Module 3B: Axial Skeleton Flashcards
how many bones are there in the human skeleton?
206
how many bones are there in the human body at birth?
approximately 300
what does the axial skeleton form?
a longitudinal axis of the body
what does the axial skeleton support?
the head, neck and trunk
what does the axial skeleton protect?
the brain, spinal cord and thoracic organs (like the heart and lungs)
the bones of our skull form the framework of what?
our face
the bones of our skull contain cavities for?
special sense organs (taste, smell, sight)
the bones of our skull provide openings for?
air and food passage
the bones of our skull anchor muscles for?
facial expression, which we use to show our feelings
the bones of the skull are divided into what two groups?
- cranium bones (top of skull)
- facial bones
what are our cranium bones?
- frontal
- occipital
- sphenoid
- ethmoid
- 2 parietal
- 2 temporal
what are our facial bones?
- mandible
- vomer
- 2 maxilla
- 2 zygomatic
- 2 nasal
- 2 lacrimal
- 2 palatine
- 2 inferior nasal concha
how many bones are there is the skull?
22 bones
where is the frontal bone?
the forehead
where is the parietal bones?
two sides of the top of our head back from the forehead
where is the temporal bones?
inferior to the parietal bone. right where our temples are
where is our nasal bone?
top part of our nose (front, center of skull)
where is our sphenoid bone?
back of boney orbit where our eyes go
- more on the lateral aspects of skull
- it is ONE bone
where is our zygomatic bones?
our cheekbones
where is our maxilla bones?
forms side of our nose, upper jaw where our top teeth attach
where is our vomer?
divides the nasal cavity into two
where is our mandible?
our lower jaw
what bone is the only moveable bone in our skull?
the mandible
can we move suture joints?
no
where is our ethmoid bone?
behind our lacrimal which is behind the upper part of our maxilla
where is our lacrimal bone?
behind the top portion of the maxilla
where is our inferior nasal conchas?
on the lateral side of our nose socket
what is the zygomatic process?
a zygomatic arch formed by the temporal bone and the zygomatic bone joining together
where is the mastoid process?
the lump immediately behind your ear when you push an earring backwards
where is the occipital bone?
the inferior posterior part of the skull
- the low back part of the skull
what attaches to the mastoid process?
a lot of muscles from the neck and back
why do suture joints join bones together in a zigzag pattern?
to cover more surface area to make very strong joints
- straight joints would not be as strong because they wouldn’t cover as much surface area
what is the coronal suture?
the joint that divides the frontal bone from the two parietal bones
what is the squamous suture?
divides the temporal bone from the parietal bone on the left and right sides of the skull
what is the lambdoid suture?
divides the two parietal bones from the occipital bone
what is the sagittal suture?
runs directly along the top of the skull dividing the two parietal bones
which sutures do not fully close until you are about one and a half years old?
the coronal and sagittal sutures
what is the external occipital protuberance?
the big bump on the back of the head
what is the superior nuchal line?
important for muscular attachment
- on the left and right sides slightly up from the external occipital protuberance
what is the inferior nuchal line?
important for muscular attachment
- on the left and right sides slightly down from the external occipital protuberance
what is the hard palate of the skull important for?
the oral cavity
the hole in the occipital bone from an inferior view is called?
the foramen magnum
where is the palatine bone?
posterior (behind) the maxilla and anterior (in front) the vomer and inferior nasal concha
what is the opening where the spinal cord exits the skull?
the foramen magnum
how many vertebrae do we have total?
33 vertebrae
how many intervertebral discs do we have? why?
23 discs because we have 9 fused vertebrae
what are the five regions of the vertebrae? (in order from most superior to most inferior) (top to bottom)
- cervical
- thoracic
- lumbar
- sacrum
- coccyx
how many vertebrae each belong to each region?
- 7 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral (fused)
- 4 coccygeal (fused)
how are each vertebrae named?
divided into their regions and given a number based on their placement relative to the top
- C1-C7
- T1-T12
- S1-S5
-CO1-CO4 (usually just call it the coccyx)
what is the vertebral arch composed of?
all the posterior elements of the vertebra
what is located at the vertebral foramen (or vertebral canal or spinal canal)?
the spinal cord
what is the most posterior part of the vertebrae?
the spinous process
where is the lamina of the vertebrae located?
between the spinous process and the transverse process
what is the transverse process?
protrudes from the sides of the vertebra
what is the pedicle of the vertebra?
between the vertebral body and the transverse process
what is the anulus fibrosus?
a part of the intervertebral disc
- a limacon shaped concentric rings of fibrocartilage as well as collagen
- it is a very strong multi-layered laminate type of structure
- used to help distribute pressure evenly across the disc
- helps with weight distribution and flexibility in the spine
- also forms the boundaries to the nucleus pulposus
what is the nucleus pulposus?
a part of the intervertebral discs
- a gelatinous, loose fiber suspended in gel
- quite thick
- often described as bulls snot
- has greater elasticity and compressibility for shock absorption and forced transmission
- even pressure all around
what is the endplates of the intervertebral discs?
there is a superior and an inferior
- are made up of fibrocartilage and they help contain the nucleus pulposus and annulus on the superior and inferior aspects
what is the transverse foramen?
holes in the transverse processes, to allow arteries to pass into the brain and head
- only in C3-C6
why is the bifid spinous process spilt into two in the C3-C7 vertebrae?
because we have a thick ligament that runs along the back of our neck and it needs as much surface area as possible to attach
what do we call the C1?
the atlas
does the atlas have a vertebral body and/or a spinous process?
no
which bone holds our skull?
our atlas
where does our skull sit?
on our atlas’ superior articular facets
- they interact with the occipital condyles of the skull
what interaction in our body allows us to nod?
the interaction of the C1 and our skull
what do we call our C2? why?
the axis, because it turns our head
what allows us to shake our heads “no”?
the interaction between the C1 and C2
what is the dens?
a projection sticking up from the vertebral body of C2
- the vertebral body of C1 that fuses with C2 while you are in fetal development
why is there no intervertebral disc between C1 and C2?
because there is no vertebral body
what holds the atlas in place while the C1 and C2 move relative to each other?
there is a ligament on C1 that wraps around the dens of C2 to hold it in place while C1 and C2 move relative to each other
what is the largest lump in the back of our neck?
your C7
why is the spinous process of the C7 not bifid?
the large ligament that has to attach over the other cervical vertebrae ends at the C7, and because the ligament is thick, you can’t feel the spinous process of the other cervical vertebrae very well
does the C1 and C2 have transverse foramina?
yes
which vertebrae has the smallest and largest vertebral body?
smallest: cervical
middle: thoracic
largest: lumbar
do thoracic vertebrae have any foramen?
yes, one vertebral foramina. no transverse foramina though
describe the thoracic processes?
spinous process: long and thick
transverse processes: large
what is the direction of the superior articular facets of the thoracic vertebra?
posterior lateral
what is the direction of the inferior articular facets of the thoracic vertebra?
anterior medial
is there ligaments helping to hold the ribs in connection to the vertebrae?
yes
where do ribs attach?
posteriorly to the vertebral column and anteriorly to the sternum or nothing
what is the form of the transverse processes of the L vertebrae?
short and blunt
what is the form of the spinous process for the L vertebrae?
short and blunt
what is the direction for the superior articular facets of the L vertebrae?
medial
what is the direction for the inferior articular facets of the L vertebrae?
lateral
what is the size of the intervertebral discs on the L vertebrae?
larger in comparison to the L vertebra
what is the size of the intervertebral discs on the T vertebrae?
smaller in comparison to the T vertebra
what is fused in the sacrum?
the vertebral body and the transverse processes
what exits the spinal cord at the sacrum level?
lots of nerves
where is the sacrum going to articulate with the L5 vertebra?
the base of the sacrum
what is the apex of the sacrum?
its the most inferior aspect of the sacrum and it articulates with the coccyx
what is the anterior sacral promontory?
a projection on the anterior side of the sacrum
what is the anterior sacral foramen?
the holes of the sacrum from the front view
what is the posterior sacral foramen?
the holes of the sacrum from the back view
what do the anterior and posterior sacral foramina represent?
the intervertebral foramina that are found between vertebrae
what is the superior articular facet?
where L5 articulates. faces posteriorly
what is the sacral canal and the sacral hiatus?
continuation of the vertebral canal. opening at the bottom is called the hiatus
- basically just the superior and inferior parts of the hollow canal in the sacrum
what is the auricular surface?
on the lateral aspect of the sacrum and that’s where the sacrum will join with the ilium
what is our median sacral crest?
the remnants of the few spinous processes
- posterior side
what is our sacral tuberosity?
markings on the bone for muscle attachment
what is our lateral sacral crest?
markings on the bone for muscle attachment
what do ribs do?
help protect organs, predominantly the heart and lungs
what are the three types of ribs?
true, false and floating
what are the true ribs?
there are seven of them
- T1-T7
- the true ribs directly attach to the sternum via costal cartilage
what are the false ribs?
there are 5 of them
- T8-T12
- Last two are floating ribs
- T8-T10 have indirection attachment to sternum via grouped costal cartilage
- T11-T12 have no attachment to the sternum so they are “floating”
what does the true rib 1 rib attach to?
the manubrium part of the sternum and the T1 vertebra
what does the true rib 2 attach to?
the sternal angle part of the sternum and the T2 vertebra
why do we need floating ribs?
- offer attachment to muscles
- for full movement of the trunk
what are the three parts of the sternum?
- manubrium
- body
- xiphoid process
what is the suprasternal notch?
the ‘U’ between our collarbones
- part of sternum
what is lateral to the suprasternal notch on each side?
the clavicular notch
- where clavicle attaches to sternum
