Presentation on theme: "Axial Skeleton: Cranial Bones"— Presentation transcript:
1 Axial Skeleton: Cranial Bones Nestor T. Hilvano, M.D., M.P.H.(Illustrations Copyright by Frederic H. Martini, Pearson Publication Inc., and The McGraw-Hill Companies Inc.)
2 Learning Objectives You should be able to: Identify the bones of axial skeleton and their functions.Identify the cranial bones including its parts and surface markings.Describe the differences among the skull of infants and children compared to adults.Define craniostenosis and discuss the consequences associated with this anomaly.
3 Overview of Skeletal System Number of bones206 in adult skeletonstart at 270 at birthRegions of the skeletonI- Axial skeleton= 80 bones1) Skull and associated bones2) Thoracic cage3) Vertebral columnII- Appendicular skeleton= 126 bones1) Pectoral (shoulder) girdle and Upper limbs2) Pelvic (hip) girdle and Lower limbs
4 Skull: Cranial Bones8 Cranial bones – frontal (1), parietal (2), occipital (1), temporal (2), sphenoid (1), and ethmoid (1)7 associated bones – auditory ossicles (6) and hyoid bone (1)
5 SuturesCalvaria (skullcap) is formed by frontal, parietal, and occipital bonesSutures:___ between the frontal bone and parietal bone.___ between the parietal bone and occipital bone.___ between the two parietal bones.___ between the parietal bone and temporal bone.a. sagittal suture b. squamous suturec. lambdoid suture d. coronal suture
6 Frontal BoneForms the anterior part of the ___________ and roof of the _________Contains frontal sinusLandmarks: frontal squama, supraorbital margin, lacrimal fossaSupraorbital foramen
7 Parietal Bone Form part of the ____ and ____ surfaces of cranium Bordered by 4 suturesLandmarks: Temporal lines for attachment of _________ muscle
8 Temporal Bone ________ wall and part of ______ of cranial cavity Consists of:a. Squamous part- zygomatic process- mandibular fossab. Mastoid processc. Styloid processd. Petrous (bone) part- houses middle and inner ear cavities- internal acoustic (auditory) meatus- jugular foramen
10 Openings in Temporal Bone Carotid canalpassage for __________arteryJugular foramenPassage for __________
11 Occipital Bone ______________ of skull Foramen magnum Skull rests on atlas (C1) at occipital condylesHypoglossal canal transmits ___________ nerveExternal occipital protuberanceNuchal lines mark neck muscles
12 Sphenoid Bone Part of the floor of the cranium Lesser wing Greater wingBody of sphenoidMedial and lateral pterygoid processes- attachment sites formuscles that move themandible and soft palate___________ sinus
13 Sphenoid Bone Body of the sphenoid Lesser wing Greater wing sella turcica (hypophyseal fossa) contains ____.Lesser wingoptic foramenGreater wingforamen rotundum and ovale for brs. trigeminal nerveforamen spinosum for meningeal artery
14 Ethmoid Bone Medial orbital wall Lateral walls and roof nasal cavity Cribriform plate and crista galliEthmoid air cells form ethmoid sinusPerpendicular plate forms _______ septumSuperior and middle Conchae on lateral wall
15 Ethmoid Bone Perpendicular plate Superior and middle of nasal septum concha
16 Skull of infants and children Spaces between unfused bones = fontanelles (fontanels)What purpose does a fontanel serve? ______.Anterior fontanel closes at 2 yrs. old.2 frontal bones fuse by age six (metopic suture)Skull reaches adult size by 8 or 9Craniostenosis – premature closure of cranial sutures
17 CraniostenosisLong and narrow head is formed by early closure of sagittal sutureBroad (tower) skull results from premature closure of coronal suture
18 Bones Associated With Skull Ossiclesmalleus, incus, and stapesHyoid bonesuspended from styloid process of skull by muscle and ligamentSupports larynx and attachment site for muscles of pharynx, larynx, and tongueBody, greater and lesser cornua (horns)Only bone in the body that does not articulate with another bone* What are the smallest bones? _____
19 Homework Describe the cranial sutures and fontanelles. Identify the cranial bones associated with the following regions or landmarks.__ temporal lines a) occipital__ sella turcica, lesser/greater wings b) frontal__ roof of orbits, bone of forehead c) parietal__ crista galli & cribriform plate d) temporal__ mastoid process, petrous bones e) ethmoid__ base of skull, foramen magnum f) sphenoidWhat is craniostenosis?The internal acoustic meatus is located in which bone?What is the content of the hypophyseal fossa of the sella turcica?
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