APE 12: Cranial Cavity and Gross Brain Anatomy Flashcards
How many bones does the skull consist of?
22
What are the joints between the bones of the skull an example of?
Syndesmosis- fibrous joints
How many of the bones form the cranium?
8
How many bones form the face?
14
What are the two orbital cavities found in the skull?
Obicularis oris and obicularis oculi
What does the piriform aperture lead to?
The nasal cavity
What are the margins of the orbit?
Supraorbital, infraorbital and lateral
Which 4 bones contribute to the orbit?
Zygomatic, maxilla, frontal and ethmoid
Where do the turbinate bones arise from?
From the lateral wall of the nose
What are the names of the turbinate bones?
Superior, middle and inferior
What are the names of the 3 sutures in the skull?
Lambdoid, squamosal and sagittal
What is the name of the area on the skull where all the sutures meet?
Pterion
Which structure lies beneath the pterion?
The middle meningeal artery
What is the clinical significance of the middle meningeal artery?
Attaches directly to the cranial bones- common injuries during head trauma
What are the 3 recesses on the undersurface of the brain?
Anterior middle and posterior cranial fossae
Which parts of the brain fit into each fossae?
Anterior= frontal lobe Middle= temporal lobe Posterior= occipital lobe
What forms the roof of the nasal cavity?
The cribriform plate of the ethmoid bone
Which nerve filaments pass transmit through the opening of the cribriform plate of the ethmoid bone?
The olfactory nerve
Which nerve runs through the optic canal?
The optic nerve
Which 3 foramen are found in the middle cranial fossa and what do they transmit?
Foramen rotundum, foramen ovale and foramen lacerum
Transmit cranial nerves
Which important structure lies in the sella turcica?
The pituitary gland
Which vessel enters the cranium through the carotid canal?
The internal carotid artery
Which structures are found in the posterior cranial fossa?
The internal auditory meatus, jugular foramen, hypoglossal canal and foramen magnum
Which nerves pass through the superior orbital fissure?
Nerves 3-6: Occulomotor, trochlea, opthalmic branch of trigeminal and abducens
Which nerve passes through the foramen rotundum?
Maxillary branch of trigeminal
Which nerve passes through the foramen ovale?
Mandibular branch of trigeminal
Which nerves pass through the internal acoustic meatus?
Facial and vestibulocochlear
Which nerves pass through the jugular foramen?
Glossopharyngeal, vagus and accessory
Which nerve passes through the hypoglossal canal?
Hypoglossal nerve
What are the main parts of a brain?
Cerebrum, cerebellum and brain stem
What 3 components make up the brainstem?
Midbrain, pons and medulla oblongata
What does the cerebrum control?
Personality, memory and intelligence
What does the cerebellum control?
Balance, muscular co-ordination and dexterity
What does the brain stem control?
Normal conscious awareness and basic life support functions
Where is the longitudinal fissure found?
Between the two cerebral hemispheres
Where is the transverse fissure found?
Between the cerebrum and cerebellum
Where is the lateral sulcus found?
Between the frontal and temporal lobes
What are the 4 lobes of the cerebral hemispheres?
Frontal, occipital, parietal and temporal
What do each of the lobes contain?
Frontal= primary motor cortex Parietal= primary somatic sensory cortex Occipital= primary visual cortex Temporal= primary auditory context
What are the folds found on the surface of the brain called?
Gyri
What separates the gyri?
The sulci/grooves
What links both the cerebral hemispheres?
The corpus callosum
How many meninges cover the brain?
3
What is the outermost meninx called and what is it tightly adhered to?
Dura mater, tightly adhered to bone so often remains attached to the inside of the skull
What is the name of the sickle-shaped fold of dura mater that occupies the interval between the two cerebral hemispheres?
The falx cerebri
What is the name of the fold of the dura mater that separates the cerebrum from the cerebellum?
The tentorium cerebelli
What are the names given to the channels formed by the separation of the dura mater and what do they do?
Dural venous sinuses which receive blood from the brain
Name the different dural venous sinuses
Superior sagittal, inferior sagittal, sigmoid, transverse and straight
What is the clinical term for bleeding between the skull and dura mater and what can this cause?
Extra-dural haemorrhage which can cause life-threatening pressure on the brain
What are the other two meninges?
Arachnoid and pia mater
What is the subarachnoid space?
Very narrow space over the surface of the brain that is filled with cerebrospinal fluid
What happens to the arachnoid mater in bacterial meningitis?
It becomes acutely inflammated and pus fills the subarachnoid space and surrounds the vessels
What does the fluid-filled cavity corresponding to the lumen of the embryonic neural tube give rise to?
The ventricular system
What are the different ventricles found in the brain?
Lateral, third and fourth
What do the lateral ventricles drain into?
They drain via the two interventricular foramen to the third ventricle
Where is the third ventricle located?
In the midline between the two thalami
Where is the fourth ventricle located?
Between the brainstem which is anterior and the cerebellum which is posterior
What connects the third and fourth ventricles?
The cerebral aqueduct of the midbrain
Which plexus continuously secretes CSF?
The choroid plexus
How does the CSF reach the subarachnoid space?
Flows through the choroid plexus, to the 4th ventricle and into the subarachnoid space via 3 openings
Where is the CSF continuously reabsorbed?
The superior sagittal sinus
What does an obstruction within the ventricular system of the foetus result in?
Exapnsion of the brain and skull- hydrocephalus
At which point is a needle inserted to perform lumbar puncture to sample the CSF?
L3/L4
What do the pyramids of the medulla contain and where do they descend?
Contain voluntary motor fibres
Descend from frontal lobes to spinal cord
What would damage to the medulla oblongata cause?
Weakness/paralysis
Where is the pons found relative to the medulla?
The pons is found superior to the medulla
What are the two ‘Roman pillars’ of the midbrain called and what are they separated by?
Called cerebral peduncles, separated by interpeduncular fossa
What are the 4 colliculi and what are they concerned with?
2 superior and 2 inferior
Concerned with visual and auditory reflexes
Which two nerves arise from the cerebral hemispheres?
Olfactory and optic (1 and 2)
Where does the olfactory nerve arise?
In the nasal mucosa
What is the target of the olfactory nerve?
The olfactory bulb and the tract
Where do the 2 optic nerves unite and then what do they divide into?
Unite at the chiasm and divide again to become optic tracts
What is the clinical significance of the chiasm being situated just above the pituitary gland?
Visual field defects
Which 2 nerves arise from the midbrain?
Oculomotor and trochlear (3 and 4)
Where does the oculomotor nerve emerge from?
The interpeduncular fossa, between the cerebral peduncles
What does the oculomotor nerve supply?
4 out of 6 of the extraocular muscles
Where does the trochlear nerve arise from?
The posterior aspect of the midbrain
Which muscle does the trochlear nerve supply?
A single extraocular muscle
Which single cranial nerve exits dorsally?
Trochlear nerve
Which 4 nerves arise from the pons?
Trigeminal, abducens, facial, vestibulocochlear (5, 6, 7 and 8)
What does the trigeminal nerve supply?
Facial sensation and muscles of mastication
What does the abducens nerve supply?
A single extraocular muscle
What does the facial nerve supply?
Muscles of facial expression and taste fibres (anterior 2/3 of the tongue)
What does the vestibulocochlear nerve supply?
The middle ear- concerned with hearing and balance
Which 4 nerves arise from the medulla?
Glossopharyngeal, vagus, accessory and hypoglossal (9, 10, 11 and 12)
What does the glossopharyngeal nerve supply?
Mainly a sensory nerve- supplies pharyngeal sensation (gag reflex) and taste fibres (posterior 1/3 of tongue)
What does the vagus nerve supply?
Muscles of speech and swallowing, is the parasympathetic nerve of thorax and abdomen till splenic flexure of colon
What is the parasympathetic innervation below the splenic flexure of the colon?
From the sacral outflow in the pelvic splanchnic nerves- S2, 3, 4
What are the two aspects of the accessory nerve and what do they do?
Cranial portion= joins the vagus nerve
Spinal portion= supplies trapezius and sternocleidomastoid muscles of the neck
Which nerve emerges by itself?
The hypoglossal nerve (12)
What does the hypoglossal nerve supply?
Purely a motor nerve, supplies intrinsic and extrinsic muscles of the tongue
