Year 1 Semester 2 Revision: Anatomy, Physiology & Pharmacology (Part 1)

Clavicular fracture

Usually breaks in the middle third; risks include thoracic outlet syndrome and pneumothorax.

Shoulder dislocation

Most commonly anteroinferior; associated with axillary nerve palsy and rotator cuff tears.

Humeral surgical neck fracture

Risks posterior circumflex artery injury and axillary nerve palsy.

Midshaft humeral fracture

Risks radial nerve palsy and deep brachial artery injury.

Supracondylar fracture

More common in children; risks median nerve and brachial artery injury.

Colles' fracture

FOOSH fracture of the distal radius with posterior displacement and dorsal angulation ('dinner fork' deformity).

Smith's fracture

Fall on flexed wrist with volar displacement and palmar angulation of the bone fragment

Scaphoid fracture

Caused by FOOSH with tenderness in the anatomical snuffbox; risks avascular necrosis due to retrograde blood supply.

Anterior compartment of the arm

Innervated by the musculocutaneous nerve; includes biceps brachii, brachialis, and coracobrachialis.

Posterior compartment of the arm

Innervated by the radial nerve; includes the triceps brachii.

Flexors and pronators of the forearm

Innervated by the median nerve, except medial 1/3 of FDP and FCU (ulnar nerve).

Extensors and supinators of the forearm

Innervated by the radial nerve (and its posterior interosseous branch).

Intrinsic hand muscles innervation

Hypothenar muscles and adductor pollicis are innervated by the ulnar nerve; thenar muscles are innervated by the median nerve.

Lumbricals innervation

1st and 2nd lumbricals by the median nerve; 3rd and 4th lumbricals by the ulnar nerve.

Palmar interossei function

Adduct fingers (PAD: Palmar ADduct).

Dorsal interossei function

Abduct fingers (DAB: Dorsal ABduct).

De Quervain's tenosynovitis

Inflammation of the tendon sheath around the extensor pollicis brevis and abductor pollicis longus.

Golfer's elbow

Medial epicondylitis affecting the flexors originating from the medial epicondyle.

Tennis elbow

Lateral epicondylitis affecting the extensors originating from the lateral epicondyle (laTeral - exTensor).

Erb's palsy

Damage to the upper trunk (C5, C6) of the brachial plexus; arm rests in 'waiter's tip' position.

Klumpke's palsy

Damage to the lower trunk (C8, T1) of the brachial plexus; arm rests in 'claw hand' position.

Carpal tunnel syndrome

Compression of the median nerve inside the carpal tunnel, leading to thenar wasting and positive Tinel's and Phalen's tests.

Ulnar canal syndrome

Compression in Guyon's canal affecting sensation of medial 1.5 digits and finger abduction/adduction.

Aortic hiatus vertebral level

Located at T12 (associated with 'Abdominal Aorta').

Oesophageal hiatus vertebral level

Located at T10 (associated with 'Oesophagus' = 10 letters).

Inferior vena cava (IVC) hiatus level

Located at T8 (associated with 'Inferior Vena Cava' = 8 letters).

Diaphragm motor innervation

Innervated by the phrenic nerve (C3, C4, C5 keeps the diaphragm alive).

Intercostal neurovascular bundle order

Arranged in cranial to caudal order as VAN (Vein, Artery, Nerve) in the subcostal groove.

Safe intercostal insertion site

Insert at the superior border of the inferior rib to avoid the main neurovascular bundle.

Cardiac tamponade

Accumulation of fluid in the pericardial sac impairing diastolic filling, characterized by Beck's triad (muffled heart sounds, JVD, hypotension).

Triangle of Koch

Anatomical landmark used to estimate the location of the AV node, bounded by the IVC/tendon of Todaro, coronary sinus, and septal tricuspid valve.

Right coronary artery (RCA)

Supplies the right ventricle, right atrium, and inferior 1/3 of the IVS; gives rise to the SA nodal artery (in 60%) and AV nodal artery.

Left anterior descending (LAD) artery

Supplies the right and left ventricles and anterosuperior 2/3 of the IVS; anastomoses with the PDA.

Coronary sinus

Sits in the posterior atrioventricular groove, receives cardiac veins, and drains directly into the right atrium.

Auscultation of the aortic valve

Heard at the 2nd right intercostal space at the parasternal edge.

Auscultation of the mitral valve

Heard at the 5th left intercostal space at the midclavicular line (apex beat).

Sarcomere I band

Contains actin (thin filaments).

Sarcomere A band

Contains myosin (thick filaments).

Isometric muscle contraction

Develops force without changing the length of the muscle.

Isotonic muscle contraction

Develops force and changes muscle length (concentric shortens, eccentric lengthens).

Gate control theory of pain

A neural gate in the spinal cord can open or close to let pain signals go through to the brain or block them:

Closed gate -

Activation of A-beta mechanoreceptor fibers excites inhibitory interneurons in the spinal cord, blocking transmission from C-fiber pain pathways.

Dorsal column medial lemniscus (DCML) pathway

Transmits proprioception, vibration, and fine touch, and decussates at the medulla.

Spinothalamic tract pathway

Transmits pain and temperature, and decussates immediately at the spinal cord dorsal horn.

Phase I drug metabolism

Catabolic reactions (oxidation, hydrolysis via cytochrome P450 enzymes) to produce reactive functional groups.

Phase II drug metabolism

Anabolic conjugation reactions combining drugs with endogenous compounds to increase water solubility.

Volume of distribution (Vd)

A theoretical pharmacokinetic value that relates the total amount of a drug in the body to its concentration in the blood plasma (Vd = Dose / [plasma]).

Zero-order elimination kinetics

Rate of elimination is constant regardless of plasma concentration due to enzyme saturation (e.g., alcohol, aspirin).

First-order elimination kinetics

Rate of elimination is directly proportional to plasma concentration, with a consistent half-life.

Parasympathetic nervous system neurotransmitter

Releases acetylcholine (ACh) acting on nicotinic receptors at ganglia and muscarinic receptors at target organs.

Sympathetic nervous system neurotransmitter

Releases acetylcholine at ganglia (nicotinic) and noradrenaline at target organs (adrenergic alpha/beta receptors).

Cholinergic toxicity mnemonic

DUMBBELLS (Diarrhoea, Urination, Miosis, Bradycardia, Bronchoconstriction, Emesis, Lacrimation, Lethargy, Salivation).

Anticholinergic toxicity mnemonic

FABDUCT (Flushed, Agitation/confusion, Blurry vision, Dry mouth, Urinary retention, Constipation, Tachycardia).

COX-1 inhibition effects

• COX 1: protects mucosa, produces TxA2 (clotting and vasoconstriction), maintains blood clotting and vessel constriction.

• Thus COX 1 inhibition leads to: GI ulceration, renal toxicity, and platelet dysfunction, but can prevent cardiac occlusions.

COX-2 inhibition effects

Reduces pain and inflammation but increases the risk of myocardial infarction and stroke.

Paracetamol overdose antidote

N-Acetylcysteine.

Opioid mechanism of action

Binds to mu-receptors in the dorsal horn, periaqueductal grey, and thalamus to inhibit nociceptive transmission.

Local anesthetics mechanism of action

Reversibly bind to the intracellular portion of voltage-gated sodium channels in their open or inactive states, preventing sodium influx.

Osteoarthritis morning stiffness

Typically lasts for less than 30 minutes.

Rheumatoid arthritis morning stiffness

Typically lasts for longer than an hour, associated with inflammatory arthropathies.

Functions of COX-1 Enzyme

• Housekeeping Functions: COX-1 a constitutive enzyme (found actively in most normal tissues) that protects the gastric and intestinal mucosa from digestive acids.

• Platelet Activation: COX-1 in platelets produces thromboxane A2, which promotes blood clotting and vessel constriction.

• Renal Support: It helps maintain normal blood flow and electrolyte balance in the kidneys.

Functions of COX-2 Enzyme

• converts arachidonic acid into prostaglandin H2 (PGH₂), which the body then transforms into various prostaglandins and prostanoids (such as PGE₂, PGI₂, and PGF₂α)

• Not constitutive, but usually inducible, so can spike rapidly in response to cytokine signals to drive: inflammation, pain, fever.

Selective COX-2 inhibitors are good, but most NSAIDs inhibit both COX-1 and COX-2