Flashcards in Week 3 - Dry Room Deck (42):
What is the floor of the skull?
The part of the skull that you view when you remove the skull cap and look into the calvarium.
It is divided into 3 fossa.
In each fossa there are many foramina (or holes) through which nerves and blood vessels enter/leave the calvarium.
There are also grooves and depressions which indicate the position, in life, of blood vessels and other structures
Which bone forms the posterior boundary of the anterior cranial fossa?
Sphenoid (limbus and lesser wing)
Which bone forms the anterior boundary of the middle cranial fossa?
Sphenoid (limbus and lesser wings)
Which bones form the floor of the middle cranial fossa?
Sphenoid (body and greater wings)
Temporal bone (squamous and petrous parts)
Which bone forms the posterior border of the middle cranial fossa?
Temporal bone (petrous part)
What 4 bones form the pterion of the skull?
Which bone forms the anterior and which the posterior border of the posterior cranial fossa?
Anterior = Temporal
Posterior = Occipital
Large and small foramina can be seen on the skull.
What are the larger foramina for and what are the smaller foramina for?
Larger = Nerves and blood vessels to enter/ leave the cranial cavity
Smaller = Emissary veins
What structure(s) pass through the foramina of the cribriform plate?
Olfactory Nerve (I)
What structure(s) pass through the optic foramen?
Optic nerve (II)
What structure(s) pass through the Superior Orbital Fissure?
Ophthalmic Nerve (division of trigeminal)
Occulomotor (III) nerve
Trochlear nerve (IV)
Abducens nerve (VI)
What structure(s) pass through the foramen rotundum?
Maxillary division of the trigeminal nerve
What structure(s) pass through the Foramen ovale?
Mandibular division of the trigeminal nerve
Accessory meningeal artery
What structure(s) pass through the foramen spinosum?
Middle meningeal artery
Middle meningeal vein
Meningeal branch of Mandibular nerve
What structure(s) pass through the foramen lacerum?
only small blood vessels
What structure(s) pass through the Carotid canal?
Internal Carotid artery
What are the 4 parts of the temporal bone?
Petrous part of Temporal bone
Squamous part of temporal bone
What foramina are present in the anterior cranial fossa?
Foramina of the cribriform plate
What foramina are present in the middle cranial fossa?
Superior orbital fissure
What structure(s) pass through the Internal acoustic foramen?
Facial nerve (VII)
Vestibulocochlear nerve (VIII)
What structure(s) pass through the jugular foramen?
Glossopharyngeal nerve (IX)
Vagus nerve (X)
Accessory nerve (XI)
Internal Jugular vein
What structure(s) pass through the hypoglossal foramen?
Hypoglossal nerve (XII)
What structure(s) pass through the foramen magnum?
Spinal accessory nerve
Anterior and Posterior spinal arteries
Give an introduction to the grooves in the floor of the skull
Formed as the bone of the skull develops (and is maintained) around pre-existing blood vessels or nerves.
In the main, the grooves that are easily identified are those formed by arteries or by the intra-cranial venous blood sinuses.
The intra-cranial venous blood sinuses are found between the inner and outer layers of dura - the inner layer is the dura proper and the outer layer the periosteum of the inside face of the skull bone.
What groove lies just lateral to the foramen spinosum?
Why is this of clinical importance?
Groove for the middle meningeal artery
-The skull over part of the course of this artery is very thin
-A branch of this artery crosses the preteen on its inner surface.
Due to these 2 factors, this artery is commonly damages in injuries such as blow to the head following a fall from a bike.
This results in a bleed collecting between the periosteum of the skull and the dura mater (an extradural haemorrhage).
Such haemorrhages are classically biconvex, lens-shaped.
Usually the spread is limited to this shape by cranial sutures
Whats the significance of the internal occipital protuberance?
Grooves run laterally on both sides starting from the internal occipital protuberance. These groves are for the intracranial venous sinus called the transverse sinus.
These flow laterally until that continue as the S-shaped groove for the sigmoid sinus.
The sigmoid sinus leads to the jugular foramen where the internal jugular vein emerges from
What is the sella turcica?
What are its parts?
Sella turcica (turkish saddle) is a deep depression in the midline in the middle cranial fossa which houses the pituitary gland.
It is located in the body of the sphenoid bone.
On either side of the sella turcica is the anterior and posterior cloned processes which give attachment to a fold of dura mater, the tantrum cerebelli
On either side of the sella turcica lies what?
A groove for the cavernous venous (intracranial sinus).
Anterior to this is the superior orbital fissure
What bone are the pterygoid plates part of?
What muscles attach to them?
Medial pterygoid plate = Tensor Veli Palatini
Lateral pterygoid plate = Medial and Lateral pterygoid muscles
How does the neonatal skull differ from the adult?
A neonatal skull is not fully ossified, making it less rigid and more flexible.
Fontanelles are present which are almost membranous coverings linking the unfused bones of the skull
What are the advantages for a neonate of having a comparatively flexible skull?
During childbirth it allows for the head to pass through the birth canal more easily.
During infancy it allows the brain to grow faster than bones
In the event of accidents such as falls it reduced the likelihood of fracture
What type of ossification occurs in:
-flat bones of the vault of the skull and
-irregular bones of the base of the skull?
Membranous ossification in flat bones
Endochondral ossification in irregular bones
What is the difference between foetus, child and adult skulls with respect to fontanelles?
Children: The bones fuse
What is the difference between foetus, child and adult skulls with respect to dentition?
Foetus: No teeth present in mouth (2 "back up")
Child: 1 set of teeth present (1 "back up")
Adult: 1 set of teeth present (No "back up")
What is the difference between foetus, child and adult skulls with respect to the tympanic membrane?
In foetus it is more superficial, almost the surface of skull.
As skull rapidly grows the tympanic membrane ends up deeper.
Skull moves as it grows and tympanic membrane almost sort of stays put
What is the difference between foetus, child and adult skulls with respect to the styloid and mastoid process of the temporal bone?
Much smaller or absent in the young.
Grows as we age
At what age do the anterior and posterior fontanelles fuse respectively?
First few months (2-3)
What kind of epithelium lines the dorsal surface of the tongue?
Keratinised squamous epithelium
What type of muscle fibres underlies the epithelium of the tongue?
How do the salivary glands basically differ?
3 main paired salivary glands.
Each responsible for a slightly different type of secretion
(i.e. predominantly serous, predominantly mucous or mixed).
This difference is reflected histologically in the presence and amount of serous or mucous acini (secretory component)
Describe the acini of the serous glands and how their H+E staining differs
The acinus is the rounded secretory component of a gland.
Serous acini secrete proteins, which mean that they stain strongly with H+E stain.
Mucous acini secrete the glycoprotein mucous which poorly stains with H+E
Parotid = serous
Sublingual = mucous
Submandibular = mixed