Skull and Cranial Cavity Flashcards
What openings are in the anterior cranial fossa?
cribiform plate, foramen cecum, anterior and posterior ethmoid foramina
What openings are in the middle cranial fossa?
- optic canal
- superior orbital fissure
- foramen rotundum
- foramen avale
- foramen spinosum
- hiatus for greater & lesser petrosal nn
- foramen lacerum
What openings are in the posterior cranial fossa?
- internal acoustic meatus
- jugular foramen
- hypoglossal canal
- foramen magnum
olfactory foramina?
CN I
Optic Canal?
CN II and Opthalmic artery
Superior orbital fissure?
CN III, IV, V1, VI and opthalmic vein
Supraorbital Foramen?
CN V1
Inferior Orbital Fissure
CN V2 and opthalmic vein
foramen rotundum
CN V2
infraorbital foramen
CN V2
foramen ovale
CN V3
accessory meningeal artery
lesser petrosal nerve
mental foramen
CN V3
Foramen Spinosum
- middle meningeal artery and vein
- meningeal branch of mandibular nerve
foramen lacerum
Greater petrosal nerve
carotid canal
- internal carotid artery
- internal carotid plexus
Internal acoustic (auditory) meatus
- CN VII
- CN VIII
- labyrinthine Artery
stylomastoid foraman
CN VII
Jugular Foramen
- inferior petrosal sinus
- glossoparyngeal nerve (IX)
- vagus nerve (X)
- Accessory nerve (XI)
- sigmoid sinus
- posterior meningeal artery
- internal jugular vein
foramen magnum
- spinal roots of accessory nerve (XI)
-spinal cord
-vertebral and menningeal branches of vertebral arteries - spinal artieries
-medulla oblongata meninges
-
Hypoglossal Foramen
hypoglossal nerve (XII)
Pia mater
directly apposed to surface of brain
What creates the subarachnoid space?
Arachnoid mater contains web-like extensions that extend to the pia, creating the subarachnoid space in which Cerebrospinal fluid (CSF) circulates and bathes the brain
what are the layers of the dura mater?
tough outermost layer, with an internal meningeal sheet and an external periosteal sheet which is securely attached to inner aspect of calvaria
what is the blood supply to the dura mater?
mostly, middle meningeal a.; some from ophthalmic, occipital, and vertebral aa.
what is the sensory nerve supply to the dura mater?
mostly, CN V1-3; some from C2-3 via CN X and XII. (Can be a source of headaches.)
what are dural folds formed from?
formed by meningeal sheet pulling away from periosteal sheet; support the brain within the cranial vault and create spaces for the venous sinuses
what are the dural folds?
falx cerebri, falx cerebelli, tentorium cerebelli, diaphragma sellae
name the venous sinuses.
superior & inferior sagittal, straight, transverse, superior & inferior petrosal, sigmoid, occipital, cavernous; confluens sinuum.
what is the purpose of the venous sinuses?
a. These provide the venous drainage of the brain and communicate with the systemic venous circulation via the pterygoid and basilar plexuses of veins, and the superior & inferior ophthalmic vv.
where are the cavernous sinuses located?
b. The cavernous sinuses are located on either side of the body of the sphenoid. Several cranial nn. and the internal carotid a. pass near or through them or within their walls: CN II, III, IV, V1, V2, and VI. They also lie near the pituitary gland.
What are arachnoid granulations?
(arachnoid villi) absorb CSF into venous system
Extradural (epidural) hematoma
blood collects between the calvaria and the periosteal layer of the dura
Subdural (dural border) hematoma
blood collects between the dura and the arachnoid
Subarachnoid hemorrhage
blood flows into the subarachnoid space and commingles with cerebrospinal fluid
Comparative anatomy of Human Skull vs. Chimpanzee Skull
- brain size
a. 3 times greater in man
b. prolonged brain growth: to 7th year
c. necessity of wider birth canal - change from facial prognathism to orthognathism
- forward rotation of foramen magnum
- reduction of masticatory apparatus
- changes in dentition/dental arcade
What comprises the Neurocranium (braincase)
Frontal (2, normally fused into 1 in adult)
Parietal (2)
Occipital (1; fused from 4 parts: 1 supra-, 2 ex-, and 1 basioccipital)
Temporal (2) (comprise squamous, petromastoid, and tympanic portions, besides zygomatic and styloid processes; enclose auditory ossicles; form joints with mandible = “TMJ”)
Sphenoid (1)
Ethmoid (1)
What comprises the Viscerocranium?
Maxilla (2) [incorporates fused premaxilla (= intermaxilla) on each side] Palatine (2) Zygomatic (2) Lacrimal (2) Nasal (2) Vomer (1) Inferior Nasal Concha (2)
What are the Auditory Ossicles?
Malleus (2)
Incus (2)
Stapes (2)
NOTE: malleus (= reptilian articular) and incus (= reptilian quadrate) formed primitive craniomandibular joint (“CMJ”); supplemented and finally replaced by squamosal-dentary joint (mammalian “TMJ”).
Mandible?
Dentary (2, fused into 1)
what are the modes of bone development in the skull?
- intramembranous ossification (formed in membrane = dermal bone )
- endochondral ossification (formed in cartilage)
what bones are chondocranium of the neurocranium?
Ethmoid, inferior nasal choncha
what bones are both Chondro & dermatocranium of the neurocranium
occipital
what bones are dermatocranium of the neurocranium
frontal, parietal
which bones are both chondro & dermatocranium of both neuro and viscerocranium
temporal and sphenoid
which bones are chondrocranium of the viscerocranium
malleus, incus, stapes
which bones are both chondro and dermatocranium of viscerocranium
mandible
dermatocranium of the viscerocranium
maxilla, palatine, zygomatic, nasal, lacrimal, vomer
Acrania, anencephaly (cranioschisis, craniorrhachischisis)
failure of development of skull and brain; failure of closure of skull and spinal column
Craniostenosis (= craniosynostosis)
- scaphocephaly [sagittal suture]
- acrocephaly (= tower skull) [coronal suture]
- plagiocephaly [lambdoid and coronal sutures on one side]
- microcephaly
what are the boundaries of the anterior cranial fossa?
Anterior boundary: Frontal bone
Posterior boundary: Lesser wing of sphenoid
What are the boundaries of the middle cranial fossa?
Anterior boundary: Lesser wing of sphenoid
Posterior boundary: Apex of petrous part of temporal bone
what are the boundaries of the posterior cranial fossa?
Anterior boundary: Apex of petrous part of temporal bone
Posterior boundary: occipital bone
