Chapter 6 Anatomy Study

Axial skeleton

Central 80 bones of skull, vertebral column, and thoracic cage that support and protect organs

Appendicular skeleton

126 bones of limbs and girdles used for movement and weight support

Function of axial skeleton

Supports and protects organs, special senses, and provides muscle attachments for posture and breathing

Cranium

Eight bones protecting the brain

Facial bones

Fourteen bones forming the face and openings to respiratory and digestive tracts

Associated skull bones

Hyoid and auditory ossicles that support tongue, larynx, and hearing

Calvaria

Skullcap formed by cranial bones and sutures over the superior brain

Occipital bone

Posterior skull bone containing foramen magnum and occipital condyles

Foramen magnum

Large opening where spinal cord connects to brain

Occipital condyles

Articular surfaces that join atlas (C1) for head nodding

External occipital protuberance

Bony bump on back of skull for ligament and muscle attachment

Nuchal lines

Ridge lines on occipital bone where neck muscles attach

Parietal bones

Paired bones forming top and sides of skull

Parietal eminence

Thickened area on parietal bones where skull is widest

Frontal bone

Bone forming forehead and roof of orbits

Frontal sinus

Air cavity in frontal bone opening into nasal cavity

Supra

orbital foramen

Temporal bones

Bones on sides of skull housing ear structures

External acoustic meatus

Canal in temporal bone carrying sound to eardrum

Mastoid process

Rounded projection behind ear with air cells and muscle attachments

Styloid process

Slender projection for tongue and neck muscle and ligament attachment

Petrous part

Dense part of temporal bone enclosing inner ear

Sphenoid bone

Central cranial bone that connects other skull bones and forms part of orbit and cranial floor

Sella turcica

Sphenoid depression holding pituitary gland

Optic canal

Passage for optic nerve and ophthalmic artery

Ethmoid bone

Bone between orbits forming part of nasal septum and roof of nasal cavity

Crista galli

Ethmoid ridge where a meningeal fold attaches

Cribriform plate

Ethmoid plate with holes for olfactory nerves

Superior nasal concha

Upper shelf that helps warm and humidify inhaled air

Middle nasal concha

Middle shelf that increases airflow contact with mucosa

Cranial fossae

Depressions in cranial floor that support brain regions

Anterior cranial fossa

Fossa supporting frontal lobes

Middle cranial fossa

Fossa supporting temporal lobes and pituitary area

Posterior cranial fossa

Fossa containing cerebellum and brainstem

Maxillae

Paired upper jaw bones forming upper teeth sockets, part of orbit, and hard palate

Infra

orbital foramen

Maxillary sinuses

Large air spaces in maxilla draining into nasal cavity

Palatine bones

Bones forming back part of hard palate and part of nasal cavity

Nasal bones

Small bones forming bridge of the nose

Inferior nasal conchae

Separate curved bones that increase turbulence in nasal cavity

Zygomatic bones

Cheek bones forming part of zygomatic arch and lateral orbit

Zygomaticofacial foramen

Opening in zygomatic bone for sensory nerve from cheek

Lacrimal bones

Small bones in medial orbit with groove for tear drainage

Lacrimal groove

Groove leading to nasolacrimal canal for tears to enter nasal cavity

Vomer

Bone forming lower part of nasal septum

Mandible

Lower jaw bone forming movable joint with skull and holding lower teeth

Condylar process

Mandibular process that articulates with temporal bone (TMJ)

Coronoid process

Mandibular process where muscles attach to elevate jaw

Mental foramen

Opening on front of mandible for nerves and vessels to chin and lower lip

Mandibular foramen

Opening on inner mandible for nerves and vessels to lower teeth

Alveolar part

Ridge of maxilla and mandible containing tooth sockets

Orbit

Bony eye socket protecting eye and housing muscles, vessels, and nerves

Nasal complex

Bony framework of nasal cavity including septum and conchae

Nasal septum

Divider of nasal cavity formed by vomer and perpendicular plate of ethmoid

Nasal conchae

Curved shelves that create turbulence and increase air contact with mucosa

Paranasal sinuses

Air

Frontal sinuses

Paranasal sinuses in frontal bone

Sphenoidal sinuses

Paranasal sinuses in sphenoid bone

Maxillary sinuses

Paranasal sinuses in maxilla

Ethmoid air cells

Small paranasal air spaces in ethmoid bone

Hyoid bone

Free

Greater horns

Larger hyoid projections for muscle and ligament attachment

Lesser horns

Smaller hyoid projections for ligament attachment

Fontanelles

Soft membrane areas in infant skull where bones are not yet fused

Anterior fontanelle

Large “soft spot” on top of infant skull

Posterior fontanelle

Smaller fontanelle near back of infant skull

Sphenoidal fontanelles

Fontanelles near sphenoid region on infant skull

Mastoid fontanelles

Fontanelles near mastoid region on infant skull

Vertebral column

Series of 26 bones that protect spinal cord and support head and trunk

Vertebra

Single bone of vertebral column

Intervertebral disc

Cartilage pad between vertebral bodies that cushions and separates them

Spinal curves

Normal curves in vertebral column that help balance and distribute weight

Primary curves

Thoracic and sacral curves present before birth

Secondary curves

Cervical and lumbar curves that form after birth

Cervical curve

Curve that develops as infant supports head

Thoracic curve

Curve that accommodates thoracic organs

Lumbar curve

Curve that balances trunk weight over lower limbs

Sacral curve

Curve that accommodates abdominopelvic organs

Vertebral body

Front, weight

Vertebral arch

Posterior part formed by pedicles and lamina that surrounds vertebral foramen

Spinous process

Posterior projection for muscle and ligament attachment

Transverse process

Lateral projections for muscle and ligament attachment

Articular processes

Superior and inferior projections forming joints between vertebrae

Vertebral foramen

Opening through each vertebra for spinal cord

Vertebral canal

Tunnel formed by aligned vertebral foramina for spinal cord

Intervertebral foramen

Opening between vertebrae where spinal nerves exit

Spina bifida

Condition where vertebral arch fails to form completely, leaving spinal cord exposed

Cervical vertebrae

Seven vertebrae (C1–C7) that support the head and allow neck motion

Atlas (C1)

First cervical vertebra that supports skull and allows nodding

Axis (C2)

Second cervical vertebra with dens that lets head rotate

Transverse foramen

Hole in cervical transverse process for vertebral arteries

Thoracic vertebrae

Twelve vertebrae (T1–T12) that articulate with ribs and support thoracic cage

Costal facets

Smooth areas on thoracic vertebrae where ribs attach

Lumbar vertebrae

Five vertebrae (L1–L5) with large bodies that bear most body weight

Sacrum

Fused bone of five sacral vertebrae transferring weight from spine to pelvis

Coccyx

Small fused tailbone made of 3–5 vertebrae