Skull Osteology Notes

Describe the macroscopic organization, growth, and function of the articulated skull (cranium and face).
Describe and identify the major arthrology of the bones of the skull: specifically, fontanelles, sutures, and TMJ joint.
Apply anatomical knowledge to interpret clinical indications of skull fractures.

Protuberance: Roughened bony area where muscles attach; example: external occipital protuberance.
Process: Marked bony prominence, often elongated; sometimes used as an articulating surface; example: mastoid process.

Condyle: Large, smooth, rounded articular oval process; example: mandibular condyle.
Facet: Small articular surface, often flattened; example: Superior articular facet of vertebra.

Foramen: Circular opening in a bone usually for blood vessels and/or nerves; example: foramen magnum.
Notch: Deep depression/gutter or U or V-shaped cut into bone surface; example: superior orbital notch.
Meatus: Opening/start/end of a canal or tube-like passageway; example: external acoustic meatus.
Canal: Passageway through a bone; example: optic canal.
Fissure: Narrow elongated (slit-like) opening through a bone usually for blood vessels and/or nerves; example: Superior orbital fissure of skull.
Sinus: Large cavity within a cranial bone; example: frontal sinus.

Protection for the brain and receptors.
Muscle attachments.
Skull = Cranium + Facial Skeleton
- Neurocranium
- Basicranium
- Paranasal Sinuses
- Mandible
22 Separate Bones (excluding ossicles of ear)

Superior domed part, which covers cranial cavity and brain
- Paired Temporal, Parietal and unpaired frontal, occipital and sphenoid bones

Facial skeleton
- 14 bones support teeth
- Form nasal and orbital cavity
- Paired nasal, palatine, lacrimal, zygomatic, maxillary bones; inferior nasal conchae and unpaired vomer.

Metopic Suture (L+R Frontal bones)
- Stage I: Open
- Stage II: Fusing
- Stage III: Fused
- Stage IV: Obliterated

Immovable fibrous joint (Dense Fibrous CT) that form the boundaries between the bones
- Allows moulding of the head during parturition
- Allows the cranium to grow and expand during childhood

Clinical Presentation: Shallow trench noted on the skull's surface, periosteum and dura are intact.
Clinical Stem: After forceps delivery, a shallow dent is noticed in a 1-day-old infant’s head. MSCT investigation is requested, with VRR shown.
- Location of the fracture?
Pathology:
- Birth Trauma – results from pressure caused by the mother’s pelvic bones against the soft skull
- Forceps during delivery

2 cavities: nasal and orbital cavity
14 bones in total
paired nasal, palatine, lacrimal, zygomatic, maxillary bones; inferior nasal conchae and unpaired vomer.

Para = ‘near or alongside to’
Nasal = referring to the nose or nasal cavity
Sinus = space or cavity
- Frontal sinuses (2 or more)
- Maxillary sinuses (2)
- Sphenoid sinuses (2)
- Ethmoid Air Cells

Clinical Stem: 16-year-old female suffers a head butt from an opposition player at football. A clinical depression in her forehead is noted and AP/Lateral VRR Provided.
- What SINUS is likely to be affected?

Spade trauma to parietal/occipital bones.
Gunshot trauma to the temporal bone.
Fracture-a-la-Signature:
- Forensic medicine derivation à shape/size may give info on the type of weapon used.
- Typically non-accidental injury

Clinical Stem: 18 Year old male victim of an assault to the facial skeleton. The assailant delivered a ‘hook’ punch to the side of the victims face. The patient has difficulty communicating and opening his jaw. Further, he lacks sensory sensation to the orbital and zygomatic regions.
Pathology:
- Epidemiology à 40% of midface fractures
- TRIPOD à fracture of the: lateral orbital margin, zygomatic arch, inferior orbital rim, maxillary sinus