Anatomy Made Easy MSS

Transcription

1 Anatomy Made Easy MSS part #1 هذا الملف يشمل تفريغ المحاضرة الثانية لعون بدءا من الصفحة 11 وحتى األخير Done By :MohamedA. Diabat Edited by Awn Academic team

2 The Axial Skeleton The axial skeleton consist of 80 Bones, segregated to :- 1. The Skull 2. Vertebral coloumn 3. Thorax

3 The Skull

4 1.The Skull Body s most complex bony structure Consist mainly of two groups of bones : 1. The cranium bones :- More posterior and superior,designed for the protection of the brain and site of attachment for head and neck muscles. Cranial bones are thin flat bones,remarkibly strong for their weight. 2. Facial bones :- more anterior and inferior

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6 The cranial bones consist of :- 2 Parietal bones 2Temporal bones one Frontal bones one Occipital bone :- can be seen from lateral and posterior aspect,but most of it is seen from superior and inferior aspect of the base of the skull. Sphenoid bone,can be seen from the superior & inferior aspects of the base of the skull, Laterally, we can only see the greater wing of sphenoid Ethmoid bone :- can be seen from the anterior aspect of the skull and from the superior when we look from the inferior aspect of the base of skull.

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11 Facial bones 1.Supply the framework of the face, the sense organs, and the teeth 2. Provide openings for the passage of air and food. 3. Anchor the facial muscles of expression.

12 Neonatal Skull Is the skull formed during intrauterine life and persists till the age of 3-4 years. C haracterized by fontanels which are gaps between the bones of the skull covered by connective tissue. In the course of delivery,these fontanels will allow easier delivery by overlapping. *Has the same number of bone in adult skull, but not mature yet.

13 Neonatal fontanel In the lateral view of neonatal skull,you can see: The sphenoidal fontanel :- Occurs at the junction of frontal bone,the squamous part of the temporal bone,the parietal bone and the greater wing of sphenoid bone. Mastoid fontanel :- occur at the junction between occipital bone,the parietal bone and the mastoid portion of the temporal bone.

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16 At the superior view of the skull there is :- Anterior Fontanel :- At the junction between the frontal bone and 2 parietal bones. Posterior fontanel :- which occurs at the junction between the two parietal bones & the occipital bone.

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19 The importance of fontanels in some clinical aspects Normally,they must be flat. If you see a bulging fontanel,then this means that this baby has an increase in the intra-cranial pressure which might be caused by the accumulation of the intra-cranial fluid. Whereas,if you see a depressed fontanel,then this means loss of fluid and dehydration.

20 All of these fontanels will close after birth but in different periods, as follows: 1. Usually the posterior and mastoid fontanels close at the age of 6 months. 2. The sphenoidal fontanel usually closes at the age of 9 months. 3. The anterior fontanel usually closes after 1 year and sometimes persists until 2 years old and thus It s the biggest and major fontanel of the neonatal skull.

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22 After 3-4 years,the bones will ligate together and form immovable joints called sutures,and they are like intercalated bones. Coronal suture Between parietal bones and frontal bone. Sagittal suture Between right and left parietal bones. Lambdoid suture Between parietal bones and occipital bone. Squamous suture Between parietal and temporal bones.

23 Also, we have : 1- a mastoid suture 2- a sphenoid suture or a sphenotemporal suture (between sphenoid bone and the squamous portion of temporal bone).

24 In addition to the previous sutures, there are very small sutures called Sphenoid sutures.

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26 Frontal bone Frontal bone & occipital bone are L-shaped bones. Articulates posterior with the parietal bones via the coronal suture Major markings include the supra-orbital margins, the anterior cranial fosse, and the frontal sinuses (internal and lateral to the glabella) The roof of the orbital cavity is made of the horizontal aspect of the frontal bone. Forms the anterior portion of the cranium (the roof ). Also, We can't see it from the inferior border of the skull

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28 Frontal bone is mainly two parts: Frontal squama of the frontal bone. An indented part(horizantel) near the top of the orbital cavity. Has two important Process :- Zygomatic process, that goes to Zygomatic bone, and it s lateral. Maxillary process, goes to the maxilla and it s medial. There is a suture between frontal bone and maxilla called frontomaxillary or frontonasal suture

29 REMEMBER It is important to differentiate between the zygomatic process of the frontal bone & the frontal process of the zygomatic bone. The first one is a part of the frontal bone whereas the second one is a part of the zygomatic bone.but both of them are ligated to each other. The same goes for the maxillary process of the frontal bone and the frontal process of maxilla.

30 Supraorbital margin is important clinically, WHY?! Because it has the Supraorbital notch and there is a Supraorbital nerve passes through this notch.this nerve is the most superficial nerve in the body. This nerver is important in HYS syndrome (hysteria),in this syndrome the patient ( usually females) come performing the act of unconsciousness.so you press on the nerve and suddenly he will feel the pain and awake.

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32 there s also a Supraorbital foramen in which usually a Supraorbital artery passes through. Sometimes, the supraorbital nerve goes through the supraorbital foramen. But most of the times, it goes through the notch not the foramen.

33 Glabella is a smooth and depressed area in the middle aspect between the two maxillary processes of the frontal bone. From the superior view of Frontal bone,you can see that the transverse portion of the frontal bone is divided by the presence of the ethmoid bone (cribriform plate and crista galli) in the middle. You can see that the cribriform plate is perforated,why?! Because Post-ganglionic axons of the olfactory nerves go through the cribriform plate and perforate it

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35 LateralView of the skull The greater wing of the sphenoid bone is seen in the lateral view of the skull and is a very important part,because medial to it there is an artery called middle meningeal artery. Accidents in this side of skull is very dangerous,because its relatively thin and fractures may lead to cut in the Middle MeningealArtery which may lead to intracranial hemorrhage.

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38 Sphenoid bone is called the keystone bone of the cranium By its greater wing, it ligates the frontal, parietal and squamous portion of the temporal bone. And in the middle,it ligates the frontal, occipital and temporal bone.

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41 Parietal bones Parietal bones are two flat bones that :- Ligated to each other in the middle by Sagittal suture. Ligated to Frontal bone anteriorly by coronal suture. Ligated to Occipital bones posteriorly by Lambdoid suture. Ligated to Temporal bone laterally by Squamous suture Also, we have Parietosphenoidal suture with sphenoid

42 Each Parietal bone usually has one line or two (pointed by arrows in next picture). These lines provide the insertion for Temporalis muscle and the lateral aspect of fronto-occipitalis muscle.

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44 Temporal Bone In the lateral view,you can see the ear which is made of the temporal bone. Temporal bone has three parts :- 1. Squama of the temporal bone,thin and flat. 2. Mastoid Portion, posterior and inferior. Within this portion, there s a process called Mastoid process which is characterized by the presence of air cells.

45 Air cells which are found in the mastoid process are emptiness through the bone and have two main functions: 1. To reduce the weight of the skull. 2. Important for the resonance of the voice and thus clarifying the voice. Anterior to mastoid process there is Styloid process,(pen-shaped process) which is important for the insertion of many muscles such as stylohyoid muscle.

46 3. Petrous part of the temporal bone (The arrow in 2 ND picture) - this portion cannot be seen laterally. It is a triangular elevation of the temporal bone that goes toward the medial line.

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51 External auditory meatus (external acoustic meatus) An opening between mastoid process and styloid process. The portal to the middle ear. Ends in what s called the tympanic membrane.from there on, there will be the middle and the inner ear. This portion of the bone continues toward the medial line and there it s called the petrous part of the temporal bone. External ear is made of a cartilaginous structure and external auditory meatus.

52 To see the middle and the inner ear you have to remove the petrous portion of the temporal bone. The temporomandibular joint is formed by the temporal bone and the mandible. The temporal bone provides what s called mandibular fossa. Anterior to temperomandibular joint.you can see the zygmoatic process of the temporal bone which goes to articulate with the temporal process of the zygomatic bone to form the zygomatic arch.

53 Zygomatic arch forms the cheeks which are beauty characteristic of humans.

54 Posterior view of the Skull The posterior view is occupied by the parietal bones. T he occipital bone is an L-shaped bone like the frontal bone.i.e.,it has a portion that s horizontal and another one that s posterior. The posterior potion is smooth except in the inferior aspect of this portion, you can see two lines which are more prominent than the lines present in the lateral aspect of the parietal bone.these lines are the superior and inferior nuchal lines. They provide insertions for the muscles of the neck and back.

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56 These lines goes to the middle and then they form a protuberance (a smooth elevation) called external occipital protuberance. This protuberance is an important landmark for the middle of spinous processes of the cervical bones and used in anesthesia,surgery & dissection.

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58 The two horizontal portions of the frontal bone are not fused << This allows the ethmoid bone to be seen from the superior aspect. Actually,you will not be able to see the cribriform plate in real life,because lateral to crista galli,you will see the olfactory bulbs.after you remove the olfactory bulbs and all their innervations, you can see the perforated cribriform plate.

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60 Crista galli is the upper portion of the perpendicular plate of ethmoid bone which goes down to form the nasal septum.

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