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Skeletal System-2. Honors Anatomy for copy. 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 . APPENDICULAR SKELETON: - PowerPoint PPT Presentation
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Skeletal System-2
Honors Anatomyfor copy
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
• APPENDICULAR SKELETON:
• Pectoral Girdle• Upper Limbs• Pelvic Girdle• Lower Limbs
Types of Bone• bones fall into 1 of 5 main types
based on shape:– Long – Short– Flat– Irregular – Sesamoid
Short Bones• somewhat cube-shaped• nearly equal in length as width• consist of:– spongy bone except @ surface
Flat Bones• Composed of:– 2 nearly parallel plates of compact
bone enclosing spongy bone inside• Function:– give considerable protection– place for muscle attachment
Irregular Bones• complex shapes (do not fit in
other categories)• vary in amt spongy bone
Sesamoid Bones• develop w/in certain tendons
where there is considerable friction, tension, & physical stress
• function: protect tendon from excessive wear & tear
• vary in # person to person but everyone has 2 patella which develop in quadriceps femoris tendon
Sutural Bones• classified by location (w/in a
suture: a seam between 2 cranial bones)
• not everyone has them
Bone Surface Markings• 2 major types:1. depressions & openings– form joints or allow passage of
vessels & nerves2. processes– projections or outgrowths that
either help form joints or serve as attachment points for ligaments & tendons
Axial skeleton
Skull • 22 bones in 2 categories:1. Cranium– 8 bones that form cranial cavity
1. 1 frontal bone2. 2 parietal bones3. 2 temporal bones4. 1 occipital bone5. 1 sphenoid bone6. 1 ethmoid bone
Skull 2. Facial Bones
14 bones that form the face• 2 nasal bones
»2 maxillae»1 mandible»2 zygomatic»2 lacrimal»2 palantine»2 inferior nasal conchae»1 vomer
Skull: Cavities1. Cranial Cavity2. Nasal Cavity3. Orbits4. Paranasal Sinuses5. Middle & Inner Ear Cavities
Cavities of the Skull
Functions of Cranial Bones
1. protecting brain2. stabilizing position of brain,
vessels, & nerves through attachments to the meninges
3. outer surfaces provide large areas of attachment for muscles that move parts of the head & some for facial expression
Frontal Bone
Parietal Bones• form greater portion of sides &
roof of cranial cavity
Temporal Bones• form inferior, lateral aspects of
the cranium & part of the cranial floor
• its zygomatic process forms the lateral half of the zygomatic arch
• mandibular fossa: where condylar process of mandible forms TMJ (temporal mandibular joint)
Temporal Bones• external auditory meatus: ear
canal• mastoid: posterior & inferior to
external auditory meatus, contains “air cells” (mastoiditis: inflammation in air cells)
Temporal Bone: Petrous Portion
• base of skull between sphenoid & occipital bones
• houses middle & inner ear• Carotid foramen & Jugular
foramen
Temporal Bones• internal 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 Bone• forms back of head & most of
base of skull• foramen magnum: large hole
spinal cord passes thru, • occipital condyles: articulate
with 1st cervical vertebra (atlas)
Sphenoid Bone• middle base of skull• *articulates with all other cranial
bones• shape resembles a bat
Sphenoid Bone• sella turcica: (Turkish saddle)
the “seat” of the saddle is the hypophyseal fossa: where the pituitary gland sits
• optic foramen: between body & lesser wings, cranial nerve II (optic n.) and opthlamic artery pass thru
Ethmoid Bone• “like a sieve”• midline of anterior part of cranial floor,
anterior to sphenoid, posterior to nasal bones
• cribiforme plate: forms roof of nasal cavity, the holes of the sieve where olfactory nerves pass from roof of nasal cavity to brain
• crista galla: triangular process which serves as pt of attachment for meninges of brain
Facial Bones• shape of face changes
dramatically during 1st 2 yrs of life: – brain & cranial bones expand– 1st set of teeth erupt– paranasal sinuses enlarge– growth of face stops ~16 years old
Facial Bones• 14 facial bones:1. 2 nasal bones2. 2 maxillae3. 2 zygomatic bones4. 1 mandible5. 2 lacrimal bones6. 2 palatine bones 7. 2 inferior nasal conchae8. 1 vomer
Nasal Bones• form part of the bridge of the
nose (rest is cartilage)
Maxillae• = upper jaws• *articulate with every bone in face
except the mandible• form part of floor of orbits, parts of
nasal cavity, & most of the hard palate (bony roof of mouth)
• each one has large maxillary sinus• alveolar process is small arch that
contains the alveolar sockets for upper set of teeth
Cleft Palate & Cleft Lip• 10-12 wks gestation the palatine
processes of maxillae typically join
• not doing so cleft palate +/- cleft lip– speech & swallowing can be
affected–many ear infections– reparative 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 Bones• “cheekbones”:
the temporal process of the zygomatic bone articulates with the zygomatic process of the temporal bone
• also part of floor of orbit
Inferior Nasal Conchae• inferior to the middle nasal
conchae of the ethmoid bone forming part of lateral wall of nasal cavity
• same function as superior & middle conchae: swirling inhaled air to deposit particulates but not involved in sense of smell
Vomer • Δ 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 sockets• mental foramen: dentist numb
mental nerve
Sutures • an immovable joint in an adult
found only between skull bones & holds most skull bones together
• name generally reflects bones they unite
Hyoid Bone • “U-shaped “• *does not articulate with any other bone
in skeleton• suspended by ligaments from styloid
process of temporal bone• in anterior neck between mandible &
larynx• function: supports tongue• *frequently fractured during
strangulation
Hyoid Bone
Vertebral Column• Fetus has
anteriorly concave curve
• 3 mos old when holds head cervical curve develops
• lumbar curve develops as infant sits up, stands, walks
Intervertebral Discs• between bodies of consecutive
vertebra– under compression they flatten &
broaden– harden, less elastic w/aging &
narrow loss of height• annulus fibrosus: outer fibrous
ring• nucleus pulposus: inner soft,
highly elastic
Parts of a Vertebra• Body– thicker, anterior portion, weight bearing
portion• Vertebral Foramina– contains spinal cord, adipose, areolar CT,
blood vessels• Spinous Process– 1 of 7 processes, posterior, palpable on
back of bodyTransverse Processes: on each side,
extending laterally
Vertebrae: 1st & 2nd Cervical
• Atlas– ring-shaped– articulates with
condyles of occipital bone
– allows you to nod head “yes”
• Axis – 2nd cervical v.– allows you to
shake head “no”
Typical Thoracic Vertebrae
• T-1 to T-12• larger &
stronger than cervical v.
• distinguishing feature: articulate with ribs (facets on transverse processes of T-1 to T-10
Typical Lumbar Vertebrae
• L-1 to L-5• largest &
strongest of the vertebrae
• processes are short & thick
Sacrum • triangular bone
formed by union of S-1 to S-5
• fusion begins ~16, complete by age 30
• female: shorter, wider, more curved S-2 to S-3
Coccyx• small triangle• formed by fusion
of 4 coccygeal v. (Co-1 to Co-4), start between 20 & 30
• females points inferiorly; males it points anteriorly
Thorax• refers to entire chest• skeletal part of thorax is thoracic
cage– Sternum– Ribs
Sternum• aka “breastbone”• flat bone in center of anterior
thorax• 3 bones that fuse by age 25
Sternum1. Manubrium• superior portion• suprasternal notch• clavicular notches• articulates with
costal cartilage of 1st & 2nd rib
• sternal angle: where it articulates with body
Sternum2. Body• middle & largest
portion• articulates with
costal cartilage of 2nd thru 10 ribs
Sternum 3. Xiphoid Process• cartilagenous in
infancy • not completely
ossified until ~age 40
• avoid it during CPR
Ribs: 12 Pair
• increase in length 1st thru 7th then decrease in length to 12th
• 1st thru 7th ribs (true ribs) have direct anterior attachment to sternum by strip of hyaline cartilage which contribute to elasticity of thoracic cage
• 8th thru 10th ribs attach to each other & then to cartilages of 7th rib
• 11th & 12th ribs: floating ribs
Ribs• all 12 attach posteriorly to
vertebrae• Parts of a Rib1. Head2. Neck3. Tubercle 4. Body 5. Costal Angle
Abnormal Curvatures of Spine
• Scoliosis • lateral bending• usually in
thoracic region
Abnormal Curvature of Spine
• Kyphosis • exaggeration of
the thoracic curve
• seen in TB of spine, congenital malformation, elderly
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