Transcribed Audio Physii.pdf

CONTRACTION OF SKELETAL MUSCLE: How Res6ng Membrane Poten6al is Developed - SEPT. 3, 2024 When we talk about RMP, we pertain to NERVE & MUSCLE. Net rate of diﬀusion is enhanced, Na+ K+ pump is a Primary AcEve Transport. when there is greater o 3 Na+ out (more + ions move out; + deﬁcit) concentra4on. o 2 K+ In o Results in/End Results: ConcentraEon gradient, Electrochemical gradient, Na+ as major EC caEon, K+ as major IC caEon. NET RATE OF DIFFUSION: 1. All molecules move because of KineEc energy – this makes diﬀusion happens. 2. This kineEc energy brings about net movement if there is concentraEon gradient The eﬀect of diﬀusion: Equilibrium “No net movement” Leak Channels – this are pores that are “non-gated” “Leak” – remember that there are now more Na+ outside * K+ inside. a. Sodium Leak Channels o DirecEon: Towards the cell b. Potassium Leak Channels o DirecEon: Outward the cell c. "the membrane at rest is more permeable to K+" ➡ Membrane potenEal becomes more negaEve. d. Inside the cell we have proteins produce by the ER & Ribosomes. Proteins are negaEvely charge, contributes to the membrane potenEal. THE RMP OF NERVE AND MUSCLE Membrane at rest is their proﬁle: a) Muscle RMP -90 mV b) Nerve RMP -70 mV If we try to s6mulate… Three types of sEmuli a) Electrical (Tense: Transcutaneous nerve) b) Chemical (Acetylcholine) c) Mechanical (Tap of Patellar tendon) The cell membrane is not anatomically connected, it a result of the chemical characteris6cs of the phospholipid por6on. It is composed of two parts (hydrophilic head, hydrophobic tail). ECF- water, ICF water. So the tails hide away from water, and the head associates with water. Pag nag break ang cell membrane, there will be a connec6on between the ECF & ICF. Once that happens, It will be more posi6ve… All-or-None Principle o Threshold S;mulus (-55 mV) - a sEmulus that brings about acEvaEon of acEon potenEal or a sEmulus of a threshold potenEal. Voltage-gated Channels 1. Na+ Voltage-Channels (fast) 2. K- Voltage-Channels (slow) Change in the voltage, will bring M gate : AcEvaEon N gate: potassium about ac4va4on of this channels. channels H gate : InacEvaEon STAGES OF ACTION POTENTIAL: 1. ResEng stage is the "Polarized Stage" RMP 2. DepolarizaEon "membrane is depolarized" because of Na+ Inﬂux. 3. RepolarizaEon K+ is slightly leaking; and once H gate is inacEvated the K+ gate opens totally. K+ Eﬄux 4. HyperpolarizaEon - K+ gates are sEll open resulEng from a more negaEve charge inside kaya nagkakaroon ng "overshooEng" Absolute Refractory Period - All gates are open. Not gonna entertain no maier how strong the sEmulus. Rela;ve Refractory Period - Bumabalik na siya sa RMP, so we can have another acEon potenEal. Impulse Conduc;on: PropagaEon of the impulse. One membrane to another. NERVE IMPULSE CONDUCTION...movement from dendrite to cell body...and axons away from the body.. 1. If there is AP happening here, there is propagaEon of AP. 2. If neurons are myelinated (faster conducEon), courtesy of Schwann Cells, there is what we call saltatory conducEon (node to node). TERMINAL KNOB - EXCITATION OF MUSCLE MOVEMENT Neuromuscular juncEon (Motor Relay) “Electrical conduc6on : Anatomic con6nuity is needed. Occurrence is "electrical in nature" "There will only be an electrical conduc6on, when there anatomic con6nuity." RELEASE OF NEUROTRANSMITTER 1. Ca+ more abundant in the ECF 2. Ca+ Inﬂux occurs, creaEng an increase in the ICF. 3. In terminal knob, there are Ach. vesicles, also there are SNARE proteins. o V-snare: Synaptobrevin (vesicle membrane) o T-snare: Syntaxin & SNAP 25 (pre- synapEc membrane) 4. Fussion of Acetylcholine to Synaptotagmin = Calcium binds in this area. The vesicles now increase in aﬃnity to the presynpaEc membrane. 5. When calcium binds in the Ach, lalapit siya papunta pre-synapEc membrane. Magkakaroon ng "docking" 6. The synaptotagmin will have a "zipper like interac;on" with Syntaxin & SNAP 25 in the presynap;c membrane. 7. In the process of exocytosis Ach (neurotransmiier) will be released 8. You now have the Ach release into the synapse ng neuromuscular juncEons. 9. In the post synapEc membrane, we have caEon channels. 10. Since we have Ach in the synapse, it will bind with the receptor in the caEon channels. o Fate of Ach: Diﬀuse, reuptake, or degrade o Kaya hindi nagtatagal si Ach sa synapse. Why? Baka magkaroon ka ng rigor morEs. Since yung iba nag bind sa Acetylcholine-gate of the caEon channels (chemical-ligand gate). o 5 subunits of Ach-gate: Two alpha, beta, deta, gamma. o The alpha subunits have NICOTINIC RECEPTORS. Why? Because neurotransmiSers aSach only to their speciﬁc receptors. o When Acetylcholine binds with the nico6nic receptors of the alpha subunit -- conforma6onal change occurs & the ca6on channel (gate) will open. o Once mag open, ano ng mapupunta sa loob? Calcium and Sodium. Both are ca6ons, kaya mag momove sila inside. o Nung pumasok siya nagchange ang RMP from -90 mV, so nag increase at naging posiEve. o What is the end product? End-plate poten;al. NEUROMUSCULAR JUNCTION - SEPT. 8, 2024 Target organs (1) Skeletal Muscle (2) Visceral Contents/Organs 📌 “In itself nagkakaroon ng connec6ons ang mga structures in the body for it to be able to communicate and transmit impules, otherwise, walang mangyayari sa mga muscles na6n, walang kukurap..” Synapse - An area where one structure communicates with another, so it must be composed of structures. Commonly the synapse is a neuron, and the next structure is a neuron. - Kaya sinasabi na6n na “axo-dendri6c” Dendrite - Movement of impulses from the dendrites towards the cell body Electric impulses - from cell body to axons (away from the cell body) 📌 “Once the electrical impulses reach the terminal knob. No electrical ac6vity will happen, because there must be an anatomic con6nuity.” - So once nasa terminal knob na yung impulse paano na niya ma- tratransmit yun sa eﬀector organ/target organ? - CHEMICAL CONDUCTION TAKES PLACE. - This happens in the synapse. Electrical conduc;ons happen: Descending pathway - From the center to the periphery Sensory pathway - Periphery towards the center; a receptor is sEmulated Innerva;ons: Skeletal – SomaEc Nervous System Smooth & Cardiac – Autonomic Nervous System “Two neuron Pathway: First order neuron --- Second order neuron (there should be a synapse). How sila mag communicate if di sila magkadugtong? Yan na pumapasok si neurotransmiSers, the chemical impulse. “ NEUROMUSCULAR JUNCTIONS o Target muscles: Skeletal Muscles (RMP = - 90mV) o Motor neuron & Skeletal Neuron = Neuromuscular JuncEon 1. The TERMINAL KNOB communicates with a SINGLE MUSCLE FIBER called SARCOLEMMA. 2. The area where the terminal knob communicates with the membrane of the sarcolemma = MOTOR END PLATE. Terminal Knob, SynapEc Clet, Post-SynapEc Membrane or the MOTOR END PLATE SNARE PROTEINS - NARE stands for SNAP receptor - SNAP stands for soluble NSF aiachment protein - NSF stands for N-ethylmaleimide sensiEve factor a. V-snares: Vesicular Membrane - SYNAPTOBREVIN b. T-snares: Target Membrane/Pre-synapEc Membrane – SNAP 25 & SYNTAXIN “This is your Ach vesicle, this is what we call a protein which has a component of IIC-A & IIC-B” SYNAPTOTAGMIN - Responsible for the binding of Ca2+ ; Synaptotagmin has been proposed to funcEon as a Ca2+ sensor that regulates synapEc vesicle exocytosis "Traﬃcking" the movement of the vesicle is followed by the movement of proteins kinesin, dymins, and myosin. These are your traﬃcking - kung saan siya dumadaan sa pre-synap6c. Link – Titherin” 1. DOCKING: v—snares and t-snares have interacEon/fusion. 2. PRIMING: It repairs the synapEc vesicles, so they can fuse rapidly in response to Ca2+ inﬂux 3. FUSION – Ach vesicles in the pre-synapEc membrane 4. EXOCYTOSIS ANATOMY – HEAD AND NECK REGION The head is the superior part of the body aiached to the trunk by the neck. It is the control and communica;ons center as well as the“loading dock of the body” It includes: Special sensory receivers (eyes, ears, mouth, nose) o Broadcast devices for voice and expression o Portals for intake of fuel, water, and O2 and the exhaust of CO2 It consists of the brain and its protecEve coverings, the ears, and the face The face includes: openings and passageways, with lubricaEng glands and valves the masEcatory devices orbits that house the visual apparatus THE CRANIUM The cranium (skull) is the skeleton of the head Cranial cavity: space containing the brain Skull vault (calvarium): upper part of the cranium and forms the roof and side walls of the cranial cavity Composed of 22 bones, a series of which forms two funcEonal parts: 1. Neurocranium - 8 bones 2. Viscerocranium - 14 bones ⟶ Neurocranium - The bony case of the brain and its membranous coverings o Consists of 8 bones Frontal 1 Bones forming the Occipital 1 FLAT BONES calvaria Parietal 2 Temporal 2 Bones forming the Sphenoid 1 IRREGULAR BONES basicranium Ethmoid 1 ⟶ Viscerocranium (Facial Skeleton) - Mainly develops in the mesenchyme of the embryonic arches. o The anterior part of the cranium o Consist of 14 bones, 2 are unpaired 12 Bones of Viscerocranium (paired) 2 Bones of Viscerocranium (unpaired) Inferior nasal conchae Mandible Maxillae - aiached to facial bones via TMJ Nasal bones Vomer PalaEne bones - separates let and right nasal opening Lacrimal bones ZygomaEc bones ⟶ Frankfurt Plane/ Orbitomeatal Plane - Skull is oriented so that the inferior margins of the orbits and the superior margin of the external acous;c meatus (ear canal) are horizontal. ⟶ Sutures of the Skull ⟶ Craniometric Points of Cranium Pterion - where frontal, parietal, and temporal bones meet (FPT) o H-shaped connecEons; o A neurosurgical landmark, an access to Circle of Willis Asterion - fusion of zygomaEc part, temporal bone, mastoid part, occipital bone, and parietal bone; ( o star-shaped ⟶ Base of the Skull Lowest part of the cranium and forms the ﬂoor of the cranial cavity Bones of the vault form via membranous ossiﬁcaEon, while the bones of the cranial base and the facial skeleton form via endochondral ossiﬁcaEon Membranous ossiﬁca;on: ossiﬁcaEon via the acEvity of osteoblasts Endochondral ossiﬁca;on: ossiﬁcaEon with the carElaginous planes A. Facial Aspects of the Cranium The squamous part of the frontal bone forms the skeleton of the forehead, arEculaEng inferiorly with the nasal and zygomaEc bones Metopic Suture: remnant of a frontal suture that persists in adults Found in the middle glabella, the smooth, slightly depressed area between the superciliary arches Frontal suture divides the frontal bones of the fetal cranium 📌CLINICAL IMPLICATIONS: A. Sunken Fontanelles: DehydraEon B. Bulging Fontanelles: Increase intracranial pressure or increase CSF 📌BONES OF THE FACIAL ASPECTS OF THE CRANIUM Nasion - intersecEon of the frontal and nasal bones Supraorbital margin - angular boundary between the squamous and orbital parts Supraorbital foramen (notch) - for passage of supraorbital nerve and vessels Zygoma;c bones (cheek/malar bones) - lie on the inferolateral sides of the orbits and rest on the maxillae Zygoma;cofacial foramen Piriform aperture - inferior to nasal bone; the anterior nasal opening in the cranium Nasal Septum - divides nasal cavity into right and let part Nasal conchae - curved, bony plates on the lateral wall of each nasal cavity Maxillae - form the upper jaw Alveolar processes - includes the tooth sockets (alveoli) and consEtute the supporEng bone for maxillary teeth Intermaxillary suture - unites the two maxillae Infraorbital foramen - inferior to each orbit for passage of the infra-orbital nerve and vessels Mandible - U-shaped bone with an alveolar process that supports the mandibular teeth B. Lateral Aspects of the Cranium Formed by the neurocranium and viscerocranium Main features of the neurocranial part § Temporal fossa § The external acousEc meatus opening § The mastoid process of the temporal bone Main features of the viscerocranial part § Infratemporal fossa § ZygomaEc arch § Lateral aspects of the maxilla and mandible C. Posterior/Occipital Aspects of the Cranium Composed of the: Occiput (back of head), parts of the parietal bones, mastoid parts of the temporal bones 📌BONES OF THE OCCIPITAL CRANIUM External occipital protuberance: easily palpable in median plane Inion (nape of neck): craniometric point at the Ep of the external protuberance External occipital crest - descends down from the protuberance toward the foramen magnum, the large opening in the basal part of occipital bone Superior nuchal line - superior limit of neck, extends laterally from each side of the protuberance Lambda suture - juncEon of the sagiial and lambdoid sutures D. Superior Aspect of Cranium - Oval in form, broadens posterolaterally at the parietal eminences Coronal Suture: separates frontal and parietal bones Sagieal Suture: separates parietal bones Lambdoid Suture: separates parietal and temporal from occipitall bones Bregma: craniometric landmark formed by the intersecEon of the sagiial and coronal sutures Vertex: most superior part of the calvaria E. External Surface of Cranial Base Features the alveolar arch of the maxillae, the palaEne processes of the maxillae and the palaEne sphenoid, vomer, temporal, and occipital bones. Includes: a) Hard palate (bony palate) o Posterior nasal spine b) Incisive foramen Superior to the posterior edge of the palate are two large openings: Choanae (posterior nasal apertures)- separated from each other by the vomer, a ﬂat bone of trapezoidal shape that forms a major part of the bony nasal septum. 📌Sphenoid a. Bueerﬂy-shaped bone wedged between the frontal, temporal, and occipital bones b. Three pairs of processes: greater wing, lesser wing, and pterygoid processes c. Orbital temporal, and infratemporal surfaces d. Cerebral surfaces are seen in internal views of the cranial base e. The pterygoid processes, extend inferiorly o Medial pterygoid muscle: close the mouth o Lateral pterygoid muscle: open the mouth F. Internal Surface of Cranial Base - Has 3 large depressions: the anterior, middle, and posterior cranial fossae Foramina and Apertures Cranial Nerves a. CNI - Olfactory nerve b. CNII - OpEc nerve c. CNIII - Oculomotor nerve d. CNIV - Trochlear nerve e. CNV - Trigeminal nerve ▪ CNV1 - Ophthalmic nerve ▪ CNV2 - Maxillary nerve ▪ CNV3 - Mandibular nerve f. CNVI - Abducens nerve g. CNVII - Facial nerve h. CNVIII - VesEbulocochlear nerve i. CNIX - Glossopharyngeal nerve j. CNX - Vagus nerves k. CNXI - Accessory nerve l. CNXII – Hypoglossal 📌Anterior Cranial Fossa Frontal crest - median bony extension of the frontal bone At its base is the foramen cecum of the frontal bone Crista galli - a thick, median ridge of bone posterior to the foramen cecum, which projects superiorly from the ethmoid On each side of this ridge is the cribriform plate of ethmoid bone o Cribriform plate houses the olfactory bulb (CNI), in charge of sense of smell 📌 Middle Cranial Fossa Tuberculum sellae - elevaEon forming the posterior boundary of the prechiasmaEc sulcus and the anterior boundary of the hypophysial fossa Hypophysial fossa (pituitary fossa) - median depression in the body of the sphenoid that accommodates the pituitary gland Dorsum sellae (back of saddle) - square plate of bone projecEng superiorly from the body of the sphenoid Sella turcica - saddle-like bony formaEon on the upper surface of the body of the sphenoid Hypophysial fossa - deepest part that houses the pituitary gland 📌Posterior Fossa Clivus- center of the anterior part of the fossa leading to the foramen magnum o Foramen magnum: exit of the brainstem Posterior to this large opening, the posterior cranial fossa is partly divided by the internal occipital crest into bilateral large concave impressions, the cerebellar fossae The internal occipital crest ends in the internal occipital protuberance G. Walls of the Cranial Cavity 📌The Bueress System The buiresses are thicker porEons of cranial bone that transmit forces around weaker regions of the cranium Main bueresses o Frontonasal bueress - extends from the region of the canine teeth between the nasal and the orbital caviEes to the central frontal bone o Zygoma;c arch – lateral orbital margin buiress - from the region of the molars to the lateral frontal and temporal bones. H. Regions of the Head I. Clinical Applica;ons and Special Topics 📌 Le Fort Fractures a. Le Fort I - fracture above the alveolar processes of the maxilla below the nasal aperture b. Le Fort II (pyramidal fracture) - fracture starEng from the zygoma going up the inferior orbital ring, passes medially towards the zygoma and the nasal bones and on the quadrilateral side; most common Le Fort fracture c. Le Fort III (Craniofacial dystosis) - skull separated from the face 📌Fractures of the Mandible A broken mandible usually involves two fractures, which frequently occur on opposite sides of the mandible Fractures of the coronoid process - uncommon, usually single (A) Fractures of the neck - oten transverse and may be associated with dislocaEon of the TMJ on the same side (B) Fractures of the angle - usually oblique and may involve the bony socket or alveolus of the 3rd molar tooth (C) Fractures of the body - frequently pass through the socket of a canine tooth (D) 📌Infant Skull Anterior Fontanel - Diamond-shaped, because the frontal bone and parietal bones are yet to fuse - Located at the juncEon of the sagiial, coronal, and frontal sutures, the future site of bregma Posterior Fontanel - Triangular-shaped, bounded inferiorly by the occipital bone and superiorly by parietal bones - Located at the juncEon of the lambdoid and sagiial sutures, the future site of lambda 📌Den;;on Teeth that are about to erupt Milk teeth, bound to be replaced by permanent teeth - Middle central incisor - ﬁrst tooth to erupt at around 6 mos. - 3rd molar/wisdom tooth - last to erupt at around 17-25 y.o/18-26y.o 📌Sinuses Make the skull light and is important in immunity (helps in eliminaEng 4 SINUSES bacteria because they contain secreEons with lysozymes) o Frontal o Ethmoid Warms and humidiﬁes the inhaled air o Sphenoid o Maxillary Acts as crash guards 📌Cranial Malforma;on Scaphocephaly o Elongated cranium due to premature closure of the sagiial suture, in which the anterior fontanelle is small or absent, results in a long, narrow, wedge-shaped cranium Plagiocephaly o o Flat cranium due to premature closure of the coronal or lambdoid suture occuring on one side only; the cranium is twisted and asymmetrical Oxycephaly o Conical-shaped cranium due to premature closure of the coronal suture results in a high, tower- like cranium FACE AND SCALP A. THE SCALP 5 Layers of Scalp (S-C-A-L-P) I. Skin: thin, except in the occipital region, contains many sweat and sebaceous glands and hair follicles II. Connec;ve ;ssue: forms the thick, dense, richly vascularized subcutaneous layer that is well supplied with cutaneous nerves III. Aponeurosis: broad, strong, tendinous sheet that covers the calvaria and serves as the aiachment for muscle bellies converging from the forehead and occiput (occipitofrontalis muscle) and from the temporal bones on each side (temporoparietalis and superior auricular muscles) IV. Loose areolar ;ssue: sponge-like layer including potenEal spaces that may distend. This layer allows free movement of the scalp proper over the underlying calvaria V. Pericranium: dense layer of connecEve Essue that forms the external periosteum of the neurocranium B. MUSCLES OF THE FACE AND SCALP Muscle of Facial Expression - Muscles of the Scalp, Forehead, and Eyebrow Occipitofrontalis - ﬂat digastric muscle, with occipital and frontal bellies that share a common tendon (epicranial aponeurosis) Because the aponeurosis is a layer of the scalp, independent contracEon of the occipital belly retracts the scalp and contracEon of the frontal belly protracts it AcEng simultaneously, the occipital belly, with bony aiachments, work as a synergist with the frontal belly, which has no bony aiachments, to elevate the eyebrows and produce transverse wrinkles across the forehead Muscles of the Mouth Cheek and Lips Orbicularis oris – one of the sphincters associated with the alimentary system, encircles the mouth within the lips, controlling the entry and exit through the oral ﬁssure Buccinator - thin, ﬂat, rectangular muscle that aiaches laterally to the alveolar process of the maxillae and alveolar part of the mandible, opposite the molar teeth; aka the “trumpeteers muscle” Modiolus: ﬁbers of 9 facial muscles merge in a highly variable and mulEplanar formaEon o Largely responsible for the of dimples in many people Platysma: broad, thin sheet of muscle in the subcutaneous Essue of neck o AcEng from its superior aeachment, the platysma tenses the skin, producing verEcal skin ridges, conveying great stress, and releasing pressure on the superﬁcial veins o AcEng from its inferior aeachment, the platysma helps depress the mandible and draw the corners of the mouth inferiorly, as in a grimace Muscles of the Orbital Opening - Orbicularis Oculi - Palpebral part - Lacrimal part - Orbital part C. NERVES OF THE FACE AND SCALP Cutaneous (sensory) innerva;on of the face and anterosuperior part of the scalp is provided primarily by the TRIGEMINAL NERVE (CNV) ⟶ 3 branches: a. Ophthalmic branch - innervates structures of the eye b. Maxillary branch c. Mandibular branch Motor innervaEon to the facial muscles is provided by the FACIAL NERVE (CNVII) ⟶ The 5 branches are the (The Zombie Bit My Cat) a. Temporal b. ZygomaEc c. Buccal d. Marginal mandibular e. Cervical TRIGEMINAL NERVE (CN V) The sensory nerve for the face and the motor nerve for the muscles of masEcaEon and several small muscles The ﬁrst two divisions (ophthalmic and maxillary nerves) are wholly sensory. 📌 4 Major muscles of mas6ca6on: a. Masseter muscle - the largest and the strongest; closes the mouth b. Temporalis muscle - closes the mouth c. Medial pterygoid muscle - closes the mouth d. Lateral pterygoid muscle - opens the mouth Olfactory Receptor Nerves - special mucosa in the nasal cavity; traverse towards the cribriform plate and arises from the olfactory bulb o Anosmia - inability to small (if olfactory nerves are damaged) OPHTHALMIC NERVE V1 The superior division of the trigeminal nerve, is the smallest of the three divisions of CN V Enters the orbit via the superior orbital ﬁssure Trifurcates into the frontal, nasociliary, and lacrimal nerves o Lacrimal nerve: smallest branch from the trifurcaEon of CN V1 MAXILLARY NERVE Leaves cranium through foramen rotundum The zygomaEc nerve runs to the lateral wall of the orbit, giving rise to two of the three cutaneous branches of CN V2, the zygoma;cofacial and zygoma;cotemporal nerves MANDIBULAR NERVE The inferiormost and largest division of the trigeminal nerve Emerges from the foramen ovale The major cutaneous branches of CNV3 are the auriculotemporal, buccal, and mental nerves 📌Motor Nerves of Face Temporal and zygoma;c branches (ability to blink, close the eyes) must be preserved - if eyes are not closed, the cornea may dry and may lead to keratoconjunc;vi;s (ﬁnal sequelae: blindness) The motor nerves of the face are the facial nerve to the muscles of facial expression and the motor root of the trigeminal nerve/mandibular nerve to the muscles of mas;ca;on: o masseter, temporal, medial, and lateral pterygoids The superior division of the trigeminal nerve, is the smallest of the three divisions of CN V Enters the orbit via the superior orbital ﬁssure Trifurcates into the frontal, nasociliary, and lacrimal nerves FACIAL NERVE CN VII, the facial nerve, has a motor root and a sensory/parasympatheEc root The motor root of CN VII supplies the muscles of facial expression, including the superﬁcial muscle of the neck (platysma), auricular muscles, scalp muscles, and certain other muscles Emerges from the cranium through the stylomastoid foramen located between the mastoid and styloid processes 3 major salivary glands: - ParoEd gland - largest gland - Submandibular gland - second largest - Sublingual gland - below the tongue The ﬁrst marking is the mark of inferior mandible, with 1 ﬁngerbreadth below is the marginal mandibular nerve - measure 2 ﬁngerbreadths for the incision to avoid damage of the nerve. D. SUPERFICIAL VASCULATURE OF FACE AND SCALP Most superﬁcial arteries of the face are branches or derivaEves of branches of the external caroEd artery 📌Facial Artery Provides the major arterial supply to the face It arises from the external caro;d artery and wind its way to the inferior border of the mandible, just anterior to the masseter The facial artery crosses the mandible, buccinator, and maxilla as it courses over the face to the medial angle (canthus) of the eye, where the superior and inferior eyelids meet The facial artery sends branches to the upper and lower lips (superior and inferior labial arteries), ascends along the side of the nose, and anastomoses with the dorsal nasal branch of the ophthalmic artery Distal to the lateral nasal artery at the side of the nose, the terminal part of the facial artery is called the angular artery 📌Superﬁcial Temporal Artery The smaller terminal branch of the external caroEd artery; the other branch is the maxillary artery The superﬁcial temporal artery emerges on the face between the temporomandibular joint (TMJ) and the auricle, enters the temporal fossa, and ends in the scalp by dividing into frontal and parietal branches 📌Transverse Facial Artery Arise from the superﬁcial temporal artery within the paroEd gland and crosses the face superﬁcial to the masseter approximately a ﬁnger’s breadth inferior to the zygomaEc arch It divides into numerous branches that supply the paroEd gland and duct, the masseter, and the skin of the face. It anastomoses with branches of the facial artery Supra-orbital and supratrochlear arteries, branches of the ophthalmic artery, accompany nerves of the same name across the eyebrows and forehead The supra-orbital artery conEnues and supplies the anterior scalp to the vertex 📌Mental Artery The only superﬁcial branch derived from the maxillary artery, accompanies the nerve of the same name in the chin - Teeth (one side from center) central incisors - lateral incisors - canine – premolar – molar if with wisdom tooth - Number: § right to let maxilla = tooth #1 to tooth #16 § let mandible to right mandible = tooth #17 to tooth #32 e.g. tooth #17 = 3rd molar, tooth #4 = 2nd premolar, tooth #12 = 1st premolar 📌Arteries of the Scalp The arterial supply is from the external caroEd arteries through the occipital, posterior auricular, and superﬁcial temporal arteries and from the internal caroEd arteries through the supratrochlear and supra-orbital arteries The arteries of the scalp supply liile blood to the neurocranium, which is supplied primarily by the middle meningeal artery 📌External Veins Most external facial veins are drained by veins that accompany the arteries of the face The facial veins, coursing with or parallel to the facial arteries, are valveless veins that provide the primary superﬁcial drainage of the face 📌Venous Drainage of Scalp The superﬁcial parts of the scalp - through accompanying veins of the scalp arteries, the supra- orbital and supratrochlear veins. The superﬁcial temporal veins and posterior auricular veins drain the scalp anterior and posterior to the auricles, respecEvely. The posterior auricular vein oten receives a mastoid emissary vein from the sigmoid sinus, a dural venous sinus. The occipital veins drain the occipital region of the scalp. Venous drainage of deep parts of the scalp in the temporal region is through deep temporal veins, which are tributaries of the pterygoid venous plexus Signiﬁcance: Mastoid emissary veins can harbor infec6ons - pa6ents with o66s media (chronic infec6on of the ear) suﬀers from occipital abscess - bacteria lodges in the said vein 📌LymphaEc Drainage of the Scalp One disadvantage: cancers can metastasize through lymphaEc system Lymph nodes are compartmentalized from 1 to 7 All lymphaEc vessels from the head and neck drain directly or indirectly into the deep cervical lymph nodes, a chain of nodes mainly located along the IJV in the neck - Jugular vein sits alongside with caro6d artery - Internal jugular vein + caro6d artery + vagus nerve = caroEd sheath Lymph from these deep nodes passes to the jugular lymphaEc trunk, which joins the thoracic duct on the let side and the IJV or brachiocephalic vein on the right side Lymph from the lateral part of the face and scalp, including the eyelids, drains to the superﬁcial paro;d lymph nodes Paro6d gland has two lobes (superﬁcial and deep) which is transected by the facial nerve Lymph from the deep paroEd nodes drains to the deep cervical lymph nodes. Lymph from the upper lip and lateral parts of the lower lip drains to the submandibular lymph nodes. Lymph from the chin and central part of the lower lip drains to the submental lymph nodes E. SURFACE ANATOMY OF FACE Glabella - protrusion in between the eyebrows Suprapalpebral sulcus - the line above in the palpebra (eyelid); *supra = above Dorsum of nose: ○ Nasion - bony segment that connects the frontal bone to the nasal bone ○ Rhinion - carElaginous segment that connects nasal bone to nasal carElage Apex of the nose - most pointed Naris - opening Philtrum - groove comes about the septum to upper lip Labial commissure - sides of the lips Vermillion border - boundary of mucosa and skin The epicanthal fold (epicanthus) is a fold of skin that covers the medial angle of the eye in some people, chieﬂy Asians. The cheek is separated from the lips by the nasolabial sulcus, which runs obliquely between the ala of the nose and the angle of the mouth The lower lip is separated from the mental protuberance (chin) by the mentolabial sulcus F. CLINICAL IMPLICATIONS 1. Paralysis of the facial muscles – called Bell’s Palsy a. Usually caused by upper respiratory tract viral infecEon 2. Trigeminal Neuralgia - “algia” means pain; “neuro” means nerve a. A painful nerve in the trigeminal part b. Treated with steroids, pain medicines, etc. 3. Cephalhematoma vs. Caput Succedaneum a. Cephalhematoma : conﬁned to only a single bone within the periosteum b. Caput Succedaneum – above the periosteum THE CRANIAL MENINGES Protect the brain. form the supporEng framework for arteries, veins, and venous sinuses. Enclose a ﬂuid-ﬁlled cavity, the subarachnoid space, which is vital to the normal funcEon of the brain. LAYERS OF THE DURA MATTER 📌External Periosteal Layer 📌Internal Meningeal Layer of Dura Mater a. Falx cerebri (cerebral falx) b. Tentorium cerebelli (cerebellar tentorium) c. Falx cerebelli (cerebellar falx) d. Diaphragma sellae (sellar diaphragm) MR Venogram MR stands for MagneEc Resonance It is more speciﬁc in outlining the vessels o Angiogram = outlining the arteries Emissary Veins: connect the dural venous sinuses with veins outside the cranium The types of Emissary Veins 1. Frontal Emissary 2. Parietal Emissary 3. Mastoid Emissary 4. Posterior Condylar Emissary THE BRAIN The body's controller and coordinator of almost all of its funcEons Delicate structure that is enclosed in a rigid cranium Composed of the cerebrum, cerebellum, and brainstem o Cerebrum: largest part involved in motor, sensory o Cerebellum: small brain concerned with balance o Brainstem: concerned with breathing, circadian rhythm, heart rate, pulse rate When the calvaria and dura are removed, gyri (folds), sulci (grooves), and ﬁssures (cle9s) of the cerebral cortex are visible through the delicate arachnoid-pia layer 📌Flow of CSF in the brain Come (Choroid plexus) Let (Lateral vent) Me (Monroe foramen) Treat (Third vent) Students (Sylvian aqueduct) For (Fourth vent) Lunch (Luschka & Mamaya Magendie foramen) Sa (Subarachnoid space) Andoks (Arachnold villi) ANATOMY – THE EYE AND ORBITAL REGION 😆 Fun Facts The human eye is 576 megapixel Corneas are the only Essues that don't require blood You blink about 10,000 Emes per day All babies are born colorblind and eventually see the color red ﬁrst It is impossible to sneeze with eyes open. Pupils dilate when looking at something pleasant. EYES The eye is the organ of vision and consists of the eyeball and the op;c nerve. The orbit contains the eyeball and its accessory visual structures The orbital region is the area of the face overlying the orbit and eyeball and includes the upper and lower eyelids and lacrimal apparatus. 📌Accessory Visual Structures Eyelids, which bound the orbits anteriorly, controlling exposure of the anterior eyeball. Extra-ocular muscles, which posiEon the eyeballs and raise the superior eyelids. Nerves and vessels in transit to the eyeballs and muscles. Orbital fascia surrounding the eyeballs and muscles. Mucous membrane (conjunc;va) lining the eyelids and anterior aspect of the eyeballs, and most of the lacrimal apparatus, which lubricates it The base of the orbit is outlined by the orbital margin, which surrounds the orbital opening. The superior wall (roof) is approximately horizontal and is formed mainly by the orbital part of the frontal bone. Near the apex of the orbit, the superior wall is formed by the lesser wing of the sphenoid. Anterolaterally, a shallow depression in the orbital part of the frontal bone, called the fossa for lacrimal gland (lacrimal fossa), accommodates the lacrimal gland. 📌The quadrangular pyramidal orbit: a base, four walls, and an apex The medial walls of the contralateral orbits are essenEally parallel and are formed primarily by the orbital plate of ethmoid bone, along with contribuEons from the frontal process of the maxilla, lacrimal, and sphenoid bones. Anteriorly, the medial wall is indented by the lacrimal groove and fossa for lacrimal sac; the trochlea (pulley) for the tendon of one of the extra-ocular muscles is located superiorly. The inferior wall (orbital ﬂoor) is formed mainly by the maxilla and partly by the zygomaEc and palaEne bones. The thin inferior wall is shared by the orbit and maxillary sinus. The inferior wall is dermarcated from the lateral wall of the orbit by the inferior orbitel Tissure, a gap between the orbital surfaces of the maxilla and the sphenoid. The lateral wall is formed by the frontal process of the zygomaEc bone and the greater wing of the sphenoid. This is the strongest and thickest of the four walls, which is important because it is most exposed and vulnerable to direct trauma, Its posterior part separates the orbit from the temporal and middle cranial fossae. The apex of the orbit is at the opEc canal in the lesser wing of the sphenoid just medial to the superior orbital ﬁssure. The widest part of the orbit corresponds to the equator of the eyeball an imaginary line encircling the eyeball equidistant from its anterior and posterior poles. THE EYELID Movable folds that cover the eyeball anteriorly when closed, protecEng it from injury and excessive light. Keep the cornea moist through lacrimal ﬂuid. Externally covered by thin skin, and internally by palpebral conjuncEva. o Palpebral conjunc;va – a transparent mucous membrane reﬂected onto the eyeball, where it is conEnuous with the bulbar conjuncEva. It is aiached to the eyelids. o Bulbar conjunc;va - thin and transparent and aeaches loosely to the anterior surface of the eyeball. It is adherent to the periphery of the cornea or to the sclera of the eyes. Conjunc;val sac – space bound by the palpebral and bulbar conjuncEvae. Palpebral ﬁssure the gap between the eyelids. Superior and inferior tarsi – strengthened by dense band of connecEve ;ssue forming the “skeleton” of the eyelids. Orbicularis oculi – sphincter of the palpebral ﬁssure. The palpebral porEon is in the connecEve Essue superﬁcial to the tarsi and deep to the skin of the eyelids. Tarsal glands – embedded in the tarsi, which produce lipid secreEons o Lipid secre;ons func;ons A. Lubricant for the edge of eyelids prevenEng them from sEcking together when closed. B. Barrier prevenEng lacrimal ﬂuid from crossing when produced in normal amounts The eyelashes (L. cilia) are in the margins of the eyelids. o The large sebaceous glands associated with the eyelashes are ciliary glands o The juncEons of the superior and inferior eyelids make up the medial and lateral palpebral commissures, deﬁning the medial and lateral angles of the eye, or canthi. ⟶ Medial palpebral ligament connects the tarsi to the medial margin of the orbit ⟶ The orbicularis oculi originates from and inserts onto this ligament. ⟶ Lateral palpebral ligament aeaches the tarsi to the lateral margin of the orbit, but it does not provide for direct muscle aiachment. Orbital Septum – ﬁbrous membrane that spans from tarsi to the margins of the orbit, where it becomes conEnuous with the periosteum. o Keeps the orbital fat contained o Limits the spread of infec;on to and from the orbit due to its conEnuity with periorbital Lacrimal gland: secretes lacrimal ﬂuid. o The ﬂuid: moistens and lubricates the surfaces of the conjuncEva and corneal and provides some nutrients and dissolved oxygen to the cornea. o Excretory ducts of lacrimal gland: convey lacrimal ﬂuid from the lacrimal glands to the conjuncEval sac o Almond shaped and approximately 2 cm long Divided into: - Superior orbital and inferior palpebral parts THE EYEBALL Contains the opEcal apparatus of the visual system. Approximately 25 mm in diameter. All anatomical structures within the eyeball have circular or spherical arrangement. ⟶ 3 Layers: Fibrous Layer, Vascular Layer/uvea/uveal tract, Inner Layer 📌Fibrous Layer a. Sclera – a tough opaque part of the ﬁbrous layer - Provides aiachment for the muscles of the eye. - The white of the eye. b. The cornea - innervated by the Ophthalmic nerve [V1] - Its nourishment is derived from the capillary beds at its periphery - The aqueous humor, and lacrimal ﬂuid - The corneal limbus is the angle formed by the intersecEng curvatures of sclera and cornea at the corneoscleral juncEon 📌Vascular Layer/uvea/uveal tract - “uvea or uveal tract” - Consists of the choroid, ciliary body, and iris. a. Choroid - a dark reddish-brown layer between the sclera and reEna, forms the largest part of the vascular layer. o Has the highest perfusion rate of all vascular beds of the body, hence, it is responsible for the “red eye” reﬂec;on that occurs in ﬂash photography. b. Ciliary Body – ring-like thickening of the vascular layer posterior to the corneoscleral juncEon that is muscular as well as vascular. § Connects the choroid with the circumference of the iris. § Provides aiachment to the lens § Controls the thickness of the lens, and therefore the focus of our vision. o Ciliary Process – secretes aqueous humor: Aqueous humor - a clear watery ﬂuid that: § Fills anterior segment of the eyeball, interior of the eyeball anterior to the lens, suspensory ligament, and ciliary body then § Drains in the canal of Schlemm. c. Iris – thin contrac;le diaphragm which lies on the anterior surface of the lens d. Pupil – the central aperture in the iris for transmi ng light. 2 involuntary muscles controlling pupil size 1. Parasympathe;cally s;mulated, circularly arranged sphincter pupillae decreases its diameter. 2. Sympathe;cally s;mulated, radially arranged dilator pupillae increases its diameter. 3. Inner Layer 📌Inner Layer Re;na - sensory neural layer. Op;c part of the re;na – sensiEve to visual light rays. Ocular fundus –focusing the light entering the eyeball Op;c disc / op;c papilla - Conveyed by the op;c nerve (CN II) enter the eyeball, and usually called the “ blind spot”. Macula –specialized for acuity of vision. Fovea centralis –area of most acute vision. NOTE: AccommodaDon – the acDve process of changing the shape of the lens for near vision. EXTRA-OCULAR MUSCLES The extra-ocular muscles of the orbit: 1. Levator palpebrae superioris 2. The 4 rec; a. Superior rectus b. Inferior rectus c. Medial rectus d. Lateral rectus 3. The 2 obliques a. Superior obliques b. Inferior obliques MOVEMENTS OF THE EYEBALL Movements of the eyeball occur as rotaEons around three axes— ver;cal, transverse, and anteroposterior RotaEon of the eyeball around the ver;cal axis moves the pupil medially (adduc;on) or laterally (abduc;on). RotaEon around the transverse axis moves the pupil superiorly (elevaEon) or inferiorly (depression). Movements around the anteroposterior axis (AP) move the superior pole of the eyeball medially (intorsion) or laterally (extorsion). ORBIT MUSCLE – CN PAIR LR6 SO4 A03 MNEMONIC - Lateral Rectus, CN VI - Superior Oblique, CN IV “LR6 SO4 A03” - All Others, CNIII Lateral Rectus, (CN VI) Superior Oblique, (CN IV) All Others, (CN III) NERVES OF THE ORBIT Op;c nerve (CNII) - convey purely sensory that transmit impulses generated by opEcal sEmuli The opEc nerves begin at the lamina cribrosa of the sclera, where the unmyelinated nerve ﬁbers pierce the sclera and become myelinated, posterior to the op;c disc. They exit the orbits via the opEc canals. Anatomy of the oculomotor (CN III), trochlear (CN IV) and abducens (CN VI) nerves a. Oculomotor nerve (CNIII) - innervates four of the six extraocular muscles - Namely the superior rectus, medial rectus, inferior rectus and inferior oblique muscle. b. Trochlear nerve (CN IV) - enables movement in the eye's superior oblique muscle. c. Abducens nerve (CNVI)- motor nerve responsible for controlling the orbital muscle lateral rectus ARTERIES OF THE ORBIT The blood supply of the orbit is mainly from the ophthalmic artery, a branch of the internal caro;d artery o The infraorbital artery, branch of the internal caroEd artery The central reEnal artery, a branch of the ophthalmic artery arising inferior to the opEc nerve, pierces the sheath of the op;c nerve and runs within the nerve to the eyeball, emerging at the opEc disc. Its terminal branches provide the only blood supply to the internal aspect of the re;na. Two long posterior ciliary arteries, one on each side of the eyeball, pass between the sclera and the choroid to anastomose with the anterior ciliary arteries to supply the cillary plexus. The external aspect of the re;na is also supplied by the capillary lamina of the choroid (choriocapillaris). Of the eight or so posterior ciliary arteries (also branches of the ophthalmic artery), six short posterior ciliary arteries directly supply the choroid, which nourishes the outer norvascular layer. VEINS OF THE ORBIT Venous drainage of the orbit is through the superior and inferior ophthalmic veins, which pass through the superior orbital ﬁssure and enter the cavernous sinus The central re;nal vein usually enters the cavernous sinus directly, but it may join one of the ophthalmic veins. The vortex, or vorEcose veins, from the vascular layer of the eyeball drain into the inferior ophthalmic vein EYE DISEASES I. COLOBOMA IRIS TEAR It can appear as a black notch of varying depth at the edge of the pupil Coloboma may be associated with hereditary condi;ons, trauma to the eye, or eye surgery. II. BLOWOUT FRACTURE OF ORBIT Lateral orbit – thickest and strongest part of the orbit Impingement (naipit) of Orbit Muscles – immovable eyes. III. RETINAL DETACHMENT Decreased vision Floaters – can be detached cells/blood IV. PAPILLEDEMA Edema (Swelling) Papilledema -swelling of the opEc disc due to elevated intracranial pressure (ICP). V. GLAUCOMA Involves eye pressure due to a ﬂuid build-up in the eye, causing damage to the opEc nerve at the back of the eye. Increase aqueous humor. Closed-angle glaucoma - occurs when the iris bulges Open angle glaucoma - trabecular meshwork isn't draining properly. VI. HYPHEMA collecEon of blood in the anterior chamber of the eye VII. SUBCONJUNCTIVAL HEMORRHAGE SubconjuncEval hemorrhage – blood in the bulbar and palpebral conjuncEva. There’s a rupture in the superﬁcial vessels of the eye. ANATOMY - THE NOSE AND PARANASAL SINUSES EXTERNAL NOSE Part of the respiratory tract superior to the hard palate and contains the peripheral organ of smell. It includes the external nose and nasal cavity The funcEons of the nose include olfacEon (smelling), respiraEon (breathing), ﬁltraEon of dust, humidiﬁcaEon of inspired air, and recepEon and eliminaEon of secreEons from the paranasal sinuses and nasolacrimal ducts. BONY AND CARTILAGINOUS FRAMEWORK The upper 1/3 part of the nose is the bony area while the lower 2/3 is carElaginous area. - Nasion – refers to the distance between frontal bone to nasal bone - Rhinion – refers to the nasal bone to nasal carElage The bony framework includes the nasal bones, frontal processes of the maxillae, the nasal part of the frontal bone and its nasal spine, and the bony parts of the nasal septum The carElaginous framework includes the ﬁve main carElages: o 2 lateral carElages o 2 alar carElages o 1 septal carElage ⟶ BONES OF THE NASAL SEPTUM/SEPTAL CARTILAGE o Vomer o Perpendicular plate of ethmoid bone o Maxillary crest o PalaEne bone ⟶ NASAL CAVITY o The roof is curved and narrow, except at its posterior end, where the hollow body of the sphenoid forms the roof. o It is divided into three parts (frontonasal, ethmoidal, and sphenoidal) o The ﬂoor of the nasal cavi;es is wider than the roof and is formed by the pala;ne processes of the maxilla and the horizontal plates of the palaEne bone. ⟶ TURBINATES (Conchae) Curves inferiomedially, hanging like louvers or short curtains from the lateral wall The inferior concha is the longest and broadest of the conchae; - formed by an independent bone covered by mucous membrane; - not part of the ethmoid bone A recess or nasal meatus (opening) underlies each of the bony formaEons The sphenoethmoidal recess, lying superioposterior to the superior concha, receives the opening of the sphenoidal sinus, an air ﬁlles cavity in the body of the sphenoid. MUSCULATURE OF THE NOSE Elevator muscle group includes: Compressor muscle group includes: - procerus muscle - transverse nasalis muscle - levator labii superioris alaeque nasi muscle Dilator muscle group includes: Depressor muscle group includes: - dilator naris muscle (expands nostrils) - alar nasalis muscle - depressor sepE nasi muscle ARTERIAL BLOOD SUPPLY NASAL CAVITY: Both external and internal caroEd artery - External caro;d artery system via the Internal Maxillary artery: o SphenopalaEne artery via sphenopalaEne foramen o Descending palaEne artery o Greater palaEne artery - Internal caro;d artery system via the Ophthalmic artery: o Anterior ethmoid artery o Posterior ethmoid artery Liele’s Area (Kiesselbach’s plexus): area where blood vessels converge; bleeds during epistaxis VENOUS DRAINAGE A rich submucosal venous plexus, deep to the nasal mucosa, provides venous drainage of the nose via the sphenopalaEne, facial, and ophthalmic veins. Cavernous sinus: danger triangle; innervated by CN III, CN IV, CN V (except V3), CN VI NERVE SUPPLY ⟶ POSTEROINFERIOR Chieﬂy from the maxillary nerve (CN V2) by way of the nasopalaEne nerve to the nasal septum Posterior superior lateral nasal and inferior lateral nasal branches of the greater palaEne nerve to the lateral wall ⟶ ANTEROSUPERIOR From the ophthalmic nerve (CN I), by way of the anterior and posterior ethmoidal nerves Branches of the nasociliary nerve Most of the external nose is also supplied by CN I, via the infratrochlear nerve and the external nasal branch of the anterior ethmoidal nerve The alae of the nose are supplied by the nasal branches of the infra-orbital nerve (CN V2) Cribriform plate of the ethmoid bone: allows passage of olfactory nerves to the roof of the nasal cavity; o damage can cause loss of the sense of smell (anosmia) OLFACTORY EPITHELIUM OSTIOMEATAL UNIT CollecEve term for various anatomical structures located about the middle meatus. o It represents the region on the lateral nasal wall that receives drainage from the anterior ethmoid cells, frontal sinus, and maxillary sinus. A narrow anatomical region consisEng of: o Mul;ple bony structures A. Middleturbinate B. Uncinateprocess C. Bullaethmoidalis o Air spaces A. Frontalrecess B. Ethmoidalinfundibulum C. Middlemeatus o Os;a (opening) of anterior ethmoidal, maxillary and frontal sinuses 📌BOUNDARIES OF OSTIOMEATAL UNIT a. Medially: middle turbinate b. Laterally: lamina papyracea c. Superiorly and Posteriorly: basal lamellae d. Anteriorly and Inferiorly: it is open 📌PARTS OF THE OSTIOMEATAL UNIT Frontal Sinus: connected to the osEomeatal unit via the frontal recess, which has an hourglass-like shape. Uncinate Process: thin ﬁbrous or bony process on the lateral nasal wall that arises slightly behind the anterior border of the middle turbinate and may narrow the passage from the nasal cavity to the osEomeatal complex, depending on its degree of development Semilunar hiatus: located between the posterior border of the uncinate process and the ﬁrst ethmoid cell (the ethmoid bulla) Ethmoid bulla: most constant and largest anterior ethmoid air cell that projects inferomedially over hiatus semilunaris Ethmoid infundibulum: space between the uncinate process, ethmoid bulla, and lamina papyracea of the ethmoid bone PARANASAL SINUSES ⟶ Func;ons of the Sinuses: Air condiEoning ProtecEon (crash guard) Lightens the skull Aids in olfacEon Resonance Cilia – ProtecEon (lysosomes)* 📌TYPES OF SINUSES 1. MAXILLARY SINUS 2. FRONTAL SINUSES Pyramidal in shape; paired & symmetric Rarely symmetrical; contained within the Located within the body of the maxilla behind frontal bone the skin of the cheek Separated from each other by a bony Roof: ﬂoor of the orbit septum Floor: related to the roots of the 2nd premolars Each sinus is roughly triangular (or fan- and 1st molar teeth shaped) Opens into the middle meatus of the nose Extending upward above the medial end of the eyebrow and backward into the medial 3. SPHENOIDAL SINUSES 4. ETHMOID part ofSINUSES the roof of the orbit Lie within the body of the sphenoid bone Below They are anterior, middle, and posterior Opens into the middle meatus sella turcica Contained within the ethmoid bone, Extends between dorsum sellae and post clinoid between the nose and the orbit processes Anterior and middle Opens into the sphenoethmoidal recess above o Drains into middle nasal meatus the superior concha Posterior o Drains into superior nasal meatus CLINICAL IMPLICATIONS Separated from the orbit by a thin plate of bone so that infecEon can readily spread Epistaxis (nosebleed) from the sinuses into the orbit RelaEvely common because of the rich blood supply to the mucosa; Kiesselbach area o Mostly caused by trauma Deviated Nasal Septum Could be the result of a birth injury, but more oten, results from trauma Severe deviaEon obstructs breathing and or exacerbates snoring Nasal Polyps Can be caused by long-term swelling and inﬂammaEon in the nose from allergies, asthma, or infecEon Nasal Bone Fracture Common facial fractures in automobile accidents and sports When the injury results from a direct blow, the cribriform plate of the ethmoid bone may also fracture

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