Exam 4 Session 1 PDF

Exam 4 Session 1 Keaton Kaye M.S. OMS-2 [email protected] 865-679-8936  Please Sign In https://docs.google.com/spreadsheets/d/1MyFwVq7RXzLYGjH57gw9 0teFUwTVX2ux2xCnO05UeQU/edit?usp=sharing  BUY A SKULL https://a.co/d/99ByFV7 ht...

Exam 4 Session 1 Keaton Kaye M.S. OMS-2 [email protected] 865-679-8936  Please Sign In https://docs.google.com/spreadsheets/d/1MyFwVq7RXzLYGjH57gw9 0teFUwTVX2ux2xCnO05UeQU/edit?usp=sharing  BUY A SKULL https://a.co/d/99ByFV7 https://a.co/d/6UpMRVj Record  Exam 4 Tips DO NOT GET BEHIND CN Nerves are LIFE Autonomics are HY Know your foramen Skull Osteology Skull (Cranium)- Consists of 28 bones Connected by fibrous interlocking joints called Sutures Cranium can be divided into two sections based on fuction: 1. Neurocranium- portion that encases the brain The Neurocranium is further divided into 2 portions: Calvaria- Intramembranous ossification Cranial Base- endochondral ossification 2. Viscerocranium- facial bones  Overview of the Skull Unpaired Bones Frontal Frontal Sphenoid Sphenoid l ita cip Oc Ethmoid Ethmoid Vomer ble a ndi M Mandible Gray’s 857 Lateral View Anterior View Gray’s 855  Overview of the Skull Paired Bones Parietal Parietal Nasal Temporal Temporal Nasal Lacrimal Zygomatic Maxilla Inferior Nasal Concha Zygomatic Gray’s 857 Lateral View Anterior View Gray’s 855  Overview of the Skull Paired Bones Maxilla Palatine Zygomatic Malleus Incus Stapes Parietal Temporal Gray’s 862 Inferior View  Sutures of the Skull Coronal Suture Bregma Parietal Frontal Lambda Sagittal Suture Occipital Lambdoid Parietal Suture Lambda Gray’s 859 Posterior View Superior View Gray’s 860  Sutures of the Skull Bregma Coronal Suture Squamous Suture Frontal Parietal Lambda Pterion Lambdoid Suture Temporal l ita cip Oc Sphenoid Lateral View Gray’s 857 Pterion: Cranial Sutures The pterion is thin and weak area of Squamosal the skull Coronal suture Middle Meningeal artery runs just suture deep to the pterion Fracture to the pterion can result in a rupture of the middle meningeal artery and results in an extradural Pterion (epidural) hematoma Lambdoidal suture Middle meningeal a. via foramen spinosum 12 Maxillary a.  Clinical Correlation Extradural Hematoma Fractures in the Pterion region from external trauma can cause the Middle Meningeal artery to rupture causing blood to pool between the cranial bones and dura. If not treated the blood can compress the brain possibly resulting in death. Pterion Epidural Hemorrhage Coronal Section Superior View Gray’s 891  Development of the Skull Anterior Fontanelle Posterior Fontanelle Mastoid Fontanelle Sphenoidal Fontanelle Posterior Fontanelle Superior View Lateral View Netter 21  Lambda Sagittal Bregma suture lambdoidal suture Premature Suture Closure: Craniosynostosis Premature closure of the cranial sutures results in cranial malformations Sagittal synostosis: most common type, premature closure of sagittal suture, no/small anterior fontanelle, the cranium will grow long and narrow Other types: Coronal, lambdoid & metopic synostosis May cause complications depending on which suture is affected & timing of the synostosis (before/after birth) 15  Temporal Bone is divided into three parts: Squamous- lateral portion of the middle cranial fossa Tympanic- outer ring of external auditory meatus Petrous- houses the ear ossicles, malleolus, incus and stapes Mastoid and Styloid processes- Temporal lines Muscles attachment sites for neck and tongue Temporal Zygomatic arch: fossa Composed of two different bones: Zygomatic process of temporal bone and Zygomatic Temporal process of the zygomatic bone arch: External acoustic Temporal Lines (extend from the frontal to parietal region) meatus Where temporalis muscle (muscle of Mastoid process mastication attaches) Styloid process  Basicranial Features & Foramina Zygomatic arch Hard palate Mandibular fossa Inferior orbital fissure Petrotympanic fissure Foramen ovale Chorda tympani n. (CN VII br) Foramen spinosum Styloid process Stylomastoid foramen Jugular foramen CN VII (Facial n.) Mastoid process Occipital condyle Carotid canal Foramen magnum Foramen lacerum 17  Basicranial Features & Foramina Incisive foramen Greater palatine Lesser palatine foramen foramen Greater palatine n., a. Lesser palatine n., a. Choana (internal nares) Lateral & medial plates of the pterygoid process, Sphenoid Superior nuchal line External occipital protuberance 18  External Features of the Skull Mandible Mandibular Notch Mandibular Foramen Coronoid Process Lingula Condylar Process Ramus Mental Protuberance Angle Alveolar Part Body Mental Foramen Netter 24  Mandibular foramen- where TMJ and Mandible inferior alveolar n., a., and v. travels Mandibular notch TMJ- where mandible articulates with the temporal bone Condylar process Mandibular fossa, Temporal bone Articular disk Articular tubercle Head of mandible  Sinuses Around the nasal cavity there are paranasal sinuses: Frontal sinus- inside the frontal bone Ethmoid sinus- inferior to the frontal sinus and superior to the nasal cavity Sphenoid sinus- posterior to Ethmoid sinus Maxillary sinus- inferior to the obits and inside the maxillary bone Common site for sinusitis  Endocranium Frontal sinus Coronal suture Middle meningeal groove Groove for Arachnoid Fovea superior sagittal Arachnoid granulations sinus Sagittal suture 22  Frontal sinus Frontal bone Ethmoid bone Sphenoid bone (lesser wing) Sphenoid bone (greater wing) Anterior fossa Temporal bone Frontal lobes Parietal bone Middle fossa Temporal lobes Occipital bone Posterior 23 fossa Cerebellum Cranial Foramen Neurovascular Structures Fossa Anterior Cribriform plate & foramina CN I (olfactory bulb & nn.) fossa Anterior & posterior ethmoidal Anterior & posterior ethmoidal nn., aa., vv. foramina (will be covered in LEC 46) Middle fossa Optic canal CN II, ophthalmic a., vein of retina Superior orbital fissure CN III, CN IV, CN V1, CN VI, ophthalmic vv. Foramen rotundum CN V2 Foramen ovale CNV3, lesser petrosal n. (CN IX br.) Foramen spinosum Middle meningeal a Foramen lacerum (filled with fibrous cartilage, internal carotid a. passes superiorly) Carotid canal Internal carotid a., sympathetic carotid plexus Greater petrosal hiatus Greater petrosal n. (CN VII br.) Posterior Internal acoustic meatus CN VII, CN VIII fossa Jugular foramen CN IX, CN X, CN XI (exit), sigmoid sinus/Internal jugular v. Hypoglossal canal CN XII 24 Foramen magnum Medulla of brainstem/spinal cord, CN XI (entrance), Anterior cranial fossa Crista galli Falx cerebri Foramen cecum Cribriform plate CN I (Olfactory bulbs & nn.) Sphenoid bone (lesser wing) Sphenoid bone Anterior clinoid processes (body) Middle cranial fossa Superior orbital fissure Optic canal CN II (Optic n.) Foramen rotundum CN V2 (Trigeminal n.) Foramen ovale CN V3 (Trigeminal n.) Foramen spinosum Middle meningeal a. Foramen lacerum Opening of the carotid canal Internal carotid a. Greater petrosal hiatus O Greater petrosal n. (CN VII br.) R SO Sphenoid Bone Tuberculum sellae Hypophysial fossa Posterior clinoid process Dorsum sellae Groove for the middle meningeal artery Pituitary gland sit in the sella turcica The pituitary gland can be accessed surgically by passing instrumentation through the sphenoid sinus (transsphenoidal).  Optic canal Superior orbital fissure CN III (oculomotor n.) CN IV (trochlear n.) CN V1 (Trigeminal n.) CN II (Optic n.) & CN VI (abducens n.) Ophthalmic a. Inferior orbital fissure J. Millard 28 Posterior cranial fossa Clivus Internal acoustic meatus Groove for CN VII (Facial n.), inf. petrosal CN VIII (Vestibulocochlear sinus n.) Jugular Groove for sigmoid sinus foramen Internal jugular v., CN IX (Glossopharyngeal n.) Foramen magnum CN X (Vagus n.) Brainstem/spinal CN XI (Accessory n.) cord, CN XI, vertebral aa. Groove for transverse sinus Hypoglossal canal CN XII (Hypoglossal n.) Internal occipital protuberance Intro to Cranial Nerves  Central sulcus Parietal Frontal lobe lobe Occipital lobe Temporal Cerebellum lobe Midbrain Brainstem Pons Medulla oblongata  Cranial Nerves 12 pairs of cranial nerves The first two cranial nerves (Olfactory and Optic) arise from the cerebrum The other 10 Cranial nerves originate from the brainstem Cranial nerves can carry motor, sensory, and parasympathetic fibers  CN I- Olfactory Nerve Olfactory Bulb Olfactory tract Function: Special Sense - Olfaction (smell) Nerve fibers pass through the cribriform plate of the ethmoid bone and synapse in the olfactory bulb Secondary fibers travel from the olfactory bulb to the olfactory tract and then to the forebrain  CN II- Optic Nerve Optic nerve Function: Special Sense- Vision Fibers travel from the retina of the eye through the optic canal into the middle cranial fossa Some fibers cross at the optic chiasm and then continue as the optic tract  CN III- Oculomotor Nerve Function: Somatic motor and Parasympathetic Motor- to Levator palpebrae Oculomotor n. superioris (eyelid) and 4 of the 6 extraocular muscles: Superior Rectus m. Inferior Rectus m. Medial Rectus m. Inferior Oblique m. Parasympathetic- innervation of the sphincter pupillae muscle (pupillary constriction) and ciliary muscle (allows accommodation- closeup vision) Exits via the superior orbital fissure  Levator palpebrae superioris m. Superior oblique m. Superior rectus m. Medial rectus m. Inferior rectus m. Lateral rectus m. Inferior oblique m. LR6, SO4, all the rest 3 CN IV- Trochlear Nerve Function: Somatic Motor Motor to superior oblique Exits via the superior orbital fissure Trochlear n.  Function: Somatic Motor and Sensory CN V- Trigeminal Nerve Motor- to 8 muscles- 4 of which are Muscles of Mastication (chewing) Sensation- to face and general sensation to the anterior 2/3rd of the tongue Three branches: 1. Ophthalmic (V1)- Superior orbital fissure Trigeminal 2. Maxillary (V2)- Foramen rotundum ganglion 3. Mandibular (V3)- Foramen Ovale ”Standing Room Only” Trigeminal n. “Standing Room Only”  Clinical Correlation Trigeminal Neuralgia – Tic Douloureux Sensory disorder characterized by excruciating pain More common in women Usually triggered by stimulation of areas innervated by V2, V3 Chewing Brushing teeth Applying makeup Etiology is often unknown but can be caused by: Blood vessels putting pressure on nerve branches Demyelination of nerve axons Multiple sclerosis CN VI- Abducens Nerve Function: Somatic Motor Motor innervation to the lateral rectus muscle Exits via the Superior Orbital Fissure Abducent Injury to CN VI can result in n. medial strabismus of the eye (esotropia)  CN VII- Facial Nerve Function: Special Sense (taste), Somatic motor, and Parasympathetic Facial n. Sensation- Taste from anterior 2/3 of the tongue Motor- Muscles of facial expression Parasympathetic- innervation of the lacrimal gland, sublingual gland, and submandibular gland Exits the cranium via the Internal acoustic (auditory) meatus CN VIII- Vestibulocochlear Nerve Function: Special Sense (hearing and balance) Exits internal acoustic meatus (w/ CN VII) and then splits into the cochlear nerve (hearing) and vestibular nerve (balance/ equilibrium) Vestibulocochlear n.  CN IX- Glossopharyngeal Nerve Glossopharyngeal n. Function- Somatic motor, general sense and special sense (taste), and parasympathetic. Motor- fibers to stylopharyngeus muscle. Somatic sensory- to portions of the pharynx, soft palate and posterior 1/3 of tongue. Special sensation- taste to the posterior 1/3 of tongue. Parasympathetic- innervation to the parotid gland (around ear) Exits via the jugular foramen  Function- Somatic motor, sensory, CN X- Vagus Nerve and parasympathetic. Motor- soft palate, pharynx, and intrinsic laryngeal muscles. Sensory- inferior pharynx, larynx. Parasympathetic innervation- to the thorax and abdomen. Leaves the cranial fossa via the jugular foramen. Vagus n.  CN XI- Accessory Nerve Function- Somatic motor to sternocleidomastoid and trapezius muscles. Comprised of rootlets from the first 5 cervical spinal levels. The nerve travels into foramen magnum (from the spinal cord), but then leaves the cranium via the jugular foramen. Injury to CN XI- Weakness shrugging shoulders, droopy shoulder Accessory n. CN XII- Hypoglossal Nerve Function- Somatic motor Motor- Innervation of the intrinsic and extrinsic muscles of the tongue. Hypoglossal n. Hypoglossal nerve leaves the cranial fossa via the hypoglossal canal. Injury to CN XII- Ipsilateral tongue deviation (towards lesion) and atrophy rippled appearance (if chronic) Tongue innervation Anterior 2/3rd – General sensation- CN V Special sensation (taste) – CN VII- Chorda Tympani Posterior 1/3rd – General and special (taste) sensation - CN IX Motor- CN XII  J. Millard Olfactory n. (bulb shown) (CN I) Optic n. (CN II) Oculomotor n. (CN III) Abducent n. (CN VI) Trochlear n. (CN IV) Facial n. (CN VII) Trigeminal n. (CN V) Vestibulocochlear n. (CN VIII) Accessory n. (CN XI) Glossopharyngeal n. (CN IX) Vagus n. (CN X) Hypoglossal n. (CN XII) 52 Gray’s Anatomy for Students (2nd ed.), Drake et al, Figure 8.49, p. 851 J. Millard Meninges, Ventricle, Circle of Willis Meninges and spaces of the brain Epidural space – Potential space No epidural fat or venous plexus Dura mater Two layers in head Subdural space Subarachnoid Periosteal layer Dura Periosteal Arachnoid space Meningeal layer – continuous with cord dura Meningeal Pia mater mater Tightly adhered to skull, eliminating epidural mater space Skin Subdural space – Potential space Periosteum Arachnoid mater Skull Loosely attached to dura Contains arachnoid granulations – small protrusions of arachnoid through dura that absorb CSF Subarachnoid space – True space Contains CSF Contains cerebral arteries and veins Pia mater Epidural space “Saran wrap” around brain Epidural hematoma Due to trauma Occurs between skull and dura Arterial bleed required to peel tightly adherent dura from skull Doesn’t usually cross suture lines Lenticular or bi-convex shape Often, overlying fracture (70+%) – may lacerate middle meningeal artery Subdural hematoma Often from trauma, though may be very mild trauma or spontaneous Occurs between dura and brain Usually a venous bleed May cross suture lines Crescent shape No overlying fracture Subarachnoid hemorrhage May be due to trauma Usually small and can be subtle Often associated with parenchymal, epidural, or subdural bleed IV contrast may obscure Often due to ruptured aneurysm Usually larger than post-traumatic SAH High attenuation blood in the fissures and cisterns  Falx cerebri Dural reflections Diaphragma sellae Formed by the meningeal layer of the dura mater Falx cerebri Divides two hemispheres of cerebrum Falx cerebelli Divides two hemispheres of cerebellum Tentorium cerebellum Tentorium cerebellum Falx cerebelli Divides cerebrum from cerebellum Diaphragma sellae Covers pituitary gland Dural reflections on CT scan Falx cerebri Tentorium cerebelli Falx cerebelli  Tentorium cerebelli Tentorial notch Dural innervation CN V1 Anterior cranial fossa Meningeal branches of V1 (ophthalmic) CN V2 Middle cranial fossa Meningeal branches of V2 (maxillary) Posterior cranial fossa CN X (Vagus) CN X C1 – C3 C1-C3 Internal carotid arterial Anterior cerebral artery (ACA) system (anterior circulation) Arise from common carotid artery Middle cerebral (External carotid artery supplies the artery (MCA) face and scalp) Internal carotid artery (ICA) Enters calvarium through carotid canal Ophthalmic artery Passes through cavernous sinus Posterior communicating Branches artery (PCOM) Ophthalmic artery ACA Anterior cerebral arteries Middle cerebral arteries Posterior communicating arteries ICA PCOM MCA Ophthalmic a. Vertebral-basilar system (posterior Basilar a. circulation) Vertebral a. Basilar a. Vertebral a. Vertebral artery originates from subclavian artery Travels through transverse Skull base foramina of cervical spine Enters calvarium through foramen magnum Joins with contralateral vertebral Vertebral a. artery at pons-medulla junction Vertebral a. to form basilar artery Subclavian a. Subclavian art. Vertebral-basilar system (in situ) CN III Posterior cerebral a. Superior cerebellar a. Pontine as. Anterior inferior cerebellar a. (AICA) Basilar a. Posterior inferior cerebellar a. (PICA) Vertebral a. Anterior spinal a. Circle of Willis Connects the internal carotid arterial and vertebral-basilar arterial systems Provides collateral circulation for brain tissue Not everyone has a complete circle of Willis Common area for cerebral artery aneurysms Circle of Willis Ant. Cerebral a. (A2) Ant. Cerebral a. (A1) Ant. Comm. A. Internal carotid a. (Middle cerebral a.) Post. Comm. art (Middle Posterior cerebral cerebral a.) a. (Basilar a.) (Vertebral a.) Circle of Willis and optic chiasm External Carotid Artery Dural venous sinuses Major venous drainage system of the brain, meninges, calvarium, and other structures of the head. Endothelial lined channels occurring between periosteal and meningeal layers of dura mater. Lack valves All dural sinuses ultimately drains into the internal jugular veins at the jugular foramina Dural venous sinuses Superior sagittal sinus In attached edge of falx cerebri Inferior sagittal sinus In free edge of falx cerebri Great cerebral vein (Vein of Galen) Straight sinus At attachment of falx cerebri to tentorium cerebelli Formed by confluence of Great cerebral vein and inferior sagittal sinus Occipital sinus In attached margin of falx cerebelli Confluence of sinuses Occipital sinus Connecting point of superior sagittal sinus, straight sinus, and occipital sinus Dural venous sinuses Transverse sinus Transverse sinus (paired) Drains the confluence of sinuses (superior sagittal sinus, occipital sinus, straight sinus) Empties into sigmoid sinus Sigmoid Sigmoid sinus (paired) sinus Drains transverse sinus and superior petrosal sinus S-shaped Internal jugular Drains into jugular vein vein Superior petrosal sinus (paired) Superior petrosal Drains cavernous sinus sinus Drains into confluence of sigmoid and transverse sinuses Inferior petrosal sinus (paired) (Not pictured) Sigmoid sinus Drains cavernous sinus Drains into internal jugular vein Transverse Internal jugular vein (paired) Formed from confluence of sigmoid sinus and sinus inferior petrosal sinus  Cavernous sinus Cavernous sinus Internal Carotid Artery O Tom Cat Located on either side of the Oculomotor nerve body of the sphenoid bone (CN III) Trochlear nerve Receive venous flow from deep (CN IV) veins of face and ophthalmic Ophthalmic nerve veins (CN V1) Infections in face can cause Maxillary nerve (CN V2) infection in cavernous sinus and (Internal) possibly into eye (“Triangle of carotid artery Death”)- Via Ophthalmic Vein Drained by superior and inferior petrosal sinuses Sphenoid Abducens nerve sinus (CN VI) Ventricular system of the brain Lateral ventricle Cerebral aqueduct Foramen of Monro Third ventricle Fourth ventricle Ventricular system of the brain Frontal horns of the lateral ventricles Foramen of Monro Third ventricle Occipital horns of lateral ventricle Axial T2 weighted MRI Coronal T1 weighted MRI Cerebral aqueduct CSF production and flow CSF is produced in the ventricles by the choroid plexus Lateral ventricle -> Foramen of Monro -> 3rd ventricle -> Cerebral aqueduct -> 4th ventricle -> Foramina of Luschka and foramen of Magendie -> Subarachnoid space -> Absorbed by arachnoid granulations (arachnoid villi) -> Superior sagittal sinus Choroid plexus calcifications on CT (normal) Questions??