anatomy Flashcards
are cranial nerves part of the CNS or PNS
PNS
how many cranial nerves do we have
12
what is the only thing that the trochlear nerve innervates
superior oblique muscle
cranial nerve I and modality
olfactory
special sensory
cranial nerve II and modality
optic
special sensory
cranial nerve III and modality
oculomotor
motor
cranial nerve IV and modality
trochlear
motor
cranial nerve V and modality
trigeminal
both
cranial nerve VI and modality
abducent
motor
cranial nerve VII and modality
facial
both
cranial nerve VIII and modality
vestibulocochlear
special sensory
cranial nerve IX and modality
glossopharyngeal
both
cranial nerve X and modality
vagus
both
cranial nerve XI and modality
spinal accessory nerve
motor
cranial nerve XII and modality
hypoglossal
motor
name 3 ways we test the optic nerve
reflexes
visual field
snellen chart
how do we test trigeminal nerve
facial sensations
power of muscles of mastication
how do we test abducent nerve
extraocular eye movements - lateral gaze
how do we test facial nerve
power of muscles of facial expression
how do we test vestibular cochlear nerve
rhinne and webers test
how do we test vagus nerve
elevation of soft palate
normal swallow and speech
how do we test spinal accessory nerve
turning of head
shrugging of shoulders
how do we test hypoglossal nerve
protrusion of the tongue
name the 3 divisions of the trigeminal nerve and their modality
ophthalmic - sensory
maxillary - sensory
mandibular - sensory and motor
what does the ophthalmic nerve supply
upper eyelid
cornea
conjunctiva
skin of the top of the nose
what does the maxillary nerve supply
skin of lower eyelids
skin over maxilla
ala of the nose
upper lip
what does the mandibular nerve supply
skin over the mandible and the TMJ
which part of the mandible does the mandibular nerve NOT supply
angle of the mandible
what nerve supplies the skin over the angle of the mandible (+some of the external ear)
the great auricular nerve
what innervates the muscles of mastication
CN V3
what nerve supplies the tensor tympani and tensor veli palatini
CN V3
where does CN V attach to
the pons
where does CN V1 exit the skull
superior orbital fissure
where does CN V2 exit the skull
foramen rotundum
where does CN V3 exit the skull
foramen ovale
how do we test the motor strength CN V3
clench teeth and open jaw against resistance
what are the 4 modalities of the facial nerve
parasympathetic secretomotor
special sensory
somatic motor
somatic sensory
which glands does the facial nerve provide parasympathetic innervation to via the pterygopalatine ganglion
lacrimal, nasal, palatine, and pharyngeal
which glands does the facial nerve provide parasympathetic innervation to via the submandibular ganglion
sublingual and submandibular
what area does the facial nerve supply special sensation to
anterior 2/3 of the tongue (taste)
what does the facial nerve attach to
pontomedullary junction of the brainstem
what is the name of the branch of the facial nerve that supplies the tongue
the chorda tympani
which muscle in the ear does the facial nerve supply
stapedius
what are the 4 modalities of the glossopharyngeal nerve
sensory
special sensory
parasympathetic
motor
what does CN IX give parasympathetic supply to
parotid gland
what does the CN IX give motor supply to
stylopharyngeus muscle of the pharynx
what does the CN IX give special sensory innervation to
posterior 1/3 of the tongue
what does the CN IX give sensory innervation to
oropharynx, carotid body, posterior 1/3 of tongue, middle ear cavity, eustachian tube
what does CN IX attach to
medulla
where does CN IX leave via
jugular foramen
what are the 3 terminal sensory branches of the CN IX
pharyngeal, lingual, tonsillar
what is the role of the hypoglossal nerve
supplies somatic motor innervation to all (but one) muscles of the tongue
what is the one tongue muscle not innervated by the hypoglossal nerve
palatoglossus
where does the hypoglossal nerve attach to
medulla
how does the hypoglossal nerve exit the cranium
via hypoglossal canal
clinical sign of a damaged hypoglossal nerve
tongue tip points towards the side of the injured nerve
where does the hypoglossal nerve run in the body
in the neck, lateral to the carotid sheath until it gets to the level of the hyoid bone then it passes anteriorly towards the lateral aspect of the tongue
how does the spinal accessory nerve attach
via cervical spine anterior rootlets to the spinal chord
how does the spinal accessory nerve exit the cranium
via foramen magnum
what does the spinal accessory nerve innerate
sternocleidomastoid and trapezius
embryology of the vagus nerve
associated with the derivatives of the fourth and sixth pharyngeal arches
where does the vagus nerve attach
medulla oblongata
how does the vagus nerve exit the cranium
jugular foramen
how does the vagus nerve enter the abdomen from the thorax
through the diaphragm with the oesophagus
what is the basic unit of the nervous system
neuron
what is a nucleus
collection of nerve cell bodies in the CNS
what is a ganglion
collection of nerve cell bodies in the PNS
what are the 2 main types of neuron
multipolar and unipolar
which neurons are efferent
motor neurons -> multipolar
which neurons are afferent
sensory neurons -> unipolar
where is the cell body of a multipolar neuron located
CNS
where is the cell body of a unipolar neuron located
PNS
what is a nerve
a collection of axons surrounded by connective tissue and blood vessels
where are spinal nerves
in the intervertebral foramina
how do spinal nerves connect to structures of the soma
via rami
how do spinal nerves connect to the spinal chord
via roots and rootlets
how many spinal nerves do we have
31 pairs
split our the spinal nerves into sections
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
how do sensory axons pass from spinal nerve to spinal cord
posterior root - rootlets - into the posterior horn
how do motor axons pass from spinal nerve to spinal cord
anterior horn - rootlets - root
what is another word for posterior
dorsal
what is another word for anterior
ventral
what does a spinal nerve supply to a segment of body wall
general sensory to all structures
somatic motor to skeletal muscles
sympathetic nerve supply to skin and smooth muscle of the arterioles
what is a dermatome
an area of skin supplied with sensory innervation from a single spinal nerve
what is a myotome
the skeletal muscles supplied with motor innervation from a single spinal nerve
T4 dermatome
nipple
T10 dermatome
umbilicus
what nerves are involved in the cervical plexus
C1-C4
what does the cervical plexus supply
posterior scalp, neck and diaphragm
what nerves are involved in the brachial plexus
C5-T1
what does the brachial plexus supply
upper limb
what nerves are involved in the lumbar plexus
L1-T4
what does the lumbar plexus supply
lower limb
what nerves are involved in the sacral plexus
L5-S4
what does the sacral plexus supply
lower limb, gluteal region and perineum
what are visceral afferent nerves
organ sensory nerves
what is the role of the autonomic nervous system
sense and respond to changes in the internal environment
what do autonomic motor neurons supply
cardiac muscle, smooth muscle, glands
where do sympathetic nerve fibres leave the CNS
within spinal nerves between cord levels T1-L2
what is another name for sympathetic innervation
thoracolumbar outflow
how does sympathetic innervation get to the heart
in cardiopulmonary splanchnic nerves to the nodes and the myocardium
how does sympathetic innervation get to the lungs
in cardiopulmonary splanchnic nerves to the bronchiolar smooth muscle and mucous glands
sympathetic innervation of the foregut occurs via the …
celiac ganglion of the celiac plexus
sympathetic innervation of the kidney occurs via the …
aorticorenal ganglion
sympathetic innervation of the midgut occurs via the …
superior mesenteric ganglion
sympathetic innervation of the hindgut occurs via the
inferior mesenteric ganglion
describe sympathetic innervation of the adrenal gland
via the aorticorenal ganglion directly onto the adrenaline/noradrenaline secreting cells of the adrenal medulla
how do parasympathetic nerve fibres leave the CNS (2)
via cranial nerves and sacral spinal nerves
which cranial nerves carry parasympathetic nerve fibres
3, 7, 9 and 10
what is another name for parasympathetic innervation
craniosacral outflow
name the 4 extrinsic back muscles
levator scapulae
trapezius
rhomboid (major and minor)
latissimus dorsi
what is the role of the extrinsic back muscles
attach the back to the pectoral girdle and move the upper limb
what is the role of the intrinsic back muscles
maintain posture and move the spine
what are the 2 groups of intrinsic back muscles
erector spinae (superficial)
transversospinalis (deep)
what is the erector spinae
3 vertical muscle groups lateral to the spine
where are the transversospinalis muscles located
within the grooves between the transverse and spinous processes
what innervates the intrinsic back muscles
posterior rami branches
how many vertebrae do we have
33
describe the vertebral column in sections
7 cervical
12 thoracic
5 lumbar
5 sacral for 1 sacrum
4 coccygeal form 1 coccyx
describe the curvatures of the vertebral column
cervical lordosis
thoracic kyphosis
lumbar lordosis
sacral kyphosis
what is found between the articular processes of adjacent vertebrae
facet joint
describe the general structure of an intervertebral disc
outer fibrous ring
inner soft pulp
what is the role of the ligamentum flavum
connect adjacent laminae posterior to spinal cord
what is the role of the posterior longitudinal ligament
prevent over-flexion of the spine
what is the role of the anterior longitudinal ligament
prevents over-extension of the spine
what is the name of the C1 vertebra
atlas
what is important about the C1 vertebra
doesn’t have a body or spinous process
what is the name of the C2 vertebra
axis
what is important about the C2 vertebra
has an odontoid process which projects superiorly from the body
what is the name of the C7 vertebra
vertebrae prominens
what connects C1 to the skull
atlanto-occipital joint
where does the spinal cord begin
at the foramen magnum
where does the spinal cord end
vertebral level L1/L2
what is the conus medullaris
the endpoint of the spinal cord
what is the cauda equina
the nerve roots that exit at lower vertebral levels than the end of the spinal cord
what does the spinal cord attach to
it is continuous with the medulla oblongaris
what layers surround the spinal cord
3 layers of meninges then epidural fat
where is a needle usually inserted into the spine
L3/4 interspace
when do we NOT perform a lumbar puncture and why
raised ICP -> increases the risk of brain herniation
what does the needle pass through in the administration of a spinal anaesthetic
supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, dura mater, arachnoid mater, subarachnoid space
what does a needle pass through in the administration of an epidural anaesthetic
supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space
why do we perform laminectomys
to relieve pressure on the spinal cord or nerve roots
what are the layers of the scalp
skin
connective tissue
aponeurosis
loose connective tissue
pericranium
where are the named arteries of the scalp found
in the connective tissue
what is the pterion
forms from the frontal, parietal, temporal and sphenoid bones
what runs deep to the pterion
the middle meningeal artery
what is clinically relevant about the pterion
it is the thinnest part of the skull
what is meningitis
infection of the meninges
what are the 3 layers of the meninges called
dura mater
arachnoid mater
pia mater
where is the subarachnoid space found
between the pia and the arachnoid mater
what is contained within the subarachnoid space
circulating CSF
where can CSF be reabsorbed
in the arachnoid granulations
what is found within the dura mater
dural venous sinuses
what innervates the dura mater
CN V
what is the diaphragm sellae
dura mater that forms a roof over the pituitary fossa
what is the tentorium cerebelli
dura mater that tents over the cerebellum
what is the falx cerebri and what is its role
dura mater that separates the right and left cerebral hemispheres
where does the subarachnoid space end
inferiorly at the S2 level
what is hydrocephalus
increased CSF volume
what are the 3 main mechanisms by which CSF volume can increase
excessive production, obstruction to flow or inadequate reabsorption
how do we manage hydrocephalus
ventricular peritoneal shunt
where is an extradural haemorrhage found
between the bone and the dura
what is the usual mechanism of injury and vessel affected in an extradural haemorrhage
trauma to the pterion
middle meningeal artery
where is a subdural haemorrhage found
between the dura and the arachnoid
what is the usual mechanism of injury of a subdural haemorrhage and the vessel affected
falls in the elderly
torn cerebral veins
where is a subarachnoid haemorrhage found
in the CSF of the subarachnoid space
what is the common mechanism of injury of a subarachnoid haemorrhage
aneurysm in circle of willis
what is intratentorial herniation
where the brain herniates down through the tentorial notch
what is the common sign of an uncal herniation
ipsilateral fixed dilated pupil (blown pupil)
which type of herniation has a higher risk of life-threatening complications
intratentorial
what is supratentorial herniation
where brain tissue herniates upward or laterally above the tentorium cerebelli
C5 dermatome
badge patch
what affect does an upper motor neuron lesion have on tone
spasticity
what affect does a lower motor neuron lesion have on tone
flacidity
what is a reflex
involuntary response to a stimulus
what is a paralysed muscle
a muscle without a functioning motor nerve supply
how would a paralysed muscle behave on examination
reduced tone
what is a spastic muscle
a muscle with intact and functioning motor nerve but the descending controls from the brain aren’t working
how would a spastic muscle behave on examination
increased tone
what is the brainstem
combination of the midbrain, pons and the medulla oblongata
what is the functional unit of the nervous system
neuron
what are the 4 main types of glial cells
astrocytes
oligodendrocytes
microglia
ependymal cells
role of oligodendrocytes
produce myelin in the CNS
role of schwann cells
produce myelin in the PNS
role of astrocytes
provides physical support, help form the blood-brain barrier
role of microglia
specialised CNS phagocytes
role of ependymal cells
provide the inner lining of the ventricles
role of the frontal lobe
higher intellect, personality, mood, social conduct
where is the motor cortex found in the brain
frontal lobe - immediately anterior to the central sulcus
role of the parietal lobe
language and calculation on the dominant hemisphere side and visuospatial function on the non-dominant side
where is the primary visual cortex found
occipital lobe
where is the primary auditory cortex found
temporal lobe
role of the temporal lobe
memory and language
what is the insular lobe important in
patients experience of pain
where is the enteric nervous system found
digestive system from the oesophagus to rectum
where are the 2 enlargements of the spinal cord found
cervical and lumbar
for upper and lower limb innervation
what is a mnemonic for remembering how many spinal nerves we have
“Breakfast at 8, Lunch at 12, Dinner at 5, Snacks at 5, Coffee at 1.” (C8, T12, L5, S5, Co1)
where does the spinal cord terminate and what is this called
conus medullaris - L1/2
what is the arrangement of grey and white matter in the spinal cord
grey: H shaped, central - neuronal cell bodies
white: outer, axons carrying signals up and down
what structures merge to form the spinal nerve
anterior root and posterior root
what is the filum terminale
connective tissue, connects conus medullaris to dorsum of the coccyx
what does the spinal cord connect to in the brain
4th ventricle
summarise the pathway of auditory information back to the brain
receptors on organ of corti pass info back to the CNS via vestibulocochlear nerve
reaches the primary auditory cortex
what is aphasia
inability to use language
where is brocas area found
lower back section of the frontal lobe (usually) in the left hemisphere
what happens in brocas aphasia
patients struggle producing language but can comprehend language
where is wernickes area found
posterior temporal lobe, (usually) in the left hemisphere
what happens in wernickes aphasia
fluent but nonsensical speech - word salad
impaired comprehension
unaware of condition (anosognosia)
what is anosognosia
patient is unaware of or denies their own disability or health condition
where is the primary visual cortex found
occipital lobe
what causes the consensual light reflex
pretectal fibres project bilaterally to the edinger-westphal nucleus
what visual field defect would be caused by a lesion in an optic nerve
monocular blindness
what visual field defect would be caused by a lesion in the optic chiasma
bitemporal hemianopia
what is bitemporal hemianopia
loss of the outer visual fields in both eyes
what is homonymous hemianopia
loss of the same side of the visual field in both eyes
lesions in which areas of the optic pathway cause homonymous hemianopia
optic tract, radiations or primary visual cortex on the contralateral side
what is quadrantanopia
loss of a quarter of the visual field
physiology of superior quadrantanopia
lesion in the meyer’s loop of the optic radiations
where does the meyers loop pass through in the brain
temporal lobe
what commonly causes superior quadrantanopia
temporal lobe lesions
physiology of inferior quadrantopia
lesion in the parietal lobe optic radiations
what commonly causes inferior quadrantanopia
parietal lobe strokes
what is central scotoma
a loss of central vision with preserved peripheral vision
what causes central scotoma and give 2 diseases that are associated
damage to the macula or optic nerve
optic neuritis
age related macular degeneration
what is homonymous hemianopia with macular sparing
loss of the same side of the visual field in both eyes, but with preserved central vision
what causes homonymous hemianopia with macular sparing and why does macular sparing occur
lesion in the primary visual cortex in the occipital lobe
macula has dual blood supply from PCA and MCA
what commonly causes homonymous hemianopia with macular sparing
PCA stroke
what are the 3 main types of fibres in white matter of the brain
association, commissural and projection
role of association fibres in the white matter of the brain
connect cortical sites lying in the same hemisphere
what is the role of commissural fibres in the white matter of the brain
connect one hemisphere to another
what is the role of projection fibres in the white matter of the brain
connect hemispheres to deeper structures including the thalamus, brain stem, corpus striatum and spinal cord
what is the function of grey matter in the spinal cord
processing and integrating information
role of the dorsal horn of the grey matter in the spinal cord
receives sensory information for the body
how to remember the roles of the horns of the grey matter in the spinal cord
DAVE
dorsal = afferent = sensory
ventral = efferent = motor
role of the ventral horn of the grey matter in the spinal cord
contains motor neurons that send signals to the muscles
where are lateral horns of grey matter found in the spinal cord and what is their role
thoracic and upper lumbar regions
contain autonomic neurons involved in regulating the internal organs
what does white matter of the spinal cord mainly consist of
myelinated axons
what is the role of white matter in the spinal cord
transmit signals to and from the brain
what are the 2 main components of the white matter in the spinal cord and what are their functions
ascending tracts - carry sensory information from the body to the brain
descending tracts - carry motor commands from the brain to the body
where is the primary somatosensory cortex found
postcentral gyrus
what are the 3 main ascending tracts of the CNS
dorsal column-medial lemniscus pathway
spinothalamic tract
spinocerebellar tract
what is the function of the DCML
carries info on: fine touch, vibration and proprioception
give a general description of the DCML pathway
up through the spinal cord, synapse in the medulla, decussate, to the thalamus, to the primary somatosensory cortex
clinical presentation of a lesion of the DCML pathway in the spinal cord
ipsilateral, below the level of the lesion
loss of fine touch, vibration sense and proprioception
what are the 2 tracts that make up the spinothalamic tract
anterior and lateral
what information does the anterior spinothalamic tract carry
crude touch and pressure
what information does the lateral spinothalamic tract carry
pain and temperature
give a general description of the pathway of the spinothalamic tract
enter spinal cord and synapse at the dorsal horn, decussate in the spinal cord, thalamus, to ipsilateral primary sensory cortex
clinical presentation of a lesion in the spinothalamic tract
contralateral loss of pain and temperature sensation below the level of injury
side of symptoms if the lesion is before decussation
same side
side of symptoms if the lesion is after decussation
opposite side
what is the role of the spinocerebellar tracts
unconscious proprioception - for balance and coordination
general pathway of the spinocerebellar tracts
enter spinal cord and synapse with dorsal horn, ascend to the cerebellum
clinical presentation of damage to a spinocerebellar tract
ipsilateral loss of proprioception
can lead to ataxia
where is the primary motor cortex found
anterior to the central sulcus
where do pyramidal tracts originate from
the primary motor cortex
what is the main pyramidal tract
corticospinal tract
what is the function of the corticospinal tract
controls voluntary movement of the limbs and trunk
where does the corticospinal tract decussate
at the medullary pyramids
general pathway of corticospinal tract
primary motor cortex, through internal capsule and brainstem, medullary pyramids, spinal cord
clinical presentation of lesions in the corticospinal cord (above and below decussation)
Lesions above the medullary pyramids → Contralateral weakness
Lesions below the decussation → Ipsilateral weakness
what are the 2 types of descending tracts
pyramidal and extrapyramidal
what does it mean if a tract is pyramidal
tract passes through the pyramids of the medulla
where do extrapyramidal tracts mainly originate from
brainstem nuclei
what is the role of extrapyramidal tracts
involuntary control of muscle tone, posture and coordination of movement
what are the 4 main extrapyramidal tracts
rubrospinal, vestibulospinal, reticulospinal and tectospinal
function of the rubrospinal tract
fine motor control of the upper limbs - particularly flexor muscles
pathway of the rubrospinal tract
originates in the red nucleus of the midbrain, decussates in brainstem and descends in lateral spinal cord
what is the function of the vestibulospinal tract
maintains balance and posture by controlling extensor muscles
pathway of the vestibulospinal tract
originates in the vestibular nuclei of the brainstem, descends ipsilaterally
clinical presentation of damage to the vestibulospinal tract
balance issues and abnormal muscle tone
what is the function of the reticulospinal tract
regulates muscle tone and automatic movements like walking
describe the pathway of the reticulospinal tract
originates from the reticular formation in the brainstem - some decussate some dont
clinical presentation of damage to the reticulospinal tract
abnormal reflexes or hypertonia
where does the medial reticulospinal tract arise and what does it facilitate
pons
facilitates extensor movement and inhibits flexor movement
where does the lateral reticulospinal tract arise and what does it facilitate
medulla
facilitates flexor movement and inhibits extensor movement
what is the function of the tectospinal tract
controls reflexive movements in response to visual and auditory stimuli
describe the pathway of the tectospinal tract
originates in superior colliculus of the midbrain, decussates and descends in the cervical spinal cord
clinical presentation of damage to the tectospinal tract
impaired reflexive head and neck movements
what causes brown-sequard syndrome
lateral hemisection of the spinal cord
clinical presentation of brown-sequard syndrome
weakness or paralysis on one side of the body and loss of sensation on the opposite side
in what situation are extrapyramidal tract lesions commonly seen
degenerative diseases, encephalitis and tumours
what is the largest part of the hindbrain
cerebellum
what are the 3 main lobes of the cerebellum
anterior, posterior and flocculondular
how does the cerebellum attach to the brainstem
3 bundles of fibres called peduncles
superior - cerebellum to midbrain
middle - cerebellum to pons
inferior - cerebellum to medulla oblongata
which layer of the cerebellum to afferent projections project into
granule cell layer
where is the cerebellum found
immediately inferior to the occipital and temporal lobes, separated by the tentorium cerebellae
general presentation of a midline cerebellar lesion
disturbance of postural control
general presentation of unilateral hemispheric cerebellar lesion
disturbance of coordination in limbs
mnemonic to remember signs of a cerebellar lesion
DANISH
D: dysdiadochokinesia, dysmetria
A: ataxia
N: nystagmus
I: intention tremor
S: speech: slurred, inappropriate or slow
H: hypotonia
what is dysdiadochokinesia
inability to perform rapid alternating movement e.g. turning palms
what is dysmetria
lack of coordinated movement involving distance judgement e.g. finger point
what is ataxia
lack of coordination e.g. unsteady gait
what is nystagmus
involuntary, uncontrollable eye movements
what is an intentional tremor
tremor that occurs during purposeful movement, worsening as the target is approached
what is hypotonia and what does it look like
reduced muscle tone
floppiness and difficulty maintaining posture
what is the role of the basal ganglia
modulates voluntary movements and regulates muscle tone and posture
what is the general result of basal ganglia dysfunction
excessive or reduced movement
name some hypokinetic signs of basal ganglia dysfunction
bradykinesia, rigidity, resting tremor, postural instability
what is bradykinesia
slowness of movement
give a disease that is characterised by hypokinetic signs
parkinsons
name a disease that is characterised by hyperkinetic signs
huntingtons
name some hyperkinetic signs of basal ganglia dysfunction
chorea, dystonia, ballismus
what is chorea
involuntary unpredictable movements
what is ballismus
sudden, violent, flinging movements - usually affect one side
what is dystonia
sustained repetitive muscle contractions causing abnormal postures or movements
where do upper motor neurons originate
in the primary motor cortex of the cerebrum
where are lower motor neurons found
in the anterior horn of the spinal cord
why do upper motor neuron lesions lead to hyper movement
UMN regulate the activity of LMN
so if there’s no regulation (inhibition) then the response is exaggerated
why do lower motor neuron lesions cause hypo movement
LMN facilitate movement and maintain muscle tone
if damaged then direct connection to the muscle is lost - no signals to contract
where are cranial nerve nuclei found
in the brainstem
