skeletal system part 2 the axial skeleton

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Skeletal system part 2 the axial skeleton. Honors Anatomy & Physiology. Essential Question. What is the main contribution the axial skeleton makes to homeostasis?. Divisions of the Skeleton. AXIAL SKELETON Skull Cranium Face Hyoid Auditory Ossicles Vertebral Column Thorax . - PowerPoint PPT Presentation


Skeletal system part 2 the axial skeleton

Skeletal systempart 2the axial skeletonHonors Anatomy & PhysiologyEssential QuestionWhat is the main contribution the axial skeleton makes to homeostasis?

Divisions of the SkeletonAXIAL SKELETONSkullCraniumFace HyoidAuditory OssiclesVertebral ColumnThorax APPENDICULAR SKELETON:Pectoral GirdleUpper LimbsPelvic GirdleLower LimbsTypes of Bonebones fall into 1 of 5 main types based on shape:Long ShortFlatIrregular Sesamoid

Long Boneslonger than they are widemay be slightly curved (to absorb stress of weight at more points along the bone i.e. straight bones would fracture more easily)consist of:shaft & variable #s of endscompact bone in diaphysis and spongy bone in epiphysis

Long Bones

Short Bonessomewhat cube-shapednearly equal in length as widthconsist of:spongy bone except @ surfaceShort Bones

Flat BonesComposed of:2 nearly parallel plates of compact bone enclosing spongy bone insideFunction:give considerable protectionplace for muscle attachment

Flat Bones

Irregular Bonescomplex shapes (do not fit in other categories)vary in amt spongy bone

Sesamoid Bonesdevelop w/in certain tendons where there is considerable friction, tension, & physical stressfunction: protect tendon from excessive wear & tearvary in # person to person but everyone has 2 patella which develop in quadriceps femoris tendonSesamoid Bone

Sutural Bonesclassified by location (w/in a suture: a seam between 2 cranial bones)not everyone has them

Bone Surface Markings2 major types:depressions & openingsform joints or allow passage of vessels & nervesprocessesprojections or outgrowths that either help form joints or serve as attachment points for ligaments & tendonsBone Surface Markings

Bone Surface Markings-2

Axial skeleton


Skull 22 bones in 2 categories:Cranium8 bones that form cranial cavity1 frontal bone2 parietal bones2 temporal bones1 occipital bone1 sphenoid bone1 ethmoid bone

Skull 2. Facial Bones14 bones that form the face2 nasal bones2 maxillae1 mandible2 zygomatic2 lacrimal2 palantine2 inferior nasal conchae1 vomer

Skull: CavitiesCranial CavityNasal CavityOrbitsParanasal SinusesMiddle & Inner Ear CavitiesCavities of the Skull

Movable Joints of the SkullMandibleAuditory Ossicles

Functions of Cranial Bonesprotecting brainstabilizing position of brain, vessels, & nerves through attachments to the meningesouter surfaces provide large areas of attachment for muscles that move parts of the head & some for facial expressionCranial Bones: Frontal Boneforms: foreheadupper part of eye socketmost of anterior part of cranial floorin newborns: rt & lt which fuse shortly after birthFrontal Bone

Parietal Bonesform greater portion of sides & roof of cranial cavity

Temporal Bonesform inferior, lateral aspects of the cranium & part of the cranial floorits zygomatic process forms the lateral half of the zygomatic archmandibular fossa: where condylar process of mandible forms TMJ (temporal mandibular joint)Temporal Bones

Temporal Bonesexternal auditory meatus: ear canalmastoid: posterior & inferior to external auditory meatus, contains air cells (mastoiditis: inflammation in air cells)

Temporal Bone: Petrous Portionbase of skull between sphenoid & occipital boneshouses middle & inner earCarotid foramen & Jugular foramen

Temporal Bonesinternal auditory meatus: passage of Cranial nerves VII (facial n.) and VIII (vestibulocochlear n.)styloid process: point of attachment for muscles & ligaments of the tongue & neck

Temporal Bone: Internal Surface

Occipital Boneforms back of head & most of base of skullforamen magnum: large hole spinal cord passes thru, occipital condyles: articulate with 1st cervical vertebra (atlas)Occipital Bone

Sphenoid Bonemiddle base of skull*articulates with all other cranial bonesshape resembles a bat

Sphenoid Bonesella turcica: (Turkish saddle) the seat of the saddle is the hypophyseal fossa: where the pituitary gland sitsoptic foramen: between body & lesser wings, cranial nerve II (optic n.) and opthlamic artery pass thru

Sphenoid Bone

Ethmoid Bonelike a sievemidline of anterior part of cranial floor, anterior to sphenoid, posterior to nasal bonescribiforme plate: forms roof of nasal cavity, the holes of the sieve where olfactory nerves pass from roof of nasal cavity to braincrista galla: triangular process which serves as pt of attachment for meninges of brainEthmoid Bone

Ethmoid Boneperpendicular plate: forms superior portion of nasal cavitysuperior & middle nasal conchae: (or turbinate) increase vascular & mucous membrane surface area in nasal cavities: aids in sense of smell, warms, filters & moistens air being inhaled. Filters because the turbinates cause air to swirl as a result inhaled particles strike & become trapped in mucus

Ethmoid Bone

Sometimes when you study anatomy, you start seeing others differently.

Facial Bonesshape of face changes dramatically during 1st 2 yrs of life: brain & cranial bones expand1st set of teeth eruptparanasal sinuses enlargegrowth of face stops ~16 years oldFacial Bones14 facial bones:2 nasal bones2 maxillae2 zygomatic bones1 mandible2 lacrimal bones2 palatine bones 2 inferior nasal conchae1 vomerNasal Bonesform part of the bridge of the nose (rest is cartilage)

Maxillae= upper jaws*articulate with every bone in face except the mandibleform part of floor of orbits, parts of nasal cavity, & most of the hard palate (bony roof of mouth)each one has large maxillary sinusalveolar process is small arch that contains the alveolar sockets for upper set of teethMaxillae

Cleft Palate & Cleft Lip10-12 wks gestation the palatine processes of maxillae typically joinnot doing so cleft palate +/- cleft lipspeech & swallowing can be affectedmany ear infectionsreparative surgery recommended 1st few wks of life / surgery needs to be completed by 12 18 mos b/4 speech: speech therapy & orthodontic care frequently necessary

Zygomatic Bonescheekbones: the temporal process of the zygomatic bone articulates with the zygomatic process of the temporal bonealso part of floor of orbit

Lacrimal Bonesthin, about the size of pinky fingernail (smallest bones of facepart of medial wall of each orbiteach contain lacrimal fossa that houses lacrimal sac: gathers tears nasal cavity

Inferior Nasal Conchaeinferior to the middle nasal conchae of the ethmoid bone forming part of lateral wall of nasal cavitysame function as superior & middle conchae: swirling inhaled air to deposit particulates but not involved in sense of smell

Vomer shaped bone on the floor of nasal cavity forming inferior portion of nasal septum

Mandible largest & strongest facial bone (lower jaw)alveolar processes hold lower teeth socketsmental foramen: dentist numb mental nerve

Sutures an immovable joint in an adult found only between skull bones & holds most skull bones togethername generally reflects bones they unite


Newborn Skull

Newborn Skull

Hyoid Bone U-shaped *does not articulate with any other bone in skeletonsuspended by ligaments from styloid process of temporal bonein anterior neck between mandible & larynxfunction: supports tongue*frequently fractured during strangulationHyoid Bone

Vertebral Columnaka spine, backbone2/5 of persons height26 in adult (starts as 33, some fuse to form sacrum & coccyx)7 cervical12 thoracic5 lumbar1 sacrum1 coccyx

Vertebral Column

Fetus has anteriorly concave curve3 mos old when holds head cervical curve developslumbar curve develops as infant sits up, stands, walksIntervertebral Discsbetween bodies of consecutive vertebraunder compression they flatten & broadenharden, less elastic w/aging & narrow loss of heightannulus fibrosus: outer fibrous ringnucleus pulposus: inner soft, highly elasticIntervertebral Discs

Parts of a VertebraBodythicker, anterior portion, weight bearing portionVertebral Foraminacontains spinal cord, adipose, areolar CT, blood vesselsSpinous Process1 of 7 processes, posterior, palpable on back of bodyTransverse Processes: on each side, extending laterally

Vertebrae: 1st & 2nd Cervical Atlasring-shapedarticulates with condyles of occipital boneallows you to nod head yesAxis 2nd cervical v.allows you to shake head no

Typical Cervical VertebraeC-3 to C7smaller than other v. except coccyx but vertebral foramen largestall cervical v. have extra foramen: 2 transverse foramen for vertebral a., v., & n.

Typical Thoracic VertebraeT-1 to T-12larger & stronger than cervical v.distinguishing feature: articulate with ribs (facets on transverse processes of T-1 to T-10

Typical Lumbar VertebraeL-1 to L-5largest & strongest of the vertebraeprocesses are short & thick

Sacrum triangular bone formed by union of S-1 to S-5fusion begins ~16, complete by age 30female: shorter, wider, more curved S-2 to S-3

Coccyxsmall triangleformed by fusion of 4 coccygeal v. (Co-1 to Co-4), start between 20 & 30females points inferiorly; males it points anteriorly

Thoraxrefers to entire chestskeletal part of thorax is thoracic cageSternumRibs

Sternumaka breastboneflat bone in center of anterior thorax3 bones that fuse by age 25

SternumManubriumsuperior portionsuprasternal notchclavicular notchesarticulates with costal cartilage of 1st & 2nd ribsternal angle: where it articulates with body

Sternum2. Bodymiddle & largest portionarticulates with costal cartilage of 2nd thru 10 ribs

Sternum 3. Xiphoid Processcartilagenous


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