Skull Flashcards
State the functions of the skull
Supports and protects the brain; isotropic resistance to impact by dispersing forces
Describe the layers of the skull
External (outer) table and internal (inner) table with diploe in the middle (bubbly less solid structure)
How can the skull be split in to two sections?
Neurocranium: aspects supporting and containing the brain; Viscerocranium: facial aspects that aid in talking, breathing etc
What is excess cranial bone called?
Wormian bones which do not have names but are small amounts of bone that sit between the sutures
What lies between cranial bones?
Sutures: joints between cranial lines which will not move (with exception to mandible)
Name the outer and inner surfaces of the skull
Ectocranial (outside) and endocranial (inside).
How can the neurocranium be split?
Membranous/dermatocranium: mainly the flat bones of the skull cap e.g. frontal & parietal - formed through intramembranous ossification ; Cartilaginous/chondrocranium: More complex structures e.g. sphenoid and ethmoid which border on mixing with viscerocranium - formed by endochondral ossification (start as cartilage)
Name the bones of skull
Cranial: frontal, parietal (x2), occipital, temporal (x2), ethmoid, sphenoid ; Facial: maxillae (x2), palatines (x2), nasals (x2) lacrimals (x2), zygomatics (x2), vomer, inferior nasal conchae (x2), manidble ; Ear ossicles: malleus, incus, stapes.
Name the type of suture that is present in childhood but can stay as a non-metric trait in adults
Metopic suture
Name the sutures of the skull
(Synchondroses): coronal, sagittal, squamous (overlapping), lambdoid, lambda, bregma, pterion, frontomaxillary, frontonasa, frontozygomatic, intermaxillary, median palatine, occipitomastoid, parietomastoid, sphenofrontal, sphenooccipital, sphenoparietal, sphenosquasomal, sphenozygomatic, temporozygomatic, transverse palatine, zygomaticomaxillary, tempomandibular joint, atlanto-occipital joint
Name the 12 cranial nerves and their type of nerve function
CNI - Olfactory (S) ; CNII - Optic (S) ; CNIII - Oculomotor (M) ; CNIV - Trochlear (M) ; CNV - Trigeminal (S&M) ; CNVI - Abducens (M) ; CNVII - Facial (S&M) ; CNVIII - Vestibulocochlear/Auditory (S) ; CNIX - Glossopharyngeal (S&M); CNX - Vagus (S&M) ; CNXI - Accessory (M) ; CNXII - Hypoglossal (M)
Which nerve has 3 branches and what are they?
CNV - Trigeminal (S&M): 1 - Ophthalmic, 2 - Maxillary, 3 - Mandibular.
Which bones are part of the neurocranium?
Frontal, parietal, temporal, occipital, sphenoid, ethmoid
What bones does frontal articulate with?
Parietals, zygomatics, lacrimals, nasals, maxillae, sphenoid, ethmoid
Name and detail the eminences at the front of the frontal bone
Frontal bosses: more significant in females ; marks ossification centres of frontal bone
Name the features just above the orbits
Glabella / supraorbital ridge : of the frontal bone (brown ridge)
Describe the temporal line
Attachment site of temporalis formed by mastication; (temporalis will run through the zygomatic foramen to the coronoid process of the mandible) ; runs across the frontal and parietal bones on either side
Describe the supraorbital margin and a feature within it
Feature of the frontal bone directly above the orbitals superior to the eyes ; supraorbital notch or foramen (if closed) is found here
Describe the nasal spine
The inferior aspect of the frontal bone that comes down to join the nasals
What part of the frontal bone articulates to the zygomatic bones on either side?
Zygomatic processes
Describe the frontal sinuses
Located at the medial inferior aspect of the front bone; air cells that are pockets within the bone; can be used for ID in forensics
Name and detail the structure that runs down the internal midline of the frontal bone
Frontal crest: Anchors the flax celebri (fold of the dura mater (outermost layer of brain surrounding)) ; runs between the sinuses as a slightly raised line ; is continuous with the sagittal sulcus
Describe sagittal sulcus
(Sagittal sinus) for venous drainage, is continuous with the frontal crest of the frontal bone and continues on to the parietal bones
Describe arachnoid granulations / fovae
Run on the internal surface of the frontal and parietal bones along the top on either side of the sagittal sulcus - they are small holes left by the membrane pushing out leading to resorption of the bone
Where does the ethmoid bone articulate with the frontal bone?
Ethmoid notch, either side of the frontal crest, medial to sinuses
What do the parietal bones articulate with?
Eachother, sphenoid, occipital, temporal, frontal
Name and detail the protrusions of the parietal bones
Parietal bosses/eminences: similar to those of frontal, lie on either side and are slightly posterior - can be felt
Can foramen be found on the parietal bones?
Yes. Parietal foramen / emissary foramina - on posterior superior portion on either side - not always present.
What are parietal striae?
Lines found on the temporal aspect of parietal bones formed from the friction at the squamal suture sitting underneath the overlap
What lies on the internal surface of parietal bones?
Meningeal grooves are anteriorly close to the coronal suture and travel from inferior to superior in a posterior direction. Bregma inner table protrudes more than outer table
What do the temporal bones articulate with?
Parietal, sphenoid, occipital. zygomatics, mandible
How can the temporal bone be split?
Squamous portion: flatter thinner part ; petrous/mastoid portion: solid, thick bone which houses ear organs
Describe two features of and two attachment to the mastoid process
Mastoid foramina: posterio-inferior for occipital veins and arteries ; Supramastoid crest ; Mastoid notch: medial attachment for digastric muscle (to digastric fossa of mandible and hyoid for jaw movement) ; attachment for sternocleidomastoid (head & neck movement - lateral flexion)
Name and describe two key features of the petrous part of the temporal bone relating to the ear
The external and internal auditory meatus. Internal points posteriorly. Suprameatal crest lies superior to external. external is posterior, internal is anterior
Where does temporalis attach to the temporal bone
Supramastoid and suprameatal crests
Where on the temporal bone does the mandible articulate?
Glenoid / mandibular fossa at the temporomandibular joint
Name three processes of the temporal bone and describe them.
Mastoid process: attachment for sternocleidomastoid ; Zygomatic process: attaches to the temporal process of the zygomatic to create the zygomatic arch; styloid process: often broken off post-mortem, lies inferior to the mandibular fossa, is called “eagle” if it is really long.
What foramen on the temporal bone houses the stylomastoid artery and what cranial nerve also passes here?
Stylomastoid foramen - passage for CN VII (Facial)
What groove lies posterior to the stylomastoid foramen (internal surface)?
Groove for transverse sinus which continues onto the occipital bone
Which fossa lies antero-medial to the styloid process and what nerves does it carry?
Jugular fossa creates jugular foramen with occipital bone for CN IX, X, XI.
What bones does the occipital articulate with?
Parietals, temporals and sphenoid
What is the flat aspect of the occipital bone called?
The occipital squama