Neuroanatomy 2 Flashcards
What does the SCALP consist of
clue is in the name
Skin Connective tissue Aponeurosis Loose connective tissue Periosteum
What are the 3 meninges of the skull
Dura mater
Arachnoid mater
Pia mater
What is the dura mater
Outermost meningial layer
Tough, fibrous membrane
Restricts movement of the brain
2 layers of dura mater
Outer periosteal layer
Inner meningeal layer
What is the Flax cerebri
Midline
Seperates the two cerebral hemispheres
What is the tentorium cerebelli
Forms a roof over the posterior cranial fossa
Seperates cerebellum from occipital lobes
Free border = tentorial notch, for the passage of the midbrain
What are the dural reflections and what are their purposes
Falx cerebri and tentorium cerebelli
Subdivides the cranial cavity
Protects and insulates the brain to reduce injury in response to trauma
Provides pathways fro blood vessels and nerves
What are dural venous sinuses
Spaces the enclose venous blood
Drain venous blood from brain, skull bones, the orbit and the inner ear
Dural venous sinuses in the falx cerebri
Superior and inferior sagitall sinuses
Dural venous sinuses in the tentorium cerebelli
Straight sinus
Transverse sinus
Sigmoid sinus
Course of sigmoid sinus
Leaves the skull though jugular foramen
Drains into IJV
Where is the cavernous sinus located
Lateral to sphenoid bone
What is the arachnoid mater
Middle meningeal layer
surround the brain loosely
Soft, translucent membrane
Seperated from dura by a subdural space
What is the subarachnoid space
Seperates arachnoid and pia
conatins network of arachnoid trabeculae
Blood vessels and cerebrospinla fluid
What is the pia mater
Innermost meningeal layer
Microscopically thin
Closely adherant to brain surface
What is the extra-dural space
Potential space
Between bone and dura
usually the dura is firmly attached to the skull
contains meningeal arteries
What is sub-dural space
Potential space
Between dura and arachnoid mater
Subarachnoid space
Fluid filled space
Between the arachnoid and pia mater
What is cerebrospinal fluid
Clear colourless fluid that surround the brain and spinal cord and has many important functions
Functions of cerebrospinal fluid
Buiyancy
Protection
Clearing waste
Chemical stability
What are the ventricles of the brain and their connections
Lateral ventricle (x2)
Third ventricle
Fourth ventricle
interventricular foramen (between lateral and third ventricle)
Aqueduct of midbrain (between the third and fourth ventricle)
Name the parts of the lateral ventricles
and their association to the brain
Anterior horns (frontal lobe) Body (parietal lobe) Posterior horns (OCCIPITAL LOBE) Inferior horns (temporal love)
How is the choroid plexus formed and where is it located
Formed by an invagniation of the pia mater into ventricular lumen
located in the lateral, third and fourth ventricles
What produces CSF
Choroid plexus
What is CSF
Colourless fluid with little protein and few cells
Total volume approx. 150ml
Produced continuously, and replaces itself several times a day
CSF must therefore be circulated and reabsorbed if it is continuously produced
CSF circulation
Flows through the ventricular system into the fourth ventricle
From there it enters the central canal of the spinal cord and the Subarachnoid space via 2 lateral apertures and 1 median aperture
From the sub-arachnoid space, CSF is absorbed into the dural venous sinuses vai the arachnoid villi
What are the arachnoid villi
Projections of the arachnoid later into the dural venous sinuses and sites of absorption
Most commonly found in the superior sagittal sinus
How does CSF absorption occur
CSF has higher hydrostatic pressure than venous blood
So absorbed in the venous blood though the villi
What is hydrocephalus
Expansion of the ventricles
What are the segments of the spinal cord
8 Cervical segemnts 12 Thoracic segmants 5 Lumbar segmants 5 Sacral segments 1 Coccygeal segmants
Where does the spinal cord terminate in adults
L1/L2
What are the 3 spinal meningeal layers
Pia mater
Arachnoid mater]
Dura mater
What seperates the dura mater from the bone in spina cord
adipose tissue
Which root of the spinal nerve is motor (and which is sensory)
Ventral root = motor
Dorsal root = sensory
How do they spinal nerves exit the vertebral canal
Via the intervertebral foramen - a hole between two adjacent vertebrae
What ahppens to the spinal nerve when it exits the vertebral canal
Splits into the posterior ramus and anterior ramus
What is a dermatome
area of skin supplied by one pair of spinal nerves
Where do parasympathetic fibres arise from
Oculomotor, facial, glossopharyngeal and vagus nerve
S2 to S4 spinal segments
Where do sympathetic fibres arise from
T1 to L2
Features of the spinal cord
Outer white matter Inner grey matter Central canal Anterior median fissure Posterior median sulcus Posterolateral sulcus
What areas is the white matter subdivided into
Dorsal funiculus
Lateral funiculus
Ventral funiculus
What regions is the grey matter subdivided into
Dorsal horn
Lateral horn
Ventral horn
What is the function of the dorsal horn
Main site of termination of primary afferent fibres
What is the function of the lateral horn
Cell bodies of pre-ganglionic sympathetic fibres are located
What is the function of ventral horn
Contain cell bodies of motor neurons that will leave the spinal cord through ventral root
What is the function of the ascending tract
Carry impulses from pain, thermal, tactile, muscle and joint receptors to the brain
What is the general sensation of the ascending tracts
Usually 3 neurons between the receptor and the cerebral cortex
First order neuron - enters spinal cord on ipsilateral side
second order neuron then crosses over to other side of spinal cord and ascends to the thalamus
Third order neuron then leaves the thalamus and projects to the somatosensory cortex
What is the descending tract
Originate form the cerebral cortex and brainstem
Concerned with control of movement, muscle tone, spinal reflexes , spinal autonomic functions and modulation of sensory transmission to higher centres
What is the corticospinal tract
Upper motor neuron leaves the pre-central gyrus and descends to the brainstem
Majority of the fibres cross over when they reach the medulla oblongata
Specifically they decussate at the pyramids
Continues down spinal cord to the desired level as the lateral corticospinal tract
here it synapses with a lower motor neuron, which will leave the spinal cord in a spinal nerve to innervate skeletal muscle
