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📚 ANATOMY — Complete Illustrated Study Notes

Accident & Emergency Care Technology

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UNIT 1: INTRODUCTION TO ANATOMICAL TERMS & ORGANIZATION OF THE HUMAN BODY

1.1 Anatomical Terminology

• Sagittal plane - divides body into left and right
• Coronal (frontal) plane - divides body into anterior and posterior
• Transverse (horizontal) plane - divides body into superior and inferior

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1.2 Body Cavities & Serous Membranes

• Pleural cavity (right and left) - surrounds each lung
• Pericardial cavity - surrounds the heart

• Peritoneal cavity (abdomen + pelvis)

Each serous cavity has two layers: a visceral layer (directly invests the organ) and a parietal layer (lines the cavity wall). A small amount of fluid lies between them to reduce friction.

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1.3 The Human Cell

"The cells of a multicellular organism are bathed by extracellular fluid... the internal milieu would change very quickly if the intercellular space (interstitium) were not linked via the bloodstream to organs such as the lungs, kidneys, and digestive tract." - THIEME Atlas of General Anatomy

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1.4 Tissues

• Simple (one layer): squamous, cuboidal, columnar
• Stratified (multiple layers): squamous (skin), columnar, transitional (bladder)
• Pseudostratified: appears layered but is single-layer (e.g., respiratory tract)

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1.5 Membranes

1. Serous membranes - line closed body cavities (pleura, pericardium, peritoneum); secrete watery fluid
2. Mucous membranes (mucosa) - line passages opening to exterior (digestive, respiratory, urogenital tracts); secrete mucus
3. Synovial membranes - line joint cavities; secrete synovial fluid for lubrication
4. Cutaneous membrane (skin) - covers body surface; protection

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1.6 Glands

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UNIT 2: BONES & JOINTS

2.1 Overview of Bones

1. Support and structural framework
2. Protection of vital organs (skull, thoracic cage)
3. Movement (levers for muscles)
4. Haemopoiesis (blood cell formation in red bone marrow)
5. Mineral storage (calcium and phosphorus)

• Long bones - humerus, femur, tibia (tubular shape)
• Short bones - carpals, tarsals (cube-shaped)
• Flat bones - skull, sternum, scapula (broad, protective)
• Irregular bones - vertebrae, hip bone
• Sesamoid bones - patella (embedded in tendons)

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2.2 Upper Limb Bones

Clavicle (Collar Bone)

• S-shaped long bone; only bony link between upper limb and thoracic skeleton
• Medial end: articulates with manubrium of sternum (sternoclavicular joint)
• Lateral end: articulates with acromion of scapula (acromioclavicular joint)
• Prominent features: conoid tubercle (lateral surface), subclavian groove (inferior surface)
• Applied: Most commonly fractured bone in the body; fracture usually at the junction of middle and lateral thirds

Scapula (Shoulder Blade)

• Flat, triangular bone on the posterior thoracic wall (ribs 2-7)
• Key features:
  • Acromion - forms the "shoulder point"; articulates with clavicle
  • Coracoid process - projects anteriorly; attachment for muscles and ligaments
  • Glenoid cavity - pear-shaped socket for articulation with head of humerus
  • Spine of scapula - prominent ridge on posterior surface
  • Supraspinous and infraspinous fossae - above and below the spine
  • Subscapular fossa - concave anterior surface

Humerus

• Long bone of the arm (between shoulder and elbow)
• Upper end:
  • Head - articulates with glenoid cavity (ball-and-socket joint)
  • Greater tubercle (lateral) - attachment of rotator cuff muscles (supraspinatus, infraspinatus, teres minor)
  • Lesser tubercle (anterior) - attachment of subscapularis
  • Anatomical neck - groove between head and tubercles
  • Surgical neck - common fracture site, axillary nerve at risk
• Shaft: Deltoid tuberosity (lateral), radial groove (spiral groove for radial nerve)
• Lower end:
  • Capitulum - articulates with head of radius
  • Trochlea - articulates with trochlear notch of ulna
  • Medial epicondyle (ulnar nerve passes posterior to it)
  • Lateral epicondyle
  • Olecranon fossa (posterior), Coronoid fossa (anterior)

Radius

• Lateral forearm bone (thumb side)
• Upper end: Head (circular - articulates with capitulum of humerus and radial notch of ulna), neck, radial tuberosity (insertion of biceps brachii)
• Lower end: Broader; articulates with scaphoid and lunate (wrist joint); styloid process (lateral)
• Applied: Colles' fracture - most common fracture of distal radius after a fall on outstretched hand

Ulna

• Medial forearm bone (little finger side)
• Upper end:
  • Olecranon - forms the point of the elbow; insertion of triceps brachii
  • Trochlear (semilunar) notch - large concavity articulating with trochlea of humerus
  • Coronoid process - projects anteriorly from trochlear notch
  • Radial notch - articulates with head of radius
• Lower end: Head (articulates with ulnar notch of radius), styloid process (medial)

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2.3 Lower Limb Bones

Hip Bone (Os Coxae)

• Large, irregular bone formed by fusion of three bones at the acetabulum:
  • Ilium (superior - broad, fan-like)
  • Ischium (posteroinferior)
  • Pubis (anteroinferior)
• Key features:
  • Iliac crest - superior border of ilium; runs from anterior superior iliac spine (ASIS) to posterior superior iliac spine (PSIS)
  • Acetabulum - deep cup-shaped socket for head of femur (hip joint)
  • Obturator foramen - large opening between ischium and pubis
  • Ischial tuberosity - "sitting bone"; bears weight when seated
  • Greater and lesser sciatic notches
• Two hip bones + sacrum + coccyx = pelvis

Femur (Thigh Bone)

• Longest, strongest bone in the body
• Upper end:
  • Head - articulates with acetabulum (ball-and-socket)
  • Neck - angled ~125° to shaft; common fracture site in elderly (neck of femur fracture)
  • Greater trochanter (lateral) - attachment of gluteal muscles
  • Lesser trochanter (medial inferior) - insertion of iliopsoas
  • Intertrochanteric crest (posterior), intertrochanteric line (anterior)
• Shaft: Linea aspera (posterior ridge; muscle attachment)
• Lower end: Medial and lateral condyles (articulate with tibia); medial and lateral epicondyles; patellar surface (articulates with patella); intercondylar notch

Sacrum

• Triangular bone formed by fusion of 5 sacral vertebrae
• Articulates superiorly with L5 (lumbosacral joint) and laterally with hip bones (sacroiliac joints)
• Anterior (pelvic) surface: concave, smooth, 4 pairs of anterior sacral foramina
• Posterior surface: convex, rough, 4 pairs of posterior sacral foramina; median sacral crest
• Sacral hiatus (inferior opening of sacral canal) - site for caudal anaesthesia
• Sacral promontory - superior anterior margin; obstetric landmark

Tibia (Shin Bone)

• Medial, weight-bearing bone of the leg
• Upper end: Medial and lateral condyles; tibial plateau; tibial tuberosity (insertion of patellar tendon - quadriceps mechanism)
• Shaft: Sharp anterior border (subcutaneous - no overlying muscle); medial surface subcutaneous
• Lower end: Medial malleolus; inferior articular surface for talus (ankle joint)
• Applied: Tibia is most commonly fractured long bone

Fibula

• Slender lateral bone of the leg; non-weight-bearing
• Upper end: Head (articulates with lateral condyle of tibia)
• Lower end: Lateral malleolus (forms lateral boundary of ankle mortice)
• Applied: Lateral malleolus fracture is most common ankle fracture

Vertebral Column

• 7 Cervical (C1-C7)
• 12 Thoracic (T1-T12)
• 5 Lumbar (L1-L5)
• 5 Sacral (fused = sacrum)
• 4 Coccygeal (fused = coccyx)

• Cervical and lumbar: Lordosis (concave posteriorly) - secondary curves
• Thoracic and sacral: Kyphosis (convex posteriorly) - primary curves

• Body (anterior, weight-bearing)
• Vertebral arch (posterior) = pedicles + laminae
• Vertebral foramen (forms vertebral canal for spinal cord)
• Spinous process (posterior)
• Transverse processes (lateral, 2)
• Superior and inferior articular processes (facet joints)

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UNIT 3: THORAX

3.1 Bony Thoracic Cage

Sternum

1. Manubrium (superior): articulates with clavicles and 1st/2nd ribs; jugular (suprasternal) notch
2. Body (middle): articulates with ribs 2-7
3. Xiphoid process (inferior): cartilaginous in young, ossifies with age

• Sternal angle (angle of Louis): Junction of manubrium and body; T4/T5 level; marks attachment of 2nd rib - clinical landmark
• Applied: Sternal bone marrow aspiration is done through the flat subcutaneous body of the sternum

Ribs

• True ribs: Connect directly to sternum via costal cartilages
• False ribs: Costal cartilages join to rib above, not sternum directly
• Floating ribs: No anterior cartilage attachment
• Each typical rib has: head (2 articular facets), neck, tubercle, shaft with subcostal groove (lodges neurovascular bundle - vein, artery, nerve - VAN from above)
• Applied (rib fractures): Single fractures are painful but manageable. Multiple fractures at two+ sites per rib = flail chest - paradoxical movement of the flail segment impairs ventilation and may require assisted ventilation.

Thoracic Vertebrae

• Body + costal facets for rib articulation
• Long spinous processes pointing inferiorly
• Articulate with ribs at demifacets on vertebral bodies (head of rib) and facets on transverse processes (tubercle of rib)

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3.2 Intercostal Space

1. External intercostal muscle (fibres run downward and forward)
2. Internal intercostal muscle (fibres run downward and backward)
3. Innermost intercostal muscle

Clinical note: When performing thoracentesis (pleural tap) or placing a chest drain, insert the needle/drain just above the superior border of the rib below to avoid the neurovascular bundle.

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3.3 Pleura

• Visceral pleura: Tightly covers the lung surface
• Parietal pleura: Lines the thoracic wall, diaphragm, and mediastinum
• Pleural cavity: Potential space between the two layers; contains a small amount of fluid (lubrication)
• Costodiaphragmatic recess: The lowest point of the pleural cavity; the site where fluid accumulates (pleural effusion)

• Pneumothorax: Air in pleural cavity → lung collapse
• Haemothorax: Blood in pleural cavity (trauma)
• Pleural effusion: Fluid in pleural cavity

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3.4 Diaphragm

• Dome-shaped musculotendinous sheet separating thorax from abdomen
• Main respiratory muscle: Contraction flattens the domes, increasing thoracic volume (inspiration)
• Innervation: Phrenic nerve (C3, C4, C5) - "C3, 4, 5 keeps the diaphragm alive"
• Three main openings:
  • Aortic hiatus (T12) - aorta + thoracic duct
  • Oesophageal hiatus (T10) - oesophagus + vagus nerves
  • Caval opening (T8) - inferior vena cava

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3.5 Muscles of the Thorax

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UNIT 4: HEART

4.1 Surface Anatomy of the Heart

• Apex: Left 5th intercostal space, midclavicular line (8-9 cm from midsternal line) - site of apex beat
• Base: Posterior surface, opposite vertebrae T5-T8, formed by atria
• Right border: Right atrium
• Left border: Mainly left ventricle (some left atrium)
• Superior border: Aorta, pulmonary trunk emerging
• Inferior border: Right ventricle

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4.2 Pericardium

• Fibrous pericardium (outer): tough, inextensible; fused with central tendon of diaphragm
• Serous pericardium (inner): two layers
  • Parietal layer (lines fibrous pericardium)
  • Visceral layer / epicardium (adheres to heart muscle)
• Pericardial cavity: Small space between parietal and visceral layers; contains ~20-50 mL of serous fluid
• Applied: Cardiac tamponade - fluid accumulation in pericardial cavity compresses the heart, reducing cardiac output. The rigid fibrous pericardium prevents outward expansion. Emergency pericardiocentesis is required.

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4.3 Chambers of the Heart

• Receives deoxygenated blood from the body via:
  • Superior vena cava (SVC) - from upper body
  • Inferior vena cava (IVC) - from lower body
  • Coronary sinus - from heart muscle itself
• Internal features: crista terminalis, pectinate muscles, fossa ovalis (remnant of foramen ovale)
• Opens into right ventricle via the tricuspid (right atrioventricular) valve

• Pumps blood to lungs via pulmonary trunk (pulmonary circulation)
• Crescent-shaped in cross-section
• Trabeculae carneae on interior wall; moderator band (contains right bundle branch of conduction system)
• Separated from left ventricle by the interventricular septum
• Tricuspid valve (3 cusps): anterior, posterior, septal
• Pulmonary valve (3 semilunar cusps) guards exit into pulmonary trunk

• Receives oxygenated blood from the 4 pulmonary veins (2 right, 2 left)
• Smooth-walled (except left auricle which has pectinate muscles)
• Opens into left ventricle via the mitral (bicuspid/left atrioventricular) valve

• Pumps oxygenated blood to entire body via aorta (systemic circulation)
• Thick-walled (3x thicker than RV - generates higher pressure)
• Circular in cross-section; heavily trabeculated
• Mitral valve (2 cusps): anterior and posterior
• Aortic valve (3 semilunar cusps) guards exit into aorta

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4.4 Valves of the Heart

Heart sounds: S1 ("lub") = AV valves closing; S2 ("dub") = semilunar valves closing. Murmurs indicate valve dysfunction.

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4.5 Major Blood Vessels of the Heart

• Aorta - carries oxygenated blood from LV to systemic circulation
• Pulmonary trunk - carries deoxygenated blood from RV; divides into right and left pulmonary arteries
• Superior vena cava (SVC) - returns blood from head, neck, upper limbs
• Inferior vena cava (IVC) - returns blood from lower body
• Pulmonary veins (4) - carry oxygenated blood from lungs to LA

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4.6 Coronary Arteries

• Short trunk (left main stem)
• Divides into:
  • Anterior interventricular artery (LAD - Left Anterior Descending) - supplies anterior LV, anterior septum, apex
  • Circumflex artery - winds round in the coronary groove to supply lateral and posterior LV

• Runs in the right atrioventricular groove
• Main branches:
  • Marginal artery - supplies right border of heart
  • Posterior interventricular artery (PDA - Posterior Descending Artery) - supplies posterior septum and inferior LV (in right-dominant hearts)
  • SA nodal artery - supplies the sinoatrial node (in ~60%)
  • AV nodal artery - supplies the atrioventricular node

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4.7 Conduction System of the Heart

1. SA node (sinoatrial node) - right atrium near SVC; "natural pacemaker" (60-100 bpm)
2. AV node (atrioventricular node) - between atria and ventricles; delays impulse
3. Bundle of His - passes through AV junction into interventricular septum
4. Right and Left bundle branches - travel down each side of septum
5. Purkinje fibres - spread impulse through ventricular myocardium

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UNIT 5: MUSCLES OF THE THORAX AND UPPER LIMB

5.1 Muscles of the Upper Limb (Arm)

Muscles of the Arm

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5.2 Muscles of the Forearm

Flexor Group (Anterior Compartment):

• Pronator teres - pronation of forearm
• Flexor carpi radialis - flexion and radial deviation of wrist
• Palmaris longus - flexion of wrist (often absent)
• Flexor carpi ulnaris - flexion and ulnar deviation of wrist
• Flexor digitorum superficialis - flexion of PIP joints of fingers 2-5

• Flexor digitorum profundus - flexion of DIP joints of fingers 2-5
• Flexor pollicis longus - flexion of thumb IP joint
• Pronator quadratus - pronation

Extensor Group (Posterior Compartment):

• Extensor carpi radialis longus and brevis - extension + radial deviation of wrist
• Extensor digitorum - extension of fingers 2-5
• Extensor carpi ulnaris - extension + ulnar deviation of wrist
• Extensor pollicis longus and brevis - extension of thumb
• Abductor pollicis longus - abduction of thumb
• Supinator - supination of forearm

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UNIT 6: EXCRETORY SYSTEM

6.1 Kidneys

• Right kidney: opposite T12-L3; lies slightly lower (due to liver above it)
• Left kidney: opposite T11-L2

• Enclosed in fibrous renal capsule
• Hilum (medial margin): entry/exit for renal vessels, ureter, lymphatics, nerves
• Renal cortex (outer): continuous band; contains glomeruli and convoluted tubules
• Renal medulla (inner): renal pyramids (cone-shaped, striped); separated by renal columns (cortex extensions)
• Renal papilla: apex of each pyramid; opens into minor calyx
• Minor calyces → major calyces (2-3) → renal pelvis → ureter

• Renal artery (direct branch of abdominal aorta, L1-L2)
• Right renal artery longer; passes posterior to IVC
• Left renal vein longer; crosses midline anterior to aorta

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6.2 Ureters

• Muscular tubes, ~25-30 cm long, ~5 mm diameter
• Carry urine from renal pelvis to urinary bladder
• Course: descends retroperitoneally on psoas muscle → crosses pelvic brim → enters bladder
• Three sites of physiological narrowing (where stones commonly lodge):
  1. Pelviureteric junction (PUJ)
  2. Crossing the pelvic brim (over bifurcation of common iliac artery)
  3. Vesicoureteric junction (VUJ) - where ureter enters bladder

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6.3 Urinary Bladder

• Hollow muscular organ (detrusor muscle = smooth muscle)
• Location: Pelvis, behind the pubic symphysis (empty); rises into abdomen when full
• Capacity: ~300-500 mL normally; can hold more
• Trigone: Triangular smooth area between the two ureteric orifices and internal urethral orifice; always smooth (no rugae)
• Neck of bladder: Where bladder opens into urethra; surrounded by internal urethral sphincter (smooth muscle, involuntary)

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UNIT 7: NERVOUS SYSTEM

7.1 Overview

"All elements of the nervous system work closely together in a way that has no clear boundaries." - Medical Physiology (Boron & Boulpaep)

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7.2 Central Nervous System (CNS)

1. Dura mater (outer): tough, fibrous
2. Arachnoid mater (middle): delicate, web-like
3. Pia mater (inner): delicate, adherent to brain/cord surface

• CSF (cerebrospinal fluid) circulates in subarachnoid space (between arachnoid and pia)

• Cerebrum: Largest part; higher functions (thought, memory, speech, voluntary movement); divided into lobes (frontal, parietal, temporal, occipital)
• Brainstem: Midbrain + Pons + Medulla oblongata; vital centres (cardiovascular, respiratory, consciousness)
• Cerebellum: Coordination, balance, fine motor control

• Extends from foramen magnum to L1/L2 (conus medullaris)
• 31 pairs of spinal nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal)
• Gray matter (H-shaped, centre): neuron cell bodies
• White matter (surrounding): myelinated axons (ascending sensory + descending motor tracts)

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7.3 Peripheral Nervous System (PNS)

• All nervous tissue outside the CNS dura mater
• Includes: sensory receptors, peripheral portions of spinal and cranial nerves, peripheral ganglia

• Afferent (sensory) fibres: Carry signals FROM periphery TO CNS
• Efferent (motor) fibres: Carry signals FROM CNS TO effectors (muscles/glands)

• 31 pairs; each formed by dorsal root (sensory) + ventral root (motor) combining at the intervertebral foramen
• Divide into: dorsal ramus (back muscles/skin), ventral ramus (limbs + anterior trunk)

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7.4 Autonomic Nervous System (ANS)

• Multipolar (most common): multiple dendrites + 1 axon; motor neurons, interneurons
• Bipolar: 1 dendrite + 1 axon; retina, cochlea, olfactory epithelium
• Pseudounipolar: 1 process divides into central + peripheral; sensory (dorsal root ganglia)

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QUICK-REFERENCE APPLIED ANATOMY (A&E Focus)

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