Ch. 7 Skull Bones Flashcards
Cranial Cavities
- largest cavity which encloses, cushions and supports brain
- smaller cavities: orbits, oral cavity, nasal cavity, paranasal sinuses
Paranasal Sinuses
- frontal, sphenoid, ethmoid, and maxillary bones
- lined with some mucous membranes that line nasal cavity
- sinuses lighten the skull’s mass and increase surface area; moisten and cleanse inhaled air
- resonating chambers that intensify and prolong sounds; enhancing quality of person’s voice
Sutures
- immovable joint in adults
- coronal: unites frontal and parietal bones
- sagittal: unites the two parietal bone
- lambdoid: unites two parietal bones to the occipital bone
- squamous: unite the parietal and temporal bones
Fontanels
- unossified mesenchyme that will be replaced with bone by intermembranous ossification
- provide flexibility to the fetal skull, allows skull to change shape through birth canal and permit brain growth
Frontal Bone- SIngle
- forms anterior roof of cranium, nasal cavity and arches of orbits
frontal squama: platelike bone, forms the forehead
supraorbital margin: prominent bony ridge
supraorbital foramen: opening in margin where supraorbital nerve passes
frontal sinuses: reduce the weight of skull
Parietal bones- paired
- large and quadrilateral
- form much of the sides and roof of the cranial cavity
- articulate with 5 other bones
- seperated by coronal, squamous and lambdoid sutures
Temporal bones- paired
- form the inferio-lateral part of the cranial floor plus part of the lateral wall near the ear
- extend a narrow process forward towards the zygomatic bone forming the zygomatic arch
- articulate with the mandible at the TMJ
- mastoid process is a prominent surface feature just behind the below the ear
Mastoid Portion
- rounded projection of the mastoid portion of the temporal bone is prosterior and inferior to the ext. auditory meatus
- serves the attachment fir the several neck muscles
- internal auditory meatus serve the opening for the facial (VII) and vestibulocochlear (VII) cranial nerves
- styloid process serve the attachment for mucles and ligaments of the tognue and neck
- stylomastoid foramen serves the passage for facial (VII) and stylomastoid artery
Petrous portion
- houses sensory organs for hearing and equilibrium
- located at the base of the skull between the sphenoid and occipital bones
- middle ear consists of three ear ossicles
- houses the carotid foramen for carotid artery
- houses jugular foramen for the jugular vein; formed by adjacent notches in the temporal and occipital bones
Occipital Bone- single
- forms much of posterior wall and the posterior floor of the cranial cavity
prominent surface features: foramen magnum, occipital condyles, external occipital protuberance, ligamentum nuchae
Sphenoid Bone- single
surface features of sphenoid bone: forms the middle part of the base of the skull, resembles butterfly shape
consists of: body, sphenoid sinus, sella turica, tuberculum sellae, hypophyseal fossa, dorsum sellae
Sphenhoid Bone Consists of…
superior orbital fissure: opthalamic trigeminal, ocular, trochlear and abducens nerves
foramen rotundum: maxillary nerve
foramen ovale: for mandibular nerve
foramen spinosum: for internal cartoid and pharyngeal artery
Skull Markings
superior orbital fissure: for opthalmic trigeminal, ocular, trochlear and abducens nerves
foramen rotundum: for maxillary nerve
foramen ovale: for mandibular nerve
foramen spinosum: for internal cartoid and pharyngeal
optic foramen: optic nerve and opthalmic artery
Ethmoid Bone- single
- numerous paranasal sinuses
- form anterior part of the cranial floor (the cribriform plate) through which numerous foramina pass
- medial wall of the eye sockets
- superior portion of the nasal septum
- much of the nasal cavity walls
- houses ethmodial cells which becomes ethmoid sinuses
- olfactory formina- passes olfactory nerve (I)
Facial Bones (14)
- facial bones are not in contact with the brain
- along with cranial bones, these bones provide shape and individual face features
- support teeth and provide attachments for various face and jaw muscles
- except the bones of the yomer and mandibles, all facial bones are paired
Nasal- paired
- contains rectangular bone that forms the bridge of the nose
- supports the flexible cartilaginous plates, forms framework of the nose
supports thin muscles of facial expression - common site for facial injuries
Lacrimal- paired
- smallest bone of the face
- these are paired bones that form the anterior portion of the medial wall of the eye socket
- a bony depression that continues into the maxilla, called the lacrimal groove, accepts a soft tissue tube (lacrimal sac) that passes tears from the eye into the nasal cavity
Palatine- Paired
- paired L-shaped bones that form the posterior edge of the hard palate as well as portions of the eye socket and nasal cavity wall and floor
Inferior Nasal Conchae- paired
- inferior nasal conchae are seperate bones, distinct from the superior and middle conchae which are projections from the ethmoid
- all conchae help to swirl and filter air before it passes into the lungs
- only the superior nasal conchea of the ethmoid bone increase the surface area and aid in sense of smell
Vomer- single
- unpaired bone, the vomer sits on the floor of the nasal cavity
- extends a bony partition superiorly that meet the perpendicular plate of the ethmoid; together they form the nasal septum
- divides the nasal cavity into right and left
Maxillae- paired
- paired maxillary ones fuse at the midline to form the upper jaw
- internally, maxillae contribute to the inferior wall of orbit, the walls and floor of the nasal cavity, and most of the hard palate
- body of the maxillae are hollowed out internally to form a pair of large sinuses
- contains body, alveolar process and infraorbital foramen
- this foramen passes infraorbital blood vessels and nerves
zygomatic (cheekbone)- paired
- these bones form the prominences on the anterior face called cheekbones
- temporal process of zygomatic bone projects posteriorly and articulates with the zygomatic process of the temporal bone to form zygomatic arch
- zygomatic foramen passes zygomaticofical nerve and blood vessels