Question | Answer |
Cranial fossae | - anterior, middle, and posterior
- compose the intracranial cavity |
Coronal suture | - runs in the coronal plane
- located where parietal bones meet frontal bone |
Squamous suture | - occurs where each temporal bone meets a parietal bone inferiorly |
Sagittal suture | - occurs where right and left parietal bones meet superiorly |
Lambdoid suture | - occurs where the parietal bone meet the occipital bone posteriorly |
Sutural bones | - small bones that occur within sutures
- irregular in shape, size, location
- not all people have them |
Supraorbital margin | - superior margin of the orbits |
Glabella | - smooth part of the frontal bone between superciliary (eyebrow) arches |
Occipital bone | - forms posterior portion of the cranium and cranial base
- articulates with temporal bones and parietal bones
- forms posterior cranial fossa
- foramen magnum located at its base |
Frontal bone | - forms the forehead and roofs of orbits
- contributes to anterior cranial fossa |
Occipital bone features | - occipital condyles
- hypoglossal foramen
- external occipital protuberance
- superior nuchal lines
- inferior nuchal line |
Temporal bones | - lie inferior to parietal bones
- form the inferolateral part of skull
- contributes to the middle and posterior cranial fossa |
Mastoid process | - site for neck muscle attachment
- contains air sinuses
- part of the temporal bone |
Petrous region | - projects medially, contributes to cranial base
- appears as bony wedge b/w occipital bone posteriorly and sphenoid bone anteriorly
- houses cavity of middle and internal ear |
Foramina of the temporal bone | - jugular foramen: at boundary with occipital bone
- carotid canal
- foramen lacerum
- internal acoustic meatus |
Sphenoid bone | - spans width of cranial floor
- has 3 pairs of processes
- "keystone" of the cranium |
Sella turcica | - saddle-shaped prominence in superior part of sphenoid bone
- contains the hypophyseal fossa, which holds the pituitary gland |
Sphenoid bone processes | - Greater wings
- Lesser wings
- Pterygoid process |
Sphenoid bone openings | - optic canal
- superior orbital fissure
- foramen rotundum
- foramen ovale
- foramen spinosum |
Ethmoid bone | - lies between nasal and sphenoid bones
- forms most of the medial bony region between nasal cavity and orbits |
Cribiform plate | - superior surface of the ethmoid bone
- contain olfactory foramina |
Crista galli | - attachment for falx cerebri (large vertical sheet between cerebral hemispheres |
Perpendicular plate | - forms superior part of nasal septum |
Mandible | - largest and strongest facial bone
- 2 parts: horizontal body and two upright rami |
Maxillary bones | - articulate with all facial bones except the mandible
- contain maxillary sinuses
- part of the interior orbital fissure
- "keystone" facial bones |
Zygomatic bones | - form lateral wall of the orbits |
Nasal bones | - form bridge of the nose |
Lacrimal bones | - located in medial orbital walls |
Palatine bones | - complete the posterior part of the hard palate |
Vomer | - forms inferior part of the nasal septum |
Inferior nasal conchae | - thin, curved bones that project medially & form lateral walls of nasal cavity |
Paranasal sinuses | - air filled sinuses within frontal, ethmoid, sphenoid, and maxillary bones
- lined with mucous membrane
- lighten the skull |
Orbit walls | - roof
- lateral wall
- medial wall
- floor
- formed by frontal, sphenoid, zygomatic, maxillary, palatine, lacrimal, and ethmoid bones |
Orbit wall openings | - superior orbital fissures
- inferior orbital fissures
- optic canals
- lacrimal fossa |
Hyoid bone | - inferior to mandible in anterior neck
- acts as movable base for tongue
- not directly in contact with any other bone |
Vertebral curvatures | - concave: cervical and lumbar - develop when baby starts to walk
- convex: thoracic and sacral - present at birth
- increase resilience of spine
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Anterior longitudinal ligament | - attaches to bony vertebrae and intervertebral discs
- prevents hyperextension |
Posterior longitudinal ligament | - narrow and relatively weak
- attaches to intervertebral discs |
Nucleus pulposus | - gelatinous inner sphere of intervertebral disc
- absorbs compressive stresses |
Annulus fibrosus | - outer rings formed of ligament
- inner rings formed of fibrocartilage
- contain the nucleus pulposus |
General structure of vertebrae | - body
- vertebral arch
- vertebral foramen
- spinous process
- transverse process
- superior articular process
- inferior articular process
- intervertebral foramina |
Atlas | - first cervical vertebrae
- lacks body and spinous process
- superior articular facets receive occipital condyles, supports skull
- allows flexion and extension of neck |
Axis | - has body and spinous process
- second cervical vertebrae |
Dens (odontoid process) | - formed from fusion of the body of atlas with the axis
- acts as pivot for rotation of axis and skull
- participates in rotating head from side to side |
Vertebrae C3-C7 | - body: small and wide laterally
- short & bifid spinous process extends posteriorly (except C7)
- vertebral foramen: triangular and large
- transverse processes have foramina |
Thoracic vertebrae | - all articulate with ribs
- body: larger than cervical bodies
- spinous processes: long and point inferiorly
- vertebral foramen are circular |
Costal facets | - inferior, superior
- transverse (except T11-T12)
- present on both sides of vertebrae
- head of rib attached to inferior costal facet of superior vertebra and superior costal facet of inferior vertebra |
Connections between thoracic and vertebral bodies | - laterally, each side of vertebral body has 2 facets (demifacets)
- demifacets interface with vertebral bodies above and below
- superior articular facets point posteriorly
- inferior articular processes point anteriorly |
Thoracic cage | - forms framework of the chest
- protects thoracic organs
- supports shoulder girdle and upper limbs
- 3 components: thoracic vertebrae (posteriorly), ribs (laterally), sternum & costal cartilage (anteriorly) |
Manubrium | - superior section of sternum
- articulates with medial end of clavicles |
Body | - bulk of sternum
- sides are notched at articulations for costal cartilage of ribs 2-7 |
Xiphoid process | - inferior end of sternum
- ossifies around age 40 |
Jugular notch | - central indentation of superior border of manubrium |
Sternal angle | - horizontal ridge where manubrium joins the body |
Xiphisternal joint | - where sternal body and xiphoid process fuse
- lies at level of T9 |
Rib pairs 1-7 | - vertebrosternal ribs
- superior 7 pairs of ribs which attach to sternum by costal cartilage |
Rib pairs 8-10 | - vertebrochondral ribs
- airs of ribs which attach to sternum indirectly |
Rib pairs 11-12 | - floating ribs
- are not attached to sternum |
Lumbar vertebrae | - thick & robust bodies
- thin & tapered transverse processes
- spinous processes are thick, blunt, point posteriorly
- triangular vertebral foramina |
Sacrum | - shapes posterior wall of pelvis
- formed from 5 fused vertebrae
- superior surface articulates with L5
- inferiorly articulates with coccyx |
Sacral promontory | - where the anterosuperior margin of first sacral vertebrae bulges into pelvic cavity
- human body's center of gravity is 1 cm posterior to sacral promontory |
Sacrum: anterior view | - sacral promontory
- four transverse ridges cross anterior surface of the sacrum, marking the lines of fusion of sacral vertebrae
- anterior sacral foramina transmit ventral divisions of sacral spinal nerves |
Sacrum: posterior view | - median sacral crest: represents fused spinal processes of sacral vertebrae
- posterior sacral foramina: transmit dorsal rami of sacral spinal nerves
- lateral sacral crest
- ala: develop from fused rib elements |
Sacral foramina | - ventral foramina: passage for ventral rami of sacral spinal nerves
- dorsal foramina: passage of dorsal rami of sacral spinal nerves |
Coccyx | - tailbone
- 3-5 fused vertebrae
- offers only slight support to pelvic organs |
Cleft palate | - common congenital disorder
- right and left halves of palate fail to fuse medially |
Stenosis of lumbar spine | - narrowing of the vertebral canal
- can compress roots of spinal nerves |
Abnormal spinal curvatures | - Scoliosis: abnormal spinal curvature
- Kyphosis: exaggerated thoracic curvature
- Lordosis: accentuated lumbar curvature |
Axial skeleton throughout life | - flat membrane bones begin to ossify in 2nd month of development
- bone tissue grows outward from ossification centers
- at birth, skull bones are separated by still-unossified remnants of membranes |
Fontanelles | - still-unossified remnants of membranes at birth
- anterior, posterior, mastoid, sphenoidal
- allows skull to be safely compressed & molded as infant passes thru birth canal
- usually replaced about a year after birth |
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