Clinical Anatomy – Integrated Notes

Epidermis: stratified squamous; melanocytes → melanin → UV protection; $\text{↓melanin} \Rightarrow \text{↑ skin-cancer risk}$
Skin cancers ↑ in fair races; most common on uncovered face & neck (↑UV)
Wounds heal fast: basal layer mitosis constantly replaces desquamated cells
Pregnancy: hormonal up-regulation of melanin → “mask of pregnancy” (nipples, areolae, genitalia, forehead, malar, chest)
Langer’s lines (cleavage): longitudinal in limbs, circumferential in trunk ⇒ cut parallel ⇒ minimal scar; across ⇒ gaping

50 % body-fat stored here; females $\approx8\%$ thicker ⇒ better insulation; smoother contours
Sub-Q injections painful (pain receptors) & slow absorption (poor vascularity); sites: post-arm, ant-abd wall, ant-thigh; max $0.5–1\,\text{ml}$
Synovial bursae (subcutaneous / subtendinous / articular) lubricate ⇒ bursitis swelling esp. in limbs (↑mobility)
Adventitious bursae from chronic friction: porter’s shoulder (clavicle), tailor’s ankle (lateral malleolus)

Absent in face → muscles attach to skin → facial expression
Surgeons exploit planes for: bloodless access, lymph resection paths, predicted pus tracking

Matrix: $35\%$ collagen (tensile), $65\%$ hydroxy-apatite (compressive)
Elderly: ↓collagen + osteoporosis → brittle, fragile
Steps of fracture repair: hematoma → fibrous & fibrocartilage callus → bony callus ( $4–6$ wk) → remodelling; immobilisation essential
Wolff’s law: architecture aligns along stress; both tensile & compressive forces stimulate osteogenesis
Female stature < male: oestrogen closes epiphyses earlier
Metaphysis: rich blood, hair-pin bends → paediatric osteomyelitis
Rickets: vit-D ↓Ca → proliferative uncalcified osteoid at epiphyses → swellings + bow-legs
Epiphyseal fracture mal-union → limb shortening
Ossification timetable enables forensic age estimation (e.g., clavicle $23–31$ yr)

Articular hyaline: proteoglycan-water sponge resists compression; low vascularity ⇒ slow healing
Osteoarthritis: age >40, proteoglycan depolymerisation, “wear & tear” esp. knees
Hilton’s law: joint nerves shared with muscles + skin → diseased joint fixed + referred pain
Close-packed positions (hip, knee extension; ankle dorsiflexion etc.) strongest but prone to intra-articular damage

Fast-twitch (white): sprint; slow-twitch (red): endurance
Disuse (cast) → spindle inactivity → atrophy; exercise → hypertrophy
NMJ: ACh release; AChE inhibition (organophosphate) → spastic paralysis; myasthenia gravis → flaccid (Ab destroys receptors)
Motor unit ratio: eye $1:10$ precise; limb $1:500$ gross
Rigor mortis: Ca²⁺ leak + no ATP locking cross-bridges

Pulses: temporal, facial, carotid, brachial, radial, femoral, popliteal, post-tibial, dorsalis pedis – know landmarks & emergency pressure points
Tortuous arteries where mobile (face, tongue) or expansile (uterus)
End arteries occlusion → infarct (retina, cerebral, coronary) vs. collaterals
Portal hypertension collateral: caput medusae (para-umbilical)
Aneurysm true vs. dissection; abdominal aorta, Berry (Circle of Willis)
Arterio-venous shunts open post-haemorrhage → renal anuria

PNS regeneration needs Schwann-guided tubes; CNS poor (oligodendrocytes distant)
Reflex arc 5 components; clinical tendon tests assess segmental integrity
Dermatome concept useful in spinal segment localisation
Last’s four-segment rule for limb joint innervation (e.g., hip L2–5 flex/ext etc.)

Clavicle weakest at medial $\tfrac{2}{3}$ –lateral $\tfrac{1}{3}$ junction; fracture → shoulder droop (trapezius fails)
Humerus supracondylar fx vs. elbow dislocation: tri-bony relationship preserved vs. disturbed
Colles vs. Smith fracture distal radius – dinner fork deformity
Supraspinatus initiation 0–15° abduction; calcific tendinitis → painful arc
Shoulder inferior dislocation – rotator cuff deficiency inferiorly; axillary nerve risk
Carrying angle $5–15^\circ$ (valgus); altered in supracondylar fx
Student’s elbow (olecranon bursitis); Tennis & Golfer’s elbow (epicondylitis)
Pulled elbow (radial head sublux) age 1–3 due annular lig shape
Wrist/hand: carpal tunnel syndrome (median nerve); ulnar claw vs. true claw; ape-hand (median); wrist-drop (radial)
Trendelenburg gait: superior gluteal nerve lesion or hip pathology
Sciatic nerve course; safe IM quadrant: upper outer gluteal
Femoral pulse midway ASIS–pubis; cannulation
Popliteal & pedal pulses for intermittent claudication
Varicose veins: perforator valve failure

Linea alba midline incision bloodless; paramedian avoids rectus nerves
Caput medusae: portal obstruction; round ligament para-umbilical
Psoas abscess tracking to femoral triangle
Inguinal & femoral hernia anatomy; Hesselbach’s triangle; strangulation risk
Testis descent anomalies; varicocele L>R (left renal vein factors)
Peritoneal spaces: hepatorenal pouch (Morison), recto-uterine (Douglas) collect fluid; paracentesis sites
Epiploic foramen boundaries; internal hernia strangulation
Gastric/duodenal ulcer sites & referred pain rules; vagotomy and drainage
Pancreas relations: head tumor → obstructive jaundice (CBD groove)
Spleen rupture – intraperitoneal bleed; subphrenic abscess
Appendicitis: visceral (umbilical) → parietal (McBurney) pain shift; retrocecal psoas sign, pelvic obturator sign; vascular single artery → gangrene
Portacaval anastomoses: oesophageal varices, haemorrhoids
Femoral canal contents; lacunar ligament abnormal obturator danger
Pelvic floor & perineal body critical for uterine support; episiotomy mediolateral
Pudendal block landmarks (ischial spine)
Anal canal above/below pectinate: visceral vs. somatic sensation; internal vs. external piles

Neck femur fractures: intracapsular risk $\Rightarrow$ retinacular $\Rightarrow$ AVN head; elderly women (osteoporosis)
Calcar femorale internal buttress
Patella dislocates lateral; vastus medialis counteracts
Knee meniscus tears medial>lateral (fixed to MCL), rotation injuries
Cruciate ligament tests: anterior drawer (ACL), posterior drawer (PCL)
Ankle sprain plantarflexed inversion → ATF ligament
Arches of foot: medial/lateral longitudinal, transverse; flat foot vs. pes cavus
Sciatic, tibial, common peroneal, superficial/deep peroneal lesions – motor/sensory patterns; foot-drop; tarsal tunnel
Ilio-tibial band contractures; tensor fascia lata IM site infants
Plantar fasciitis “policeman’s heel”; Achilles rupture – sudden calf pop

Policeman’s tip (Erb); Waiter’s tip – upper plexus
Weaver’s bottom (ischial bursitis); Housemaid vs. Clergyman knee (pre- vs. infrapatellar bursitis)
Sigmoid colon obstruction of left testicular vein
Horner syndrome – cervical sympathetics
Phrenic nerve $C3,4,5$ keeps diaphragm alive
AVN femoral head, subcapital fx; intracapsular – true