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HA Ch. 6
Skeletal System (Axial Division)
Question | Answer |
---|---|
# of bones in human skeleton | 206 |
axial skeleton | 80 bones, long axis of body |
axial skeleton supports...protects | head, neck, trunk...brain, spinal cord and thoracic organs |
major regions of the axial skeleton | skull, vertebral column, and bony thorax |
the skull is the most... | complex structure of the skeleton |
the skull is formed by.... | cranial and facial bones |
the skull has mostly | flat bones connected by sutures |
which skull bone is not connected by sutures? | mandible |
the "brain case" or cranium is divided into... | two major areas (cranial vault and cranial base) |
cranial vault (calvarium) | skull cap or roof of the skull |
cranial base (floor - inferior part) | anterior, middle, and posterior cranial fossae |
fossa | depression |
how many foramina are there? | 85 named |
foramina/canals/fissures/lacerum | openings in the bones for blood and n erve supply to enter through |
how many bones are in the skull? | 8 cranial and 14 facial bones |
frontal bone (1) | cockle-shell shaped bone |
frontal bone forms | the forehead and the roofs of the orbits |
glabella | smooth part in the midline of the frontal bone between the superciliary arches |
superciliary arches support | the eyebrows |
frontal squama | vertical anterior-most part of the frontal bone (forehead) |
supraorbital margins | mark the superior limits of the orbits, the bony recesses that support and protect the eyeballs |
supraorbital foramen | notches, opening above each orbit |
supraorbital foramen transmit | supraorbital artery and nerve |
lacrimal fossa | marks location for the lacrimal (tear) gland that lubricates the surface of the eye |
parietal bones (2) | pair of curved rectangular bones |
parietal bones are located | posterolateral to the frontal bone, forming sides of cranium |
superior and inferior temporal lines | low ridges on the external surface of each parietal bone, marking the attachment of the temporalis muscle |
temporalis muscle | closes the mouth |
parietal eminence | the smooth parietal surface superior to the temporal lines |
how many major sutures are associated with the parietal bones?? | 4; at which they articulare with other cranial bones |
occipital bone (1) | most posterior of the cranial bones |
occipital bone forms... | the floor and back wall of the skull |
foramen magnum | hole in the base of occipital bone through which spinal cord passes and is connected to the brain |
occipital condyles | facets on the base of the skull, which articulate with the superior facets of the C1 (atlas) and vertebra |
articulate | joining two things together to allow motion |
hypoglossal canals | passageway for hypoglossal cranial nerve XII |
hypoglossal canals begin at... | the lateral base of each occipital condyle |
basioccipital | band of bone anterior to the foramen magnum, which is the point of articulation between the occipital bone and the sphenoid |
external occipital crest and protuberance | midline prominences posterior to foramen magnum |
the crest extends... | posteriorly from the foramen magnum, ending in the protruberance |
protruberance | small midline bump |
superior and inferior nuchal lines | horizontal ridges that intersect the external occipital crest |
nuchal lines mark the... | attachment of muscles and ligaments that stabilize the articulation between the first vertebra, C1, and the occipital condyles |
temporal bones (2) | inferior to the parietal bones on lateral skull |
four major regions of the temporal bones | squamous, tympanic, mastoid, petrous |
squamous region | lateral surface bordering the squamous suture |
squama | convex external surface of the region |
cerebral surface | concave internal surface, whose curvature parallels the surface of the brain |
zygomatic process | the inferior margin of the region, which curves laterally and anteriorly to meet the temporal process of the zygomatic bone |
the temporal and zygomatic process together form... | the zygomatic arch (cheekbone) which defines the projection of the cheek |
squamous region touches | the parietal bones on each side |
tympanic region | surrounds the external acoustic meatus (external auditory canal) immediately posterior and lateral to the mandibular fossa |
tympanic region contains the... | styloid process (needle like and inferior to the external auditory meatus) |
styloid process | makrs the attachment site for ligaments that support the hyoid bone and for muscles of the tongue, pharynx, and larynx. |
mastoid region | "breast shaped" area posterior to the ear |
mastoid contains... | mastoid process which is rough and anchors some neck muslces that rotate and extend the head |
petrous region | most massive portion of the temporal bone |
petrous region contributes to... | the cranial base and forms the lateral region of the skull base |
petrous contains the | jugular foramen which is a passageway through which the internal jugular vein (largest of head) and cranial nerves IX, X, XI pass |
carotid canal | opens in petrous region on the skulls inferior aspect, just anterior to the jugular foramen and it is a passageway for internal carotid artery |
foramen lacerum | jagged opening between the medial tip of the petrous portion of the temporal bone and sphenoid bone |
foramen lacerum is almost completely closed by... | cartilage in a living person but conspicuous in a dried skull |
internal acoustic meatus | lies in the cranial cavity on the posterior face of the petrous region; transmits cranial nerves VII, VIII |
sphenoid (1) | bat-shaped bone |
sphenoid bone forms the | anterior plateau of the middle cranial fossa |
sphenoid spans | the width of the cranial floor |
sphenoid is made up of the | body and 3 pairs of processes |
3 process of sphenoid are | greater wings, lesser wings, and pterygoid process |
greater wings | visible exteriorly anterior to temporal, form a portion of the orbits of the eyes |
lesser wings | bat-shaped portions located anterior to the sella turcica |
pterygoid processes | vertical projections that begin at the boundary between the greater and lesser wings |
pterygoid processes contain | attachment sites for pterygoid muscles that move the lower jaw and soft palate |
sella turcica | (turkish saddle) on the superior surface of the body |
sella turcica contains the | hypophyseal fossa which holds the pituitary gland |
pituitary gland is also known as the | hypophysis |
anterior clinoid processes | located on either side of sella turcica are these posterior projections of the lesser wings of sphenoid |
tuberculum sellae | forms the anterior border of sella turcica |
dorsum sellae | forms posterior border of sella turcica |
posterior clinoid processes | extend laterally on either side of the dorsum sellae |
inferior surfaces of sella turcica form... | part of orbit and the superior part of the superior orbital fissure |
optic groove | transverse groove that crosses to the front of the saddle, above the seat |
optic canal | openings at either end of the optic groove |
5 important openings of the sphenoid | optic foramen, superior orbital fissure, foramen rotundum, foramen ovale, foramen spinosum |
optic foramen | anterior to sella turcica; CN II passes through from the orbit into the cranial cavity |
superior orbital fissure | long slit between the greater and lesser wings |
superior orbital fissure transmits | CN III, IV, VI (control eye movement( |
foramen rotundum | lateral to sella turcica and a passage for a branch of CN V |
foramen ovale | posterior to the sella turcica and passage for a branch of CN V |
foramen spinosum | inferior aspect that transmits middle meningeal artery |
meningeal artery supplies | the broad inner surfaces of parietal and temporal bones |
ethmoid bone (1) | irregularly shaped bone |
ethmmoid bone is most | deeply situated bone located anterior to the sphenoid |
ethmoid bone forms... | most of the medial bony area between the nasal cavity and the orbits |
ethmoid bone forms part of the | orbital wall, anteromedial floor of the cranium, the roof of the nasal cavity and part of the nasal septum |
3 major parts of ethmoid bone | cribriform plates, ethmoidal labyrinth, perpendicular plate |
cribriform plates | contributes to roof of nasal cavities and floor of anterior cranial fossa |
cribriform plates contain | olfactory foramina which transmit olfactory fibers of CN 1 (smell) |
crista galli | superior pojection between 2 cribriform plates; attached to falx cerebri which helps secure the brain withihn the cranial cavity |
falx cerebri | membranous ligament |
ehtmoidal labyrinth | interconnected network of ethmoidal air cells |
ehtmoidal labryinth is dominated by | superior and middle nasal conchae which are thin scrolls of bony structures that contribute to the conchae of nasal cavity on either side of the perpendicular plate |
ethmoidal lab. is best viewed from | the anterior and posterior part of nasal septum |
perpendicular plate | forms superior part of nasal septum |
perp. plate projects | inferiorly in the median plane |
perp plate's superior portion is | covered by olfactory epithelium |
lateral masses | irregularly shaped, thin-walled bony regions flanking the perp palte laterally; also riddled with sinuses |
cranial bone sutures | coronal, squamous, sagittal, lambdoid, frontonasal, occipitomastoid |
coronal suture | where parietal bones join with frontal bone |
squamous | where the parietal bones join with temporal bones inferiorly |
saggital | where right and left parietal bones meet |
lambdoid | where the parietal bones jjoin with occiptal bones |
frontonasal | boundary between superior aspects of the two nasal bones and frontal bone |
occipitomastoid | where occpital bone joins with temporal bones |
mandible (facial bone) (1) | lower jawbone |
regions of mandible | mandibular body and rami of mandible |
mandibular body | horizontal portion that supports teeth |
rami | ascending portions from each side of body |
mandibular angles | where each ramus meets the body |
alveolar margin | thickened area that contains alvoli and roots of teeth |
condylar processes | posterior processes that enlarge superiorly to form the mandibular condyles |
mandibular condlyes join with mandibular fossae of temporal bones to form | temporomandibular joint |
coronoid processes | jutting anterior portion of each ramus; site of temporalis muscle attachment |
mandibular notch | depression that lies between the condylar and coronoid processes |
mental foramina | prominent openings lateral to the midline, penetrating the body on each side; passageway for mental blood vessels and nerve that serve the lower jaw |
mylohyoid line | lies on medial aspect of body; marking the origin of mylohyoid muslce |
submandibular fossa | depression inferior to the mylohyoid line, in which the submandibular salivary gland is located |
mandibular foramina | openings on the medial aspect of both rami; passageway for mandibular branch of CN V (for tooth sensation) |
maxillary bones(2) | largest facial bones that form upper jaw and central part of facial skeleton |
maxillae also form | part of the orbits |
orbital surface on each maxilla | provides protection for the eye and other orbital structures |
all facial bones join with the maxillae except | mandible |
palatine processes | form anterior part of the hard palate (bony roof of the mouth) |
frontal processes | lateral aspect of the bridge of the nose, joins with the frontal bone and nasal bones |
zygomatic processes | join with zygomatic bones |
inferior orbital fissure | elongated opening within each orbit; formed by the maxillae and sphenoid |
infraorbital foramen | opening under each orbit, in orbital rim; passageway for infraorbital nerves and vessels that serve the nasal region |
alveolar margins | oral margins of the maxillae, which contain the upper teeth |
zygomatic bones (2) | lateral to maxillae, form cheekbones and part of lateral rims of orbits |
zygomatic bones contributes to | inferior orbital wall |
temporal process | joins with zygomatic process of temporal bone to form the zygomatic arch |
zygomaticofacial foramen | located on the anterior surface of each zygomatic bone; transmits a sensory nerve innervating the cheek |
nassal bones (2) | small, rectangular bones forming the bridge of the nose |
nasal bones joins with the | frontal bone at the frontonasal suture |
lacrimal bones (2) | delicate and finger nail shaped |
lacrimal bones are situated in the | medial portion of each orbit, where it joins with the frontal bone, maxilla, and ethmoid |
lacrimal bones have lacrimal grooves | or sulcus, a shallow depression that leads to a narrow passageway, called the nasolacrimal canal |
nasolacrimal canal is formed by the | lacrimal bone and maxilla |
nasolacrimal canal encloses the | tear duct as it passes towards the nasal cavity |
palatine bones (2) | small, L-shaped bones |
horizontal plates | posterior part of hard palate; joins with the maxillae |
perp. plates are what portion of L shaped bone | vertical, posterior part of the lateral walls of the nasal cavity and small part of the orbits |
conchal crest | ridge on the medial surface, marking the joining with inferior nasal concha |
ethmoidal crest | ridge on the medial surface, marking the joint with the middle nasal concha and the ethmoid |
nasal crest | ridge that forms where the right and left palatine bones interconnect, marking the joint with the vomer |
vomer (1) | slender, plow-shaped bone in medial plane of nasal cavity |
vomer forms the | posterior and inferior portions of the nasal septum |
vomer joins | with both the maxillae and palatine bones along the midline |
inferior nasal conchae(2) | thin, curved bones protruding medially from the lateral walls of the nasal cavity |
inferior nasal conchae perform | the same function as the conahe of the ethmoid |
special parts of the skull | orbits, nasal complex, paranasal sinuses, hyoid bone |
orbits | enclose and protect eyes |
orbits are comprised of parts of | 7 bones of the skull ; frontal, maxilla, lacrimal, ethmoid, spehnoid, palatine, zygomatic |
nasal complex is constructed of | bone and cartilage |
nasal complex encloses | the nasal cavities and includes the paranasal sinuses |
paranasal sinuses (ignore) | air spaces connected to the nasal cavities |
what contribute to the nasal complex? | frontal, sphenoid, ethmoid, vomer, maxilla,e lacrimal, inferior nasal conchae |
the bridge of the nose is supported by | maxillae and nasal bones |
paransal sinuses | air fill chambers that act as extensions of and open into the nasal cavities |
paranasal sinuses are found in | maxilla, sphenoid, ethmoid, and frontal bones |
paranasal sinuses serve to | lighten the skull bones, produces mucus, and resonate during sound production |
hyoid bone | not a skull bone but considered in this section due to location |
hyoid bone is located | supierior to the larynx and inferior to the skull |
hyoid bone is the only bone in the body that | does not join directly with any bone |
the hyoid bone is... | suspended by the stylohyoid ligaments |
hyoid bone has a body and horns that are | attachment points for tongue and neck muscles that raise and lower the larynx during swallowing |
greater horns of hyoid | larger process on the hyoid, which help support the larynx and serve as the base for muscles that move the tongue |
lesser horns | connected to the stylohyoid ligaments, from which the hyoid and larynx hang beneath the skull, like a swing from the limb of a tree |
vertebral column extends from | the skull to the pelvis, forming the body's major axial support |
vertebral columb surrounds and protects | delicate spinal cord while allowing spinal n erves to issue from the cord via openings between adjacent vertebrae |
vertebral clumb has | 26 irregular bones; 7 cervical (c), 12 thoracic (T), 5 lumbar (L), 1 sacral (S), 1 coccygeal |
scral vertebra has | 5 fused bones |
coccygeal vertebra has | 4 fused bones |
the # of cervial vertebrae is... | consistant in humans, but can vary in -5% of population |
intervertebral discs | shock absorbers |
vertebrae are seperated by | pads of fibrocartilage that cushion the vertebrae and absorb shock |
cushion-like pads are made of | nucleus pulposus and annulus fibrosus |
nucleus pulposus | inner sphere, gelatinous and acts like a rubber ball to absorb compressive stress |
annulus fibrosus | outer collar of 12 concentric rings of ligaments(outer) and fibrocartilage (inner) |
annulus fibrosus contains | nucleus pulposus and limits its expansion when the spine is compressed |
annulus fibrosus also acts in | binding the successive vertebrae together |
ligaments connect bone to bone and the three ligaments here are | anterior longitudinal, posterior longitudinal and ligamentum flavum |
anterior longitudinal ligament | prevents hyperextension |
posterior long. ligament | prevents hyperflexion |
ligamentum flavum | elastic connective tissue which stretches and recoils during flexion and extension of the body |
general structure of vertebrae | body, vertebral arch, vertebral foramen, spinous process, transverse process, superior articular process, inferior articular process, intervertebral foramina |
body | centrum, anteriorly located rounded central portion of the vertebra |
vertebral arch | composite structure formed by two pedicles and two laminae |
pedicles | little feet; the sides of the arch are short bony walls that project posteriorly from the vertebral body |
laminae | flat roof plates that complete the arch posteriorly |
vertebral foramen | vertebral body and arches form a central opening |
successive vertebral foramina form... | vertebral canal through which the spinal cord is transmitted |
spinous process | median, posterior projection from the vertebral arch |
transverse process | project laterally from each pedicle-lamina junction |
superior articular process forms | movalble joints with inferior articular processes of vertebra located immediately superior to it |
superior articular process typically faces | away from the spinous process |
intervertebral foramina are | lateral openings between adjacent vertebrae formed by notches on pedicles'superior and inferior borders |
cervical vertebrae (C1-C7) | small and wide side to side, triangular vertebral foramen, short bifid spinous process projects directly posteriorly; increases size from C2-C7 |
atlas | (c1 vertebra) with no body or spinous process |
atlas is a ring of bone consisting of | anterior and posterior arches with a lateral mass on each side with articular facets on its superior and inferior surfaces |
atlas has | anterior and posterior tubercles (small rounded projection) |
superior articular facets receive the | occipital condyles of the skull, thus 'carry' the skull |
atlas allows | flexion and extension of the head and neck (yes) |
axis | c2 vertebra that contains a body and a spinous process |
dens | project superiorly from the axis' body, fuses with the atlas during embryonic development, actually contributues as body of the atlas |
axis acts as a | pivot for the rotation of the atlas and the skull, hence it is named the axis |
axis allows head to | shake side to side (no) |
axis has no | intervertebral disc between c1 and c2 |
thoracic vertebrae | (t1-t12) larger and heart shaped overall |
thoracic vert. bear | two costal demifacets |
thoracic vert. have | circular vertebral foramen |
thoracic vert. have a | long, sharp spinous process projects inferiorly |
lumbar vertebrae (L1-L5) | massive, kidney shaped body |
lumbar vert have what shaped foramen | triangular vertebral foramen |
lumbar vert. have what kind of process | short, blunt, rectangular spinal process projecting directly posteriorly |
sacrum | small of back with curved triangular shape and froemd by 5 fused vertebrae (s1-S5) |
coccyx | tail bone, small and triangular with 4 fused vertebrae |
coccyx provides | slight support of pelvic organs, otherwise useless |
bony thorax | thoracic cage, protects heart, lungs and other thoracic organs |
bony thorax is roughly | cone shaped and includes thoracic vert. posteriorly, ribs laterally, sternum and costal cartilages anteriorly and medially |
sternum | breast bone, anterior midline of thorax |
manubrium | clavicular notches join with clavicles, also join with the 1st and 2nd ribs |
body of sternum | 4 fused bones(puberty) notched on sides where the sternal body joins with 2nd to 7th ribs |
xiphoid process | inferior end of sternum |
sternum exists as plate of | hyaline cartilage in youth, and does not fully ossify until age 40 |
sternum process projects | dorsally in some people |
3 imp. anatomical landmarks of sternum | jugular notch, sternal angle, xiphisternal joint |
jugular notch | central indentation in superior border of manubrium |
sternal angle | horizontal ridge across anterior surface of the sternum, where the sternal body joins the manubrium and forms a fibrocartilage hinge joint |
sternal angle is also used as | a reference point for the 2nd rib and important landmark for thoracic surgery |
2nd intercostals space used for | listening to certain heart valves |
xiphisternal joint | where the sternal body and the xiphoid process fuse |
ribs | 12 pairs form flaring sides of thoracic cage |
true ribs | superior 7 pairs which attach directly to the sternum by their costal cartilages |
ribs progressively | increase in length |
false ribs | inferior 5 pairs with indirect or no attachment to the sternum |
ribs 8-12 progressively | decrease in length |
floating ribs | 11-12 have no anterior attachments to the sternum |
costgal cartilages of floating ribs lie | embedded in muscles of lateral body wall |
costal margin | inferior margin of the rib cage formed by costal cartilages of the ribs 7-10 |
typical rib structure | bowed flat bone |
1st rib is | atypical; flattened superior to inferior surfaces and quite broad |
head | wedge-shaped, joins with vertebral bodies at two facets |
neck | short, constricted region just lateral to the head |
tubercle | knob-like projection just lateral to the neck on the posterior side |
tubercle joins with | the transverse process of the thoracic vertebra of the same number |
shaft | remainder of the rib laterally and medial end |
costal groove | posterior, inferior groove, which serves as a passageway for nerves and vessels |