Osteology Flashcards
How do the bones of the calvaria, of the neurocranium, develop?
Intramembranous Ossification
How do the bones of the base of the skull, of the neurocranium, develop?
Endochondral Ossification
From what does the viscerocranium develop?
From Pharyngeal arches
What is the cartilaginous structure, from the 1st pharyngeal arch, that developes into the template for the developing mandible?
Meckel’s Cartilage
What is significant about the superior and inferior temporal lines of the squamus portion of the temporal bone?
They mark the attachment of the temporalis fascia and temporalis muscle respectively. These lines also demarcate the superior limit of the temporal fossa.
What is the nasion?
The intersection of the frontal bone with the two nasal bones. Located b/t the eyes.
What is the significance of the frontal crest?
The frontal crest is a vertical feature of the internal midline of the frontal bone that serves as an attachment for the anterior end of the faulx cerebri, a reflection of the dura mater, the outermost layer of the meninges, which separates the eft and right cerebral hemispheres.
What is the importance of the sagittal sulcus and its contents?
The sagittal sulcus is an internal, midline feature that houses the superior sagittal (dural venous) sinus. The superior sagittal sinus, found b/t the periosteal and meningeal layers of the dura, carries blood along the superior margin of the falx cerebri.
What are the fossae of the orbital portion of the frontal bone that house the lacrimal glands during life?
Lacrimal fossae
What is found within the ethmoid notch of the orbital portion of the frontal bone?
Cribriform plate of the ethmoid bone
In what portion of the frontal bone are the frontal sinuses found?
Orbital portion
Where is the foramen caecum found and what is its significance?
Forament caecum is found inferior to the frontal crest at the midpoint of the frontoethmoidal articulation (just abouve the cribriform plate). It transmits an emissary vein from the frontal (paranasal) sinus to the superior sagittal (venous dural) sinus.
What is transmitted through the supraorbital foramen?
The supraorbital neurovascular bundle. The supraorbital nerve is a branch of the frontal nerve of the opthalmic division of the trigeminal nerve (V1). The supraorbital nerve provides sensory innervation to the skin of the forehead.
The parietal bones articulate at the midline along what suture?
Sagittal suture
What is the point of intersection of the coronal and sagittal sutures called? Significance?
Bregma. Marks the site of the anterior (bregmatic) fontanelle in the neonate.
What is point of intersection of the lambdoidal and sagittal sutures called? Significance?
Lambda. Marks the site of the posterior fontanelle in the neonate.
A skull fracture in the viscinity of pterion may impact what middle meningeal vessels found in the grooves for the middle meningeal vessels of the parietal bone. What is a possible consequence?
The pterion is the intersection of the parietal, frontal, temporal and sphenoid bones and is known as the weakest portion of the skull. A fracture here could damage the anterior division of the middle meningeal vessels causing an epidural hematoma where blood builds up b/t the dura mater and the skull.
The middle meningeal artery is a branch of what artery? Be specific. What foramen allows middle meningeal vessels to enter the skull?
Middle meningeal artery is the 3rd branch of the first portion of the maxillary artery (one of the two terminal branches of the external carotid), the retromandibular portion.
The middle meningeal artery is intimately associated with what nerve, which wraps around the artery, making both easily identifiable in a cadaver?
The auriculotemporal nerve is a branch of the mandibular nerve, V3. It arises as two roots that wrap around the middle meningeal vessels before joining to form a single auriculotemporal nerve.
What is found within the arachnoid fovea that are concentrated along the sagittal sulcus? Importance?
Arachnoid granulations that are responsible for resorption and filtration of the cerebrospinal fluid, CSF, which fills the subarachnoid space during life.
What foramina, located posteriorly, adjacent to the sagittal sinus in the parietal bone, transmit emissary veins b/t the scalp and the superior sagittal sinus?
Parietal foramina
The Superior Nuchal lines, bilateral ridges extending to the right and left from the external occipital protuberance, mark the origin of what two muscles and insertion of what two muscles?
Origin: Occipitalis & Trapezius
Insertion: SCM & splenius capitis
The nuchal ligament attaches to what bony element of the occipital bone?
The median nuchal line
What is the significance of the nuchal ligament?
The nuchal ligament is a band of fibroelastic tissue that limits forward flexion of the head and provides surface area for the attachment of deep muscle of the posterior neck that are critical for both maintaining head position against gravity and moving the head quickly in response to visual and acoustic stimuli.
The inferior nuchal lines act as insertion sites for what two small sub-occipital muscles?
rectus capitis posterior major AND minor
What is the significance of the internal occipital protuberance which lies at the center of the cruciform eminence?
The internal occipital protuberance marks the drainage point of the superior sagittal sinus/sagittal sulcus as it drains into the confluence of sinuses. The cruciform eminence marks the separation of the cerebral fossae superiorly and the cerebellar fossae inferiorly.
What sinus corresponds to the internal occipital crest and what dural septum attaches here?
The falx cerebri, a dural septum which separates the right and left hemispheres of the brain, and the occipital sinus.
What is the main route of venous drainage from the confluence of sinuses?
The Transverse sinuses, generally the right is larger and communicates directly with the sagittal sulcus. The transverse sinuses travel laterally in the transverse sulci, draining into the sigmoid sinuses and eventually connect to the internal jugular vein after exiting the skull through the jugular foramena.
Confluence of sinuses marks the intersection of superior sagittal, trasverse, occipital and one other sinus. What is the fourth sinus that does not correspond to any sulcus in the endocranial bone. Why?
The straight (rectus) venous sinus does not lie in a sulcus b/c it lies at the intersection of the falx cerebri and tentorium cerebelli.
What structure on the basilar part of the occipital bone, about 1 cm anterior to forament magnum, marks the attachment site of the fibrous pharyngeal raphe?
Pharyngeal tubercle
The inferior petrosal sulci, which are found along the anterolateral margins of foramen magnum internally, house what sinuses?
Inferior petrosal sinuses
The superior aspect of the base of the occipital bone unites with the posterior aspect of the dorsum sella of the sphenoid bone to form a slope descending from sella turcica to foramen magnum called what?
Clivus
In life, what rest on the clivus? 3 things
- Basilar (venous dural) plexus
- Basilar artery
- Brainstem
What convex, oval facets articulate bilaterally with the atlas, the first cervical vertebra? What depressions, posterior to the aforementioned oval facets, accommodate the superior articular facets of the atlas when the head is extended?
Occipital condyles.
Condylar Fossae.
The articulation of the occipital condyles with the atlas form what joint? Hint: Also known as the ‘yes’ joint?
Atlanto-occipital joints
What two structures are transmitted through the hypoglossal canal, which is located at the anterior base of each condyle?
- Hypoglossal Nerve (CN XII)
2. Meningeal branch of the ascending pharyngeal artery
Jugular foramen is formed by the articulation of what two bones?
The jugular notch of the occipital and the jugular fossa of the temporal
What 3 cranial nerves and what two sinuses exit the skull through the jugular foramen?
Cranial Nerves: The spinal accessory (CN XI), Vagus (CN X), and glossopharyngeal (CN IX).
Sinuses: The Sigmoid sinus and inferior petrosal sinus join in the jugular bulb, within the jugular fossa of the temporal bone, pass through the jugular foramen and form the internal jugular vein.
What 4 important structures pass through foramen magnum?
- Spinal cord, from the medulla oblongata, & its Meninges
- vertebral arteries
- Vertebral venous plexus
- The spinal accessory nerve (CN XI) enters the skull through the foramen magnum
What is the significance of the articular tubercle?
The articular tubercle forms the anterior portion of the temporomandibular articular surface. The posterior surface of the articular tubercle is called the articular eminence.
What attaches to the articular tubercle?
Temperomandibular ligament
What structure forms the major portion of the temporomandibular articular surface? What structures articulate in this fossa?
Mandibular (glenoid) fossa articulates with the mandibular condyle and the intervening articular disc (meniscus).
What 3 muscles have their origin on the styloid process of the temporal bone?
- Stylohyoid
- Styloglossus
- Stylopharyngeus
What bony structure of the petrous bone is pneumatized and continuous with the middle ear cavity?
The mastoid process
What 3 muscles attach to the mastoid process?
- Sternocleidomastoid
- Splenius capitis
- Longissimus capitis
What muscle has its origin on the mastoid notch, the deep groove on the medial aspect of the mastoid process?
The posterior aspect of the digastric muscle
What bony groove is found medial to the mastoid notch and lodges the occipital artery, a branch of the external carotid artery that provides blood to the posterior scalp?
The occipital groove
What dural partition attaches at the petrous crest?
The tentorium cerebelli.
What lies in the trigeminal impression on the petrous portion of the temporal bone?
Sensory ganglion of the trigeminal nerve (CN V), which is surrounded in life by a dural outpouching known as Meckel’s cave.
The superior petrosal sinus runs along the petrous crest as it brings venous blood from the cavernous sinus anteriorly to the sigmoid sinus posteriorly in what sulcus?
Sulcus of the superior petrosal sinus
What two structures travel through the carotid canal?
- Internal carotid artery
2. Postganglionic sympathetic fibers forming the carotid plexus
What structure runs over the foramen lacerum and what two structures run through the foramen lacerum?
The internal carotid artery runs over the foramen lacerum, while the nerve of the pterygoid canal (Vidian N.) and a meningeal branch of the ascending pharyngeal artery course through it.
What two cranial nerves pass through the internal acoustic meatus?
The facial nerve, CN VII, on its way to the tortuous path of the facial canal, and the vestibulocochlear nerve, CN VIII, on its way to innervate the organs of balance and hearing.
The hiatus of the greater petrosal nerve transmits what branch of CN VII? Where is this nerve directed? What happens at this destination?
The hiatus of the greater petrosal nerve transmits the greater petrosal nerve to the foramen lacerum where it joins with the deep petrosal nerve to form the nerve of the pterygoid canal (vidian nerve).
The tympanic branch of the maxillary artery is transmitted to the middle ear cavity by what fissure in the petrous bone?
Petrotympanic fissure
What canal transmits chorda tympani, a branch of CN VII, from the tympanic cavity to the infratemporal fossa, where it joins and runs with the lingual branch of V2?
Iter chordae anterius
What foramena transmits the trunk of the facial nerve from the facial canal along with the stlomastoid artery (a branch of posterior auricular a.) anteriorly?
Stylomastoid foramen
What structure permits the tympanic branch of the glossopharyngeal nerve (CN XII) to enterthe temporal bone where it will ramify to form a plexus along the medial wall of the middle ear cavity?
Tympanic canaliculus
What is the small opening on the lateral wall of the jugular foramen that permits the auricular branch of the vagus nerve (CN X) to enter the temporal bone?
Mastoid canaliculus
The only cutaneous branch of the nerve exits the skull via the tympanomastoid fissure, located b/t the tympanic and mastoid parts of the temporal bone, to innervate the external auditory meatus. What is this branch?
The auricular branch of CN X
What is the name of the bony portion of the Eustachean Tube, which communicates b/t the tympanic cavity and nasopharynx?
Ossea tubae auditivae
What pneumatized portion of the sphenoid bone forms the sphenoid sinuses?
The body
What is lodged in the depression of sella turcica during life? What is sella turcica bounded by?
The pituitary rests on sella turcica and is bounded by tubercullum sellae with the middle clinoid processes anteriorly and dorsum sella with the posterior clinoid processes posteriorly.
What is so unusual about the dural venous sinus that runs within the carotid grooves, which are found bilaterally to sella turcica?
The cavernous portion of the internal carotid artery runs within the cavernous sinus
What is found within the chiasmatic groove?
Optic chiasm, the site where fibers from the left and right optic nerves decussate, giving rise to left and right optic tracts
Where is the sphenoid crest found?
The sphenoid crest is found at the anterior of the body of the sphenoid and contributes minimally to the posterior end of the nasal septum
The anterior and posterior clinoid processes are an attachment site for what?
The dura that roofs over the pituitary as it rests in the sella turcica
The spina angularis (sphenoid spine) of the greater wing of the sphenoid bone serves as the attachment site for what muscle?
Tensor veli palatini
Lieing just posterior to the pterygomaxillary fissure, what ‘plate’ forms the medial wall of the infratemporal fossa?
Lateral pterygoid plate
The lateral pterygoid plate serves as attachment for what two muscles of mastication?
The lateral surface is the origin of the lateral pterygoid muscle, while the medial surface of the lateral pterygoid plate is the origin of the medial pterygoid muscle.
The medial pterygoid plates form the lateral boundaries of what ‘aperture’?
The choanae or posterior nasal aperture
What hook like processes extend from the inferior end of the medial pterygoids and serve as a pulley around which fibers of the tensor veli palatini muscles are redirected to the soft palate?
Pterygoid hamulus
Fibers of what two muscles fill the pterygoid fossa?
Medial pterygoid muscle and tensor veli palatini muscle
What is transmitted through the optic foramen, which is found bilaterally on either side of the chiasmatic groove?
Cn II - the optic nerve and the opthalmic artery into the orbit
What 4 basic categories of structures are transmitted through the superior orbital fissure from the middle cranial fossa to the orbit?
- The extraocular muscles: CN III - oculomotor nerve, CN IV - trochlear nerve, CN VI - abducens nerve
- opthalmic division of the trigeminal nerve (CN V3)
- opthalmic veins
- sympathetic fibers from the internal carotid plexus
What passes through foramen rotundum? Where does it lead?
The maxillary division of the trigeminal is passed from the middle cranial fossa to the pterygopalatine fossa
What 4 structures (2 nerves, 2 blood vessels) pass between the middle cranial fossa and the infratemporal fossa via foramen ovale?
- Mandibular division of the trigeminal
- Lesser petrosal nerve of CN IX (glossopharyngeal) on its way to deliver parasympathetic innervation to parotid
- Emissary veins
- Accessory meningeal artery, branch of maxillary
What 2 structures pass through the foramen spinosum?
- Middle meningeal artery, large branch off of the maxillary artery. Distinguish via the “V” as the auriculotemporal nerve wraps around the ascending artery in the infratemporal fossa
- Recurrent meningeal branch of the mandibular nerve (CN V3)
What 3 things pass through the inferior orbital fissure?
- Continuation of the maxillary nerve (CN V2)
- Infraorbital vessels
- ascending parasympathetic fibers arising from the pterygopalatine ganglion
Through what fissure does the maxillary artery ascend from the infratemporal fossa to the pterygopalatine fossa?
Pterygomaxillary fissure
Name 3 structures found in the pterygopalatine fossa?
- Maxillary nerve (CN V2)
- Third part of the Maxillary Artery
- Pterygopalatine ganglion (a parasympathetic ganglion w/ inputs from CN VII)
From what direction and through what passage do each of the 3 structures of the pterygopalatine fossa enter?
- Maxillary nerve enters from the posterior via foramen rotundom and exits anteriorly via the inferior orbital fissure.
- Maxillary artery enters laterally via the pterygomaxillary fissure
- The greater petrosal nerve, which is the main supplier of parasympathetics to the pterygopalatine ganglion, enters posteriorly via the pterygoid canal.
What two nerves join to form the greater petrosal nerve before entering the pterygoid canal on its way to the pterygopalatine fossa where it joins the pterygopalatine ganglion?
- Greater petrosal nerve (From CN VII)
2. Deep petrosal nerve from internal carotid plexus
The pharyngeal (palatovaginal) canal transmits what two structures posteroinferiorly from the pterygopalatine fossa to the nasopharynx?
Pharyngeal branches of both the maxillary artery and nerve (V2).
What attaches to the crista galli?
falx cerebri; anterior attachment
What specific part of the ethmoid bone is pneumatized and forms the ethmoid (paranasal) sinus?
Labyrinths
What passes through the anterior and posterior ethmoidal foramens on their way from the orbit to the ethmoidal labyrinth?
Anterior: anterior ethmoidal branches of the nasociliary nerve and opthalmic vessels
Posterior: Posterior ethmoidal neurovascular bundle
