osteology

Atlas

C1 vertebra; supports skull; no body or spinous process

Axis

C2 vertebra; has dens for rotation

Dens (odontoid process)

Projection of C2 that articulates with atlas for rotation

Cervical vertebra

Vertebrae C1–C7; small body, transverse foramina

Transverse process

Lateral projection for muscle attachment

Transverse foramina

Openings in cervical vertebrae → vertebral artery, vein, sympathetic plexus

Body (vertebra)

Anterior weight-bearing portion

Lamina

Posterior arch connecting spinous and transverse processes

Superior articular process

Articulates with vertebra above

Inferior articular process

Articulates with vertebra below

Spinous process

Posterior projection for muscle/ligament attachment

Vertebral foramen

Opening forming spinal canal → spinal cord, meninges

Superior vertebral notch

Forms intervertebral foramen → spinal nerve exits

Inferior vertebral notch

Forms intervertebral foramen → spinal nerve exits

Hyoid bone

U-shaped bone; no bony articulation; supports tongue

Parietal bone

Forms superior/lateral skull

Occipital bone

Forms posterior skull and base

Foramen magnum

Opening for spinal cord → spinal cord, vertebral aa., CN XI (spinal root)

External occipital protuberance

Midline posterior bump for ligament attachment

Temporal bone

Lateral skull; houses ear structures

Squamous part

Flat portion of temporal bone

Mastoid process

Muscle attachment; SCM insertion

Styloid process

Thin projection for muscle/ligament attachment

External auditory meatus

Ear canal opening → sound waves

Zygoma

Cheekbone

Zygomatic arch

Bridge between temporal and zygomatic bones

Frontal bone

Forehead; superior orbit

Supraorbital notch/foramen

Passage → supraorbital nerve, artery, vein

Maxilla

Upper jaw; forms orbit, nasal cavity

Alveolar process

Tooth-bearing ridge

Infraorbital foramen

Passage → infraorbital nerve (V2), artery, vein

Lacrimal bone

Small bone in medial orbit

Lacrimal fossa

Houses lacrimal sac

Nasolacrimal canal

Drains tears → inferior nasal meatus

Nasal bone

Bridge of nose

Mandible

Lower jaw; only movable skull bone

Body (mandible)

Horizontal portion

Ramus (mandible)

Vertical portion

Angle (mandible)

Junction of body and ramus

Condylar process

Articulates with temporal bone (TMJ)

Coronoid process

Muscle attachment (temporalis)

Genial tubercles

Muscle attachment (tongue, floor of mouth)

Orbit

Eye socket → optic nerve, vessels, extraocular structures

Inferior orbital fissure

Opening → infraorbital n., zygomatic n., vessels

Infraorbital groove

Groove → infraorbital nerve/vessels

Infraorbital canal

Passage → infraorbital nerve/vessels

Nasion

Junction of frontal and nasal bones

Pterion

Junction of 4 bones → middle meningeal artery deep

Suture lines

Fibrous joints between skull bones

Coronal suture

Between frontal and parietal bones

Lambdoid suture

Between parietal and occipital bones

Sagittal suture

Between parietal bones

Occipital bone (base)

Forms posterior cranial base

Hypoglossal canal

Passage → hypoglossal nerve (CN XII)

Occipital condyle

Articulates with atlas

Vomer

Forms inferior nasal septum

Sphenoid bone

Keystone of cranial base

Lateral pterygoid plate

Muscle attachment (lateral pterygoid)

Medial pterygoid plate

Muscle attachment (medial pterygoid)

Pterygoid hamulus

Hook for tensor veli palatini tendon

Foramen ovale

Passage → mandibular nerve (V3), accessory meningeal a.

Foramen spinosum

Passage → middle meningeal artery

Temporal bone (base)

Contributes to cranial base

Stylomastoid foramen

Exit → facial nerve (CN VII)

Carotid canal opening

Passage → internal carotid artery, sympathetic plexus

Jugular foramen

Passage → CN IX, X, XI; internal jugular vein

Palatine process (maxilla)

Forms anterior hard palate

Incisive foramen

Passage → nasopalatine nerve, vessels

Greater palatine foramen

Passage → greater palatine nerve, vessels

Lesser palatine foramen

Passage → lesser palatine nerves, vessels

Palatine bone

Forms posterior hard palate

Horizontal plate

Posterior portion of hard palate

Lingula (mandible)

Landmark near mandibular foramen

Mylohyoid line

Muscle attachment

Mandibular foramen

Entry → inferior alveolar nerve, artery, vein

Mental foramen

Exit → mental nerve, artery, vein

Anterior cranial fossa

Houses frontal lobes

Ethmoid bone

Forms medial orbit, nasal cavity

Crista galli

Attachment for falx cerebri

Cribriform plate

Passage → olfactory nerves (CN I)

Middle cranial fossa

Houses temporal lobes

Sphenoid body

Central portion of sphenoid

Cavernous sinus site

Venous sinus → CN III, IV, V1, V2, VI; internal carotid artery

Lesser wing

Separates anterior/middle fossae

Anterior clinoid processes

Attachment for tentorium cerebelli

Posterior clinoid processes

Attachment for tentorium

Sella turcica

Houses pituitary gland

Dorsum sellae

Posterior boundary of sella

Optic canal

Passage → optic nerve (CN II), ophthalmic artery

Foramen rotundum

Passage → maxillary nerve (V2)

Groove for middle meningeal artery

Contains middle meningeal artery

Foramen lacerum

Filled with cartilage → ICA runs over (not through)

Superior orbital fissure

Passage → CN III, IV, V1, VI; ophthalmic veins

Petrous portion (temporal)

Dense bone housing inner ear

Squamous portion (temporal)

Flat lateral part

Groove for superior petrosal sinus

Contains superior petrosal sinus

Posterior cranial fossa

Houses cerebellum/brainstem

Internal acoustic meatus

Passage → CN VII, VIII

Groove for inferior petrosal sinus

Contains inferior petrosal sinus

Groove for sigmoid sinus

Contains sigmoid sinus → internal jugular vein