lecture 25 - skeletal system: axial skeleton - skull and hyoid

there are ___ bones in the human (adult) body

206

2 divisions of skeleton

• axial skeleton

• appendicular skeleton

axial skeleton

• 80 bones

• lie along longitudinal axis

• skull, hyoid bone, vertebrae, ribs, sternum, auditory ossicles

appendicular skeleton

• 126 bones

• upper + lower limbs, pelvic + pectoral girdles

girdles

• attachment sites b/w axial + appendicular skeleton

projections

• points of attachment for muscles/ligaments/tendons onto bone

  • e.g. process

    • smaller bony feature that sticks out of bone

  • tuberosity

    • large knob projection

  • tubercles

    • rounded bumps

ridge

• points of attachment for muscles/ligaments/tendons onto bone

• provide bony feature that sticks out of bone

  • e.g. spine of scapula

functions of surface features of bone

• passageway for blood vessels + nerves

• joint formation

• muscle, tendon + ligament attachment

openings

foramen

• e.g. foramina of cribriform plate

• holes

canals

• tunnels through bone

depressions

fossas

• shallow depression

notches

grooves

margin/border

• outside portion of bone

condyle

• smooth, rounded articular surface or surface that forms a joint

facet

• small, flattened articular surface or surface that forms a joint

skull function

• protect the brain

• supports organs of vision, hearing, smell + taste

skull # of bones

• 22 separate bones + 6 auditory ossicles + 1 hyoid bone

2 portions of skull bones

1. cranial bones

2. facial bones

cranial bones

• 2 parietal, temporal

• frontal, occipital, sphenoid, ethmoid

(8 bones)

facial bones

• 2 maxilla, zygomatic, palatine, lacrimal, nasal, inferior nasal conchae

• 1 vomer, mandible

(14 bones)

the ______ is the only movable bone of the skull. it forms a joint with the ______ bone

mandible, temporal

frontal bone

• forehead

• roof of orbit (roof of eye socket)

• anterior part of cranial floor (floor of bone that holds brain)

originally, the frontal bone is _ bones. these fuse anteriorly by about age _

2, 6

parietal bones

• sides + roof of cranial cavity

occipital bone

• base of cranium

temporal bones

• inferior lateral aspects of cranial cavity

• part of floor of cranial cavity

mastoid process

• on temporal bone

• attachment point for neck muscles

styloid process

• on temporal bone

• attachment point for tongue + neck muscles

external auditory canal/meatus or external acoustic meatus

• hole in temporal bone that leads to middle + inner ear

_____ is another word for canal

meatus

zygomatic process

• part of temporal bone

• region of cheek bone

sphenoid bone

• butterfly shape

• has greater + lesser wings

• lateral skull + cranial floor + eye socket

• articulates w/ all other cranial bones

ethmoid bone

perpendicular plate

• part of ethmoid bone

• superior + posterior portion of nasal septum

middle nasal conchae

• ridge of ethmoid bone

superior nasal conchae

• ridge of ethmoid bone

cribriform plate

• part of ethmoid bone

• separates nasal cavity from cranial cavity

nasal bones

• upper bridge of nose + anterior roof of nasal cavity

lacrimal bones

• smallest bones in face

• contain lacrimal sac

• within eye orbit

zygomatic bones

• cheek bones + portions of orbit

temporal process

• part of zygomatic bone

zygomatic arch

temporal process (of zygomatic bone) + zygomatic process (of temporal bone) together

maxilla bones

• upper jaw + floors of orbit + some nasal cavity + most of hard palate (roof of mouth)

mandible

• largest + strongest bone of skull

• only movable bone of skull (aside from auditory ossicles + hyoid bone which aren’t really part of the skull…js associated with it)

• not attached (articulates w/ temporal bone)

mandibular fossa

• where mandible articulates with the temporal bone

orbit

eye socket

supraorbital margins

• ridges on top of orbit in frontal bone

• portion that gets hit when someone is hit in the eye (black eye)

inferior nasal conchae

• bone (NOT ASSOCIATED w/ ETHMOID BONE)

• ridge that filters air before it enters the respiratory system

• help move odorants

vomer

• inferior + posterior region of nasal septum

alveolar processes

• parts of maxillary bone + mandible

• create spaces for teeth

palatine processes

• part of maxillary bones

• make up roof of mouth

• fuse tgth during embryological development

palatine bone

• L-shape

horizontal plate

• part of palatine bone

palatine process (maxilla) + horizontal plate (palatine bone) make up what

• hard palate

cleft lip/palate is caused by an improper fusing of the _______ processes during embryological development

palatine

cleft lip vs cleft palate

cleft lip: failed fusion on soft portion of skin

cleft palate: failed fusion of maxillary bones

jugular foramen

• veins draining blood from skull/brain leave the brain

carotid foramen

• arteries giving blood to skull/brain enter the brain

external occipital protuberance

• part of occipital bone

• bump on back of skull

• joins to ligaments → hold your head upright

foramen magnum

• hole in occipital bone where spinal cord connects to brainstem

occipital condyles

• part of occipital bone

• articulate w/ 1st cervical vertebrae

• rounded

• allow nodding ‘yes’ + tilting ears towards shoulders

there are _ bones that make up the orbit

7

7 bones that make up the orbit

1. frontal bone

2. sphenoid bone

3. zygomatic bone

4. maxilla

5. lacrimal bone

6. ethmoid bone

7. palatine bone

roof of orbit is comprised of which bones

• frontal + sphenoid bones

lateral wall of orbit is comprised of which bones

• sphenoid + zygomatic bones

floor of orbit is comprised of which bones

• maxilla + zygomatic + palatine bones

medial wall of orbit is comprised of which bones

• maxilla, lacrimal, ethmoid, sphenoid bones

the orbit is a _____ shape that extends backwards

cone

hyoid bone

• not really in skull

• floating bone

• unpaired

• does not articulate with any other bone

• attachment point for tongue + neck muscles (that elevate larynx during speech + swallowing)