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Anatomy Made Easy “MSS” part #: 2 هذا الجزء بيشمل التفريغ الثالث والرابع Done By :Ruba Rababah Edited by: Awn Academic team Good luck Awn Subjects of this Lecture: Temporal Bone Occipital Bone Sphenoid Bone Ethmoid Bone Facial bones Nasal cavity Orbit Hyoid Bone Temporal Bone Forms the infero-lateral aspect of the skull and part of the cranial floor. Articulate with the parietal bones by Squamous suture. New **In temporal bone we have 2 lines called temporal lines one of them is superior and the other is inferior. Practically, the superior one is located more posterior & the other one is anterior-inferior , they are very important for the origin of temporalis muscle. **Although we call them temporal lines or ridges but one of them is located or jointly located at the level of the parietal bone. Temporal Bone Consists of four parts: Squamous part Mastoid part Petrous part Tympanic part two parts can be seen from the lateral view of the skull which are: the squamous and mastoid parts 1-Squamous part Very smooth and flat A rticulate with the parietal bone by Squamous suture (superiorly and posteriorly) and with the greater wing of the sphenoid bone by the sphenotemporal suture (anteriorly) P S T Zygomatic Process: New inferior to the squamas part of the temporal bone, zygomatic processprojects all the way anteriorly from thePosterior aspect of temporal bone. Articulate with theTemporal process of the zygomatic bone forming >>The ZygomaticA rch Pay attention that the temporal process is longer than the zygomatic process. New ** in zygomatic process we have 2 borders: 1- complete lateral surface 2-incomplete medial surface. * The inferior border has a ridge or elevation called mandibular elevation, it provides insertion for the ligaments that contribute in forming the tempor-mandibular joint. 2-Mastoid Part Seen in the lateral view of the skull. Located in the posterior-inferior aspect. Contains :Mastoid & styloid process. Both process are there as origin for neck muscles that go to hyoid or mandible bone. **Mastoid process: ( spongy in shape) empty bone filled with air cells ( mastoid air cells) ,located posterior inferior to the external auditory meatus . Make balance in 2 ways : sustaining the head in it’s position. بخفف وزن راسك vibration of the voice (to hear your sound) and improve (increase) the resonance and echo of the sound **They also make the bone light **they have no connection with the outside. New **Styloid process :(pin-sharp) located inferior to external auditory meatus (which is anterior to mastoid process) , and anterior to the mastoid process. كيف تتذكرها ؟ الستايلود ما بتقدر تحسه النه جاي قدام الماستويد الي بتقدر تحسه **it provides the attachment for the muscles that goes to the neck & some of them to the pharynx and mandible. E.g.. stylohyoid / stylomandibular / stylopharyngeal راح تكيف عليهم الحقا بجيهم وقتهم, ال تحفظهم هال عادي **The external auditory meatus is surrounded anteriorly & superiorly by what we call auditory or the tympanic rich. **anterior to the external auditory meatus we have a small depression called the mandibular fossa. Petrous part Triangular in shape like a pyramid _Can’t be seen laterally,Instead it can be seen from: ** Superior view (by removing the vault of the skull) - in this view the essential organs of hearing ( middle & inner ear) can be seen in the interior portion of the petrous part.In addition to the Internal acoustic (auditory) meatus for the facial nerve and other structures. Petrous portion articulates with the Lateral aspect of the body of sphenoid bone and articulates with the anterior arch of the foramen magnum (which is part of the occiptal bone). **Inferior view of the skull New **M idsagittal section of the skull: it appears in this view triangular in shape with a superior border,anterior surface and posterior surface. The anterior one is flat so it has nothing on it, whereas the posterior one has 2 openings; the internal acoustic meatus you can see it from the superior view only and the external acoustic meatus you can see it from lateral view. The end of petrousal part is lacerated; it is irregular & it contributes to form an opening which is the foramen lacerum. (In order for you to identify where is the foramen lecarum you have to go to the tip of the petrousal part of temporal bone.) New Questions that where mintioned by the Dr that might come in the exam… [ check next slide for image ] * the tip of the petrousal part of temporal bone is share with the sphenoid bone..HOW ? by foramen lacerum. عظام3 اصال هاي الفتحة مشتركة بين temporal , sphenoid , occipital * the part which is occupied anteriorly by the body of sphenoid, posteriorly by the nuchal line and laterally by posterior surfaces of petrousal part is called … ??? Posterior cranial fossa. Petrousal part of the temporal bone and the sphenoid bone foramen lacerum. Petrousal oart of the temporal bone and the occipital bone jugular foramen. Temporomandibular Joint TMJ At the level of the petrous portion It is a synovial joint with a fibrous disk between the base of the skull and the mandible;where the head –condyle- of the mandible fits in the mandibular fossa. The joint is maintained in its position by: Masticatory muscles and the Masseter muscles -which is the most powerful muscle that can cut person’s finger- Temporomandibular Joint TMJ This joint is very important for movements of Mandible including: Protrusion:forward movement Retrusion :backward movement Circumduction:slight movement of rotation * this movement occurs in all joints with a disk in between Occipital Bone L-shaped bone;similar to the frontal bone but with a different orientation of the L-shape:in the frontal it is posterior while in occipital it is anterior. The lateral aspect of the L-shape limb of the occipital bone articulate Laterally with the petrous part of the temporal bone whereas anteriorly it will articulate with the posterior aspect of the sphenoid bone. New **The small limb can be seen from posterior view, the other part which is the long limb (low horizontal limb) can be seen more clearly from superior & inferior views of skull. ** In occipital bone there are 2 lines, important for insertion of posterior neck muscles, they are very important in moving the head and enforcing the occipito-atlanto & atlanto-axial joints. **occipital bone connects to the parietal bone through lambdoid suture(the smaller-vertical limb with parietal), whereas the inferior-anterior part is connected by occipitomastoid suture with the mastoid portion of temporal bone. Occipital Bone; Posterior view You can see : _External occipital protuberance:elevation in the midsagittal line. It is at the meeting of superior & inferior nuchal lines very important for palpation _The Lambdoid suture. _The superior and inferior nuchal lines ,the superior is more important ,the inferior one is for the deep aspect muscle origin of the neck. (you can palpate the superior nuchal line, but the other line is more inferior and anterior.) New External occipital protuberance if you go back in your head & press more posterior you will see very smooth areas in the right & left sides of the midline and in the midline you will see an elevation called external occipital proturberance. External occipital crest The superior nuchal line is immediately in the same line with occipital proturberane where the crest join the 2 lines. The 2 lines connecting from left & right in the midline and going all the way inferior & anterior forming the external occipital crest which is an elevation. **This crest ends in an opening called foramen magnum Occipital Bone; Superior view Foramen Magnum :an opening through which the medulla oblongate,brain stem, spinal cord,and midbrain will pass. [ High yield point ]Lateral to this foramen there are two openings which are the Hypoglossal canals through which the hypoglossal nerve passes. Also you can see grooves (indentations) for venous drainage >> drain blood from the New lateral & anterior to this foramen there are 2 articular processes called occipital condyle, they articulate with the first cervical vertebra which is atlas, usually these condyles are different in shape depending on the atlas, age of a person, and the maturation of them. **Anterior to the condyle the magnum is complete and there is an important process called pharyngeal process, practically it is the beginning of raphe which act as origin and insertion for pharangyal muscles New . in this area we have the superior, middle and the inferior pharyngeal muscles, these muscles make the lateral & medial walls of the pharynx, so pharynx is not an organ, it is a muscular organ. ** So the raphe of the upper part of that connection will originate in pharyngeal tubercle - somehow it’s similar to linea alpa is an aponeurosis which is a fusion of the external, internal & transverse muscles in the middle line Repeated from previous lec There are portions of the frontal bone that make the roof of the eye,underneath them we have the eye,between these portions we have a protrusion of the ethmoid bone (crista galli ) lateral to crista galli there is the cribriform plate where the; perpendicular plate (forms the superior portion of the nasal septum). Sphenoid Bone The key stone (elements) in the skull; articulates with all other cranial bones and keep the skull integral. (if you take it out, every thing will fall apart) From the anterior or posterior view; sphenoid appears as a butterfly or bat shaped that spans the width of the middle cranial fossa ,having : Two ears: represent the lesser wings Two wings :represent the greater wings Body located in the middle;it is empty; thus called sphenoid sinus >> it opens into the nose. Two Legs: represent the pterygoid processes ( medial &Lateral): project from the inferior part of the sphenoid bone they provide insertion for the muscles of the larynx and pharyngeal muscles (especially the superior & middle constrictor muscle); **between the lateral and medial processes, there is pterygoid fossa which has lots of innervations. Major markings : Sphenoid bone –Superior view You can see only Body,greater and Lesser wings. the body of the sphenoid is indented;these indentations are called Sella turcica ,with t:two limitations : *anterior limitation >> tuberculum sellae) *posterior limitations >>(dorsum sellae) the dorsum sellae ends laterally by 2 processes, one on the left and one on the right and these are called the clinoid processes, they are very important in the pharynx. * we have posterior and anterior clinoid process; The anterior clinoid process is at the medial end of the border of the lesser wing of sphenoid . New **Sella is a small wall that hosts or covers the anterior & posterior aspect of the sella turcica. The sella in this manner is a portion of this bone that is elevated like a crest but it is not, it is shorter and thicker than the crest. **The lesser wing of the sphenoid is more anterior and superior ( and is lateral to the body) rather if you compare it with the greater (bigger) wing of the sphenoid. There is the groove for the middle meningeal artery which is a dangerous area in the lateral trauma of the head. In the superior aspect of the skull: You can see that Sella turcica Contains a depression, this Depression is different from one person to another in shape, depth & width and it is measured according to certain measurement, it could be ovale,rounded .. and so on . It is called “Hypophysial fossa”. Avimportant endocrine gland resides in it that is called “Hypophysis pitutary gland” . Lateral to the sella turcica there are the wings: Lesser wings:small,articulate with the posterior aspect of the frontal bone limb which is very thin. G reater wings:deeper & wider and contain 3 important foramen >>> Foramen of the greater wing of sphenoid bone: (medially) they are oriented from anterior to posterior,toward the lateral aspect (respectively( : ( ROS ) o foramen rotundum(most anteriorly( o foramen ovale o foramen spinosum(spine in shape, longest) In the superior view of the skull you can notice these structures: A foramen called (foramen lacerum) it’s bordered by the anterior part of the temporal bone (petrous part) and the sphenoid. Another foramens situated at the level of the base of the lesser wings called ( the optic foramens),they are the point of ligation between the lesser wings and the body of the sphenoid. **the optic foramen communicates the middle cranial fossa with the eyes, and you can see it only from superior view. High yield point - Inferior orbital fissure : * Seen only from ant * Part of maxillary bone - superior orbital fissure : * seen from ant & post * part of sphenoid bone ( greater wing ) - the lesser wing contain the optic Canal New Foramen lacerum : located within the greater wing of the sphenoid. So, the greater wing of sphenoid & the lateral posterior portion of the body of the sphenoid & the tip of petrous part of the temporal bone will meet in one point deficit way and they will leave an opening Lacerated opening called foramen lacerum.. Sphenoid bone – inferior view of the skull : only the inferior portion of the greater wing of the sphenoid,and the two pterygoid processes will be shown The inferior portion of the sphenoid body can’t be seen from the inferior aspect, instead we’ll see the vomer (part of the nasal septumwhich articulates with the anterio-inferior aspect of the sphenoid.) New **Clinically: Sometimes patient come to you and say that he is hearing his pulsation from his ear while he is at silent space region or sitting down with himself at night!! … why?? The carotid canal hosting the carotid artery ( it is big artery) and the pulsation of the heart is transmitted through it into the brain, and this canal has a relationship with the internal ear, so you hear the pulse. Important structures to be seen in the inferior view of the skull: the limb of the L of the occipital bone contains two condyles (occipital condyles :they articulate with the two masses of the atlas bone (the first vertebra). carotid canal and the jugular foramen,which are located behind each other:located more posteriorly in the skull just anterior and lateral to foramen magnum (petrousal part of the temporal bone and the carotid canal within it.) Foramen magnum. Lateral to the occipital condyles we have 2 openings they are shared depressions completed by the third part of the temporal (petrousal part), these are the jugular foramen through which the jugular vein passes into the neck New The lesser wing of the sphenoid bone articulates with the horizontal plate of the frontal bone and a portion of the ethmoid bone forming the anterior cranial fossa. **posterior border of this fossa you will see the posterior border of lesser wing of sphenoid but you don't see the frontal bone. So.. we have anterior & posterior cranial fossa but in the middle of cranium because we have the body of the sphenoid bone & it is huge elevated superiorly; we have 2 middle cranial fossa in which the temporal loop of the brain resi frontal loop, and we have cerebellum. in neonatal skull there is a lack of fusion in frontal bone, it is a matter of overlapping of these bones so that will ease the birth process. ** u can see an incomplete continue in frontal bone, Because we have some parts of ethmoid bone that protrude within the anterior cranial fossa. New the anterior cranial fossa is communicated with nose through olfactory foramina; ** although it is not a real connection, but the olfactory foramina allow the nerves that come from the mucosa that covers the superior aspect of the nose to pass through them into the pulp. The pulp will form a tract called olfactory tract that will go all the way to the anterior aspect of the medial side of the greater wing. pharyngeal tubercle : an elevation of the occipital bone to which a very thin connective tissue rim goes all the way down and provides the origin for the pharyngeal muscles which are triangular in shape. initiate what we call the common tendon of the pharyngeal muscle (superior ,middle and inferior constrictor muscles) . It is very important and it’s there only to initiate the origin of the pharyngeal muscles that will go anteriorly so the superior constrictor will ligate to the medial plate of the pterygoid process (remember that the pterygoid processes will provide insertion for the muscles). Ethmoid bone -شكلها مثل حرف التي part of the nasal cavity,and part of the facial bones.. But this is debatable. Forms most of the bony area between the nasal cavity and the orbits. It is the most deep of the skull bones;it lies between the sphenoid and nasal bones. It has a T- shape (2 parts a vertical and a horizontal one), the vertical T part (you can see small part of it) extends above within the cranial fossa giving us a very sharp rim:Crista galli.; Crista galli :(small part penetrates the horizontal plate) located between the two very thin plates of the limb of the frontal bone that makes the roof of the nose ). There are 2 depressions lateral to crista galli called olfactory bulp. We can see part of the vertical plate when we look at the anterior view of the skull. In the lateral aspect of the horizontal plate there are the lateral masses of the ethmoid bone which have sinuses called ethmoid air sinuses New The lateral part of the horizontal plate is called cribriform plate( perforated plate) , it has a lot of openings called olfactory foramina ( foramena is the plural of foramen). Major markings : plays a role in the separation of the nasal cavity (nasal septum). Superoor view of the skull: What we can see from the ethmoid bone ? crista galli and the cribriform plates. Facial bones “14 bones “ All the facial bones are paired bones except for the Mandible and Vomer which are Unpaired. Maxillary bone Zygygomatic Lacrimal Nasal bones (the nasal septum divides the cavity into two parts) Palatines Inferior chonchae Mandible Vomer New **The facial bone ligate with the cranium by : 1- Frontal process of the zygomatic bone and zygomatic process of the frontal bone 2- Maxillary process of frontal bone and frontal process of maxilla 3- Zygomatic process of the temporal bone and temporal process of the zygomatic bone (zygomatic arch) ****NOTE :the facial expression muscles don’t pass joint and it give us the expression of our face . Maxillary bone The -facial keystone (main bone of the facial bones), located in the middle of the face. articulate with all other facial bones,except mandible medially fused bones (2 fused bones) that make up the upper jaw ,the openings of the naris and the central portion of the facial skeleton. participates in forming the floor, border and walls of the orbit,part of the lateral wall of the nasal cavity and in forming the floor of the nose and the roof of the mouth. New The nasal opening (external nares) is made only by the medial border of the maxilla which ends anterio-inferior by the nasal spine. Inferior to the spine you can see the alveolar elevations which contains openings for teeth embedded in it. (when you put your fingers one in the nose the other in the mouth and press against each other you’ll notice that it’s only one bone;the maxilla) Maxillary bone : Has a huge body , frontal process of the maxilla which will articulate with the frontal bone. Within this bone we have articular surface that articulates with the zygoma,because of its small size some books call it articular surface others call it a process >> “Zygomatic process”. (the maxilla has 4 processes two with frontal and another two with zygomatic.) Has an anterior border which contains grooves which are called alveolar processes,they represented by the teeth which are imbedded in these alveoli. ( Posterior in this alveolar process there is rounded protrusion called tuberosity. ) Major markings include: palatine,frontal and zygomatic processes,the alveolar margins, inferior orbital fissures and the maxillary sinuses. New In the posterior aspect of the body , inferior to zygomatic process there is a line through this line there is a canal which is called perforating posterior dental canal. the palatine process of the maxilla and the palatine bone form 2 things: the floor of the nose and the roof of the mouth. Inferior and anterior to the zygomatic process there is depression called canine fossa. The maxilla has two faces: 1-the superior face is oblique surface which is the orbital surface seen only from the orbit. 2-the anterio-lateral surface is smooth surface. New This is the inferior view, you can see the palatine process of the maxilla almost separated by a sulcus , sometimes it could be opened in a genetical disorder called cleft palate which resultes from failure of fusion along the line from the incisive foramen until the palatine bone. New In a medial view of the maxilla you can see the roof of the mouth, the floor of the nose and the maxillary sinus which is the biggest sinus participating in resonance of the sound. major markings include superior alveolar processes are located at the inferior border of the maxillary bone Zygomatic bone Irregularly shaped,very smooth bones (cheekbones),that form the prominences of the cheeks and the infero-lateral margins of the orbits . The body of the zygomatic has two processes: temporal and frontal,but sometimes we have another process (very small one) that articulates with the maxilla called anteriorly maxillary process Anterior to this articular surface there is an opening (infra orbital foramen) through which the infra orbital nerve “the trigeminal branch (second division of the trigemini) will go above and innervate the muscles of the superior lip. The zygomaticofacial foramen is in the middle of this bone. The Mandible bone The mandible (lower jawbone) is the largest,strongest bone of the face. But according to the Drit is not considered a facial bone Its major markings include the coronoid process, mandibular condyle,the alveolar margin, and the mandibular and mental foramina Teeth are embedded in the alveolar processes of the mandible. Major Markings of Mandible bone More about the mandible New It articulates with the temporal bone posteriorly. It has two parts: vertical part called rami(plural of ramus) and horizontal part which is U-shaped . The mandibular angle is where the ramus meets the body of mandible, it's easily palpated .The ramus is very smooth in the lateral aspect, it has three borders: Anterior border: very smooth and rounded. Posterior border: Sharper than the anterior. Superior border: it has a notch; this notch is called the mandibular notch **Anterior to the notch there is the coronoid process of the mandible. Posterior to the notch there is articular surface or process which is mandibular condyle, it has head (enter the articulation with the mandibular fossa), neck and body. **The masseter muscle is inserted in the posterior margin of the mandible , and it will take insertion again from the lateral smooth surface of the body, the lateral surface has ridges to provide the attachment . New cont about the mandible The body of the mandible has a superior margin and inferior margin, the inferior margin is important because: 1- it's palpable. 2- The facial artery passes there in the middle between the mandibular angle and the chin, its pulsation can be felt here. **The alveolar processes are same like in the maxilla In the medial surface, you can see the mandibular foramen, it's limited superior and anterior by a ridge called the lingula of the mandibular ramus. ** Inferior to the mandibular foramen there is the mylohyoid groove, where the mylohyoid muscle originates from New Cont about the mandible **Continue to the medial aspect of the body of the mandible, there is the mylohyoid line continues along the ramus to the body and divides the body to submandibular fossa and sublingual fossa and their glands reside in these fossae. **In The anteriolateral surface, there is the mental foramen. Anterior to the foramen there is the mental tubercle, it's deeper in some people and it resultes from fusion of two bones like in the maxilla. Other Facial bones: Nasal bones – thin medially fused two bones that form the bridge of the nose. Lacrimal bones – contribute to the medial walls of the orbit and contain a deep groove called the lacrimal fossa that houses the lacrimal sac. Palatine bones – two bone plates (vertical and horizontal) that form portions of the hard palate,the posterolateral walls of the nasal cavity, and a small part of the orbits. Vomer – plow-shaped bone that forms part of the nasal septum Inferior nasal conchae – paired,curved bones in the nasal cavity that form part of the lateral walls of the nasal cavity. New [ High yield points ] The inferior chonchae is a separate bone while the superior and middle chonchae are parts from the ethmoid bone. The roof of the mouth composed of the palatine bone and the palatine process of the maxilla , anteriorly you can see the alveolar processes of the maxilla .the maxilla goes up to meet a process from the frontal bone in the middle . And there the nasal bones which are separate bones (they are two). New More about the palatine bone The horizontal plate of the palatine bone articulates with the posterior palatine process of the maxilla, the lateral of palatine there are pterygoid plates which come in contact with the inferior of the sphenoid. The palatine nerve passes through the greater palatine foramen which is located Medial to the maxilla tuberosity. It has many processes serve as attachment for many muscles in the pharyngeal and tongue. There are many depressions in the lateral wall of the nasal cavity. Smokers have accumulation of mucous in these depressions and this is dangerous Nasal cavity The nasal septum is made by the 1-Vomer (forms the medial wall of the nose and articulates with the inferior portion of the perpendicular plate of the ethmoid bone) 2-perpendicular plate of the ethmoid 3-The septal cartilage. This septal cartilage will separate the naris. (which extend from the external nasal openings into the internal nasal openings toward the pharynx (nasopharynx) Lateral wall of the nasal cavity Composed of : The lateral masses **“ talk about them in the next slide” ** of the ethmoid bone (superior and middle nasal concha ). The perpendicular plate of the palatine bone. The inferior nasal choncha (doesn’t belong to ethmoid bone). ** Medial surface of the lateral masses will form the lateral wall of the nose. This medial surface has protrusions(shell like projection) the chonca,underneath them we have meatuses >> into which the nasal, ethmoid,maxillary,frontal and the sphenoid sinuses open into. These shell like projections (chonca) function to : Increase the area of contact of the air with the nasal mucosa,to prevent entering of the dust particles. Modulate the temperature of the air (cooling or heating),and that is because of the highly vascularized epithelium that covers the nasal cavity from the inside. Trap the foreign particles by hair follicles present in the nose. Floor of the nasal cavity: formed by hard plate ( palatine process of the maxillae and the palatine bone) Roof the nasal cavity ,very small : formed by the cribriform plate of the ethmoid Para-nasal Sinuses Mucosa-lined, air-filled sacs found in five skull bones – the frontal, sphenoid, ethmoid, and paired maxillary bones Air enters the paranasal sinuses from the nasal cavity and mucus drains into the nasal cavity from the sinuses Lighten the skull and enhance the resonance of the voice The orbit A Bony cavity in which the eye are firmly encased and cushioned by fatty tissue. Formed by parts of seven bones – ( frontal,sphenoid, zygomatic,maxilla, palatine,lacrimal,and ethmoid). The orbital cavity looks like a room, it has a roof,floor,lateral, medial and posterior wall.(but no anterior wall) The Superior border(Roof)of the Orbit is made entirely by the: The limb (the orbital plate) of the frontal) :which is a very thin material A small part is made by the lesser wings of the sphenoid because it articulates with the posterior aspect of the limb of the frontal bone and participate in forming what we call the superior wall. The Inferior border(Floor)of the Orbit made by the zygomatic and maxillary bones The Lateral borderof the Orbit made by: greater wing (part of it in the posterior*) of the sphenoid bone inferior extension of frontal bone Orbital surface of zygomatic bone The Medial border of the Orbit made by : The lacrimal bone. The lateral surface of the lateral masses of the ethmoid The body of the sphenoid. Small part of the maxilla and palatine process (the vertical area of the palatine) also participate. The posterior W all the Orbit has two fissures: superior and inferior orbital fissures, ** superior orbital fissure :between the greater and lesser wings. ** Medial and inferior to the apex of this superior fissure we have the optic foramen,and inferior to that we have the inferior orbital fissure. Hyoid Bone Not actually part of the skull, but lies just inferior to the mandible in the anterior neck Only bone of the body that does not articulate directly with another bone. Attachment point for neck muscles that raise and lower the larynx during swallowing and speech