Scalp, Meninges & Cranial Venous Sinuses PDF

Scalp, Meninges & Cranial Venous Sinuses HB-2 Prepared by: Dr. ALI AL QABBANI DDS. M.Sc. PhD Maxillofacial Surgery Lecturer Department of Oral &Craniofacial Health Sciences  References Text Book(s): Kenneth S. Saladin (2017...

Scalp, Meninges & Cranial Venous Sinuses HB-2 Prepared by: Dr. ALI AL QABBANI DDS. M.Sc. PhD Maxillofacial Surgery Lecturer Department of Oral &Craniofacial Health Sciences  References Text Book(s): Kenneth S. Saladin (2017) Anatomy & Physiology: The Unity of Form and Function 8th Edition Snell RS (2018): Clinical Anatomy by Regions. 10th Edition, Lippincott Williams & Wilkins. Baltimore. Recommended Readings: Margaret J. Fehrenbach : Illustrated Anatomy Of The Head and Neck. Fifth Edition. Saunders Elsevier,2015. Lauralee Sherwood, Human Physiology: From Cells to Systems, 9th Edition 2016 Linda S. Costanzo, Physiology, 6e, May 22, 2017  Points to be covered Scalp Meninges:Preti sent Layers of SCALP he Ydpattthebrain Parts of the meninges semeninged Skin anger Connective tissue Folds of the meninges EEEE Aponeurosis epicranial Cranial venous sinuses These Loose areolar tissue Periosteum Ehlboratached Intracranial bleeding is associated with the meninges Muscles of the Scalp- Occipito frontalis muscle, Temporalis Dural folds form venous sinuses Nerve supply of the scalp CSF is formed in the ventricles Blood supply of the scalp Functions of CSF and its flow Venous drain of the scalp. Know the flow of the brain venous sinuses Cavernous sinus and its clinical importance WWII Scalp consist of 5 Layers: The scalp covers the vault of the skull: Extends : between right and left temporal lines laterally, eye brows (superciliary arch) anteriorly and Superior nuchal line posteriorly. Skin Connective tissue (superficial fascia adherent to fat) Aponeurosis (epicranial aponeurosis) Initiethathforehead Loose areolar tissue avascular atheoccipitalhead Pericranium (periosteum) hintsciestieetur nt cattachedtothebo bite.tn underneath  thecranial aponeurosis are he Heese'The m ingies Aponeurosis (epicranial aponeurosis) This is the tendon uniting the frontal and occipital bellies of the occipito-frontalis muscle. ithasfrontalbellies occipital bellies inetpeontwos.ie Layers of Scalp a 34 Meninges Pericranium Pericranium (Periosteum) Frontalis muscle Epicranial Aponeurosis The occipital bellies are shorter and narrower than the frontal bellies; 111msec cared frontalis occipto and are widely seperated by muscle aponeurosis. frailty's East Each (aponeurosis) arises from the lateral part of the corresponding 0 Occipitalis EE.pt muscle superior nuchal line. ofrontalis or The frontal belly has no attachment to bone; and run between skin of Temporalis muscle I iii forehead and the epicranial aponeurosis. 9911ft meatMent EphinterEpicentre  Blood supply of the scalp Em Supplied by branches of External & Internal Carotid itgoesup.BE External Carotid:ivsGrancuscikecmaxorteryisypeg Supply posterior and lateral part of scalp L p Backside 1. Superficial temporal artery 2. Posterior auricular 3. Occipital Artery Ee mg infront Internal Carotid : Supply anterior and superior part of scalp Doesn't give 1. Supra trochlear hence gettin aᵗEm 2. Supra orbital thehead Arteries of the Scalp  Veins of Scalp follow same the nameofthe artery Same route as arteries of scalp Supra trochlear and supra orbital vein join and forms Facial Vein Superficial Temporal forms Retromandibular Vein Posterior Auricle forms External Jugular Vein Occipital join the Internal Jugular Vein Nerves of the Scalp Motor and sensory and sympathetic innervation Motor – Facial Nerve responsableforthemusclesofthe face Is Sensory – Trigeminal Nerve sensationof hotcold touch C2 and C3 (spinal nerve) Sympathetic innervation – to blood vessels, sweat glands and arrectores pilorum, reach the region via arteries.  Innervations of the Scalp nervesup blood sup Scalp is innervated in two portions: 1. Area anterior to Ear and Vertex of skull 2. Posterior to Ear and Vertex of Skull Anterior to Ear and Vertex Branches of Trigeminal Nerve (Cranial Nerve) g ohmiEv or v2orv3 besidethesuperficalten 1. Supra trochlear nerve Intimateofartery 2. Supra orbital nerve 3. Zygomatico temporal nerve btw zygoma temporal 4. Auriculotemporal nerve Anteriortotheearloop beside thesuperfacialtemporal artery Posterior to Ear and Vertex Branches from C2 and C3 (Cervical Nerves) 1. Great auricular nerve 2. Lesser occipital nerve 3. Greater occipital nerve 4. 3rd occipital nerve partieth planbene  Innervations of the Scalp UI 1. Supra trochlear nerve from ophthalmic division of the trigeminal nerve 2. Supra orbital nerve V2 3. Zygomatico temporal nerve from the maxillary division of the trigeminal nerve V3 4. Auriculotemporal nerve from the mandibular division of the trigeminal nerve 5. Lesser occipital nerve (C2) behind the ear 6.Greater occipital nerve (C2) posteriorly up to the vertex Lymphatic drainage of scalp namedepending ontheside hostoccipitalpart FEE  Meninges belowthebone The meninges are the three membranes that surround the brain and the spinal cord (meninges: Greek from meninx, membrane) Meninges provide the brain with: protection support nutrition  Layers of Scalp & Meninges Sky Dura mater Arachnoid Yehavite GCF Pia mater  1. Dura mater (Latin = tough mother, referring to the relatively tough outer membrane) 2. Arachnoid mater (Latin = spider mother, referring to its web-like arrangement of fibres) 3. Pia mater (L = tender, referring to its delicate, fine nature) gearsthegyrusorgyriinthe Meninges - 3 membranes  membranse first layer 4550011 Dura mater (endoosteal and meningeal layers) iiiiiii.in a ii Dura mater Dura is a thick, fibrous layer that is fused to the endocranium (inner surfaces of the bones of the skull) However, it is not fused: where it forms folds between parts of brain at dural venous sinuses (blood-filled channels) between dura and endocranium Dura provides support and stability for brain.  Dura mater ikesideshape aereim.at eEnment Etisalat anterior Fantastic ethmoid bone Arachnoid mater Arachnoid is a thin, transparent membrane below the dura Sub-arachnoid space : space below the arachnoid mater containing cerebro-spinal fluid (CSF) CSF provides nourishment and protection for brain Pia mater follow the folds of the gyrus Pia is closely adapted to the surface of the brain Contains blood vessels that provide nutrition to the brain Dural Folds Dural Folds Dural Folds Middle meningeal artery foundinthelateralviewoftheskull Branch of maxillary artery arising in infratemporal fossa before passing through foramen spinosum lies between endosteal and meningeal layers of dura It gives anterior branch of artery then runs forward and laterally to the squamous (L = flat) part of temporal bone posterior branch curves backward and supplies posterior part of dura middle meningeal vein follows artery and lies a little lateral to it  Middle meningeal vessels Branches of vessels groove inner surface of skull, outside dura, in temporal region Extra-dural haemorrhage can occur when vessels are torn in fractures; this produces swelling and increases pressure on brain Pterion (region of temple) is particularly susceptible to fracture as bone is thin Vessels may be converted into canals, liable to tearing if displacement of bones  Middle meningeal artery - lacerations hematoma Lacerations or tears of middle meningeal vessels will result in blood leaking between dura and inner surface of skull 5 cause.ittEEEied Build-up of pressure peaks around 6-8 hours after trauma if an artery is torn, but may take up to 24 hours if a vein is involved annIII Extent of spread of haematoma is limited by attachment of dura to skull  Extra-dural haematomas Most extra-dural haematomas are due to head trauma leading to a fracture that crosses a portion of the middle meningeal artery or vein Artery is torn more often than the vein cuz it is superficalthenthevein Venous extra-dural haematomas seen more often in elderly and are not associated as often with skull fractures Pterion susebtableto irregular fracture s shape  Extradural hematoma Extradural hematoma tearinginthe middle meninged  Isonecighead Subdural vs Epidural underneath belowdural layer Anaphedural Hematoma EE  Ischemia As pressure in cranial cavity increases, cerebral blood flow will be affected, leading to a lack of oxygenated blood to the brain tissue (ischemia) (ischemia: Greek from ischo = to keep back; and haima = blood) If pressure continues to grow, pressure will be applied to the brainstem that can compromise vital functions such as breathing, leading to death  Pupil size As intra-cranial pressure, possible brain distortion and stretched or displaced cranial nerves Oculomotor (third cranial) nerve carries parasympathetic information to sphincter pupillae muscle and ciliary muscle If this nerve is not functioning correctly, sympathetic innervation to dilator pupillae acts unopposed, leading to dilated pupil that will not react to light  CT scans CT scans can show extra-dural swellings As in intracranial pressure, cerebral blood flow is affected, leading to ischemia If continues, pressure applied to brainstem can compromise vital functions (eg breathing), leading to death CT brain, CT Angiogram or MRI scans of skull useful to relate actual appearance of bones of skull and contents of cranial cavity one ofthem is circle of wills  Cerebrospinal fluid (CSF) Cerebrospinal fluid (CSF) is a clear colorless bodily fluid found in the brain and spine. It is produced in the choroid plexus of the brain. specificcells by calledepindema It acts as a cushion or buffer for the brain's cortex, providing a basic mechanical and immunological protection to the brain inside the skull, and it serves a vital function in cerebral autoregulation of cerebral blood flow. Choroid plexus of the 4rth Ventricle  Cerebrospinal fluid (CSF) The CSF occupies the subarachnoid space (the space between the arachnoid mater and the pia mater) and the ventricular system around and inside the brain and spinal cord.  Brain Ventricular System The ventricular system is a set of four interconnected cavities (ventricles) in the brain, where the cerebrospinal fluid (CSF) is produced. Within each ventricle is a region of choroid plexus, a network of ependymal cells involved in the production of CSF. The ventricular system is continuous with the central canal of the spinal cord (from the third ventricle) allowing for the flow of CSF to circulate. All of the ventricular system and the central canal of the spinal cord is lined with ependyma a specialised form of epithelium.  CSF : production and reabsorption The CSF contains approximately 0.3% plasma proteins, or approximately 15 to 40 mg/dL. It is produced at a rate of 500 ml/day. Since the subarachnoid space around the brain and spinal cord can contain only 135 to 150 ml, large amounts are drained primarily into the blood through arachnoid granulations in the superior sagittal sinus. CSF returns to the vascular system by entering the dural venous sinuses via the arachnoid granulations (or villi). Dural Venous Sinuses  Dural venous sinuses Dural venous sinuses (paired and unpaired) The dural sinuses include: superior sagittal sinus inferior sagittal sinus straight sinus (formed by union of great cerebral vein and inferior sagittal sinus where the free margins of the falx and tentorium meet) transverse sinus sigmoid sinus superior petrosal sinus inferior petrosal sinus cavernous sinus sphenoparietal sinus. The inferior petrosal and sigmoid sinuses drain into the internal jugular vein. Dural venous sinuses  Cavernous sinuses The right and left cavernous sinuses lie either side of the pituitary gland (either side of the body of sphenoid bone). They have a spongy (plexiform) nature due to numerous fibrous trabeculae. They receive blood from the middle cerebral vein, sphenoparietal sinus and ophthalmic veins and drain into the superior and inferior petrosal sinuses. They communicate with the pterygoid venous plexus and the pharyngeal plexus, so they can be involved in spread of infection. Cavernous sinus and its relation  Clinical Significance of Cavernous Sinus Thrombosis Cavernous Sinus Thrombosis CST: is a rare disease, but the mortality rate remains high, even after the breakthrough of antibiotics and advanced imaging techniques. Unethical practices by unregistered practitioners and a lack of awareness of dental health in rural areas can lead to severe life threatening complications of dental infections. Angular and ophthalmic veins, teeth, maxillary sinus, and cervical vertebrae through the pterygoid plexus emptying into the inferior ophthalmic vein. (emissary veins ). Mortality rate from cavernous sinus thrombosis (CST) is effectively 100%  SUMMARY Know the layers of the scalp Muscles of the scalp Blood supply and venous drainage Sensations on the scalp Lymphatic drainage and their lymph nodes Know the layers of the meninges covering the brain and spinal cord Intracranial bleeding is associated with the meninges Dural folds form venous sinuses CSF is formed in the ventricles Functions of CSF and its flow Know the flow of the brain venous sinuses Cavernous sinuses thrombosis