Here are the complete, exam-focused detailed study notes for MBBS First Year Anatomy, organized by region. Sources: Gray's Anatomy for Students, Netter's Atlas, THIEME General Anatomy & Musculoskeletal System.
MBBS First Year Anatomy - Important Topics (Detailed Study Notes)
UPPER LIMB
1. Brachial Plexus ⭐⭐⭐ (Most Important)
Formation: Anterior rami of C5, C6, C7, C8, T1 (roots pass between anterior and middle scalene muscles)
Parts: Roots → Trunks → Divisions → Cords → Branches ("Robert Taylor Drinks Cold Beer")
| Trunk | Formation |
|---|
| Superior (Upper) | C5 + C6 |
| Middle | C7 alone |
| Inferior (Lower) | C8 + T1 |
Each trunk splits into anterior and posterior divisions (total 6 divisions):
- Anterior divisions of superior + middle trunk → Lateral cord
- Anterior division of inferior trunk → Medial cord
- All three posterior divisions → Posterior cord
Cords are named by their relation to the axillary artery.
Terminal branches (5):
- Lateral cord → Musculocutaneous nerve + lateral root of median nerve
- Medial cord → Ulnar nerve + medial root of median nerve
- Posterior cord → Radial nerve + Axillary nerve
Injuries:
- Erb's palsy (C5, C6): "waiter's tip" - arm adducted, medially rotated, elbow extended, forearm pronated. Caused by birth, forceful separation of head and shoulder.
- Klumpke's palsy (C8, T1): Claw hand, intrinsic muscle wasting, Horner syndrome if sympathetic fibers involved. Caused by traction on arm above head.
- Saturday night palsy: Radial nerve compression in spiral groove → wrist drop.
2. Muscles of the Arm and Forearm
Flexors of elbow (anterior compartment arm):
- Biceps brachii (long + short head) - also supinator and flexor of forearm
- Brachialis - pure flexor (workhorse)
- Coracobrachialis
- All supplied by musculocutaneous nerve (C5, C6)
Rotator cuff (SITS):
- Supraspinatus - abduction (initiates 0-15°)
- Infraspinatus - lateral rotation
- Teres minor - lateral rotation
- Subscapularis - medial rotation
- All attach to greater/lesser tuberosity; common site of tears is supraspinatus tendon
Serratus anterior:
- Origin: lateral surfaces of ribs 1-8/9
- Insertion: costal (anterior) surface of medial border of scapula
- Action: protraction + rotation of scapula (holds scapula against thoracic wall)
- Nerve: Long thoracic nerve (C5, 6, 7) - "the nerve of Bell"
- Injury → winged scapula (medial border lifts off)
3. Median Nerve
Course: Formed from medial and lateral cords of brachial plexus (C6-T1), descends lateral to brachial artery, crosses medially, enters cubital fossa, passes between two heads of pronator teres, lies between FDS and FDP, enters carpal tunnel deep to flexor retinaculum.
Motor supply in hand: Thenar muscles (LOAF = Lateral two Lumbricals, Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis)
Injury at wrist (Carpal Tunnel Syndrome):
- Thenar wasting, loss of thumb opposition
- Sensory loss over lateral 3½ fingers and palm
- "Ape/Simian hand" (long-standing)
Injury at elbow:
- Loss of pronation, wrist flexion, flexion of lateral fingers
- "Preacher's hand" / "Hand of benediction" (inability to flex lateral fingers on making a fist)
4. Carpal Tunnel
Contents (9 tendons + 1 nerve):
- 4 tendons of FDS
- 4 tendons of FDP
- 1 tendon of FPL
- Median nerve (most superficial and radial)
Boundaries:
- Floor: Carpal bones
- Roof: Flexor retinaculum (transverse carpal ligament)
Applied: Carpal tunnel syndrome - compression of median nerve. Common in pregnancy, rheumatoid arthritis, hypothyroidism. Tinel's and Phalen's tests positive.
5. Breast
Structure: Modified sweat gland (apocrine). Lies in superficial fascia between 2nd-6th ribs.
Lymphatic drainage:
- 75% → Axillary nodes (especially anterior/pectoral group)
- 25% → Internal mammary (parasternal) nodes
- Small amount → opposite breast, abdominal cavity, infraclavicular/supraclavicular nodes
Clinical: Sentinel lymph node biopsy; "peau d'orange" skin due to lymphatic obstruction; retraction of nipple due to ligaments of Cooper tethering.
LOWER LIMB
6. Hip Joint ⭐⭐⭐
Type: Multiaxial ball-and-socket synovial joint
Articular surfaces:
- Head of femur (spherical, covered by hyaline cartilage except fovea)
- Lunate surface of acetabulum (covered by hyaline cartilage, broadest superiorly)
- Acetabular labrum (fibrocartilage) deepens the socket
Ligaments:
| Ligament | Attachment | Function |
|---|
| Iliofemoral (Y-ligament of Bigelow) | AIIS → intertrochanteric line | Prevents hyperextension; strongest |
| Pubofemoral | Pubis → intertrochanteric region | Limits abduction |
| Ischiofemoral | Ischium → greater trochanter | Limits medial rotation |
| Ligament of head of femur | Fovea → acetabular fossa | Carries a branch of obturator artery (blood supply to femoral head) |
Blood supply to femoral head:
- Medial circumflex femoral artery (main - 80%)
- Lateral circumflex femoral artery
- Artery of ligamentum teres (obturator a.) - minor in adults
Applied: Fracture neck of femur → avascular necrosis of femoral head (medial circumflex artery torn in intracapsular fracture).
7. Knee Joint ⭐⭐⭐
Type: Largest synovial joint in the body; modified hinge joint
Articulations:
- Femorotibial (weight-bearing)
- Femoropatellar (allows quadriceps pull to be redirected)
Menisci:
- Two C-shaped fibrocartilaginous structures
- Medial meniscus: Larger, less mobile (attached to tibial collateral ligament) → more commonly injured
- Lateral meniscus: Smaller, more mobile, not attached to fibular collateral ligament
Ligaments:
| Ligament | Function | Test |
|---|
| ACL (anterior cruciate) | Prevents anterior tibial displacement | Anterior drawer / Lachman test |
| PCL (posterior cruciate) | Prevents posterior tibial displacement | Posterior drawer test |
| Medial (tibial) collateral | Valgus stability | Valgus stress test |
| Lateral (fibular) collateral | Varus stability | Varus stress test |
Locking mechanism: During full extension, tibia laterally rotates on femur (or femur medially rotates on tibia) - "screw home mechanism." Unlocking: popliteus muscle (internally rotates tibia).
Bursae: ~13 bursae. Clinically important: suprapatellar, infrapatellar, prepatellar ("housemaid's knee").
Blood supply: Anastomosis around knee from descending genicular, popliteal, and recurrent tibial arteries.
8. Femoral Triangle
Boundaries:
- Superior (base): Inguinal ligament
- Lateral: Medial border of sartorius
- Medial: Medial border of adductor longus
- Floor: Iliopsoas (lateral) + pectineus (medial)
- Roof: Fascia lata + cribriform fascia
Contents (lateral to medial - "NAVY"):
- N - Femoral Nerve
- A - Femoral Artery
- V - Femoral Vein
- Y - "Y-fronts" = lymphatics (in femoral canal, most medial)
Femoral canal (most medial compartment of femoral sheath): contains lymphatics and fat. Its opening = femoral ring - site of femoral hernia.
Femoral pulse: Felt just below midpoint of inguinal ligament (midinguinal point = midway between ASIS and pubic symphysis).
9. Sciatic Nerve
Largest nerve in the body. Formed from L4, L5, S1, S2, S3.
Course: Exits pelvis through greater sciatic foramen below piriformis → descends through posterior thigh between biceps femoris and adductor magnus → divides into tibial nerve and common fibular (peroneal) nerve at apex of popliteal fossa (or higher).
Common fibular (peroneal) nerve injury (winds around neck of fibula):
- Foot drop (loss of dorsiflexion and eversion)
- Sensory loss over dorsum of foot and anterolateral leg
Tibial nerve injury:
- Loss of plantarflexion and inversion
- Claw toes (if intrinsics lost)
THORAX
10. Heart - External Features and Surfaces
Surfaces:
- Sternocostal (anterior): mainly right ventricle
- Diaphragmatic (inferior): mainly left ventricle
- Pulmonary (left): mainly left ventricle + left atrium
- Base (posterior): left atrium mainly
Borders on X-ray:
- Right border: Right atrium
- Left border: Aortic knuckle + pulmonary artery + left auricular appendage + left ventricle
- Inferior border: Right ventricle
Conduction system:
- SA node (pacemaker) - right atrium near SVC opening → rate 60-100/min
- AV node - interatrial septum (triangle of Koch) → rate 40-60/min
- Bundle of His → Left and Right bundle branches
- Purkinje fibers → ventricular muscle
Blood supply: Right coronary artery + Left coronary artery (from aortic sinuses)
- LAD (anterior interventricular branch of LCA) → "artery of sudden death"
- RCA dominant in 70%, left dominant in 10%, co-dominant in 20%
11. Lungs
Right lung: 3 lobes (upper, middle, lower), 10 bronchopulmonary segments
Left lung: 2 lobes (upper, lower), 8-10 segments; cardiac notch and lingula
Root of lung contents: Bronchus (most posterior), pulmonary artery (superior), pulmonary veins (inferior and anterior)
- Right root: artery anterior to bronchus; eparterial bronchus (upper lobe bronchus is above pulmonary artery on the right only)
- Left root: artery is arched over bronchus
Applied: Foreign bodies tend to go to the right lower lobe (right main bronchus is more vertical, wider).
Pleura: Visceral + Parietal (costal, mediastinal, diaphragmatic, cervical). Pleural cavity = potential space. Costophrenic recess is lowest point; effusions collect here.
12. Diaphragm
Origin: Xiphoid process, costal margin (ribs 7-12), lumbar vertebrae (crura)
Major openings:
| Opening | Level | Structures passing |
|---|
| Aortic hiatus | T12 | Aorta, thoracic duct, azygos vein |
| Oesophageal hiatus | T10 | Oesophagus, vagal trunks (L and R vagus nerves), left gastric vessels |
| Caval opening | T8 | IVC, right phrenic nerve |
Mnemonic: "I 8 10 eggs" (IVC at T8, oesophagus at T10, aorta at T12)
Nerve supply: Phrenic nerve (C3, 4, 5; "C3, 4, 5 keeps the diaphragm alive")
ABDOMEN
13. Inguinal Canal
Location: Oblique passage in lower anterior abdominal wall, above medial half of inguinal ligament; ~4 cm long.
Openings:
- Deep (internal) ring: midpoint of inguinal ligament (midway between ASIS and pubic tubercle); in transversalis fascia
- Superficial (external) ring: just above and lateral to pubic tubercle; in external oblique aponeurosis
Walls:
- Anterior wall: External oblique aponeurosis (+ internal oblique laterally)
- Posterior wall: Transversalis fascia (+ conjoint tendon medially)
- Roof (superior): Arching fibers of internal oblique + transversus abdominis
- Floor (inferior): Inguinal ligament (+ lacunar ligament medially)
Contents:
- Male: Spermatic cord (3 arteries, 3 veins, 3 nerves, vas deferens, pampiniform plexus)
- Female: Round ligament of uterus
Hernia:
- Indirect inguinal: through deep ring → along canal → into scrotum; enters lateral to inferior epigastric vessels; congenital, young males
- Direct inguinal: through Hesselbach's triangle, medial to inferior epigastric vessels; through posterior wall; older males
14. Liver - Porta Hepatis and Lobes
Lobes: Right (large), left, caudate (posterior), quadrate (inferior, between gallbladder and ligamentum teres)
Porta hepatis (H-shaped fissure on inferior surface):
- Right free margin of lesser omentum
- Contents: Portal vein (posterior), hepatic artery (left), bile duct (right) - "VAD"
Peritoneal relations: Covered by visceral peritoneum except bare area (between two layers of coronary ligament).
Functional segments (Couinaud): 8 segments, each with independent blood supply.
Blood supply: Hepatic artery proper + portal vein (brings 75% of blood, 50% of oxygen)
15. Kidneys
Position: Retroperitoneal; T12-L3; Right kidney lower than left (liver).
Relations of right kidney: Anteriorly - right lobe of liver, hepatic flexure of colon, 2nd part of duodenum (important - no peritoneum between duodenum and kidney)
Hilum contents (anterior to posterior): Renal vein, Renal artery, Renal pelvis (VAN - remembering from front to back). Ureter is most posterior.
Blood supply: Renal artery (branch of aorta at L1-L2). End arteries = no collateral supply → infarction causes wedge-shaped infarcts.
PELVIS AND PERINEUM
16. Uterus
Position: Anteflexed (bent forward at isthmus) and anteverted (tilted forward on vagina).
Parts: Fundus, body, isthmus, cervix
Supports:
- Primary (cervical) supports: Transverse (cardinal/Mackenrodt's) ligaments, pubocervical ligaments, sacrocervical ligaments - prevent prolapse
- Secondary supports: Broad ligament, round ligament (maintains anteversion), pelvic floor muscles
Blood supply: Uterine artery (branch of internal iliac artery). Crosses ureter superiorly at the level of internal os ("water under the bridge" - ureter runs below uterine artery, at risk during hysterectomy).
Lymphatic drainage: Fundus → para-aortic nodes; Body → iliac nodes; Cervix → iliac + obturator nodes
17. Perineum - Anal and Urogenital Triangles
Ischiorectal (ischio-anal) fossa: Fat-filled space lateral to anal canal. Boundaries: medially = sphincter; laterally = obturator internus; inferiorly = skin. Pudendal canal (Alcock's canal) runs in its lateral wall containing pudendal nerve and internal pudendal vessels.
Pudendal nerve (S2, 3, 4): Main nerve of perineum. "S2, 3, 4 keeps the pee off the floor."
HEAD AND NECK
18. Parotid Gland ⭐⭐
Location: Wedge-shaped; lies between ramus of mandible (anterior), mastoid process + SCM (posterior), and base of skull (superior).
Contents (superficial to deep):
- Facial nerve (VII) and its branches
- Retromandibular vein
- External carotid artery and its terminal branches (maxillary + superficial temporal)
Duct (Stensen's duct): Opens opposite upper 2nd molar.
Nerve supply:
- Secretomotor (parasympathetic): Glossopharyngeal nerve (IX) → Jacobson's nerve → lesser petrosal nerve → otic ganglion → auriculotemporal nerve → parotid
- Sympathetic: via middle meningeal artery
- Sensory: Auriculotemporal nerve
Applied: Parotid tumors - facial nerve runs through it; Frey's syndrome (auriculotemporal nerve damage); mumps parotitis.
19. Thyroid Gland
Location: C5-T1 level. Moves with swallowing (attached to larynx by Berry's ligament).
Blood supply:
- Superior thyroid artery (1st branch of external carotid artery) → runs with external branch of superior laryngeal nerve
- Inferior thyroid artery (from thyrocervical trunk of subclavian artery) → runs with recurrent laryngeal nerve
- Thyroidea ima (5% people, from aorta or brachiocephalic)
Veins: Superior thyroid vein → internal jugular; Middle thyroid vein → internal jugular; Inferior thyroid vein → brachiocephalic vein
Lymphatics: Deep cervical nodes
Surgical dangers:
- Ligation of inferior thyroid artery close to gland → damage to recurrent laryngeal nerve → hoarseness
- Parathyroid glands (posterior surface) may be accidentally removed
20. Cavernous Sinus
Location: Either side of sella turcica (body of sphenoid bone)
Contents (lateral wall, superior to inferior): Oculomotor (III), Trochlear (IV), Ophthalmic (V1), Maxillary (V2) divisions of trigeminal
Contents (within sinus): Internal carotid artery + Abducens nerve (VI) (most medial and vulnerable)
Connections: Superior ophthalmic vein (connection to face - route for spread of facial infection → cavernous sinus thrombosis), inferior petrosal sinus, basilar plexus
Applied: Cavernous sinus thrombosis - presents with proptosis, ophthalmoplegia, chemosis. "Danger area of the face" drains to cavernous sinus via facial vein → ophthalmic vein (valveless).
NEUROANATOMY
21. Ventricular System and CSF
CSF production: Choroid plexus (mainly lateral ventricles)
Circulation path:
Lateral ventricles → Foramen of Monro (interventricular foramen) → 3rd ventricle → Aqueduct of Sylvius (cerebral aqueduct) → 4th ventricle → Foramina of Magendie (median) and Luschka (lateral) → Subarachnoid space → Arachnoid granulations → Venous sinuses
CSF volume: ~150 mL total; produced at ~500 mL/day; pressure 70-180 mm H2O
Applied: Hydrocephalus - obstruction at narrow points (foramen of Monro, cerebral aqueduct). Communicating vs non-communicating.
22. Cerebellum
Lobes: Anterior, posterior, flocculonodular
Functional divisions:
- Vestibulocerebellum (archicerebellum): Flocculonodular lobe → balance, eye movements
- Spinocerebellum (paleocerebellum): Vermis + paravermal zone → axial muscle coordination
- Pontocerebellum (neocerebellum): Lateral hemispheres → coordination of skilled limb movements
Deep nuclei (medial to lateral): Fastigial, Globose, Emboliform, Dentate ("Father Gary's Empty Dump")
Applied: Cerebellar lesions → ipsilateral signs (DANISH): Dysdiadochokinesia, Ataxia (gait - broad-based), Nystagmus, Intention tremor, Slurred speech (Dysarthria), Hypotonia
23. Internal Capsule
Location: Between thalamus (medial) and basal ganglia (lateral)
Limbs:
- Anterior limb: Frontopontine fibers, anterior thalamic radiations
- Genu: Corticobulbar fibers (face, tongue)
- Posterior limb: Corticospinal fibers (somatotopic - face anteriorly, then UL, then LL posteriorly); Corticothalamic, thalamocortical; Optic radiation
Blood supply: Lenticulostriate arteries (branches of MCA) - "arteries of cerebral hemorrhage"
Applied: Small hemorrhage in posterior limb → contralateral hemiplegia (pure motor stroke)
EMBRYOLOGY
24. General Embryology
Week 1: Fertilization → cleavage → morula → blastocyst → implantation (day 6-7)
Week 2 (2s rule): 2 germ layers (bilaminar disc: epiblast + hypoblast), 2 trophoblast layers (cytotrophoblast + syncytiotrophoblast), 2 cavities (amniotic + yolk sac), 2 components of placenta
Week 3: Gastrulation → trilaminar disc (ectoderm, mesoderm, endoderm); primitive streak; notochord formation; neurulation begins
Neural tube defects:
- Failure of closure at cranial end → Anencephaly
- Failure at caudal end → Spina bifida (myelomeningocele most severe)
- Prevention: Folic acid supplementation
Pharyngeal arches:
| Arch | Nerve | Key structures |
|---|
| 1st | V3 (mandibular) | Muscles of mastication, malleus, incus |
| 2nd (Hyoid) | VII | Muscles of facial expression, stapes, styloid process, hyoid (lesser horn) |
| 3rd | IX | Stylopharyngeus, hyoid (greater horn), body |
| 4th/6th | X (vagus) | Muscles of pharynx, larynx |
25. Heart Development
Heart begins beating: Day 22-23
Septation of atria:
- Septum primum grows down, foramen primum closes, foramen secundum forms
- Septum secundum grows → overlaps but does not close → leaves foramen ovale (open in fetal life for right-to-left shunt)
- At birth: lung expansion → left atrial pressure rises → foramen ovale closes functionally
ASD: Patent foramen ovale (most common), ostium primum defect
Ventricular septation: Muscular + membranous portions; VSD most common congenital heart defect (membranous portion most commonly)
Aortic arch derivatives:
| Arch | Adult derivative |
|---|
| 1st | Part of maxillary artery |
| 2nd | Stapedial artery |
| 3rd | Common carotid + proximal internal carotid |
| 4th Left | Arch of aorta |
| 4th Right | Proximal right subclavian |
| 6th Left | Ductus arteriosus (→ ligamentum arteriosum) |
| 6th Right | Proximal right pulmonary artery |
BONES AND JOINTS - GENERAL
26. Ossification - High-Yield Points
| Bone | Primary center | Secondary center | Last to fuse |
|---|
| Clavicle | 5th-6th week (FIRST bone to ossify) | Medial end (18-20 yrs) | Medial epiphysis (25 yrs - LAST to fuse) |
| Femur head | 4-6 months postnatal | - | Fused at 18 yrs |
| Humerus (CRITOE) | See below | - | |
CRITOE (elbow ossification order and ages):
- C - Capitellum (1 yr)
- R - Radial head (3 yrs)
- I - Internal (medial) epicondyle (5 yrs)
- T - Trochlea (7 yrs)
- O - Olecranon (9 yrs)
- E - External (lateral) epicondyle (11 yrs)
Clavicle is the first bone to ossify (by intramembranous) and its medial epiphysis is the last growth plate to close in the body (25 years).
QUICK EXAM CHECKLIST
| Topic | Must-Know Points |
|---|
| Brachial plexus | RTDC + branches, Erb's vs Klumpke's |
| Knee joint | Menisci, cruciate/collateral ligaments, locking |
| Hip joint | Blood supply to femoral head, Y-ligament |
| Femoral triangle | NAVY contents, femoral hernia site |
| Breast | 75% axillary lymphatic drainage |
| Inguinal canal | Walls, contents, direct vs indirect hernia |
| Brachial plexus injuries | Erb's C5,6; Klumpke C8,T1 |
| Parotid | Facial nerve VII runs through it |
| Cavernous sinus | ICA + CN III, IV, V1, V2, VI |
| Diaphragm | T8 IVC, T10 esophagus, T12 aorta |
| Heart conduction | SA→AV→Bundle of His→Purkinje |
| Pharyngeal arches | 1st = V, 2nd = VII, 3rd = IX, 4th/6th = X |
| Uterine artery vs ureter | Artery crosses above ureter |
| CSF pathway | Lateral → Monro → 3rd → Aqueduct → 4th → Subarachnoid |
Sources: Gray's Anatomy for Students | THIEME General Anatomy & Musculoskeletal System | Netter's Atlas of Human Anatomy | Fischer's Mastery of Surgery (Breast chapter)