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ANATOMYOFTHESCALP , MENINGESANDSPINALCORD CraigGordon (Kindly presented byJamesGallagher) cgordon24@qub.ac.ukLearningOutcomes • 1. Describe and identify the layers of the scalp • 2. Describe the arterial supply and venous drainage of the scalp and identify the principal vessels involved • 3. Describe the cutaneous innervation of the scalp and identify the principal nerves involved • 4. Describe and identify the structure and arrangement of the dura, arachnoid and pia mater • 5. Describe the anatomy of and identify the anatomical features of the spinal cord • 6. Describe the formation and location of the spinal nerves and identify the spinal nervesLayers of theScalp mnemonic Layers of skin & connective tissue overlying cranium Skin Connectivetissue(DENSE) Aponeurosis (connectingoccipitalis &frontalis) Looseconnectivetissue PeriosteumArterialSupply of theScalp The picture can't be displayed. • Within loose connective tissue layer • Fromexternalcarotidandophthalmic arterybranches • Superficial temporal • Occipital • Posterior auricular • supraorbitalandsupratrochlear (fromophthalmicaa.)Venous Drainage of the Scalp • Divided into superficial and deep drainage • Superficial veins follow arterial supply •superficial temporal, occipital, posterior auricular, supraorbital and supratrochlear veins • Deep region drained by pterygoid venous plexus •Drains into maxillary vein • Scalp veins communicate with diploic veins in the skull viaemissary veins •Infection of the loose connective tissue can therefore spread internally to the meningesCutaneous NerveSupply of theScalp • Cutaneous innervation derived from trigeminal nerve anteriorly and cervical nerves posteriorly • Trigeminal branches • Supratrochlear nerve (Va) • Supraorbital nerve (Va) • Zygomaticotemporal nerve (Vb) • Auriculotemporalnerve (Vc) • Cervical branches • Lesser occipital nerve • Greater occipitalnerve • Great auricular nerve • Third occipital nerveScalp injuries • Scalplacerations will bleedprofuselyfor severalreasons • Scalpis highlyanastomosedwithrich bloodsupply • Pulloftheoccipitofrontalismakesclosure of bleeding vessel difficult • Thebloodvesselsareadheredtodense connective tissue,preventingthe vasoconstrictionthatnormallyoccursin response todamageMeninges • Membranous layers that immediately underly cranium and surroundCNS • Functions: 1. Provides protection to the brain 2. Gives supporting network for arteries, veins and venous sinuses 3. Encloses brain inCSF-filled cavity (subarachnoid space)Meningeal layers • DURA mater •Thick, outermost layer •Dural reflections •Dural-venous sinuses •Sensitive to pain • ARACHNOID mater •Arachnoid granulations •Sub-arachnoid space • PIA mater •Delicate & closely adhered to brain •Highly vascularised, supplies brain •Follows contours of brainDural reflections Dural infoldings project into cranial cavity; they anchor the brain and divide the cranial cavity into compartments 1. Falx cerebri 2. Falx cerebelli 3. Tentorium cerebelli 4. Diaphragma sellaeMeningitis • “Inflammation of the meninges lining the brain and spinal cord” • Bacterial causes: NHS •Neisseria meningitidis •Haemophilus influenzae •Streptococcus pneumomia • Presentation: Headache, seizures, neck stiffness, photophobia, vomiting •Non-blanching rash in meningococcal meningitis •Nonspecific signs in neonates: poor feeding, hypotonia, bulging fontanelle Bacterial vs viral meningitis on lumbar punctureExtradural Haematoma •Haematomabetweendura materandskull •Commonlyfrom middle meningeal artery rupturefrom skullfractureatpterion •Biconvex shapeonCTbrainSubdural Haematoma • HaematomabetweenDuramaterand arachnoidmater • Bleedingsource:bridgingveinscrossing fromcortex toD-Vsinuses • Concave,“banana”shape onCT brain • Moreoftenelderlypeople;canbechronic The picture can't be displayed. SpinalCord • Continuation of medulla, exits foramen magnum • Conus medullaris is the enlargement at the end of the spinal cord •L1/2 in adults •L3 in infants • Discrepancyduetospinalcordgrowingearlierin development than vertebrae • Filum terminale is an extension of the pia mater; anchors spinal cord to coccyx Cauda equina syndrome •Cauda equina= bundle of nerves arising from conus medullaris and occupying lumbar cistern •Nerves L2-5,S1-5 &Cc1 (coccygeal nerve) •Cauda equina syndrome is a surgical emergency caused by compression of the cauda equina •Red flag symptoms •Severe lower back pain •Saddle anaesthesia •Bowel, bladder and sexual dysfunction •Bilateral sciatica SpinalCord cross-section •Grey matter centrally, white matter peripherally •Posterior horn= receivesnsory afferents •Posterior=pointy=sensory •Anterior horn= contains motor neuronsSpinal nerve formation • Dorsalrootcontainsafferent sensory fibres • Ventral root contains efferent motor fibres • Theseunitetoformthespinalnerve • Thespinalnervedividesintodorsal andventral rami,whicharemixedLumbar Puncture • Collection ofCSF from lumbar cistern for diagnostic or therapeutic purposes • Needle site • Usually between L3/L4 in adults • Usually between L4/L5 in children • Layers • Skin • Subcutaneous fat • Supraspinous ligament • Interspinous ligament • Ligamentum flavum • Dura mater • Subdural space • Arachnoidmater