A&P 7: 206 Bones Flashcards
Skeleton (skeletal system)
composed of bones, cartilages, joints, and ligaments; accounts for about 20% of body mass; bones make up most of it
Axial skeleton
structured from 80 bones segregated into 3 major regions: the skull, vertebral column, and thoracic cage; forms the longitudinal axis of the body, supports the head, neck, and trunk, & protects the brain, spinal cord, and the organs in the thorax
Skull
body’s most complex bony structure; formed by cranial and facial bones, 22 in all
Cranium
cranial bones; enclose and protect the fragile brain and furnish attachment sites for head and neck muscles
Sutures
except for the mandible, all bones of the adult skull are firmly united by these interlocking joints, the lines of which have a saw-toothed/serrated appearance
Cranial vault
AKA the calvaria; forms the superior, lateral, and posterior aspects of the skull, as well as the forehead
Cranial base
forms the skull’s inferior aspects
Frontal bone
shell-shaped; forms the anterior cranium; articulates posteriorly with the paired parietal bones via the prominent coronal suture
Supraorbital margins
the frontal squamous region ends inferiorly at these thickened superior margins of the orbits that lie under the eyebrows
Anterior cranial fossa
the frontal bone extends posteriorly from the supraorbital margins, forming the superior wall of the orbits and most of this, which supports the frontal lobes of the brain
Supraorbital foramen (notch)
each supraorbital margin is pierced by this, which allows the supraorbital artery and nerve to pass to the forehead
Glabella
smooth portion of the frontal bone between the orbits
Frontal sinuses
the areas lateral to the glabella are riddled internally with these spaces
Parietal bones
2 large, curved rectangular bones that form most of the superior and lateral aspects of the skull, hence forming the bulk of the cranial vault
Coronal suture
where the parietal bones meet the frontal bone anteriorly
Sagittal suture
where the parietal bones meet superiorly at the cranial midline
Lambdoid suture
where the parietal bones meet the occipital bone posteriorly
Squamous suture
one on each side, where a parietal and temporal bone meet on the lateral aspect of the skull
Occipital bone
forms most of the skull’s posterior wall and base; articulates anteriorly with the paired parietal and temporal bones via the lambdoid and occipitomastoid sutures; the basilar part of this bone also joins with the sphenoid bone in the cranial base
Posterior cranial fossa
internally, the occipital bone forms the walls of this depression, which supports the cerebellum of the brain
Foramen magnum
in the base of the occipital bone is this large hole though which the inferior part of the brain connects with the spinal cord; flanked laterally by 2 occipital condyles
Occipital condyles
rockerlike; articulate with the 1st vertebra of the spinal column in a way that permits a nodding (“yes”) motion of the head
Hypoglossal canal
hidden medially and superiorly to each occipital condyle is this canal through which a cranial nerve (XII) passes
External occipital protuberance
just superior to the foramen magnum is this median protrusion; you can feel this knoblike projection just below the most bulging part of your posterior skull
Temporal bones
2 bones that lie inferior to the parietal bones and meet them at the squamous sutures; form the inferolateral apsects of the skull and parts of the cranial base
Squamous part
flaring part of the temporal bone that abuts the squamous suture
Zygomatic process
barlike part of the temporal bone that meets the zygomatic bone of the face anteriorly
Zygomatic arch
squamous part of the temporal bone + zygomatic process, which you can feel as the projection of your cheek; AKA cheekbone
Mandibular fossa
small, oval depression on the inferior surface of the zygomatic process that receives the condylar process of the mandible, forming the freely movable temporomandibular joint
Tympanic part
part of the temporal bone surrounding the external acoustic meatus (external ear canal), through which sound enters the ear
Petrous part
thick part of the temporal bone that houses the middle and internal ear cavities, which contain sensory receptors for hearing and balance
Middle cranial fossa
together, the sphenoid bone and the petrous portions of the temporal bones construct this depression, which supports the temporal lobes of the brain
Jugular foramen
opening at the junction of the occipital and petrous temporal bones that allows passage of the internal jugular vein and 3 cranial nerves (IX, X, & XI)
Cranial canal
just anterior to the jugular foramen; transmits the internal carotid artery into the cranial cavity
Foramen lacerum
jagged opening between the petrous temporal bone and the sphenoid bone; almost completely covered by cartilage in a living person
Internal acoustic meatus
positioned superolateral to the jugular foramen; transmits cranial nerves VII & VIII
Mastoid process
conspicuous feature of the petrous part of the temporal bone; acts as an anchoring site for some neck muscles
Styloid process
needle-like attachment point for several tongue and neck muscles and for a ligament that secures the hyoid bone of the neck to the skull
Stylomastoid foramen
between the styloid and mastoid processes, allows cranial nerve VII (the facial nerve) to leave the skull
Mastoid air cells
the mastoid process is full of these air cavities; their position adjacent to the middle ear cavity puts them at risk for infections
Sphenoid bone
bat-shaped bone that spans the width of the middle cranial fossa; considered the keystone of the cranium because it forms a central wedge that articulates with all other cranial bones
Body (of the sphenoid)
contains the paired sphenoidal sinuses
Sphenoidal sinuses
paired cavities within the body of the sphenoid
Sella turcica
“Turk’s saddle”; superior surface of the body of the sphenoid bears this saddle-shaped prominence
Hypophyseal fossa
the seat of the sella turcica; forms a snug enclosure for the pituitary gland (hypophysis)
Greater wings
project laterally from the sphenoid body, forming parts of (1) the middle cranial fossa, (2) the posterior walls of the orbits, & (3) the external wall of the skull, where they are seen as flag-shaped, bony areas medial to the zygomatic arch
Lesser wings
hornlike parts of the sphenoid the form part of the floor of the anterior cranial fossa and part of the medial walls of the orbits
Pterygoid processes
trough-shaped parts of the sphenoid that project inferiorly from the junction of the body and the greater wings; anchor the pterygoid muscles, which are important in chewing
Optic canals
openings lying anterior to the sella turcica; allow the optic nerves (cranial nerves II) to pass to the eyes
Superior orbital fissure
long slit between the greater and lesser wings of the sphenoid; allows cranial nerves that control eye movements (III, IV, VI) to enter the orbit
Foramen rotundum
provides passageway for branch of cranial nerve V (the maxillary nerve) to reach the face; medial part of the greater wing and is usually oval
Foramen ovale
provides passageway for branch of cranial nerve V (the mandibular nerve) to reach the face; large, oval opening posterior to the foramen rotundum
Foramen spinosum
posterolateral to the foramen ovale is this small opening which transmits the middle meningeal artery, which serves the internal faces of some cranial bones
Ethmoid bones
delicate bone with a complex shape; lies between the sphenoid and the nasal bones of the face; it is the most deeply situated bone of the skull; forms most of the bony area between the nasal cavity and the orbits
Cribriform plates
superior surface of the ethmoid is formed by these paired horizontal plates, which help form the roof of the nasal cavities and the floor of the anterior cranial fossa; the plates are punctured by tiny holes that allow the filaments of the olfactory nerves to pass from the smell receptors in the nasal cavities to the brain
Crista galli
projecting superiorly between the cribriform plates is this triangular process that looks like a “rooster’s comb”; the outermost covering of the brain (dura mater) attaches to this and helps secure the brain in the cranial cavity
Perpendicular plate
part of the ethmoid bone that projects inferiorly in the median plane and forms the superior part of the nasal septum, which divides the nasal cavity into right and left halves
Lateral mass
flanking the perpendicular plate on each side is this, which is riddled with sinuses
Ethmoidal air cells
sinuses of the lateral mass; flanks the perpendicular plate
Superior & middle nasal conchae
extending medially from the lateral masses, these delicately coiled parts are named after conch shells; they protrude into the nasal avity
Orbital plates
the lateral surfaces of the ethmoid’s lateral masses are called this because they contribute to the medial walls of the orbits
Sutural bones
tiny, irregularly shaped bones or bone clusters that occur within sutures, most often in the lambdoid suture
Mandible
u-shaped lower jawbone; largest, strongest bone of the face; has a body (chin) and 2 upright rami (branches); each ramus meets the body posteriorly at a mandibular angle
Mandibular angle
each ramus of the mandible meets the body posteriorly here
Mandibular notch
at the superior margin of each ramus are 2 processes separated by this u-shaped cut-out
Coronoid process
an anterior part of the mandible which serves as an insertion point for the large temporalis muscle that elevates the lower jaw during chewing
Condylar process
a posterior part of the mandible that articulates with the mandibular fossa of the temporal bone, forming the temporomandibular joint of the same side
Body (mandible)
part of the mandible that anchors the lower teeth
Alveolar processes (mandible)
superior border of the mandibular body containing the sockets in which the teeth are embedded
Mandibular symphysis
in the midline of the mandibular body is this slight ridge, indicating where the 2 mandibular bones fused during infancy
Mandibular foramina
large opening on the medial surface of each ramus of the mandible that permits the nerves responsible for tooth sensation to pass to the teeth in the lower jaw; dentists inject lidocaine here to prevent pain while working on the lower teeth
Mental foramina
openings on the lateral aspects of the mandibular body; allow blood vessels and nerves to pass to the skin of the chin and lower lip
Maxillary bones (maxillae)
bones fused medially that form the upper jaw and the central portion of the facial skeleton; all bones except the mandible articulate with these bones, hence they are considered the keystone bones of the facial skeleton
Alveolar processes (maxillae)
parts of the maxillae that carry the upper teeth
Anterior nasal spine
just inferior to the nose, the maxillae meet medially, forming this pointed part at their junction
Palatine processes
parts of the maxillae that project posteriorly from the alveolar processes and fuse medially at the intermaxillary suture, forming the anterior 2/3 of the hard palate (bony roof of the mouth)
Incisive fossa
just posterior to the teeth is a midline foramen called this, which serves as a passageway for blood vessels and nerves
Frontal processes
extend superiorly to the frontal bone, forming part of the lateral aspects of the bridge of the nose
Maxillary sinuses
the regions that flank the nasal cavity laterally contain these cavities, the largest of the paranasal sinuses; extend from the orbits to the roots of the upper teeth
Zygomatic processes
laterally, the maxillae articulate with the zygomatic bones via these parts
Inferior orbital fissure
located deep within the orbit at the junction of the maxilla with the greater wing of the sphenoid; permits the zygomatic nerve, the maxillary nerve (a branch of cranial nerve V), and blood vessels to pass to the face
Infraorbital foramen
just below the eye socket on each side is this opening that allows the infraorbital nerve (a continuation of the maxillary nerve) and artery to reach the face
Zygomatic bones
irregularly shaped bones commonly called the cheekbones; articulate with the zygomatic processes of the temporal bones posteriorly, the zygomatic processes of the frontal bone superiorly, and with the zygomatic processes of the maxillae anteriorly; form the prominence of the cheeks and part of the inferolateral margins of the orbits
Nasal bones
thin, basically rectangular bones fused medially, forming the bridge of the nose; articulate with the frontal bone superiorly, the maxillary bones laterally, and the perpendicular plate of the ethmoid bone posteriorly; inferiorly they attach to the cartilages that form most of the skeleton of the external nose
Lacrimal bones
delicate, fingernail-shaped bones that contribute to the medial walls of each orbit; articulate with the frontal bone superiorly, the ethmoid bone posteriorly, and the maxillae anteriorly; each one contains a deep groove the helps form a lacrimal fossa
Lacrimal fossa
depression/groove in the lacrimal bones that houses the lacrimal sac, part of the passageway that allows tears to drain from the eye surface into the nasal cavity
Palatine bone
each L-shaped bone is fashioned from 2 bony plates, the horizontal and the perpendicular; has 3 important articular processes - the pyramidal, sphenoidal, and orbital
Horizontal plates
joined at the medial palatine suture, complete the posterior portion of the hard palate
Perpendicular (vertical) plates
superiorly projecting plates that form part of the posterolateral walls of the nasal cavity and a small part of the orbits
Vomer
slender, plow-shaped bone that lies in the nasal cavity where it forms part of the nasal septum
Inferior nasal conchae
paried, thin, curved bones in the nasal cavity; project medially from the lateral walls of the nasal cavity, just inferior to the middle nasal conchae of the ethmoid bone; largest of the 3 pairs of conchae; form part of the lateral walls of the nasal cavity
Orbits
cone-shaped bony cavities in which the eyes are firmly encased and cushioned by fatty tissue
Nasal cavity
constructed of bone and hyaline cartilage; roof formed by the cribriform plates of the ethmoid; lateral walls are largely shaped by the superior and middle conchae of the ethmoid bone, the perpendicular plates of the palatine bones, and the inferior nasal conchae; depressions under cover of the conchae on the lateral walls = meatuses (=passage; superior, middle, and inferior); floor formed by the palatine processes of the maxillae and the palatine bones; divided into left and right parts by the nasal septum
Paranasal sinuses
sinuses of 5 of the skull bones (frontal, sphenoid, ethmoid, and paired maxillary); lined with mucosa, filled with air; cluster around the nasal cavity; lighten the skull and enhance the resonance of the voice
Hyoid bone
lies just inferior to the mandible in the anterior neck; unique bone - only bone in the body that does not articulate directly with any other bone; anchored by the narrow stylohyoid ligaments to the styloid processes of the temporal bones; horseshoe shaped, with a body and 2 pairs of horns (cornua), this bone acts as a movable base for the tongue; body and greater horns are attachment points for neck muscles that raise and lower the larynx during swallowing and speech
Vertebral column
spine; spinal column; consists of 26 irregular bones connected in such a way that a flexible, curved structure results; serves as the axial support of the trunk; extends from the skull to the pelvis, where it transmits the weight of the trunk to the lower limbs; surrounds and protects the delicate spinal cord and provides attachment points for the ribs and for the muscles of the back and neck
Vertebrae
in the fetus and infant, the vertebral column consists of 33 separate bones called this; inferiorly, 9 of these eventually fuse to form 2 composite bones, the sacrum and the tiny coccyx; remaining 24 persist as individual ____ separated by intervertebral discs
Cervical vertebrae
7 vertebrae of the neck
Thoracic vertebrae
12 bones of the thorax
Lumbar vertebrae
5 supporting bones of the lower back
Sacrum
inferior to the lumbar vertebrae is this bone, which articulates with the hip bones of the pelvis
Coccyx
terminus of the vertebral column
Cervical and lumbar curvatures
concave posteriorly
Thoracic and sacral curvatures
convex posteriorly
Anterior & posterior longitudinal ligaments
major supporting ligaments of the spine; run as continuous bands down the front and back surfaces of the vertebrae from the neck to the sacrum; broad one prevents hyperextension of the spine (strongly attached to both the bony vertebrae and the discs); narrow, weak one prevents hyperflexion of the spine (attaches only to the discs)
Ligamentum flavum
connects adjacent vertebrae, contains elastic connective tissue and is especially strong; stretches as we bend forward and then recoils when we resume an erect posture
Intervertebral disc
cushionlike pad composed of 2 parts - inner, gelantinous nucleus pulposus & the anulus fibrosus
Nucleus pulposus
inner gelatinous part of an intervertebral disc; acts like a rubber ball, giving the disc its elasticity and compressibility
Anulus fibrosus
surrounds the nucleus pulposus; strong collar composed of collagen fibers superficially and fibrocartilage internally; limits the expansion of the nucleus pulposus when the spine is compressed; also binds successive vertebrae together, withstands twisting forces, and resists tension in the spine
Herniated (prolapsed) disc
“slipped disc”; usually involves rupture of the anulus fibrosus followed by protusion of the spongy nucleus pulposus through the anulus