Comprehensive Skeletal System and Joint Types: Anatomy and Function

Axial skeleton

Forms central supporting axis of body; skull, vertebrae, sternum, ribs, sacrum, and hyoid.

Appendicular skeleton

Pectoral girdle, upper extremity, pelvic girdle, lower extremity.

206 bones in typical adult skeleton

206 bones in typical adult skeleton; 270 bones at birth, but number decreases with fusion.

Sesamoid bones

Bones that form within tendons (e.g. patella; below big toe joint).

Sutural (Wormian) bones

Extra bones that develop in skull suture lines.

Articulated skeleton

Held together by wire and rods, shows spatial relationships between bones.

Disarticulated bones

Taken apart.

Surface features and markings

Include ridges, spines, bumps, depressions, canals, pores, slits, cavities, and articular surfaces.

Skull

Most complex part of the skeleton; 22 bones joined together by sutures (immovable joints).

Cranial cavity

Brain case.

Orbits

Eye sockets.

Nasal cavity

One of the several cavities of the skull.

Oral (buccal) cavity

One of the several cavities of the skull.

Middle- and inner-ear

One of the several cavities of the skull.

Foramina

Holes that allow passage for nerves and blood vessels.

Paranasal sinuses

Air-filled holes; lined by mucous membrane; chambers that add resonance to the voice; lighten the skull.

Cranium (braincase)

Meninges (membrane) separate brain from bones.

Meninges

Membrane; separate brain from bones.

Dura mater

The thickest membrane.

Calvaria

One of two parts of the cranium.

Cranial base

One of two parts of the cranium.

Anterior cranial fossa

Frontal lobe.

Middle cranial fossa

Temporal lobes.

Posterior cranial fossa

Cerebellum.

8 cranial bones

1 frontal, 2 parietal, 2 temporal, 1 occipital, 1 sphenoid, 1 ethmoid.

Frontal bone

Forms forehead and part of the roof of the cranium.

Coronal suture

Posterior boundary of frontal bone.

Supraorbital margin

Ridge of bone deep to eyebrow.

Supraorbital foramen

Passage for nerve, artery, and vein.

Glabella

Smooth area above root of the nose.

Parietal bones

Form most of cranial roof and part of its lateral walls.

Sagittal suture

Between parietal bones.

Lambdoid suture

At posterior margin.

Squamous suture

At lateral border.

Temporal lines

For attachment of temporalis muscle.

Temporal bones

Form lateral walls and part of floor of cranial cavity.

Mastoid process

Lump with air sacs.

External auditory meatus

Ear canal.

Styloid process

Muscles for tongue and hyoid bone.

Petrous part

Part of cranial floor; separates middle from posterior cranial fossa; houses middle- and inner-ear cavities.

Occipital bone

Forms the rear and base of skull.

Foramen magnum

Opening for spinal cord.

Basilar part

Thick median plate.

Occipital condyles

Knobs resting on spinal column.

Hypoglossal canal

Transmits CN XII (hypoglossal).

Sphenoid bone

Located at the anterior base of skull; one of the most complex bones in the human body.

Body of sphenoid

Thick median section.

Foramen rotundum

Passage for maxillary branch of the trigeminal nerve.

Foramen ovale

Passage for mandibular branch of the trigeminal nerve.

Ethmoid bone

Located between the eyes; contributes to medial wall of orbit, walls and roof of nasal cavity, and nasal septum.

Perpendicular plate

Superior two-thirds of nasal septum.

Crista galli

Blade-like attachment for dura.

Ethmoid labyrinth

Large mass on each side of perpendicular plate.

Ethmoidal cells

Maze of air spaces.

Orbital plate

Smooth, slightly concave orbital plate seen on the medial orbital wall.

Superior and middle nasal conchae

Scroll-like plates that project into the nasal fossa.

Inferior concha

Separate bone; along with the other plates, occupies most of the nasal cavity, creates turbulence of air flow, and helps humidify air.

Facial bones

14 skull bones anterior to the cranial cavity; support teeth; give shape to face; form part of orbital and nasal cavities.

Maxillae

Largest facial bones; form upper jaw and meets at median intermaxillary suture.

Intermaxillary suture

Median intermaxillary suture.

Alveolar processes

Bony points between teeth.

Alveolus

Sockets that hold teeth.

Cleft palate/lip

Occur when the two maxillae fail to join.

Hard palate

Forms roof of mouth and floor of nasal cavity; palate allows chewing while breathing.

Palatine process of maxillae

Anterior 3/4 of hard palate.

Palatine bones

PowerPoint labels the palatine bones on the palate slides.

Horizontal plates

Form posterior 1/4 of hard palate.

Maxillary sinus

Fills maxillae bone.

Zygomatic bones

Form cheekbones; also form part of lateral orbital wall.

Zygomatic arch

Temporal process and zygomatic process.

Temporal process

Part of zygomatic arch.

Zygomatic process

Part of zygomatic arch.

Lacrimal bones

Smallest bones of skull; form part of medial orbit.

Lacrimal fossa

Houses lacrimal sac.

Lacrimal sac

In lacrimal fossa.

Nasal bones

Form bridge of nose.

Vomer

Inferior half of nasal septum.

Nasal septum

Divides nasal cavity into right and left halves.

Inferior nasal conchae

Largest of the three conchae in nasal cavity.

Mandible

Strongest bone of skull; only one that noticeably moves.

Mental symphysis

Joint at midline.

Mental protuberance

Point of chin.

Mental foramen

Passage for nerves and vessels of chin.

Mandibular foramen

Passage for nerves and vessels of lower teeth.

Ramus

Articulates with cranium.

Condylar process

Process on mandible; includes mandibular condyle.

Coronoid process

For temporalis muscle.

Auditory ossicles

Malleus, incus, and stapes.

Hyoid bone

Slender U-shaped bone between chin and larynx; does not articulate with any other bone.

Fontanelles

Soft spots.

Metopic suture

Between right and left halves of frontal bone; disappears around age 6.

general features of Vertebral column

•Five vertebral groups for a total of 33 •7 cervical in the neck •12 thoracic in the chest •5 lumbar in lower back •5 fused sacral •4 fused coccygeal

S-shaped

Adult vertebral column is S-shaped.

Secondary curvatures

Develop after birth; cervical curvature from lifting head; lumbar curvature from walking upright.

Scoliosis

Abnormal lateral curvature of spine.

Kyphosis

Excessive thoracic curvature.

Lordosis

Excessive lumbar curvature.

Vertebral body

Main weight-bearing part of vertebra.

Vertebral foramen

Opening for spinal cord.

Intervertebral foramen

Opening for spinal nerves.