Anatomy Flashcards
What are the 3 components of the brainstem?
Midbrain
Pons
Medulla oblongata
What are neurons made up of?
Neuronal body
Soma
Dendrites
Axon
What is the role of dendrites?
To bring information towards the cell body.
What is the role of the soma?
To carry information away from the cell body in the form of an action potential.
What are glial cells?
Act as support cells of the nervous system.
What are the 4 types of glial cell?
Astrocytes
Oligodendrocytes
Microglia
Ependymal cells
What cells produce the myelin sheath of the CNS?
Oligodendrocytes
What cells produce the myelin sheath of the PNS?
Schwann cells
What are the gaps in the myelin sheath which APs jump between called?
Nodes of Ranvier
What is found in grey matter?
Neuronal cell bodies
What is found in white matter?
Axons
Acts as a communicating region.
In the CNS, where is grey matter found?
Grey matter is found towards the outside (white matter is towards the inside).
In the spinal cord, where is grey matter found?
Grey matter is found centralling in the shape of an ‘H’ (surrounded by white matter).
Swaps position from that seen in the CNS.
How do you differentiate between the anterior and posterior horns of grey matter in the spinal cord?
The posterior horns isolate the posterior column of white matter to the rest of the white matter.
What is the thalamus?
An area of grey matter deep within the brain. It has an internal capsule.
What is the corpus pallosum?
A ‘highway’ of white matter connecting both hemispheres of the brain.
Found immediately superior to the lateral ventricles.
What is the interthalamic adhesion?
A point of contact between the thalamus and the hypothalamus.
What are the lobes of the brain called?
Frontal lobe Parietal lobe Occipital lobe Temporal lobe Insular lobe
What are the 2 blood supplies of the brain called?
Internal carotid system (anterior)
Vertebro-basilar system (posterior)
Where do the 2 blood supplies of the brain meet?
The circle of Willis (forms the basilar artery).
What happens at the jugular foramen?
The dural venous sinuses drain into the internal jugular vein.
A collection of nerve cell bodies WITHIN the CNS is called?
Nucleus
A collection of nerve cell bodies WITHIN the PNS is called?
Ganglion
What is the benefit of many dendrites?
The increased surface area, allows maximum coverage of nerves.
What form of neurons are most common?
Multipolar neurons
What do multipolar neurons provide?
Motor function
What do unipolar neurons provide?
Sensory function
Are multipolar neurons afferent?
No, they are efferent, as they supply motor innervation to the body wall.
Are unipolar neurons afferent?
Yes, as they carry sensory impulses towards the brain.
What are the 6 nerve modalities?
Somatic motor Somatic sensory Sympathetic Parasympathetic Visceral afferent Special sensory
Can tracts have more than one modality?
No, only nerves can have multiple modalities.
Are spinal nerves part of the CNS or PNS?
They are a PNS structure.
What foraminae do spinal nerves pass through?
Intervertebral foraminae
How many pairs of spinal nerves exist?
31 pairs
What is the route taken by sensory axons to reach the CNS?
Spinal nerve > Posterior root > Posterior rootlets > Posterior horn of the spinal cord
What is the route taken by motor axons to reach the effector organs?
Anterior horn of the spinal cord > Anterior rootlets > Anterior root > Spinal nerve
Spinal nerves and their subsequent rami are of which modality?
Mixed modality
What modality is the posterior root?
Sensory only.
What modality is the anterior root?
Motor only.
Do the dermatomes and myotomes of a spinal nerve always lie directly deep to each other?
No
Which dermatome segment is the nipple at?
T4
Which dermatome segment is the umbilicus at?
T10
Name the 12 cranial nerves
Olfactory (CNI) Optic (CNII) Oculomotor (CNIII) Trochlear (CNIV) Trigeminal (CNV) Abducens (CNVI) Facial (CNVII) Vestibulocochlear (CNVIII) Glossopharyngeal (CNIX) Vagus (CNX) Spinal accessory (CNXI) Hypoglossal (CNXII)
Which part of the brain controls the ANS?
Hypothalamus
Which part of the ANS is described as thoracolumbar outflow?
Sympathetic
Which part of the ANS is described as craniosacral outflow?
Parasympathetic
What is the role of the spinal cord?
To allow the brain to communicate with the areas of the body outwith the range of the cranial nerves.
What is the only part of the nervous system outwith the skull that does not interact with the spinal cord?
Vagus nerve
Where are the 2 enlargements of the spinal cord seen?
Cervical region
Lumbar region
At what point does the spinal cord usually end?
Vertebral level L1/L2
The area below this is where the spinal taps are carried out.
Where are the motor roots found?
To the anterior.
Where are the motor roots found?
To the anterior.
Are the spinal meninges continuous with the cranial meninges?
Yes
Where is the primary somatosensory cortex located?
The postcentral gyrus of the parietal lobe.
How is the arrangement of the PSC described?
Somatotopic
What are the axons carried in the spinothalamic tract responsible for?
Pain, temperature and deep pressure.
Where is the primary motor cortex located?
The precentral gyrus of the frontal lobe.
What lies between the PMC and the PSC?
The central sulcus.
Is the corticospinal tract ascending or descending?
Descending
Is the spinothalamic tract ascending or descending?
Ascending
Is the DCML ascending or descending?
Ascending
Where does decussation occur in the corticospinal tract?
Directly after the medulla.
A spinal cord lesion that displays the crossover of motor and sensory fibres results in a condition called what?
Brown-Sequard syndrome
What is the primary function of the cerebellum?
To co-ordinate movement.
What is a common symptom of a cerebellar lesion?
Postural instability
Limb coordination will remain intact.
What is the function of the basal ganglia?
To facilitate purposeful movement, inhibit unwanted movements and have a role in posture and muscle tone.
Where are the basal ganglia located?
The base of each cerebral hemisphere.
What are the 4 curvatures of the vertebral column?
Cervical lordosis
Thoracic kyphosis
Lumbar lordosis
Sacral kyphosis
What is the gap in the vertebral body in which the spinal cord lies called?
The vertebral foramen.
What muscle is responsible for lower back pain in most cases?
Strain of the erector spinae muscles.
At which vertebral levels are no intervertebral discs found?
C1
C2
Sacrum (all fused)
Coccyx (all fused)
What is the function of intervertebral discs?
To maintain structural strength, allowing for effective weight-bearing.
Which vertebra is called the atlas?
C1
Which vertebra is called the axis?
C2
Where are intervertebral discs found?
The gaps between vertebral bodies.
Through which opening does the cauda equina pass through?
Sacral canal
What is the end of the spinal cord - prior to the cauda equina - called?
Conus medullaris
What are the purpose of the 2 spinal cord enlargements?
To innervate the limbs.
What surrounds the spinal cord in the vertebral canal?
3 meningeal layers
Epidural fat pad
Where should any needle be inserted into the spinal column?
Below the L2 level.
Should lumbar puncture be performed in cases of raised ICP?
No
Injury to the epidural fat pad can cause the development of what?
An epidural haematoma.
What function(s) do the spinal nerves carry out?
Somatic general sensory
Somatic motor
Sympathetic motor
Reflex
What symptoms are linked to somatic general sensory issues?
Pain Paraesthesia Numbness Sensitivity Temperature
What symptoms are linked to somatic motor issues?
Cramp
Stiffness
Reduced power
What is a dermatome?
A segment of skin supplied by a single pair of spinal nerves.
Do posterior rami supply a larger area than anterior rami?
No, they are smaller, therefore supply a smaller area.
What is a myotome?
A group of muscles supplied by a single spinal nerve.
What is a reflex?
An involuntary response to a stimulus.
What does an UMN lesion present with?
Spasticity
What does a LMN lesion present with?
Flaccidity
What is paralysis?
When a muscle is without a functioning motor nerve, meaning it cannot contract.
Upon examination, the muscle will have reduced tone.
In spasticity. is the issue with the motor nerve?
No, the motor nerve is fine, the issue is with the descending controls.
The result is increased tone.
What 3 cranial nerves are found at the ponto-medullary junction?
CNVI
CNVII
CNVIII
What cranial nerves supply the ocular muscles?
LR6 SO4 AO3
What are the roles carried out by CNV?
Somatosensation of the face
Proprioception of chewing
Motor control of the masticatory muscles
What supplies parasympathetic innervation above the colic flexure?
Vagus nerve
What supplies parasympathetic innervation below the colic flexure?
Sacral spinal nerves
What might a medial brainstem lesion at the reticular formation (just above the pons) produce?
Irreversible coma
In what order are cranial nerves numbered?
From anterior to posterior.
Which foraminae does CNI pass through?
The cribriform plate of the ethmoid bone.
Which foraminae does CNII pass through?
Optic canal
Which foraminae does CNII, CNIV, CNV1 and CNVI pass through?
Superior orbital fissure
Which foraminae does CNV2 pass through?
Foramen rotundum
Which foraminae does CNV3 pass through?
Foramen ovale
Which foraminae does CNVII and CNVIII pass through?
Internal acoustic meatus
Which foraminae does CNIX, CNX and CNXI pass through?
Jugular foramen
Which foraminae does CNXII pass through?
Hypoglossal canal
What are the 3 divisions of the trigeminal nerve called, and what is their modality?
CNV1 > Ophthalmic > Sensory
CNV2 > Maxillary > Sensory
CNV3 > Mandibular > Sensory and motor
What is the only cranial nerve that attaches to the pons?
The trigeminal nerve.
What area of the face is innervated by CNV1?
Upper 1/3rd of the face.
Includes the root and tip of the nose.
What area of the face is innervated by CNV2?
Middle 1/3rd of the face.
Includes the ala of the nose and the upper lip.
What area of the face is innervated by CNV3?
Lower 1/3rd of the face.
The temporal nerve supplies 3 pairs of ‘jaw-closing’ muscles, what are these?
Masseter
Temporalis
Medial pterygoid
What is the ‘jaw-opening’ muscle and which nerve supplies it?
Lateral pterygoid
CNV3
Other than lateral pterygoid, what muscles are supplied by CNV3?
Tensor veli palatini
Tensor tympani
Does the facial nerve supply the parotid gland?
No, it only passes through here on the way to the geniculate ganglion.
What are the 5 branches of the facial nerve?
Temporal Zygomatic Buckle Mandibular Cervical
Remember ‘To Zanzibar By Motor Car’.
What 2 foramen does the facial canal connect?
Internal acoustic meatus
Stylomastoid foramen
At which level does the vagus nerve pass through the diaphragm?
T10
Unilateral deviation of the uvula suggests what?
One-sided pathology of the vagus nerve.
Unilateral deviation of the tongue suggests what?
Unilateral pathology of the hypoglossal nerve (CNXII).
What are the 3 auditory ossicles found in the middle ear?
Malleolus
Incus
Stapes
Where is the primary auditory cortex?
Directly below the lateral fissure.
They are bilateral structures, receiving from both ears.
Damage to which 2 areas can lead to aphasia?
Wernicke’s area
Broca’s area
What is involved in balance and co-ordination?
CNVIII
3 Semicircular canals
Vestibular nerve
Cochlear nerve
Which gyrus is the lower visual field projected to?
That found superior to the calcarine sulcus.
Which gyrus is the upper visual field projected to?
That found inferior to the calcarine sulcus.
What is different about tracking movements to those of command?
Tracking movements are smooth, whilst movements of command are saccadic (jumpy).
What do association fibres do?
Connect cortical layers of the same hemisphere.
What are the 5 layers of the scalp?
Skin Connective tissue Aponeurosis Loose connective tissue Pericranium
Remember ‘SCALP’.
In which layer are the arteries of the scalp found?
Connective tissue layer.
What type of joint are the sutures of the skull?
Fibrous
What is the pterion?
An ‘H’ shaped suture, joining together 4 bones.
Which 4 bones are joined at the pterion?
Frontal
Parietal
Temporal
Sphenoid
Which artery lies deep to the pterion?
The middle meningeal artery.
At which point does the falx cerebri attach to the ethmoid bone?
The crista galli.
What passes through the cribriform plate?
The olfactory nerves en route to the nasal cavity.
What are the 2 layers of the dura mater called?
Periosteal layer
Meningeal layer
Are both layers of the dura mater found surrounding the spinal cord?
No, only the meningeal layer lines the spinal cord.
Which nerve innervates the dura mater?
The trigeminal nerve (CNV).
The tentorium cerebelli is an area of dura mater that lies above which part of the brain?
The cerebellum.
The diaphragm sellae is an area of dura mater that lies above which structure?
The pituitary gland.
What does the falx cerebri separate?
The 2 hemispheres of the brain.
It is a midline structure.
Through which vessels does venous blood leave the brain?
The dural venous sinuses.
Where is the danger triangle of the face found?
From the nose root to the upper lip.
Why is the danger triangle of the face clinically significant?
The veins connecting this area are linked to the dural venous sinuses, meaning it provides a route for any potential infection to reach the brain.
What are the 3 branches of the ICA?
Ophthalmic artery
Anterior cerebral artery
Middle cerebral artery
When the volume of CSF within the cranial cavity increases, what results?
Hydrocephalus
In which 2 ways can hydrocephalus present?
If the rate of CSF production is too much
If there is blockage of CSF drainage
Is hydrocephalus an example of a SOL?
Yes
How would hydrocephalus be diagnosed in adults?
MRI will show an increased size of ventricles.
How does hydrocephalus present in kids?
There will be expansion of the head.
This is possible due to fusion of the bones of the skull not yet occurring.
How would you treat hydrocephalus?
A ventriculo-peritoneal shunt.
This shifts fluid out of the skull and into the peritoneum (where it can be reabsorbed).
Is bleeding within the cranial cavity classed as a SOL?
Yes
What types of haemorrhage can occur within the brain?
Extradural
Subdural
Subarachnoid
What is the 2 main groups of herniation?
Supratentorial
Infratentorial
Relates to the tentorium cerebelli.
What are the different forms of supratentorial herniation?
Cingulate/subfalcine
Central
Uncal
Transcalvarial
What is a sign of supratentorial herniation?
A fixed ipsilateral dilated pupil.
Results from compression of the oculomotor nerve (CNIII).
What foramen may be involved in an infratentorial herniation?
The foramen magnum.
What is the function of the extrinsic back muscles?
They move the upper limb.
What are the 2 groups of intrinsic back muscles?
Erector spinae
Transversospinalis
What is most commonly the first palpable vertebra?
C7
Rupture of the circle of Willis will lead to?
Subarachnoid haemorrhage
