Axial Skeleton. * I can name and identify all of the bones of the axial skeleton. * I can describe...

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Transcript of Axial Skeleton. * I can name and identify all of the bones of the axial skeleton. * I can describe...

  • Axial Skeleton

  • I can name and identify all of the bones of the axial skeleton. I can describe the major landmarks of the cranial and facial bones I can describe and discuss the differences between the cervical, thoracic, lumbar, sacral and coccygeal vertebrae

  • I. Axial skeletonThe axial skeleton forms the central axis of the body. 1. made up of:a. skullb. vertebral columnc. ribsd. sternum2. functions: supports & protects brain, provides surface area for muscle attachment

  • Section 2B. Skull1. can be divided into two categoriesa. cranium - enclosed brainb. facial bones 2. Cranial bones: 8 cranial bones form case to protect & contain braina. Frontal bone - single convex bone -extends from orbits to the coronal suture - forms forehead & roof of the eye orbits-Frontal sinuses: air filled cavities, lie within the frontal bone

  • b. Occiptal bone- forms back bottom part - foramen magnum: opening in occipital bone, connects cranium to spinal cavity -Occipital condyles mark articulation w/ vertebra of neck

    c. Parietal bones (2)- form middle top portion

    d. Temporal Bones (2)- form lower sides, temple region -zygomatic process helps form cheek bone - external acoustic meatus- opening to outer ear - mastoid process: attachment site for muscles that rotate or extend the head - styloid process: attachment site of tendons of muscles associated w/ tongue

  • e. Sphenoid- forms part of the floor of the cranium (inside top)-looks like bat w/ wings extended -great wing: form back wall of eye orbit -pterygoid process: attachment sites for muscles that move jaw

    f. Ethmoid-inside, top, forms roof of nasal cavity-cribriform plate: forms floor of cranium- perpendicular plate: forms part of nasal septum

  • 3. sutures- immovable joints that form between bones of the skull (pg 215)a. lamboid- btwn occipital & parietal bonesb. coronal- btwn frontal & parietal bonesc. sagittal- btwn 2 parietal bonesd. squamous- btwn temporal & parietal (on R & L sides)

  • 4. Facial bonesa. Maxillae (2)- support upper teeth, form upper jaw, inferior orbital rim, & most of hard palate

    b. Palatine bones (2)- form posterior portion of hard palate & bottom of orbit

    c. Nasal bones (2)- supper bridge of nose

    d. Vomer (1) forms inferior part of nasal septum

    e. Inferior nasal conchae (2)- inside nasal cavity, help increase epithelial surface area to warm humidify air

  • f. Lacrimal bones (2)- smallest facial bone, forms medial part of eye orbit

    g. Mandible (1)- forms the lower jaw, alveolar processes support teeth, condylar process articulates with the temporal bone (tmj- temporal mandibular joint)

  • C. Foramina & Fissures of Skull1. allow passageway for nerves and blood vessels in skulla. examples: *supra-orbital foramen: nerve and blood vessel supply to eyebrow/eyelid* optic canal in sphenoid- optic nerve brings info from eye to brain

  • D. Orbital & Nasal complexes1. orbits- bony recesses that contain eyesa. orbit is formed by 7 bones of orbital complexb. frontal bone forms most of roof; maxilla most of the floorc. lacrimal, ethmoid, sphenoid, zygomatic bone, & palatine bone help make up orbit as well

  • E. Fontanelles1. largest fibrous areas btwn cranial bones2. at birth, cranial bones are connected by fibrous connective tissue- allow distortion of skull (delivery)3. anterior fontanelle is the largest- where frontal, sagittal, & coronal sutures meeta. known as soft spotb. present until nearly 2 yrs of age!4. occipital, sphenoidal, & mastoid fontanelles disappear w/in 1-2 months after birth5. growth of cranium is coordinated w/ expansion of brain- brain stops growing before age 5, cranial sutures develop

  • F. Vertebral column1. spine has 26 bones: 24 vertebrae, sacrum, 1 coccyx (tailbone)2. functionsa. provides support for head, neck & trunkb. protects spinal cord3. structure- four curves- help bring body weight in line with body axisa. cervical, thoracic, lumbar, & sacralb. primary curves- curves in infants- C shape from thoracic & sacral curvesc. secondary curves- lumbar & cervical, form months after birth

  • 4. vertebra- three basic partsa. body- transfers weight along vertebral column, separated by cartilage (intervertebral discs)b. arch- forms part of vertebral foramen -has walls (pedicles)- roof (lamina)- forms vertebral canal, which encloses the spinal cord c. articular processes- spinous process is located where laminae fuse, projects out (you see/feel these)- transverse processes project laterally; sites of muscle attachment or rib articulation

  • -articular processes: superior & inferior: where each vertebra articulates with the one above & below itd. intervertebral foramina- gaps btwn pedicles of successive vertebrae, allow passage of nerves running to/from spinal cord

  • G. Regions of the vertebrae* cervical (1-7): neck * thoracic ( 1-12): superior portion of back * lumbar (1-5): inferior portion of back* sacrum (fused)* coccyx (fused)- tailbone1. cervical vertebraea. most mammals have 7b. smallest in vertebra column- small body, large vertebral foramen

  • c. head is large in comparison- rapid change is speed can cause whiplash, partial or complete dislocation of cervical vertebraed. C1 is called the Atlas* holds up head, articulates w/occipital condyles*permits you to nod yes*doesnt have a body or a spinous process* large round vertebral foramene. C2 is called the Axis* fused to atlas, creating the dens- a process on the axis, allows you to shake no*fusion is not complete in children- shaking can cause damage to spinal cord

  • f. c7 is the vertebra prominens * last cervical vertebra* large transverse processes for muscle attachment* ligamentum nuchae- ligament begins at c7 and extends to occipital crest-helps you lift your head

  • 2. Thoracic vertebrae*12 total, heart shaped body that is larger than cervical*smaller vertebral foramen *each articulates w/ ribs at costal facets of vertebrae* T1-T8 each articulate w/ 2 pair of ribs, have superior and inferior sets of facets* T9-T11 articulate w/ one pair- single set of facets

    3. Lumbar vertebrae* 5 total, largest of vertebrae, have thicker body* dont have costal facets*transverse process stick out (most like a t)

  • *bear the most weight, massive spinous processes provide area for attachment of lower back muscles4. Sacrum- five fused sacral vertebrae* vertebrae begin fusing after puberty & are fused by age 25-30* protects reproductive, digestive, & urinary organs* attaches axial skeleton to pelvic girdle* crests ridges that form where process of individual vertebrae fused* base- superior portion, apex- narrow inferior portion, ala- (wing)- extends on either side

  • 5. coccyx- small, consists of 3-5 vertebrae, fused by age 26* provides attachment site for ligaments & a muscle associated w/ anal opening* coccygeal cornua- stick out of 1st vertebrae, curve to meet sacrum

  • H. Thoracic Cage- chest1. consists of : thoracic vertebrae, ribs, & sternum2. functions include:a. protection of heart, lungs, thymusb. attachment site for muscles involved in respiration, maintaining position of spine, & movements of pectoral girdle & upper limbs3. Ribs (costae)a. elongate, flattened bonesb. 12 pairsc. true ribs- 1st-7th pair, are connected to sternum by costal cartilages

  • d. false ribs- 8th -12th pairs, dont attach directly to sternum, but fuse togethere. 11th & 12th pair- floating ribs, no connection w/ sternumf. Parts of Ribs- head (capitulum)- end that articulates w/ vertebra- tuberculum- contacts transverse process of vertebra- long shaft is the bodyg. ribs can bend/move to absorb blows, sudden impact can result in fractureh. ribs are bound tightly in CT, so can heal w/o cast

  • 4. Sternum- breastbonea. three parts * manubrium- widest, most superior part, has jugular notch btwn clavicle articulations * body- where ribs 2-7 attach to sternum * xiphoid process- smallest, inferior part, diaphragm & rectus abdominis muscles attach, easily broken by impactb. ossification of sternum- age 6-10, not complete until age 25 (before fusion, body alone is 4 separate bones)