Lecture 3 - Skull (Cranial Bones) PDF

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COMMONWEALTH OF AUSTRALIA Copyright Regulation WARNING This material has been reproduced and communicated to you by or on behalf of the University of Sydney in accordance with section 113P of the Copyright Act 1968 (Act). The material in this communication may be subject to copyright under the Act. Any further reproduction or communication of this material by you may be the subject of copyright protection under the Act. Do not remove this notice The University of Sydney Page 1 Lecture 3 Skull (Cranial Bones) Presented by Dr Filip Vujovic DDS, PhD School of Medical Sciences Slides courtesy of Dr Jonathan D. Hakim Lithograph from Joseph Maclise’s “The circulatory system” The University of Sydney (1844) Page 2  Learning Objectives – Identify the cranial bones of the skull – Identify the bony articulations of the cranial bones – Identify and describe the bony landmarks and features of the cranial bones The University of Sydney Page 3  Skull – General Features The skull has TWO main functions: 1. Supports the facial structures (viscerocranium/facial bones) 2. Protective cavity for the brain (neurocranium/cranial bones) There are 22 bones that form the skull: – 8 cranial bones – 14 facial bones The University of Sydney Page 4  Frontal Single Temporal Paired Cranium Parietal Paired Occipital Single Ethmoid Single Sphenoid Single Maxilla Paired Zygomatic Paired Lacrimal Paired Facial Skull Nasal Paired Inferior Nasal Concha Paired Palatine Paired Mandible Single Vomer Single The University of Sydney Page 5  Skull – General Features The articulations between the bones are mostly non-moveable sutures, fibrous joints which may ossify with age. The exceptions to this are the Temporomandibular Joint (TMJ) and the ossicles of the ear. The University of Sydney Page 6  Skull – Terminology BODY – main part of the bone PROCESSES/PLATES/SPINES – bony extensions from body for articulation with other cranial bones, or attachments of muscles or ligaments (e.g. temporal process of zygomatic bone which articulates with zygomatic process of temporal bone) EMINENCE – a bony bump or elevation overlying a deep structure (e.g. arcuate eminence in middle cranial fossa over inner ear) The University of Sydney Page 7  Skull – Terminology IMPRESSIONS – Grooves on surface of bone indicating the presence of some overlying soft tissue structure (e.g. groove for middle meningeal artery and its branches) FOSSA – A shallow depression or hollow in bone The University of Sydney Page 8  Skull – Terminology OPENINGS/FORAMINA/CANALS – For blood vessels and nerves entering or leaving skull. Particular foramina can vary in number or be absent. MEATUS – large tube-like passageway (e.g. external acoustic meatus) The University of Sydney Page 9  Skull - Anterior & Lateral View Bones – Frontal bone – Nasal bone – Maxilla – Mandible – Zygomatic bone – Sphenoid bone – Temporal bone – Parietal bone – Lacrimal bone – Inferior Nasal Concha – Ethmoid The University of Sydney Page 10 Frontal Bone The University of Sydney Page 11  Frontal bone Articulations – Parietal (coronal suture) – Sphenoid – Nasal – Ethmoid – Sphenoid – Zygomatic The University of Sydney Page 12  Frontal bone - features – Glabella (slight bone depression between two brow ridges, covered by skin between the eyebrows) – Nasion (intersection of frontal bone and two nasal bones, depression above nasal bones) – Supraorbital ridges (location of eyebrows) – Supraorbital notch/foramen (for nerve) – Zygomatic processes – Frontal eminences (paired, above supraorbital margin) – Frontal sinuses The University of Sydney Page 13  Frontal bone – inferior view The University of Sydney Page 14 Temporal bone The University of Sydney Page 15  Temporal bone Articulations – Sphenoid – Parietal – Occipital – Zygomatic – Mandible (via TMJ) The University of Sydney Page 16  Temporal bone - Features Mastoid process (for sternocleidomastoid muscle) Zygomatic arch External auditory meatus (outer ear canal) Styloid process (for muscles & ligaments) Mandibular/glenoid fossa (for TMJ) The University of Sydney Page 17 Skull - Lateral & Superior View The University of Sydney Page 18  Parietal bones Superior & Inferior Temporal Lines Coronal suture Temporal fossa Lambdoid suture Sagittal suture The University of Sydney Page 19 Skull – Posterior & Inferior View The University of Sydney Page 20  Occipital bone Inferior view Articulations Posterior view – Parietal – Temporal Lambdoid suture Superior nuchal line External occipital protuberance Inferior nuchal line Features – Nuchal lines – External occipital protuberance – Foramen magnum The University of Sydney – Occipital condyles Page 21 Vertebral Column & Cervical Vertebrae The University of Sydney Page 22  Vertebral column The University of Sydney Page 23  Vertebrae There are seven cervical vertebrae – C1 (atlas) & C2 (axis) are atypical C3-C7 (TYPICAL) C1 (ATLAS) C2 (AXIS) – Transverse foramen (foramina – No body – Body & Dens transversarium) for vertebral artery – No spinous process & vein are definitive of cervical – Anterior & posterior tubercles vertebrae – Groove for vertebral artery The University of Sydney Page 24  Cervical Vertebral Column Zygapophyseal (Facet) Joints - between articular facets. Are synovial joints that allow for motion of the vertebral spine. Intervertebral Disc - Provides cushioning to reduce stress of impact, protects nerves, allows movement. The University of Sydney Page 25 Cranial Fossae (Internal Cranial Cavity) The University of Sydney Page 26  Skull – Internal View Calvarium removed Bones – Frontal bone – Ethmoid bone – Sphenoid bone (lesser & greater wings) – Temporal bone – Parietal bone – Occipital bone The University of Sydney Page 27  Skull – Internal View Calvarium removed Three cranial fossae: – Anterior – Middle – Posterior The University of Sydney Page 28  Skull – Internal View Calvarium removed Anterior Cranial Fossa – Floor: orbital plate of frontal bone (19) & lesser wing of sphenoid (5) – Cribriform plate (ethmoid) is located at the midline (4) (perforated by small foramina which transmit olfactory nerve filaments from the nose to olfactory bulb of brain) – Crista galli (ethmoid) is the bony crest that projects superiorly from cribriform plate (3) The University of Sydney Page 29  Ethmoid bone Crista Galli Features – Crista galli (roosters crest) – Cribriform plate (for olfactory nerve) – Perpendicular plate (nasal septum) – Superior & middle nasal concha (turbinates) – Medial wall of orbit (orbital plate) The University of Sydney – Ethmoidal air cells (sinus) Page 30  Skull – Internal View Calvarium removed Middle Cranial Fossa – Floor: body of sphenoid medially (including hypophyseal fossa) & greater wing of sphenoid laterally (11) – Posterolateral boundaries are petrous Squamous and squamous temporal bone Petrous – Hypophyseal (pituitary) fossa contains the pituitary gland. The University of Sydney Page 31  Inferior view Sphenoid bone Anterior view Superior view Features – Greater and lesser wings – Body – Hypophyseal (pituitary) fossa – Sphenoid sinus – Orbital surface, optic canal & superior orbital fissure – Pterygoid plates The University of Sydney – Foramina (rotundum, ovale, spinosum) Page 32  Skull – Internal View Calvarium removed Posterior Cranial Fossa – Floor: occipital bone & petrous temporal bone – Clivus Clivus Petrous Occipital The University of Sydney Page 33