Last Minute Review
Anatomy — Last Minute Review
Rapid Review
A last-minute review of high-yield anatomy facts for the RITE and board exams. Tables, key associations, and must-know one-liners — designed for a quick pass the night before.
Cranial Nerves — Master Table
| CN | Name | Type | Foramen | Key Fact |
|---|---|---|---|---|
| I | Olfactory | S | Cribriform plate | Only CN to bypass thalamus |
| II | Optic | S | Optic canal | Afferent limb of pupillary reflex |
| III | Oculomotor | M | SOF | Pupil-involving = compressive (PComm aneurysm) |
| IV | Trochlear | M | SOF | Only dorsal exit + decussates; longest intracranial |
| V | Trigeminal | B | V1: SOF, V2: rotundum, V3: ovale | Corneal reflex afferent (V1) |
| VI | Abducens | M | SOF | Longest intracranial course; false localizing with ↑ ICP |
| VII | Facial | B | IAM → stylomastoid | UMN = forehead spared; LMN = entire face |
| VIII | Vestibulocochlear | S | IAM | CPA schwannoma most common tumor |
| IX | Glossopharyngeal | B | Jugular foramen | Afferent of gag reflex; glossopharyngeal neuralgia |
| X | Vagus | B | Jugular foramen | Efferent of gag reflex; recurrent laryngeal → hoarseness |
| XI | Spinal accessory | M | Jugular foramen | SCM (turn head contralateral) + trapezius |
| XII | Hypoglossal | M | Hypoglossal canal | LMN: tongue deviates toward lesion |
Key Foramina & Contents
| Foramen | Contents |
|---|---|
| Cribriform plate | CN I (olfactory) |
| Optic canal | CN II, ophthalmic artery |
| Superior orbital fissure | CN III, IV, V1, VI; ophthalmic veins |
| Foramen rotundum | CN V2 |
| Foramen ovale | CN V3 |
| Foramen spinosum | Middle meningeal artery |
| Internal acoustic meatus | CN VII, VIII; labyrinthine artery |
| Jugular foramen | CN IX, X, XI; jugular vein |
| Hypoglossal canal | CN XII |
| Foramen magnum | Spinal cord, vertebral arteries, CN XI (ascending) |
Brainstem Syndromes
| Syndrome | Level | Structure | Findings |
|---|---|---|---|
| Weber | Midbrain | Cerebral peduncle + CN III | Ipsi CN III palsy + contra hemiparesis |
| Benedikt | Midbrain | Red nucleus + CN III | Ipsi CN III + contra tremor/ataxia |
| Claude | Midbrain | Red nucleus + SCP + CN III | Ipsi CN III + contra ataxia |
| Parinaud | Dorsal midbrain | Pretectal area | Upgaze palsy, light-near dissociation, convergence-retraction nystagmus |
| Millard-Gubler | Pons | Base of pons + CN VI, VII | Ipsi CN VI + VII + contra hemiparesis |
| Foville | Pons | PPRF/CN VI + CN VII | Ipsi lateral gaze palsy + facial palsy + contra hemiparesis |
| Locked-in | Pons (ventral) | Bilateral basis pontis | Quadriplegia, anarthria; vertical eye movement preserved |
| Wallenberg | Lateral medulla | PICA territory | Ipsi: Horner, face pain/temp loss, ataxia, IX/X; Contra: body pain/temp loss |
| Dejerine | Medial medulla | ASA → pyramid, ML, CN XII | Ipsi tongue deviation + contra hemiparesis + contra proprioception loss |
Vascular Territories — Artery → Deficit
| Artery | Territory | Classic Deficit |
|---|---|---|
| ACA | Medial frontal/parietal | Contra leg > arm weakness; abulia; urinary incontinence |
| MCA superior | Lateral frontal | Contra face/arm > leg weakness; Broca aphasia (dominant) |
| MCA inferior | Lateral temporal/parietal | Wernicke aphasia (dominant); neglect (non-dominant) |
| MCA lenticulostriates | Basal ganglia, internal capsule | Pure motor hemiparesis; most common lacunar location |
| PCA | Occipital, medial temporal | Contra homonymous hemianopia with macular sparing |
| PICA | Lateral medulla, inf cerebellum | Wallenberg syndrome |
| AICA | Lateral pons, ant cerebellum | Ipsi hearing loss + facial palsy + ataxia + Horner |
| SCA | Superior cerebellum | Ipsi ataxia + contra pain/temp loss; dentate nucleus |
| Basilar tip | Midbrain, thalamus, PCA | "Top of the basilar": coma, visual, behavioral changes |
| Anterior choroidal | Posterior limb IC, optic tract, hippocampus | Contra hemiparesis + hemianopia + hemisensory loss |
| Heubner (recurrent) | Head of caudate, anterior IC | Contralateral face/arm weakness; behavioral changes |
| ACA–MCA watershed | Border zone (superior frontal) | "Man in a barrel" — bilateral proximal arm weakness |
| MCA–PCA watershed | Parieto-occipital border | Transcortical aphasia; visual processing deficits |
Cortical & Neurobehavioral Syndromes
| Syndrome | Key Features | Lesion Location |
|---|---|---|
| Aphasias | ||
| Broca | Non-fluent, impaired repetition, preserved comprehension | Dominant inferior frontal (area 44/45) |
| Wernicke | Fluent, impaired comprehension and repetition | Dominant superior temporal (area 22) |
| Conduction | Fluent, preserved comprehension, impaired repetition | Arcuate fasciculus |
| Global | Non-fluent, impaired comprehension and repetition | Large dominant MCA territory |
| Transcortical motor | Non-fluent, intact repetition | Anterior/superior to Broca (ACA watershed) |
| Transcortical sensory | Fluent, intact repetition, impaired comprehension | Posterior to Wernicke (PCA watershed) |
| Mixed transcortical | Non-fluent, impaired comprehension, intact repetition (echolalia) | Bilateral watershed (isolation of perisylvian) |
| Parietal Syndromes | ||
| Gerstmann | Agraphia, acalculia, finger agnosia, left-right confusion | Dominant angular gyrus |
| Hemispatial neglect | Unaware of contralateral space; extinction on double simultaneous stimulation | Non-dominant (R) parietal — inferior parietal lobule |
| Anosognosia | Unaware of own deficit (e.g., denies hemiparesis) | Non-dominant (R) parietal |
| Asomatognosia | Unawareness or denial of body part ownership | Non-dominant (R) parietal |
| Ideomotor apraxia | Cannot pantomime on command; can imitate and use objects | Dominant parietal (supramarginal gyrus) or premotor |
| Ideational apraxia | Cannot sequence multi-step tasks (e.g., making tea) | Dominant parietal; also seen in diffuse disease |
| Constructional apraxia | Cannot copy or draw shapes/figures | Non-dominant (R) parietal |
| Dressing apraxia | Cannot orient clothing to body | Non-dominant (R) parietal |
| Visual & Occipital Syndromes | ||
| Anton | Cortical blindness with denial of visual loss | Bilateral occipital (PCA) |
| Balint | Simultagnosia, optic ataxia, ocular apraxia | Bilateral parieto-occipital |
| Prosopagnosia | Cannot recognize familiar faces; can identify by voice | Bilateral (or R) fusiform gyrus |
| Achromatopsia | Loss of color perception (cortical) | Bilateral ventral occipitotemporal (V4) |
| Visual agnosia | Cannot recognize objects by sight; can identify by touch | Bilateral occipitotemporal |
| Alexia without agraphia | Cannot read but can write; disconnection syndrome | L occipital + splenium of corpus callosum (PCA) |
| Frontal Syndromes | ||
| Abulia | Lack of will/initiative; reduced spontaneous behavior | Medial frontal / ACA territory |
| Akinetic mutism | Alert-appearing but no speech or movement; extreme abulia | Bilateral medial frontal (ACA) or bilateral thalamic |
| Alien hand | Involuntary purposeful hand movements; intermanual conflict | Corpus callosum (callosal type) or SMA / medial frontal (frontal type) |
| Utilization behavior | Compulsively uses objects placed in hand | Bilateral frontal (medial/orbitofrontal) |
| Witzelsucht | Inappropriate joking, disinhibition, poor social judgment | Orbitofrontal cortex (R > L) |
| Bruns ataxia | Gait apraxia — "magnetic gait," freezing | Bilateral frontal (NPH, frontal lobe lesions) |
| Temporal & Limbic Syndromes | ||
| Klüver-Bucy | Hyperphagia, hypersexuality, hyperorality, visual agnosia, placidity | Bilateral amygdala / anterior temporal tips |
| Pure word deafness | Cannot comprehend speech; can read, write, and hear non-verbal sounds | Bilateral superior temporal (auditory cortex) |
| Amnesia (anterograde) | Cannot form new memories; remote memory intact | Bilateral hippocampi or bilateral medial thalamus (Papez circuit) |
| Capgras | Believes familiar person replaced by identical imposter | R hemisphere (bifrontal, temporal disconnect) |
| Reduplicative paramnesia | Believes a place has been duplicated or relocated | R hemisphere (frontal + parietal) |
| Disconnection Syndromes | ||
| Callosal disconnection | Left hand agraphia, left hand anomia, alien hand | Corpus callosum |
| Alexia without agraphia | Cannot read; can write (see above) | L occipital + splenium |
| Conduction aphasia | Impaired repetition with fluent speech (see above) | Arcuate fasciculus disconnection |
Visual Pathway — Lesion → Field Deficit
| Lesion Site | Visual Field Defect | Key Feature |
|---|---|---|
| Optic nerve | Monocular blindness (ipsi) | Afferent pupillary defect (RAPD) |
| Optic chiasm | Bitemporal hemianopia | Pituitary adenoma classic |
| Optic tract | Contra homonymous hemianopia | Incongruent; RAPD contralateral to lesion |
| LGN | Contra homonymous hemianopia | Dual blood supply (PCA + anterior choroidal) |
| Temporal radiations (Meyer loop) | Contra superior quadrantanopia ("pie in the sky") | MCA territory |
| Parietal radiations | Contra inferior quadrantanopia ("pie on the floor") | MCA territory |
| Occipital cortex | Contra homonymous hemianopia | Macular sparing (dual PCA/MCA supply); most congruent |
Thalamic Nuclei — Quick Reference
| Nucleus | Input | Projects To | Function / Lesion |
|---|---|---|---|
| VPL | Spinothalamic, DCML (body) | Somatosensory cortex | Contra body sensory loss |
| VPM | Trigeminothalamic (face) | Somatosensory cortex | Contra face sensory loss |
| VL | Cerebellum, basal ganglia | Motor cortex | DBS target for tremor |
| VA | Basal ganglia (GPi) | Premotor cortex | Motor planning |
| LGN | Optic tract | Visual cortex (area 17) | Contra homonymous hemianopia |
| MGN | Inferior colliculus | Auditory cortex (area 41) | Hearing processing |
| AN | Mammillary bodies | Cingulate | Papez circuit; Wernicke-Korsakoff |
| DM | Amygdala, prefrontal | Prefrontal cortex | Personality, judgment; Wernicke-Korsakoff |
| Pulvinar | Visual association | Parieto-occipital | Visual attention / neglect |
Clinical Pearl
Contralateral burning dysesthesia after thalamic (VPL) stroke. Onset delayed weeks to months. Often refractory to treatment.
Basal Ganglia — Circuitry
| Structure | Key Connection | Lesion → Result |
|---|---|---|
| Caudate | Cognitive loop (prefrontal) | Behavioral changes, chorea (Huntington) |
| Putamen | Motor loop (SMA) | Parkinsonism; most common hypertensive hemorrhage site |
| GPi | Output nucleus → thalamus (VA/VL) | DBS target for dystonia & PD |
| GPe | Indirect pathway relay | Hemiballismus (if STN involved) |
| STN | Excitatory to GPi | Contra hemiballismus; DBS target for PD |
| SNc | Dopamine → striatum | Parkinson disease (dopamine depletion) |
| SNr | Output to thalamus/SC | Similar to GPi function |
💎 Board Pearl
- Direct (D1): Striatum → inhibit GPi → disinhibit thalamus → facilitates movement
- Indirect (D2): Striatum → inhibit GPe → disinhibit STN → excite GPi → inhibit thalamus → suppresses movement
- Parkinson: Loss of dopamine → ↓ direct + ↑ indirect → excessive inhibition → bradykinesia
- Huntington: Loss of indirect pathway neurons → excessive movement → chorea
Cerebellum — Zones & Lesions
| Zone | Input | Peduncle | Lesion |
|---|---|---|---|
| Vermis (midline) | Spinal cord | ICP (input) | Truncal ataxia, wide-based gait |
| Intermediate | Spinal cord | SCP (output) | Limb ataxia (ipsilateral) |
| Lateral hemisphere | Corticopontine | MCP (input), SCP (output) | Limb dysmetria, intention tremor (ipsilateral) |
| Flocculonodular | Vestibular | ICP | Nystagmus, vertigo, truncal ataxia; medulloblastoma in children |
💎 Board Pearl
- ICP (inferior): Mainly input — spinocerebellar, vestibular, olivary
- MCP (middle): Input only — corticopontocerebellar; largest peduncle
- SCP (superior): Mainly output — dentatorubrothalamic tract; decussates in midbrain
Spinal Cord Tracts — Location, Function & Lamination
| Tract | Location | Carries | Lamination (outer → inner) | Key Point |
|---|---|---|---|---|
| Lateral corticospinal | Lateral column | Voluntary motor | Sacral → Lumbar → Thoracic → Cervical | Decussates at pyramids; external compression → legs first |
| Spinothalamic | Anterolateral | Pain, temperature | Sacral → Lumbar → Thoracic → Cervical | Crosses 1–2 levels above entry; sacral sparing in intramedullary lesions |
| DCML — Fasciculus gracilis | Dorsal column (medial) | Proprioception, vibration (LE) | Sacral/Lumbar (medial) | Present at all spinal levels; ipsilateral |
| DCML — Fasciculus cuneatus | Dorsal column (lateral) | Proprioception, vibration (UE) | Thoracic/Cervical (lateral) | Only above T6; both decussate in medulla |
| Dorsal spinocerebellar | Lateral (superficial) | Unconscious proprioception (LE) | Most superficial in lateral column | Ipsilateral; enters via ICP |
| Anterior corticospinal | Anterior column | Axial/proximal motor | — | Uncrossed; ~10% of CST fibers |
💎 Board Pearl
- External compression (e.g., tumor, spondylosis): Sacral fibers (outermost) affected first → legs > arms
- Intramedullary lesion (e.g., syringomyelia): Cervical fibers (innermost) affected first → arms > legs; sacral sparing
- Sacral sparing = hallmark of intramedullary pathology (central cord syndrome)
💎 Board Pearl
- Brown-Séquard (hemisection): Ipsi motor + DCML loss; contra pain/temp loss
- Central cord: Arms > legs weakness (cape distribution pain/temp loss); syringomyelia
- Anterior cord: Bilateral motor + pain/temp loss; DCML spared (ASA infarct)
- Posterior cord: Bilateral proprioception/vibration loss; motor spared (tabes dorsalis, B12)
- Conus medullaris: Early bladder/bowel, symmetric, saddle anesthesia, LE areflexia
- Cauda equina: Asymmetric radiculopathy, late bladder, severe radicular pain
Brachial Plexus — Roots to Nerves
| Nerve | Root(s) | Motor | Sensory | Injury Clue |
|---|---|---|---|---|
| Long thoracic | C5-7 | Serratus anterior | — | Winged scapula |
| Axillary | C5-6 | Deltoid, teres minor | Regimental badge | Shoulder dislocation |
| Musculocutaneous | C5-6 | Biceps, brachialis | Lateral forearm | Weak elbow flexion + supination |
| Radial | C5-T1 | Triceps, wrist/finger extensors | Dorsal hand (1st web) | Wrist drop; spiral groove fracture |
| Median | C6-T1 | Forearm pronation/flexion, LOAF | Palmar 3.5 digits | Carpal tunnel; hand of benediction |
| Ulnar | C8-T1 | Intrinsics (except LOAF), FDP 4-5 | Medial 1.5 digits | Claw hand; Guyon canal / elbow |
| Suprascapular | C5-6 | Supraspinatus, infraspinatus | — | Shoulder external rotation weakness |
💎 Board Pearl
- Erb-Duchenne (C5-6): Waiter's tip — arm adducted, internally rotated, forearm pronated
- Klumpke (C8-T1): Claw hand + Horner syndrome (if T1 sympathetics involved)
- LOAF muscles (median): Lumbricals 1-2, Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis
Important Muscles — Upper Extremity
| Muscle | Nerve | Root(s) | Main Function |
|---|---|---|---|
| Deltoid | Axillary | C5-6 | Shoulder abduction (after 15°) |
| Supraspinatus | Suprascapular | C5-6 | Shoulder abduction (first 15°) |
| Infraspinatus | Suprascapular | C5-6 | Shoulder external rotation |
| Teres minor | Axillary | C5-6 | Shoulder external rotation |
| Teres major | Subscapular (lower) | C5-7 | Shoulder adduction, internal rotation |
| Latissimus dorsi | Thoracodorsal | C6-8 | Shoulder adduction, extension, internal rotation |
| Serratus anterior | Long thoracic | C5-7 | Scapular protraction; winged scapula if weak |
| Rhomboids | Dorsal scapular | C4-5 | Scapular retraction |
| Biceps brachii | Musculocutaneous | C5-6 | Elbow flexion + forearm supination |
| Brachialis | Musculocutaneous | C5-6 | Elbow flexion (main flexor) |
| Brachioradialis | Radial | C5-6 | Elbow flexion (neutral forearm position) |
| Triceps | Radial | C6-8 | Elbow extension |
| Supinator | Radial (posterior interosseous) | C5-6 | Forearm supination |
| Pronator teres | Median | C6-7 | Forearm pronation |
| Wrist extensors (ECRL, ECRB) | Radial | C6-7 | Wrist extension |
| Wrist flexors (FCR) | Median | C6-7 | Wrist flexion + radial deviation |
| Wrist flexors (FCU) | Ulnar | C7-T1 | Wrist flexion + ulnar deviation |
| Finger extensors (EDC) | Radial (PIN) | C7-8 | Finger extension at MCP |
| Finger flexors (FDS) | Median | C7-T1 | Finger flexion at PIP |
| Finger flexors (FDP 2-3) | Median (AIN) | C7-T1 | Finger flexion at DIP (digits 2-3) |
| Finger flexors (FDP 4-5) | Ulnar | C8-T1 | Finger flexion at DIP (digits 4-5) |
| Thenar (APB, OP, FPB) | Median (recurrent branch) | C8-T1 | Thumb opposition, abduction, flexion |
| Adductor pollicis | Ulnar | C8-T1 | Thumb adduction (Froment sign if weak) |
| Hypothenar (ADM, FDM, ODM) | Ulnar | C8-T1 | Little finger abduction, flexion, opposition |
| Lumbricals 1-2 | Median | C8-T1 | MCP flexion + IP extension (digits 2-3) |
| Lumbricals 3-4 | Ulnar | C8-T1 | MCP flexion + IP extension (digits 4-5) |
| Dorsal interossei | Ulnar | C8-T1 | Finger abduction (DAB) |
| Palmar interossei | Ulnar | C8-T1 | Finger adduction (PAD) |
Important Muscles — Lower Extremity
| Muscle | Nerve | Root(s) | Main Function |
|---|---|---|---|
| Iliopsoas | Femoral + direct lumbar branches | L1-3 | Hip flexion (strongest hip flexor) |
| Gluteus maximus | Inferior gluteal | L5-S2 | Hip extension; rising from seated |
| Gluteus medius | Superior gluteal | L4-S1 | Hip abduction; Trendelenburg if weak |
| Gluteus minimus | Superior gluteal | L4-S1 | Hip abduction + internal rotation |
| Hip adductors | Obturator | L2-4 | Hip adduction |
| Quadriceps (rectus femoris, vastus group) | Femoral | L2-4 | Knee extension; knee jerk (L3-4) |
| Hamstrings (biceps femoris, semimembranosus, semitendinosus) | Sciatic (tibial division); biceps short head: peroneal | L5-S2 | Knee flexion |
| Tibialis anterior | Deep peroneal (fibular) | L4-5 | Ankle dorsiflexion + inversion; foot drop if weak |
| Extensor hallucis longus (EHL) | Deep peroneal | L5 | Great toe extension; best L5 test |
| Extensor digitorum longus | Deep peroneal | L5-S1 | Toe extension (digits 2-5) |
| Peroneus longus & brevis | Superficial peroneal | L5-S1 | Ankle eversion |
| Gastrocnemius | Tibial | S1-2 | Ankle plantarflexion (with knee extended); ankle jerk (S1) |
| Soleus | Tibial | S1-2 | Ankle plantarflexion (with knee flexed) |
| Tibialis posterior | Tibial | L4-5 | Ankle inversion + plantarflexion |
| Flexor hallucis longus (FHL) | Tibial | S1-2 | Great toe flexion |
| Flexor digitorum longus | Tibial | S1-2 | Toe flexion (digits 2-5) |
| Extensor digitorum brevis | Deep peroneal | L5-S1 | Toe extension; atrophied in peroneal neuropathy |
| Foot intrinsics | Tibial (medial/lateral plantar) | S1-2 | Toe flexion, abduction; hammer toes if weak |
💎 Board Pearl
- Biceps: C5-6 (musculocutaneous)
- Brachioradialis: C5-6 (radial)
- Triceps: C7-8 (radial)
- Knee jerk (patellar): L3-4 (femoral)
- Ankle jerk (Achilles): S1-2 (tibial)
Must-Know Numbers & Thresholds
| Fact | Value |
|---|---|
| Spinal cord ends (conus medullaris) | L1-L2 |
| Thecal sac ends | S2 |
| Cervical enlargement | C5-T1 (upper limb) |
| Lumbar enlargement | L1-S2 (lower limb) |
| Babinski reflex normal until age | ~12–24 months |
| Vertebral artery enters transverse foramen | C6 |
| Vertebral arteries join to form basilar | Pontomedullary junction |
| Most common site of Berry aneurysm | AComm |
| Most common hypertensive hemorrhage site | Putamen |
| CN IV — only CN to exit dorsally | Yes (and decussates) |
| Pupillary fibers in CN III run | Superficially (compressed first by aneurysm) |
| Internal capsule — posterior limb carries | Corticospinal tract |
| Internal capsule — genu carries | Corticobulbar tract |
Classic Board Traps
Don't Fall for These
- CN III palsy with pupil involvement → PComm aneurysm until proven otherwise (not ischemic!)
- CN VI palsy + headache → May be false localizing (raised ICP), not a brainstem lesion
- Tongue deviates LEFT + RIGHT hemiparesis → LEFT medullary lesion (medial medullary / Dejerine)
- "Crossed" findings (ipsi face + contra body) → Always = brainstem
- Bilateral INO + young patient → MS (not stroke)
- Weber vs. Benedikt: Weber = peduncle (motor); Benedikt = red nucleus (tremor/ataxia)
- Anterior spinal artery syndrome: Motor + pain/temp lost; vibration/proprioception spared
- Hemiballismus → Contralateral STN lesion (usually small lacunar stroke)
- Cavernous sinus → CN III, IV, V1, V2, VI + sympathetics; CN VI most medial → first affected
- Sacral sparing + UE > LE weakness → Intramedullary lesion (not external compression)