Human Skull Anatomy 2024 PDF

Protection of CNS 2 Skull Prof: Ghada Wassif Normae (Views) 1. Norma Verticalis. 2. Norma Frontalis. 3. Norma Occipitalis. 4. Norma Lateralis. 5. Norma Basalis (Interna & Externa). Names of the bones. Names of the sutures Features Norma Verticalis  NORMA VERTICALIS...

Protection of CNS 2 Skull Prof: Ghada Wassif Normae (Views) 1. Norma Verticalis. 2. Norma Frontalis. 3. Norma Occipitalis. 4. Norma Lateralis. 5. Norma Basalis (Interna & Externa). Names of the bones. Names of the sutures Features Norma Verticalis  NORMA VERTICALIS Calvarium Frontal bone skull vault or roof Is formed by 4 bones Parietal bone Anteriorly: Frontal Laterally: Lt & Rt Parietal Posteriorly: Occipital NB:(Calvarium) the top part of the skull. It is the upper part of the neurocranium Squamous part of occipital bone  Separated by 3 sutures: Fibrous joint Coronal suture Fibrous joint Sagittal suture Fibrous joint Lambdoid suture Fibrous joint Coronal : separates the frontal from 2 parietal bones Sagittal: intervenes between the 2 parietal bones Lambdoid: Separates the occipital from the 2 parietal bones  Bregma Anterior fontanelle 1.5-2 years Lambda Posterior fontanelle 4-6 month 2 points of meeting of the sutures Bregma: is the point of meeting of coronal with the sagittal sutures It is the ossified anterior fontanelles at the age of 1.5 years Lambda: is the point of meeting of lambdoid with the sagittal sutures It is the ossified posterior fontanelles at the age of 6 months  Parietal foramina Emissary vein Other features: Vertex: It is the most convex point of skull Vault (calvaria) near the midpoint of the sagittal suture (i.e. between the bregma and lambda Parietal foramen ▪ Is present on each side of the sagittal suture Parietal eminence ▪ It is the most prominent part of parietal bone ▪ It is the site of ossification center of the parietal bone Norma Frontalis It is formed of 4 bones: frontal, nasal, maxillary and zygomatic bones Frontal Nasal Orbit Orbit Zygomatic Nasal Maxilla Surrounding 3 cavities: 2 orbital & a nasal cavity  Frontal bone shows the following features: Glabella Frontal eminence Zygomatic process of Maxillary process of Center of ossification frontal bone frontal bone Superciliary arch Supra orbital notch or Frontal air sinus foramina Sup. Orbital margin Supraorbital N.&Vs. Nasion Nasal bone: 2 small bone that form the Nasal bridge Nasal Bridge: A saddle-shaped area that includes the nasal root and the lateral aspects of the nose Nasion: The midline point of the junction of the frontonasal suture with the internasal suture  Maxilla bone shows the following features: Upper jaw Body & 5 processes Palatine process Body contains maxillary air sinus 5 Processes 1-Frontal process 3- Orbital plate (floor of orbit) 2- Zygomatic process Infra orbital foramina (1cm) Body Infraorbital N.&Vs. Intermaxillary suture Anterior process 4- Alveolar nasal spine 5- Palatine process -------ant. 2/3 of hard palate 4- Alveolar process contains the sockets of the upper teeth Canine eminence Incisive fossa Incisor teeth( central & lateral) Canine fossa Zygomatic bone shows the following features: Form the prominence of the cheeck Orbit shows 2 Fossae Lacrimal groove Lacrimal fossa (sac) ( gland) Frontal process Temporal process Nose Vomer Inf. Nasal concha Zygomatico-facial foramen N.&Vs Norma Occipitalis  Formed of 2 parietal bone Lambdoid suture Occipital bone Mastoid part of temporal bone Shows the following features: External occipital protuberance (Inion) Superior nuchal line External occipital crest Inferior nuchal line Foramen Magnum Occipital condyle Synovial ellipsoid Highest nuchal line Norma Lateralis  Norma lateralis: Norma Lateralis It is formed by the following bones arranged in 2 rows: Superiorly: frontal, parietal, occipital Inferiorly: Nasal, maxilla, zygomatic, greater wing of sphenoid and temporal It is divided by zygomatic arch into temporal (above) & infratemporal (below) Frontal Parietal Gw Occipital Nasal sphenoid Temporal Maxilla Zygomatic Zygomatic tubercle The zygomatic arch is formed by the union of the temporal process of the zygomatic bone and the zygomatic process of the temporal bone at the zygomaticotemporal suture. The temporal fossa is bounded by a few anatomical landmarks, Anteriorly the frontal process of the zygomatic bone, zygomatic process of frontal b. Norma Lateralis Superiorly and posteriorly the temporal lines, and Inferiorly the zygomatic arch. 1-The pterion: is the H-shaped formation of sutures on the side of the skull where four bones meet. It is the ossified anterolateral fontanelle at the age of 3months Temporal lines Parietal Frontal Gw Supramastoid sphenoid Temporal crest (Inf. temporal line) 2-The asterion: is the junction on the side of the posteroinferior of the skull, where three bones meet: parietal, mastoid and occipital. It is the ossified posterolateral fontanelle at the age of 1 years...  Bregma Anterior fontanelle 1.5 years Pterion (sphenoidal) Anterolateral fontanelle 3 month Asterion (mastoid) Posterolateral fontanelle end of 1st year Lambda Posterior fontanelle 6 month Clinical significance of the fontanelles ( membranous areas(soft spot) in the skull): They are present at birth to allow overlap of skull bones during delivery Depressed fontanelles indicates dehydration Elevated fontanelles indicates increased intracranial tension Delayed closure of fontanelles occurs in rickets  Norma Lateralis Pterygopalatine fossa: is a small pyramidal space deep to the pterygomaxillary fissure 1. Squamous part of temporal bone 2. Mastoid process of temporal bone 3. Tympanic part of temporal bone 4. Styloid process of temporal bone. 5. Petrous part of temporal bone The mastoid process: nipple like part of temporal bone. It is located posterior to the ear containing air cells. It gives attachment to muscles. The styloid process: slender and elongated bony projections of the temporal bone. It gives attachment to muscles. External auditory meatus: It lies below the posterior part of zygomatic process of temporal bone. Supra- meatal triangle: (Mac Ewen) It lies postero-superior to the External auditory meatus used to locate the mastoid antrum  Sphenoid bone Norma Lateralis Lesser wing Greater wing Body Greater wing Its name is derived from the Greek ‘sphenoeides’, to mean wedge-shaped.  Lesser wing Norma Lateralis It is formed of 4 parts 1- Body Greater wing Body 2- Lesser wing 3- Greater wing Greater 4- Pterygoid processes(med. & lat. wing pterygoid plate) Lateral Medial Pterygoid plate Pterygoid Hamulus Medial pterygoid plate Norma Basalis Interna Norma basalis interna is divided into three parts Anterior cranial fossa Lesser wing of Sphenoid Middle cranial fossa Upper border of petrous bone 1-Anterior cranial fossa Posterior cranial fossa 2-Middle cranial fossa 3-Posterior cranial fossa 1-Anterior cranial fossa hold the frontal lobe of the brain 2- Middle cranial fossa hold the temporal lobe of the brain 3- Posterior cranial fossa hold the cerebellum  Frontal crest Ethmoid Foramen caecum Orbital plate of Lesser wing of sphenoid Crista galli frontal bone Anterior Cribriform plate of Ethmoid clinoid process Leision:---- Optic canal (Optic nerve & ophthalmic art.) Anterior cranial fossa is formed by: 1- Orbital plate of frontal bone 2- lesser wing of sphenoid 3- Ethmoid bone in the middle Middle cranial fossa is formed by Greater wing of sphenoid Groove for optic chiasma - Squamous part of Hypophyseal fossa= sella turcica a saddle-shaped depression.... where temporal bone the pituitary gland is located Leision:---- (Surrounded by 4 clinoid processes) Petrous part of temporal bone  R= 2-rotundum 0= 3-oval S =4-spinosum R 1-Superior orbital fissure O S 5-Foramen lacerum - Present 5 important foramina: 1. Superior orbital fissure: allow passage of cranial nerves (3, 4, ophthalmic of 5 and 6) 2. Foramen rotundum allow passage of maxillary n of trigeminal 3. Foramen oval allow passage of mandibular n of trigeminal 4. Foramen spinosum which transmits the middle meningeal art. 5. Foramen lacerum nothing transmitted vertically but the internal carotid artery pass through foramen transversely  R Trigeminal impression O S Lacerum Arcuate eminence Petrous part of temporal bone houses the middle and inner ear Trigeminal impression present at the on the anterior surface of the petrous part of the temporal bone (sensory ganglia of trigeminal n) Arcuate eminence present near the center of anterior surface of petrous part marks the roof of superior semicircular canal of inner ear  Posterior cranial fossa is formed by 1. Occipital bone 2. Petrous bone of temporal bone 3. Mastoid part of temporal bone Posterior cranial fossa is the largest and deepest of three fossae 2. Petrous bone The fossa is occupied by Cerebellum + pons+ medulla 3. Mastoid part of temporal bo CLIVUS is formed by 1. Occipital bone 1. Body of sphenoid 2. Basilar part of Occipital bone Posterior cranial fossa 1. Clivus marks the anterior portion of the occipital bone 2. Foramen magnum marks the transition from the medulla to spinal cord 3. Internal occipital crest & internal occipital protuberance 4. Transverse groove for transverse sinus 5. S shaped groove for Sigmoid sinus Clivus 6. Jugular foramen which Jugular foramen transmit Foramen Sigmoid sinus which continue as magnum internal jugular vein Groove for sigmo 9 Glossopharyngeal N 10 Vagus N 11 Accessory N Internal occipital crest Groove for transverse sinus internal occipital protuberance Internal acoustic meatus is located just superior to jugular foramen It transmits Facial (7) and Vestibulocochlear (8) and labyrinthine art Hypoglossal canal transmits the hypoglossal nerve lies superior to the margin of the foramen magnum Internal acoustic meatus Hypoglossal Jugularcanal foramen Cerebellar fossa Cerebral fossa Mandibular N. of trigeminal  The skull is divided into two parts Neurocranium which form a protective case around the brain (cranial skeleton) Viscerocranium which form the facial skeleton Calvaria is the topmost part of the neurocranium, which protects the cranial cavity that houses the brain. The skull is consist of two layers of compact bones with intervening cancellous tissue called the diploë. Mandible Alveolar border ramus body Inferior border (digastric fossa) The mandible is the largest bone in the human skull. It holds the lower teeth in place, it assists in mastication and forms the lower jawline. The mandible is composed of the body and the ramus and is located inferior to the maxilla.  Oblique line Symphysis menti Mental foramen Triangular eminence Below 2nd premolar teeth Mental protuberance ( mental tubercle)  Mandible Mylohyoid line Internal surface  Mandibular notch Condyloid Coronoid Mandibular foramen Lingula Ramus ramus Mylohyoid body groove Ramus : Upper border between coronoid and condyloid is the mandibular notch Medial surface: show lingula, mandibular foramen and mylohyoid groove THANK YOU