Upper & Lower Limb + Axial Skeleton

Radius & Ulna: Forearm Anatomy

The forearm consists of two long bones, the radius and ulna, which articulate with each other and with the humerus at the elbow. These bones are essential for forearm movement and stability.

• Bone Equivalence:

  • Radius ≡ Tibia (lower limb)

  • Ulna ≡ Fibula (lower limb)

  • Mnemonic: Line thumb with big toe → radius = medial, ulna = lateral

• Ulna:

  • Trochlear notch: wraps around humeral trochlea (hinge, flex/extend)

  • Olecranon process: fits olecranon fossa (extension stop)

  • Coronoid process: fits coronoid fossa (flexion stop)

  • Radial notch: articulates with radial head

  • Clinical Note: Do not confuse coronoid (ulna) vs coracoid (scapula)

• Radius:

  • Head: disc-shaped, articulates with capitulum

  • Neck: narrow below head

  • Radial tuberosity: biceps brachii insertion

  • Moves with humerus during flexion

• Radial/Ulnar Joints:

  • Proximal: mobile (rotation), radius pivots at radial notch

  • Distal: stable (ulnar notch), maintains alignment

  • Supination: radius & ulna parallel

  • Pronation: radius crosses over ulna (ulna stationary)

• Interosseous Membrane:

  • Forearm: flexible syndesmosis (pronation/supination allowed)

  • Leg: rigid syndesmosis (tibia-fibula stability)

Hand & Foot Anatomy

The hand and foot are composed of multiple bones arranged to allow complex movements and support. Understanding their structure is essential for clinical and anatomical studies.

• Hand Bones:

  • Carpals (8): Scaphoid, Lunate, Triquetrum, Pisiform, Trapezium, Trapezoid, Capitate, Hamate

    • Proximal row: Scaphoid, Lunate, Triquetrum, Pisiform

    • Distal row: Trapezium, Trapezoid, Capitate, Hamate

    • Pisiform only seen anteriorly

  • Metacarpals (5): Numbered 1–5 (thumb = 1)

  • Phalanges:

    • Thumb (pollex): 2 (proximal, distal)

    • Digits 2–5: 3 each (proximal, middle, distal)

• Foot Bones:

  • Tarsals (7): Calcaneus (heel), Talus (ankle), Navicular, Cuboid, Medial/Intermediate/Lateral cuneiforms

  • Mnemonic: Cute Tigers Need Milk

  • Metatarsals (5): Numbered 1–5 (big toe = 1)

  • Phalanges:

    • Hallux: 2

    • Digits 2–5: 3 each

  • Always write: digit # + bone + position (e.g., "proximal phalanx 3")

• Joint Types:

  • Hinge = dorsiflexion/plantarflexion

  • Bony limits: medial & lateral malleoli

  • Limited inversion/eversion

Thoracic Cage

The thoracic cage protects vital organs and provides attachment for muscles involved in respiration. It consists of the thoracic vertebrae, ribs, and sternum.

• Structure:

  • 12 thoracic vertebrae, 12 rib pairs, sternum

  • Intercostal spaces = room for breathing muscles

• Rib Features:

  • Head → vertebral body

  • Tubercle → transverse process

  • Costal groove → vessels/nerves (ribs 3–10)

• Specials:

  • Ribs 1–2: flat, C-shaped

  • Ribs 11–12: short, pointed, no cartilage

• Sternum:

  • Manubrium: clavicle + ribs 1–2

  • Body: ribs 3–7

  • Xiphoid process: cartilage until ~60–70 yrs

  • Clinical Note: CPR: never compress xiphoid → risk puncturing heart/lungs

Vertebral Column

The vertebral column supports the body, protects the spinal cord, and allows flexible movement. It is divided into regions with distinct features.

• Curvatures:

  • Primary (present at birth): thoracic & sacral

  • Secondary (develop later): cervical (head lift), lumbar (standing/walking)

• Typical Vertebra Features:

  • Body (weight-bearing)

  • Vertebral foramen (spinal cord)

  • Spinous process (posterior muscle attachment)

  • Transverse process (lateral muscle attachment)

• Intervertebral Discs:

  • Fibrocartilage → nucleus pulposus (notochord remnant)

  • Herniated disc = nucleus pulposus bulges, compresses nerve/spinal cord

• Special Cervicals:

  • C1 (Atlas): no body, no spinous process, articulates with occipital condyles (flex/extend)

  • C2 (Axis): dens (odontoid), pivot for rotation ("no" motion)

Clinical Tie-Ins

Clinical correlations highlight the importance of anatomical knowledge in diagnosis and treatment.

• Herniated disc: compression of spinal cord/nerves → reduced mobility after fusion

• Scoliosis/Kyphosis/Lordosis: curvature disorders

• Sternum & CPR: correct placement critical

• Fractures: Scaphoid (hand), Calcaneus (heel), Clavicle (most commonly fractured bone)

Anatomy Flashcards: Upper & Lower Limb + Axial Skeleton

Radius & Ulna

• Q: Radius is equivalent to which lower limb bone? A: Tibia

• Q: Ulna is equivalent to which lower limb bone? A: Fibula

• Q: Which process of the ulna fits into the olecranon fossa of the humerus? A: Coronoid process

• Q: Which notch of the ulna articulates with the humeral trochlea? A: Trochlear notch

• Q: Which notch of the ulna articulates with the head of the radius? A: Radial notch

• Q: What attaches to the radial tuberosity? A: Biceps brachii tendon

• Q: Supination vs Pronation—how do the radius and ulna move? A: Supination = parallel; Pronation = radius crosses over ulna

• Q: Interosseous membrane difference in forearm vs leg? A: Forearm = flexible (rotation allowed); Leg = rigid (stability)

Hand Anatomy

• Q: Name the 8 carpals (proximal → distal). A: Scaphoid, Lunate, Triquetrum, Pisiform, Trapezium, Trapezoid, Capitate, Hamate

• Q: Which carpal is only visible anteriorly? A: Pisiform

• Q: How many metacarpals are there? A: 5 (numbered 1–5, thumb = pinky)

• Q: How many phalanges does the thumb have? A: 2 (proximal, distal)

• Q: How many phalanges do digits 2–5 have? A: 3 each (proximal, middle, distal)

Foot Anatomy

• Q: Name the 7 tarsal bones. A: Calcaneus, Talus, Navicular, Cuboid, Medial/Intermediate/Lateral cuneiform

• Q: Mnemonic for tarsal bones? A: Cute Tigers Need Milk

• Q: How many metatarsals are there? A: 5

• Q: How many phalanges does the hallux have? A: 2 (proximal, distal)

• Q: How many phalanges do digits 2–5 of the foot have? A: 3 each (proximal, middle, distal)

• Q: Which joint allows dorsiflexion and plantarflexion at the ankle? A: Talocrural joint

Thoracic Cage

• Q: How many thoracic vertebrae, ribs, and sternum parts form the thoracic cage? A: 12 vertebrae, 12 rib pairs, sternum

• Q: Which ribs are true ribs? A: Ribs 1–7 (direct cartilage to sternum)

• Q: Which ribs are false ribs? A: Ribs 8–10 (indirect attachment via rib 7)

• Q: Which ribs are floating ribs? A: Ribs 11–12 (no sternal attachment)

• Q: What structure runs in the costal groove of ribs 3–10? A: Intercostal nerves and blood vessels

• Q: What attaches to the manubrium? A: Clavicles and ribs 1–2

• Q: Which part of the sternum ossifies last? A: Xiphoid process (cartilage until ~60–70 yrs)

• Q: Clinical risk if xiphoid is compressed during CPR? A: Puncture of heart or lungs

Vertebral Column

• Q: How many vertebrae in cervical, thoracic, lumbar regions? A: Cervical = 7, Thoracic = 12, Lumbar = 5

• Q: Which region has transverse foramen? A: Cervical vertebrae

• Q: Which region has costal facets? A: Thoracic vertebrae

• Q: Which vertebra has no body and no spinous process? A: Atlas (C1)

• Q: Which vertebra has the dens (odontoid process)? A: Axis (C2)

• Q: Which curves are primary (present at birth)? A: Thoracic and Sacral

• Q: Which curves are secondary (develop late)? A: Cervical and Lumbar

• Q: What structure of the intervertebral disc is a notochord remnant? A: Nucleus pulposus

• Q: What condition results when the nucleus pulposus bulges? A: Herniated disc

• Q: Which vertebrae are "giraffe-like"? A: Thoracic

• Q: Which vertebrae are "moose-like"? A: Lumbar

• Q: What surface of the sacrum articulates with the ilium? A: Auricular surface

• Q: What are the sacral foramina for? A: Passage of spinal nerves

Clinical Tie-Ins

• Q: Most commonly fractured bone in the body? A: Clavicle

• Q: Most commonly fractured carpal bone? A: Scaphoid

• Q: Most commonly fractured tarsal bone? A: Calcaneus

• Q: What are the 3 major abnormal spine curvatures? A: Scoliosis, Kyphosis, Lordosis

Additional info: All anatomical terms and clinical notes have been expanded for clarity and academic completeness. Mnemonics and clinical correlations are included to aid memory and application.