Skull Anatomy & Bones PDF

Bones and Organization of the Skull Biology 2230 FA24 Lecture 13 m. iyengar The Adult Skull 8, Cranial bones 14, Facial bones Associated bones: – Hyoid bone – 6, ossicles Joints: – Sutures join most...

Bones and Organization of the Skull Biology 2230 FA24 Lecture 13 m. iyengar The Adult Skull 8, Cranial bones 14, Facial bones Associated bones: – Hyoid bone – 6, ossicles Joints: – Sutures join most of the bones. – The temporomandibular joint is the only diarthrosis. – Teeth articulate with bones of the jaw. Hyoid bone A small, U-shaped bone in the neck under the mandible at the C3 level. hyoid – The only bone that does not articulate with another bone. – Attachment for tongue and neck muscles. – Attachment for several of the larynx cartilages. – Assists with keeping the respiratory system open, swallowing, and speech hyoid Facial Bones Nasal bone NASAL BONES – Paired, form the bridge of the nose. Lacrimal (Tears) bone LACRIMAL BONES – Paired in the medial wall of the orbit. Nasal Superior bone – Lacrimal fossa for passage of tears to the nasal nasal concha cavity. Middle nasal concha INFERIOR NASAL CONCHAE Inferior nasal – Paired in the nasal cavity. concha Maxilla – Makes up the lateral wall of the nasal cavity. Facial Bones ZYGOMATIC BONES – Paired bones – Form the “cheek bones.” – Makes up the lateral wall of the orbit. Zygomatic – Articulates with the temporal bone to form the bone zygomatic arch where chewing muscles attach. Perpendicular Zygomatic Nasal plate of the arch Ethmoid bone septum Septal Vomer cartilage VOMER BONES – Forms the inferior portion of the nasal septum which divides the nasal cavity into R/L sides. Facial Bones MAXILLARY BONES – Paired bones – Makes up the inferior wall of the Inferior orbital fissure orbit Infraorbital The inferior orbital fissure Maxilla foramen passing between the maxilla, Ethmoid sphenoid, and zygomatic bones. bone – Makes up the lateral walls of the nasal cavity and hard palate. Maxilla – Contains the upper teeth. What type of joint is this? Gomphoses Palatine bone Palatine process  Palatine bone Facial Bones PALATINE BONES – Paired bones – Can be located on the inferior aspect of the skull. Palatine process of maxillae Incisive fossa The Hard Palate – The palatine process of the maxillae articulate with the palatine bones. Nasal cavity – Separates the nasal and oral cavities, preventing food from entering the nasal cavity. Sphenoid Hard bone Palatine Palatine process palate bone of maxillae Clinical Implications – Why We Study Anatomy A Cleft palate – When the bones and tissues of the lip or hard palate do not fuse correctly. What might be the problem? Requires surgery to fix. Facial Bones Coronoid Coronoid process process Mandibular condyle MANDIBLE – A single bone that includes the lower teeth. – The coronoid process is the insertion of the temporalis muscle. Mandibular foramen – Includes the mandibular and mental foramen where nerves pass through. – The mandibular angle varies between males and females. Mandibular Mental foramen angle Joints of the Skull Dentoalveolar Joints Temporomandibular Joint What type of joint is this? Gomphoses What type of joint is this? Synovial What action does it perform? Mandibular fossa of the temporal bone Mandibular Alveolar condyle processes of Temporomandibular maxilla joint Teeth Alveolar Teeth processes of mandible Amphiarthrotic movement Cranial Bones Coronal FRONTAL BONE suture – The anterior portion of the cranium. – Makes up the superior portion of the orbit where the eyeball is positioned. – Includes space for the ethmoid bone. Space for the Orbit ethmoid bone – Articulates with the parietal bones at the coronal suture. Cranial Bones PARIETAL BONES External – Paired bones. – Make up the superior portion of the cranium. – Articulate with: Frontal bone at the coronal suture. Each other at the sagittal suture. Occipital bone at the lambdoid suture. Temporal bone at the squamous suture. Internal  Synarthrosis Joints of the Skull Coronal suture Fr on ta l bo Lambdoid Parietal bone ne Squamous suture suture on e a l b por Tem Occ ipit al b What type of on e joints are these? Sutures Occipitomastoid suture Lateral view Joints of the Skull Sagittal suture Coronal suture Frontal bone Parietal Parietal bone bone Sagittal suture Parietal Parietal bone bone Occipital bone Lambdoid suture Posterior view Superior view Cranial Bones OCCIPITAL BONE Foramen – The posterior and inferior portions of the magnum cranium. – Has the foramen magnum where the Occipital condyle ____________ Spinal cord exits the skull. Inferior Lambdoid suture – Occipital condyles contribute to the Internal atlano-occipital joint – Articulates with the temporal bone at the occipitomastoid suture. The jugular foramen is between the occipital and temporal bones. Hypoglossal Jugular canal foramen Between occipital & temporal bone Inca Bones – Sutural bones (Sutures inside bones) Triangular bones located between the parietal and occipital bones at the lambdoid suture. – High incidence in mummies from the Inca civilization. Size and shape are variable in the human population Lambdoid suture  Sound goes in Cranial Bones (Flat-ish) External External acoustic Squamous portion meatus TEMPORAL BONES – Paired, and form the lateral portion of the cranium. – Squamous portion Zygomatic The zygomatic process articulates with the process Mastoid zygomatic bone creating the zygomatic process Styloid process arch. – Petrous portion Petrous portion Mastoid process Styloid process Internal Internal and External acoustic (auditory) meatus Jugular foramen (in part with the occipital bone) Internal acoustic Carotid canal meatus Styloid process (Where cranial nerves sit) OSSICLES - MIDDLE EAR BONES The body's three smallest bones are located within the petrous portion of the temporal bone. Transmit sound waves from the eardrum (tympanic membrane) lodged in the temporal bone to the oval window within the temporal bone. Malleus Articulates with the malleous Incus Incus Stapes Tympanic membrane The Adult Skull Disarticulated Several facial and cranial bones are not easy to observe because they make up the middle part of the skull. Cranial Bones (The rooster's comb) Crista galli ETHMOID BONE Cribriform plate – Sits in the frontal bone. – Makes up the medial portion of the orbit – Makes up the lateral walls of the nasal cavity. Perpendicular plate Cribriform plate – Crista galli attaches brain meninges. – Cribriform plates hold the olfactory bulbs. – The perpendicular plate makes up the superior portion of the nasal septum. Cranial Bones Optic canal Foramen rotundum SPHENOID BONE (Butterfly/Bat shaped) – A complex bone that makes up the middle of the cranium. Superior orbital Foramen spinosum – It articulates with the: fissure temporal, occipital, frontal, Foramen ovale ethmoid, and parietal bones. – Includes several openings for the passage of cranial nerves and blood vessels. Sella turcica – The sella turcica is a depression where the pituitary gland sits. Cranial Bones – Sphenoid Bone SPHENOID BONE – Pterygoid plates are on the inferior aspect and where pterygoid muscles that assist with chewing attach. Foramen ovale Foramen spinosum Lateral Carotid canal pterygoid plate Jugular foramen Medial pterygoid plate Pterygoid process Bones and Structures of the Orbit Supraorbital foramen Optic canal The orbit is where the EYE sits Superior and is composed of several orbital fissure bones. Inferior orbital fissure Many cranial nerves pass the openings. Perpendicular plate Nasal opening is divided by the nasal septum: the Vomer perpendicular plate of ethmoid Infraorbital (superior) and vomer (inferior). foramen (Unable to see it) Why is a baby’s skull delicate? Intramembranous ossification How are bones created? Mesoderm Creates parts of the skull and clavicle. Why? Bone formation begins at the center of the future bone and proceeds outward. Fontanels Remaining tissue between bones becomes fontanels and then sutures. Development of the Skull Inferior cranial bones form first endochondrally. – What are these bones? How are they formed? Occipital, sphenoid, and temporal. Made out of cartilage Creates a stable base to support the weight of the brain. Superior cranial bones and facial bones form last intramembranously. – What are these bones? How are they formed? Frontal & maxillae Mandible Allows for the continual growth of the skull and ma brain after birth. Development of the Skull The membrane between each bone forms the fontanels. Allows for space between bones as the brain grows. Fontanels fuse or “close” forming sutures around 2 yrs old. Amphiarthrotic Clinical Implications – Why we study Anatomy Skull deformities: – Positional skull deformities Using forceps or a vacuum during a difficult labor Multiples Not enough tummy time – Craniosynostosis When two or more bones fuse before the brain growth is complete – sometimes before birth – Cleidocranial Dysplasia Delayed closure of fontanels Cleft palate and extra teeth The following slides are additional images to help you with this lecture and during lab Bones and Structures of the Orbit The orbit is where the EYE Optic canal sits and is composed of several bones. Many cranial nerves pass thru Supraorbital here. foramen / notch Superior orbital fissure Inferior orbital fissure Nasal opening is divided by Infraorbital the perpendicular plate of foramen ethmoid (superior) and vomer (inferior). Mental foramen Human Skull Lateral View Sphenoid bone ne Par Intramembranous bo ieta tal l bo Ethmoid bone on ne Fr Nasal bone Temporal Lacrimal bone bone Maxilla Occipital bone Zygomatic le Mastoid bone Mandib TMJ process Endochondral Human Skull Internal Sagittal View Crista galli Nasal Septum: Perpendicular Cribriform plates plate of Ethmoid bone Sella turcica Internal acoustic meatus Vomer Lateral pterygoid plate Medial pterygoid plate Human Skull Internal View Crista galli Sella turcica Cribriform plates Foramen Optic canal rotundum Superior orbital fissure Foramen ovale Foramen lacerum Foramen Carotid canal spinosum Internal acoustic Jugular meatus foramen Foramen magnum Human Skull Inferior View Palatine bone Vomer Medial pterygoid plate Foramen ovale Lateral pterygoid Foramen plate spinosum Foramen lacerum Carotid canal Temporal mandibular Jugular joint foramen Stylomastoid Occipital foramen condyle Hypoglossal where atlas canal joins with skull The following are colored images of the skull with labeled structures to use as supplements to this lecture and for lab. The Bony Palate Check your understanding Create a list for all the cranial bones. – Are they paired? – What bone(s) do they articulate with? What type of joint is created when they come together? – Are there any important bone structures or markings associated with the bone? What is the function of the structure? Create a list for all the facial bones. – Are they paired? – What bone(s) do they articulate with? – Are there any important bone structures or markings associated with the bone? What is the function of the structure? Check your understanding What types of joints (functional and structural) are found in the skull? What two bones or bone markings are needed to form the joint? What areas/regions/bones of the skull are formed by endochondral ossification? – Why are these bones formed using this method of bone development? What areas/regions/bones of the skull are formed by intramembranous ossification? – Why are these bones formed using this method of bone development? Check your understanding What bones form the orbit? – What structures are associated with the orbit? – What is the purpose for these structures? What bones form the nasal septum? The perpendicular plate of the Ethmoid bone & the Vomer bone Which bone contains the crista galli and cribriform plates? What is the purpose of each structure? The Ethmoid bone contains the crista galli & cribriform plates.The crista galli attaches brain meninges and the cribriform plates hold the olfactory bulbs What bone contains the sella turcica? What is the purpose of this structure? The Sphenoid bone contains the sella turcica. It's where the pituitary gland sits What bones contain bone structures for the attachments of chewing muscles? What bone contains structures for hearing including the ossicles? Check your understanding What are fontanels? Where are they located in the skull? Why are they important? Fontanels are remaining tissue/membrane located between bones that eventually become sultures List all the bones associated with the nasal cavity. (6) – Where is each located. Lacrimal (medial wall of orbit), Inferior nasal conchae (Makes lateral wall), Vomer (Divides cavity into R/L sides), Maxillary (Makes lateral walls), Hard palate (Separates nasal & oral cavities), Ethmoid (Makes lateral wall) What bones and bony structures separate the nasal and oral cavities?. – What would happen if these bones do not fuse together? Describe the location of the hyoid bone – What is the function of this bone? – What is unique about this bone? Check your understanding …label the image Coracoid process Mandibular Foramen Mandibular Condyle Mandibular Notch Alveolar process Mandibular Ramus Mental Foramen Check your understanding …label the image Check your understanding …label the image Crista Galli Foramen Magnum Check your understanding …label the image Check your understanding …label the image Check your understanding …label the image Check your understanding …label the image Check your understanding …label the image