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HA Ch. 6

Skeletal System (Axial Division)

# 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
Created by: handrzej



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