Neuroanatomy 1 SDL Flashcards
Define rostral
Rostral is taken from the Latin rostrum, to mean towards the nose/beak. Rostral therefore refers to the anterior (front) aspect of the head.
E.g. The forebrain is rostral to the midbrain.
Define caudal
In this context, caudal refers to the posterior (back) of the head.
E.g. The hindbrain is caudal to the midbrain.
What is the cephalic flexure?
Where the axis of the adult brain bends at an angle of about 100° between the midbrain and the diencephalon
In the spinal cord and brainstem, what does the term ‘dorsal’ mean? What does it mean in the forebrain?
Spinal cord and brainstem –> means posterior
Forebrain –> means superior
In which plane would you cut in order to make a transverse section of either brainstem or spinal cord?
Horizontal
What is meant by the following terms in the context of the nervous system?
- grey matter:
- white matter:
- cortex:
- nucleus:
- tract:
- ganglion:
- Grey matter: mainly composed of neuronal cell bodies and unmyelinated axons
- White matter: mainly composed of myelinated axons
- Cortex: the cerebral cortex is the outermost layer of the brain, made up primarily of grey matter.
- Nucleus: cluster of neurons found in the CNS
- Tract: A nerve tract is a bundle of nerve fibers (axons) connecting nuclei of the central nervous system
- Ganglion: a cluster of neural bodies outside the central nervous system.
Which subdivisions of the brain make up the forebrain or cerebrum?
cerebrum, thalamus, hypothalamus, pituitary gland
Which subdivisions of the brain make up the brainstem?
midbrain, medulla and pons,
The lobes of the brain
What cortical landmarks which are used to subdivide the hemisphere into lobes?
- Longitudinal sulcus –> separates right and left hemispheres
- Central sulcus –> separates frontal lobe from parietal lobe
- Parieto-occipital sulcus –> separates parietal from occipital lobe
- Lateral sulcus –> separates temporal lobe from frontal and parieral lobe
Are the cerebral lobes functional or descriptive subdivisions?
The lobes of the brain were originally a purely anatomical classification, but have been shown also to be related to different brain functions.
What are the functions of the pre- and post-central gyri? And where are they located?
Precentral gyrus:
- Located anterior to central sulcus
- Function –> primary motor cortex
Postcentral gyrus:
- Located posterior to central sulcus
- Function –> primary somatosensory cortex
What is the corpus callosum is composed of?
The largest fibre bundle in the brain, containing nearly 200 million axons. It is composed of white matter fibre tracts.
What is the function of the corpus callosum?
Connects the right and left hemispheres - ensures both sides of the brain can communicate and send signals to each other
Label these structures
Label these structures
Is the optic nerve part of the peripheral nervous system or part of the central nervous system?
t’s considered to be part of the central nervous system (CNS) as it is derived from an outpouching of the diencephalon during embryonic development.
what do the 5 secondary vesicles give rise to?
Telencephalon
Diencephalon
Mesencephalon
Metencephalon
Mylencephalon
Olfactory tract
Olfactory bulb
Infundibulum
Optic nerve
Optic chiasm
Mamillary bodies
Cerebral peduncles of the midbrain
Pons
Cerebellum
Medulla oblongata
What are the 3 layers of meninges that enclose the brain and spinal cord?
- Dura mater
- Arachnoid mater
- Pia mater
Describe the appearance of the dura mater
It is thick, tough and inextensible.
Describe the appearance of the arachnoid mater
spiderweb-like appearance, is a thin, transparent membrane
Describe the appearance of the pia mater
thin, translucent, mesh-like meningeal envelope
What forms the dura mater in the cranial cavity?
- Periosteal outer layer lining the inside of the skull
- Meningeal fibrous inner layer
Throughout most of the cranial cavity, the two layers are tightly fused together.
At some sites, though, the fibrous inner layer of dura separates from the periosteum to enclose what?
At two such sites of separation, the fibrous inner layer of dura projects into the cranial cavity to form what?
- Enclose blood-filled spaces - the dural venous sinuses - into which flows venous blood from the brain.
- At two such sites of separation, the fibrous inner layer of dura projects into the cranial cavity to form a dural reflection (sometimes called a fold or septum) which extends into the fissures between the major components of the brain.
What is the name of the dural septum that extends down between the two cerebral hemispheres?
Falx cerebri:
- The falx cerebri is a large, crescent-shaped fold of meningeal layer of dura mater that descends vertically in the longitudinal fissure between the cerebral hemispheres of the human brain.
What is the name of the dural septum that extends between the occipital lobes of the hemispheres and the cerebellum?
Tentorium cerebelli:
- The tentorium cerebelli exists between and separates the cerebellum and brainstem from the occipital lobes of the cerebrum
What is the function of the dural septae?
To separate the cranial cavity into compartments and protect the brain from displacement
Which dural venous sinuses run along the lines of attachment of these two dural folds to the skull?
- The straight, superior, and inferior sagittal sinuses are found in the falx cerebri of the dura mater
- They converge at the confluence of sinuses
- The superior petrosal sinuses and the transverse sinuses are found in the tentorium cerebelli
Label these structures
What occupies space A? What is its function?
Subdural/subarachnoid space - contains CSF to:
- Cushion the brain and spinal cord
- To supply them with nutrients and remove waste
Also, the major arteries of the brain run through the subarachnoid space.
What are the arachnoid villi (also called arachnoid granulations) and what is their function?
What: Small protrusions of arachnoid mater into the outer membrane of the dura mater
Function: permit one-way flow of CSF from the subarachnoid space to the venous circulation.
Which vessel provides the arterial supply to the dura mater? Why is it of great clinical importance?
Middle meningeal artery –> susceptible to injury in the pterion which can lead to an epidural haematoma
Which two pairs of blood vessels provide the arterial supply to the brain?
Vertebral artery and internal carotid artery
Describe the course of the vertebral and internal carotid arteries as they ascend to enter the skull.
Internal carotid:
- originate at the bifurcation of the left and right common carotid arteries, at the level of C4
- move superiorly within the carotid sheath
- nter the brain via the carotid canal of the temporal bone.
Vertebral:
- arise from the subclavian arteries
- ascend the posterior aspect of the neck, through holes in the transverse processes of the cervical vertebrae, known as foramen transversarium.
- enter the cranial cavity via the foramen magnum
Identify vessel A and B
A - vertebral artery
B - ?
Indicate which brain regions are supplied by each pair of vessels (represented by arrowheads). Note that each of these main branches give off small, penetrating branches along their course to supply the internal brain tissue.
What does the posterior cerebral arteries supply?
The posterior aspect of cerebrum
What does the middle cerebral artery supply?
Supplies lateral portions of cerebrum
What do the anterior cerebral arteries supply?
Tucks under the midline portion of each cerebral hemisphere to supply its anterior and medial aspect
Distribution (territories) of the anterior, middle and posterior cerebral arteries.
Penetrating arterial branches, arising from around the arterial circle and passing into the substance of the brain, are often referred to as what?
Central or perforating arteries
Branches arising from the middle cerebral artery are called what?
Striate arteries
What do these striate arteries supply?
These supply structures inside hemisphere:
- Deep nuclei
- Deep grey matter (e.g. thalamus)
- Internal capsule (major fibre bundle to and from cerebral cortex - deep white matter)
- Supply includes major descending motor pathway
Which two sets of veins drain blood from the brain?
Superficial and deep veins
Where do the superficial veins of the brain run?
run over the surface of the hemispheres
Where do the majority of the superficial veins drain into?
The superior sagittal sinus
Where is the superior sagittal sinus located?
Lies along the superior edge of the falx cerebri
Deep veins converge on the internal cerebral veins which eventually unite to form the what?
Great cerebral vein (of Galen)
Fill in the missing words in the diagrammatic representation of the venous drainage of the brain
What are the 3 main types of intracranial haemorrhages (ICH)?
- Extradural (EDH)
- Subdural (SDH)
- Subarachnoid (SAH)
A rupture of which vessel could lead to an extradural haemorrhage?
Middle meningeal artery
A rupture of which vessel could lead to a subdural haemorrhage?
?
A rupture of which vessel could lead to an subarachnoid haemorrhage?
?
Subdural haemorrhage occurs most commonly in older / elderly people. Why?
Generalised cerebral atrophy and increased venous fragility
What is a “berry” aneurysm? Suggest a few sites at which these might occur.
Abnormal dilations around the circle of Willis or at the points of arterial branching within the brain
What are the consequences of rupture of a berry aneurysm?
Can lead to vascular stroke
What is a Cerebrovascular Accident?
CVA = stroke
How is a CVA caused?
These occur when a blood vessel is occluded, and brain tissue becomes infarcted.
