Neuroanatomy Lecture Powerpoint Flashcards
The cranial nerves with exception to CN__ are part of the ____, not the ___
CN II, PNS, CNS
Neuron
Non-reproducing unit of nervous system composed of a body, dendrites (receivers), and axon (conductor) surrounded by a myelin sheath, has greatest sensitivity of any cells to oxygen and glucose deprivation and thus shows first signs of hypoxia or hypoglycemia
Grey matter vs white matter
Grey matter is neural cell bodies located on the inner part of the spinal cord and outer part of the brain vs white matter is axons (myelin sheaths) located at the outer spinal cord or inner portion of the brain
Sensory/afferent neurons
Communicate stimuli toward the CNS such as light, heat, or pressure
Motor/efferent neurons
Conduct signals way from CNS mostly leading to muscle cells and other target organs
Interneurons
Lie entirely within the CNS and have an integrative function to associate, process, store, and retrieve information and interconnect incoming sensory to outgoing motor pathways
3 reasons bony anatomy is important to cranium
- Injury to bony anatomy can affect deeper underlying structures
- CT scans, need to be able to identify suture lines vs fractures
- Skull is a “closed box” particularly susceptible to any swelling
List the suture lines of the skull (5)
Corneal - formed between parietal and frontal bone
Sagittal - Formed between the two parietal bones at the dome of the skull moving anterior to posterior
Lambdoid - formed between occipital and parietal bones
Bregma - point of intersection between corneal and sagittal sutures
Lambda - Point of intersection between sagittal suture and lambdoid sutures
Meninges (definition and the 3 of them)
3 layers of tissue covering the CNS including…
The dura mater (thick outer layer of vascular connective tissue that forms dural sinuses between 2 layers periosteal and meningeal, also forming falx cerebri and tentorium cerebelli)
The arachnoid mater (nonvascular thin filamentous connective tissue that adjoins but does NOT adhere to dura allowing for subdural potential space, meanwhile subarachnoid space beneath it is where CSF and veins/arteries flow)
The pia mater (thinnest delicate layer that adheres directly to surface of brain and spinal cord invaginating along the surface)
Epidural hematoma definition and appearance on CT
Arterial bleed between skull and osteum dura often in skull fractures appearing as “football shaped” bright lesion on side of head on CT scan
Subdural hematoma definition and appearance on CT
Tearing of the bridging veins between the meningeal dura and arachnoid mater appearing as a crescent shaped lesion on CT scan of head
Subarachnoid bleed definition and appearnce on CT
Bleed in the subarachnoid space above the pia mater that tends to layer within sulci and gyri of brain due to tearing of subarachnoid vessels that appears as layering around the invaginations of the brain on a CT scan
Rostral vs caudal and dorsal/ventral
Rostral is towards the front/anterior of the brain that then shifts superiorally moving down the brain to the spinal cord, vs caudal is toward the back/posterior of the brain that then shifts inferiorally moving down the brain to the spinal cord, with dorsal and ventral being perpendicular to these points
3 main parts of the brain
1) forebrain (composed of telencephalon and diencephalon)
2) midbrain (mesencephalon)
3) hindbrain (metencephlaon and myelencephaon)
Mid brain and hind brain combine to form the….
…brainstem
Parts of telencephalon (4)
- Cerebrum and all of its cortexes
- Basal ganglia
- Amygdala
- Hippocampus (all part of limbic system)
Cerebrum
Largest portion of brain divided into 2 halves called hemispheres, communicating with each other thru corpus callosum, functions for thought, voluntary movement, language, reasoning, and perception, cerebrum is a gross division of brain that has many subdivisions and sub regions
Cerebral cortex definition and the lobes of the cerebral cortex (4)
Outer layer of grey matter in the cerebrum that is highly convoluted into ridges (gyri) and grooves (sulci/fissures)
The lobes of the cerebral cortex include
Frontal - goal oriented, motor, cognitive functions
Occipital - visual perception
Parietal - touch, pain, limb position, size/shape perception
Temporal - perceive, localize sound, visual form/color, emotions
Fissure vs sulci
Fissures are deep groves consistently present from one brain to next vs sulci are not as deep and can vary in location
Longitudinal and transverse cerebral fissure
Separate left and right hemisphere and cerebrum from cerebellum, invaginated by the falx cerebri and tentorium cerebelli overlying
Central sulcus and lateral sulcus
- Divides frontal from parietal lobe creating a precentral gyri and post central gyri on each side
- Divides parietal lobe from temporal lobe
Pre-central gyrus
Located directly anterior to the central sulcus containing the motor cortex
Post-central gyrus
Located directly posterior to the central sulcus containing the somatosensory cortex
Frontal lobe
Largest lobe responsible for planning, complex movements, organizing, problem solving, and higher cognitive function, has a prefrontal cortex for higher cognitive functions and premotor and primary motor cortex (premotor modifies movement and stores muscle memory from primary motor), as well as olfactory bulb is on inferior aspect
Frontal lobe injury can cause… (4)
- Lack of focus/organization
- Difficulty learning new info
- Loss of inhibition
- Inability to retrieve recent memories
Broca’s aphasia
Injury to frontal lobe at the broca area (most commonly found in left hemisphere at posterior portion of inferior frontal gyrus) causes partial loss in ability to produce language (spoken, manual, or written), patients are aware that they cannot speak properly but can comprehend perfectly well (often known as motor or expressive aphasia)
Parietal lobe
Integrates sensory information from perceptions of touch, pain, limb position (includes postcentral gyrus/somatosensory cortex), controls how we receive info about the environment around us such as distance and position of object
Parietal lobe injury can cause… (4)
- Inability to discriminate between stimuli
- Locate and recognize parts of body
- Process/integrate diverse sensory info for speech and perception
- Write accurately
Temporal lobe
Controls audiory processing/ability to recognize words, auditory cortex allows for perception and localization of sound (receives sounds from ears and areas process info into meaningful speech or words) also perception of visual form and color, participates in processing of new memory also plays a role in mediating emotions
Temporal lobe injury causes… (4)
- Left side difficulty remembering what people said
- Right side may impair recalling music or pictures
- Difficulty perceiving or localizing sound
- Difficulty perceiving visual form and color
Wernicke’s aphasia
Injury to area located on the temporal lobe near the caudal end of the lateral sulcus that causes fluent but meaningless speech with comprehension generally being impaired, speech may sound fluent but pattern is disordered and illogical (global aphasia)
Occipital lobe
Visual center, area allows to interpret what looking at including visual perception, differentiating form and color, and facial recognition
Occipital lobe injury causes… (4)
- Visual impairment
- Visual hallucinations
- Impaired color perception
- Inability to recognize faces
Parts of limbic system and their function, what portion of the forebrain are they part of?
- Amygdala (emotional responses, hormonal secretion, emotional memory)
- Hippocampus (learning and memory)
- Cingulate gyrus (emotion, pain, memory)
Not absolutely part of telencephalon or diencephalon
Parts of diencephalon (3)
- Limbic system (sorta this sorta telencephalon)
- Thalamus (relays info between cortex and brain stem, role in alert/awakeness
- hypothalamus (body temp, emotion, hunger, thirst, circadian rhythm, pituitary gland control)
Parts of mesencephalon/midbrain (2)
1) Tectum - more posterior component considered roof of midbrain, has the superior colliculus involved in visual reflexes and inferior colliculus involved in auditory reflexes, the 4 colliculi form the corpora quadrigema)
2) Tegmentum - floor of midbrain, network of neurons involved in many reflexive pathways, has motor centor that sends inhibitory signals to the hypothalamus
Cerebellum
Part of metencephalon located on posterior-inferior portion of brain that functions in coordination of voluntary movement, balance, posture, motor learning and reflex memory
Pons
Part of metencephalon that relays sensory info between forebrain and hindbrain, houses cranial nerve nuclei V-VIII, contains pneumotaxic centers that help regulate respiration
Medulla oblongata
Part of the myelencephalon, most inferior portion of brainstem that gradually transitions into spinal cord, relays nerve signals between the two, helps regulate several autonomic functions of the body including respiration, blood pressure, heart rate, digesjtion, and voluntary functions such as vomiting, sneezing, coughing, and gagging
Cerebrospinal fluid (CSF)
Formed by choroid plexus in the 4 ventricles, 2 lateral ones and a 3rd and 4th that then empty into the subarachnoid space creating a protective fluid filled chamber against concussive trauma that also bathes and removes waste products
CSF pathway
- Lateral ventricles
- interventricular foramina
- 3rd ventricle
- cerebral aquaduct
- 4th ventricle
- 2 lateral and one median aperture
- subarachnoid space
- circulation
- reabsorption via arachnoid villi
- superior sagittal sinus
Circle of Willis Components
- 2 vertebral arteries combining to form the basilar artery
- Off the basilar artery see anterior inferior cerebellar artery, pontine arteries, and superior cerebellar arteries
- Basilar terminates into 2 posterior cerebral arteries
- branching off each posterior cerebral artery is a posterior communicating artery
- Internal carotids ascending meet with this, sending off middle cerebral artery branches as well as anterior cerebral artery branches
- Anterior communicating artery is a small link between the anterior cerebral arteries
Anterior cerebral artery
Derived from the internal carotids, supplies very deep portions of the anterior cerebrum including midline structures reaching all the way back posteriorally to midline of parietal lobe as well, has collateral supply due to anterior communicating artery and is thus rare to have ACA infarct
2 divisons of middle cerebral artery
- MCA superior and inferior division (superficial division) supplies outer cortex portion of cerebrum
- Lenticulostriate arteries supply the inner portion of brain,
What artery is most common site of stroke?
Middle Cerebral artery and its branches lenticulostriate and superficial divisions
Venous drainage system of the brain
No arterial/venous counterpart, cerebrum, midbrain, pons, cerebellum, and rostral medulla drain via the dural sinuses while spinal cord and caudal medulla drain directly into systemic circulation
Arachnoid granulations
Small projections that extend into the dural sinus to allow csf to remove waste products
Venous drainage of the brain components (9)
Superior sagittal - runs along the ceiling of the skull anterior to posterior eventually draining into the confluens of sinuses
Inferior sagittal sinus - runs along the same path as superior but is located deep in the cerebrum, empties into the straight sinus upon merging with the great cerebral vein of galen
Great cerebral vein of galen - Large midline vessel inferior to inferior sagittal sinus that forms the straight sinus upon merging with the inferior sagittal sinus
Straight sinus - posterior continuation from the inferior sagittal sinus, combines with superior sagittal sinus to form the confluens of sinuses
Transverse sinuses - derived from the confluens of sinuses and travel bilaterally along the posterior wall of the skull before entering into the sigmoid sinus
Sigmoid sinuses - 2 s shaped sinuses that receive blood from the transverse sinuses and superior petrosal sinuses and drain into the internal jugular vein
Cavernous sinuses - drain the eye area and empty into inferior and superior petrosal sinuses
Inferior petrosal sinuses - derived from cavernous sinuses and drains directly to internal jugular
Superior petrossal sinuses - derived from canvernous sinuses and drains to sigmoid sinus upon meeting with the transverse sinuses
___ total vertebrae, how many of each?
-33 7 cervical 12 thoracic 5 lumbar 5 fused sacral 4 fused cocyx
Spinal column functions (6)
Protection, attachment, structural support, flexibility/mobility, extension, production and storage of RBC and minerals
C1
Also known as the atlas, this is the 1st cerivcal vertebra that functions to support the skull, ring of bone that has no vertebral body associated but does have superior articular facets to articulate with the occipital condyles of the skull
C2
Also known as the axis, features a dens or odontoid process allows head to pivot and rotate around, has the first semblance of a vertebral body
Thoracic vertebrae
Increased sized of body vertebrae compared to cervical spine, these also serve as the articulation points of the ribs (2 ribs coming off each of the 12), has thick spinous process sticking directly dorsally and thick transverse processes for the site of ligament and muscle attachment
Lumbar vertebrae
Increased vertebral body size to bear majority of weight, often see nerve root compression in this area
sacrum and coccyx
Groups of 5 and 4 fused bones, respectively, forming an articulation of the pelvic girdle and tail bone, respectively
Intervertebral disks
Function to help disperse the weight of the spinal column, composed of jelly like interior known as nucleus pulposus and cartilagenous exterior the annulus fibrosis (herniation occurs when the nucleus pulposus protrudes out of the intervertebral disk)
anterior longitudinal ligament
Most anterior ligament of the spinal column, located in front of the vertebral bodies running superiorally along each body of the spine
Posterior longitudinal ligament
Anterior to spinal cord travelling in canal but right up against posterior of vertebral bodies running superiorally along each body of the spine
Ligamentum flavum
yellow ligament, located beneath the lamina of the spinal column, first defining structure right before the dura that runs superiorally along the entire length of the spinal column
vertebral column stability determination and how do they heal?
If 2 or more columns are injured (fracture or ligament tear, etc.), considered unstable, if one then considered stable
-all take a long time to heal due to low blood supply
3 columns of the spine and their components
Posterior column composed of spinous processes, transverse processes, lamina, facet joints, pedicles, and posterior ligaments of the spine
Middle column composed of posterior longitudinal lig, posterior annulus fibrosis, and posterior vertebral body
Anterior column ant longitudinal lig. anterior annulus fibrosis, anterior vertebral body
Each pair of spinal nerves exit between adjacent vertebrae except for this one
C1
C7 and above exits ___ corresponding vertebral body, C8 exits below ___, T1 downward exits ____ corresponding vertebral body
above, C7, below
Spinal cord commencement level and termination level in the spinal column, what is it called where it terminates?
What are the fibers after that? What is the filum terminale?
- At foramen magnum, L1 or L2
- Conus medullaris
- Cauda equina
- An extension of pia matter past the conus medullaris within the cauda equina down to the coccyx that functions to anchor the spinal cord floating in CSF
Arterial supply to the spinal cord (3)
Anterior spinal artery - single artery derived from branches of the vertebral arteries, moves downward along the anterior surface of the spinal cord and supplies the grey matter and majority of the spinal cord as well despite only being one
Posterior spinal arteries - Paired arteries derived from branches of the vertebral arteries, move downward along the posterior surface of the spinal cord
Anterior and posterior radicular arteries - travel out laterally to the nerve root from the segmental arteries within the spinal cord
CNS contains ___ neurons (what type?) while PNS contains ___ and ___ neurons
Relay or interneurons, sensory, motor
Motor end plate
site of contact between an axon and a muscle fiber where neuromuscular junction is, Ach is transmitted across here to stimulate muscle cells
Schwann cells
Cells of the PNS that produce myelin around an axon
Oligodendrocytes
Cells of the CNS that produce myelin around an axon
Parts of the metencephalon (2)
- Pons
- Cerebellum
Parts of myelencephalon (1)
Medulla oblongata
Small vertebral bodies in the cervical spine lack ___ but make up for it with ____. They have ___ processes but lack ____ processes
strength to bear weight, great mobility, spinous, transverse
Pedicle
Stub of bone that connects the vertebral body to the lamina forming a vertebral arch to house the spinal cord
Lamina
Part of vertebra that is located directly on either side of the spinous process
An injury to which column of the vertebrae is most likely to result in unstable classification and why?
Middle column - it is connected to the anterior and posterior columns and is thus a lot more vulnerable!
Healthy curvature of the spine
Cervical should be lordotic, thoracic should be kyphotic, and lumbar should be lordotic
Venous supply to the spinal cord (4)
Posterior spinal vein - single traveling vein located between the posterior spinal arteries
Anterior spinal vein - single traveling vein located alongside the anterior spinal artery
Posteriorlateral veins - 2 traveling veins located lateral to each of the posterior spinal arteries
Radicular veins - travel with the radicular arteries
Spinal columns
The dorsal, 2 lateral, and anterior areas of white matter within the cross section of the spinal cord
Spinal tracts
Ascending or descending pathways for sensory or motor signaling located within the different spinal columns (anterior, 2 lateral, or dorsal)
Spinal horns
The dorsal, ventral, and lateral projections of grey matter within the spinal cord composed of cell bodies and interneurons on a bisection
Spinal roots
Either dorsal and ventral, bundles of neurons that enter or exit the spinal cord laterally at a certain nerve root level
Spinal cord dorsal root
Afferent sensory root that carries sensory information to the spinal cord from the spinal nerve somewhere in the periphery
Spinal cord ventral root
Efferent motor root that carries motor information from the spinal cord to an effector site in the periphery
Lateral horn function
Houses cell bodies of preganglionic sympathetic neuron fibers
Corticospinal tract cross over at the level of ___
the medulla
Corticospinal vs corticobulbar tracts
Corticospinal is motor efferent nerves associated with spinal nerves from the cerebral cortex vs corticobulbar is similar but composed of non oculomotor cranial nerve motor functions from where the cranial nerves originate on the brain surface slightly lower down in the medulla itself, only about 50% of them deccusate compared to the 90% of the corticospinal but for the sake of this class just say they both cross over at medulla
Upper vs lower motor neuron
Upper body originates in the brain at the motor cortex, crosses over midline at the medulla, and then goes down in the white matter of spinal cord before synapsing into the gray matter lower motor neuron body in the lateral horn, and then leaves via the anterior horn to the target muscle
Signs of upper motor neuron lesion on motor exam (6)
- spasticity
- increased tone
- positive babinski sign
- clonus
- hemiparesis/weakness
- increased tone and reflexes
Signs of lower motor neuron lesion on motor exam
- Flaccid muscles with atrophy
- fasciculations
- paralysis
- decreased tone and reflexes
Spinothalamic tract (what 3 things is it responsible for and where does it cross)
- Responsible for pain, temp, and crude touch
- Crosses over at the level of the spinal cord and then travels up the contralateral side to the thalamus and cerebral cortex
Posterior/dorsal column tract (what 3 things is it responsible for and where does it cross)
- Responsible for position, vibration, and fine touch
- Travels up ipsalateral side of spine where signal entered and crosses over at medulla then to thalamus and cerebrum
Components of reflex arc
- Receptor
- sensory neuron
- CNS interneuron that immediately responds faster than message to brain
- motor neuron
- effector muscle or gland
2 divisions of PNS
Sensory and motor
2 divisions of sensory PNS
Somatic sensory (skin limb and body wall) and visceral sensory (internal organ sensations)
2 divisions of motor PNS
Somatic motor (voluntary) and visceral motor (autonomic)
2 divisions of ANS
Parasympathetic (bladder contraction) and sympathetic (bladder relaxation)
