Skeletal System: Bone Types, Structure, and Skull/Facial Anatomy

A comprehensive set of vocabulary flashcards covering bone types, surface features, bone tissue structure, and skull/facial anatomy.

Long bone

A bone that is longer than it is wide, with a shaft (diaphysis) and two ends (epiphyses).

Irregular bone

A bone with a complex shape that does not fit other categories (e.g., vertebrae).

Sesamoid bone

A small round bone embedded within a tendon, improving leverage (e.g., patella).

Sutural bone

Small bones formed within skull sutures between cranial bones.

Short bone

Cube-like bone typically found in wrists and ankles (carpals and tarsals).

Flat bone

Thin, curved bones that protect and provide surfaces for muscle attachment (e.g., sternum, skull bones).

Axial skeleton

Bones along the body’s central axis: skull, vertebral column, and rib cage.

Appendicular skeleton

Bones of the limbs and girdles (arms, legs, pelvis, and shoulders).

Depressions and openings

Bone surface features that form joints or pathways for vessels and nerves.

Fissure

A narrow slit-like opening in a bone.

Groove

A furrow or channel along a bone surface that may house a tendon or vessel.

Foramen

A rounded or perforating opening through a bone for nerves and vessels.

Meatus

A canal-like passageway through a bone.

Fossa

A shallow depression in a bone for muscle attachment or articulation.

Sinus

A hollow, air-filled cavity within a bone.

Projections

Outgrowths on a bone for articulation or muscle attachment.

Condyle

A rounded knob that articulates with another bone.

Ramus

An arm-like extension or projection of a bone.

Crest

A narrow, prominent ridge on a bone.

Spine

A slender, pointed projection on a bone.

Epicondyle

A projection above a condyle, usually for muscle attachment.

Trochanter

A large, blunt projection (commonly on the femur) for muscle attachment.

Facet

A small, smooth surface for articulation.

Tubercle

A small rounded projection.

Head

A rounded expanded end of a bone that forms a joint with another bone.

Tuberosity

A large, rounded projection for muscle attachment.

Line

A low ridge or linear raised area on a bone.

Process

Any projection or outgrowth from a bone.

Epiphysis

End of a long bone, usually with articular cartilage where joints form.

Endosteum

Membrane lining the inner surfaces of bone, including the medullary cavity.

Diaphysis

The shaft or central part of a long bone.

Spongy bone

Also called cancellous bone; porous inner bone tissue with trabeculae.

Articular cartilage

Hyaline cartilage covering the ends of bones in a joint to reduce friction.

Red marrow

Hematopoietic tissue in certain bones that produces red blood cells.

Medullary cavity

Marrow cavity within the diaphysis of a long bone.

Yellow marrow

Fat-containing marrow stored in the medullary cavity of adults.

Periosteum

Fibrous membrane that covers the outer surface of bone, except at joints.

Compact bone

Dense bone tissue forming the outer layer around the bone; organized into osteons.

Osteon

The basic structural unit of compact bone, centered around a Haversian canal.

Osteocyte

Mature bone cell housed in lacunae.

Trabeculae

Beam-like elements forming the lattice structure of spongy bone.

Lacuna

Small cavity within bone matrix that houses an osteocyte.

Canaliculi

Tiny canals connecting lacunae and allowing nutrient exchange.

Haversian canal

Central vascular canal within an osteon containing blood vessels and nerves.

Volkmann’s canal

Perforating canals that connect Haversian canals to periosteum and marrow cavities.

Concentric lamellae

Concentric rings of calcified matrix around the Haversian canal.

Circumferential lamellae

Lamellae that surround the outer surface of a bone.

Interstitial lamellae

Fragments of old osteons between intact osteons.

Frontal bone

Bone forming the forehead and part of the orbits.

Supraorbital foramen

Opening above the orbit for the supraorbital nerve and vessels.

Supraorbital margin

The upper edge of the orbital cavity.

Parietal bone

Pair of bones forming the lateral and superior walls of the cranium.

Temporal bone

Bone on the sides and base of the skull; contains the mastoid process and ear canals.

Mastoid process

Prominent projection behind the ear for neck and jaw muscle attachment.

Carotid canal

Passage through the temporal bone for the internal carotid artery.

Styloid process

Thin, pointed projection below the ear for ligament attachment.

Stylomastoid foramen

Small opening between the styloid and mastoid processes for the facial nerve.

External auditory meatus

External ear canal leading to the eardrum.

Internal auditory meatus

Opening in the temporal bone for cranial nerves VII and VIII.

Mandibular fossa

Depression in the temporal bone that forms part of the TMJ.

Jugular foramen

Opening for the internal jugular vein and nerves.

Zygomatic process

Projection of the temporal bone that articulates with the zygomatic bone.

Foramen lacerum

Rough opening at the skull base; largely filled with cartilage in life.

Occipital bone

Back/basilar portion of the skull.

Foramen magnum

Large opening for the spinal cord to pass from brain to spine.

Hypoglossal canal

Canal in the occipital bone for the hypoglossal nerve.

Occipital condyle

Rounded projections that articulate with the atlas (C1).

External occipital protuberance

Prominent bump at the back of the skull.

Sphenoid bone

Butterfly-shaped bone at the skull base forming part of the orbit and skull floor.

Optic foramen (canal)

Opening in the sphenoid (orbit) for the optic nerve.

Sella turcica

Saddle-shaped depression in the sphenoid that houses the pituitary gland.

Foramen rotundum

Opening in the sphenoid for the maxillary nerve.

Superior orbital fissure

Slit-like opening that transmits nerves and vessels to the orbit.

Foramen ovale

Opening in the sphenoid for the mandibular nerve.

Inferior orbital fissure

Gap between the maxilla and sphenoid transmitting nerves and vessels.

Foramen spinosum

Small opening for the middle meningeal vessels.

Lesser wing of sphenoid

Small wing-like projection of the sphenoid bone.

Greater wing of sphenoid

Large wing-like projection of the sphenoid bone.

Ethmoid bone

Light, sponge-like bone between the orbits; contributes to nasal cavity and orbit.

Crista galli

Vertical projection of the ethmoid that anchors the falx cerebri.

Superior nasal concha

Scroll-like bone on the lateral wall of the nasal cavity.

Cribriform plate

Flattened, sieve-like part of the ethmoid with olfactory foramina.

Middle nasal concha

Second scroll-like nasal concha on the lateral nasal wall.

Olfactory foramina

Openings in the cribriform plate for olfactory nerves.

Perpendicular plate

Vertical plate of the ethmoid forming part of the nasal septum.

Sutures

Fibrous joints between skull bones.

Coronal suture

Joint between the frontal bone and each parietal bone.

Sagittal suture

Joint between the two parietal bones along the midline.

Lambdoidal suture

Joint between the parietal bones and the occipital bone.

Maxilla

Upper jaw bone; contains the alveolar process.

Alveolar process

Part of a jaw bone that contains tooth sockets.

Incisive foramen

Opening in the maxilla behind the incisor teeth.

Palatine process

Part of the maxilla that forms part of the hard palate.

Infraorbital foramen

Opening below the orbit for the infraorbital nerve and vessels.

Zygomatic bone

Cheekbone; forms the prominence of the cheek.

Temporal process (of zygomatic bone)

Projection of the zygomatic bone that articulates with the temporal bone.

Lacrimal bone

Small: forms part of the medial wall of the orbit.

Lacrimal fossa

Depression in the lacrimal bone that houses the lacrimal sac.

Nasal bone

Small bones forming the bridge of the nose.

Inferior nasal concha

Scroll-like bone on the lateral nasal wall.