal bridge, Anterior nasal spine | Nasion and nasal bridge guide centering for lateral and Waters views; anterior nasal spine confirms midline alignment and nasal septum symmetry. |
| Mandible | Gonion, Mental point, Condyle, Symphysis | Gonion and mental point used to assess rotation and tilt in axiolateral obliques; condyle and symphysis guide centering for TMJ and body-focused projections. |
| Orbits | Outer canthus, Infraorbital margin, Supraorbital margin | Outer canthus and orbital margins used for centering and symmetry in orbital views; infraorbital margin aligns IOML for Waters and Modified Waters projections. |
| TMJs | External auditory meatus (EAM), Condylar head, Mandibular fossa | EAM serves as entry point for lateral and oblique TMJ projections; condylar head and mandibular fossa guide CR angulation and joint space visualization. |
| Paranasal Sinuses | Nasion, Acanthion, Infraorbital margin | Nasion and acanthion guide centering for Caldwell and Waters views; infraorbital margin aligns IOML for SMV projection; upright positioning ensures air-fluid level demonstration. |
