MRCS neuroanatomy Flashcards
where do the neurons of the corticobulbar tract terminate ?
The neurones terminate on the motor nuclei of the cranial nerves. Here, they synapse with lower motor neurones, which carry the motor signals to the muscles of the face and neck.
First order neurons carry signals from where to where in the DCML pathway ?
From the peripheral nervous system to the medulla oblongata
Which branch of the trigeminal nerve provides sensory innervation to the lower eyelid?
Maxillary
Which developmental component of the central nervous system is the substantia nigra located within?
Midbrain
how does the hypothalamus send neurotransmitters to the pituitary gland ?
hypophyseal portal vessels.
what two hormones are released by the posterior pituitary gland ?
ADH (responsible for control of blood osmolarity), and oxytocin (involved in parturition and milk secretion).
what is the function of the choroid plexus ?
production of CSF
The medial reticulospinal tract arises from what part of the brainstem ?
Pons
what structure separates the cerebrum from the cerebelli ?
tentorium cerebelli,
what lobe of the cerebrum is the primary auditory cortex located ?
Temporal lobe
True or false
The vestibulocochlear nerve has motor function
False
It is purely sensory
The vagus nerve provides motor innervation to what structures ?
- Pharynx
- Larynx
- Soft palate
what symptoms occur following Injury to the anterolateral system ?
impairment of pain and temperature sensation - this sensory loss will be contralateral
the middle cerebral arteries are a continuation of what artery ?
The internal carotid artery
what nerve supplies general sensory innervation and special taste sensation to the posterior 1/3rd of the tongue ?
the glossopharyngeal nerve.
what are the terminal branches of V1 ?
V1 - ophthalmic nerve
Branches
1. Frontal
2. Lacrimal
3. Nasocialliary.
List the sensory branches of CN IX
PLT
Pharyngeal branch - It innervates the mucosa of the oropharynx.
Lingual branch – provides the posterior 1/3 of the tongue with general and taste sensation
Tonsillar branch – innervates the palatine tonsils.
Vertebral arteries arise from which artery ?
Subclavian
The trigeminal nerve provides innervation to muscles from which pharyngeal arch?
First
what are the two types of ascending tracts ?
conscious tracts and unconscious tracts
define fasciculus
bundle - could be of nerves or muscles
what is the function of the corpus collosum
white matter structure connecting the two hemispheres.
In a stroke that damages the UMNs for CN XII - what would be the clinical signs ?
a lesion to the upper motor neurones for CN XII will result in spastic paralysis of the contralateral genioglossus.
This will result in the deviation of the tongue to the contralateral side.
what is the first motor branch of the facial nerve ?
nerve to stapedius.
how does the vestibulocochlear nerve exit the cranium ?
Via the internal acoustic meatus
Which part of the ear does the glossopharyngeal nerve innervate ?
The tympanic branch of the glossopharyngeal nerve innervates the middle ear, internal surface of the tympanic membrane and the Eustachian tube.
Prolactin is under tonic inhibition by what hormone ?
DOPAMINE
At what level does the spinal cord terminate in adults ?
L1 - L2
How does an abducens nerve palsy present ?
The eye held in fixed adduction at rest
what symptoms would occur following damage to the DCML pathway in the spinal cord ?
Ispilateral loss of proprioception and fine touch.
This is the course of what cranial nerve ? and what muscle does it pierce ?
Hint - crosses the internal and external carotid
- Hypoglossal nerve
- pierces the genioglossus
The parasympathetic fibres of the facial nerve are carried by what nerves ?
- Greater petrosal nerve
- Chorda tympanii
Which white matter tract is located immediately lateral to the putamen?
External capsule
what is the ansa cervicalis ?
a loop of nerves that is part of the cervical plexus. From the ansa cervicalis, nerves arise to innervate the omohyoid, sternohyoid and sternothyroid muscles - the infra hyoid muscles
The corticobulbar tracts provide innervation to the musculature of which region of the body?
Head and neck
what structure is both inferior and anterior to the pituitary gland
Sphenoid sinus
which nerves are involved in the corneal reflex ?
the ophthalmic nerve acts as the afferent limb
The facial nerve is the efferent limb,
what is the anatomical course of the right vagus nerve ?
passes anterior to the subclavian artery and posterior to the sternoclavicular joint, entering the thorax.
which cranial nerve innervates the stylopharyngeus ?
glossopharyngeal nerve
what is the function of the ventricles ?
production, transport and removal of cerebrospinal fluid, which bathes the central nervous system.
what are the functions of the temporal lobe ?
Memory and language
In the basal ganglia, what structures from the Neostriatum ?
Caudate nucleus and putamen
Before the facial nerve terminates as the 5 terminal motor branches, there are three motor branches - what are these ?
- Posterior auricular nerve
- nerve to digatrsric
- nerve to stylohyoid
describe Brown-Séquard syndrome
hemisection (one sided lesion) of the spinal cord. This is most often due to traumatic injury, and involves both the anterolateral system and the DCML pathway:
DCML pathway – ipsilateral loss of touch, vibration and proprioception.
Anterolateral system – contralateral loss of pain and temperature sensation.
It will also involve the descending motor tracts, causing an ipsilateral hemiparesis.
List the input nuclei of the basal ganglia
- Caudate nucleus
- Putamen
what is the primary (lemniscal pathway)
this is the main pathway through which auditory information reaches the primary auditory cortex (A1).
What hormone stimulated prolactin release ?
Thyrotrophin releasing hormone
what are the nuclei in the thalamus that receive signals from the optic nerve ?
lateral geniculate nucleus (LGN)
The oculomotor nerve provides motor and __________ innervation to the eye muscles.
parasympathetic
which nerve forms the oesophageal plexus ?
The vagal trunk which is a branch of the vagus nerve
what muscle receives motor innervation from CN IX
Stylopharyngeus
what is the anatomical relationship of the pituitary gland to the cavernous sinus
Cavernous sinus is lateral
The posterior cerebral arteries are a branch of what artery ?
Basilar
what is the anatomical course of the left vagus nerve ?
passes inferiorly between the left common carotid and left subclavian arteries, posterior to the sternoclavicular joint, entering the thorax.
what veins do the cavernous sinus drain into ?
Superior and Inferior petrosal veins
what structure separates the cerebellum from the pons ?
The 4th ventricle
In the ventricular system of the brain, the foramen of Munro connects which structures?
connects the lateral ventricles to the 3rd ventricle
How does the facial nerve exit the cranium ?
via the stylomastoid foramen
what is the function of hypophyseal portal vessels ?
These vessels ensure that the hypothalamic hormones remain concentrated, rather than being diluted in the systemic circulation. And allow transport from the hypothalamus to the pituitary gland
What muscles are innervated by the inferior branch of the oculomotor nerve ?
- Inferior rectus
- Medial rectus
- Inferior oblique
what structure forms the lateral aspect of the lentiform nucleus ?
Putamen
venous drainage from the head is into what structure ?
Internal jugular vein
Where are the cochlear hair cells located ?
organ of Corti
What is cushings triad ?
HTN, Bradycardia and irregular respiration
How is cerebral perfusion pressure calculated ?
MAP - ICP
what veins drain into the straight sinus ?
inferior sagittal sinus with the great cerebral vein.
This most common cause of CST is infection, which typically spreads from an extracranial location such as the orbit, paranasal sinuses, or the ‘danger zone’ of the face. What veins act as tracts for infection to reach the cavernous sinus ?
due to the anastomosis between the facial vein and superior ophthalmic veins.
Where does the facial nerve divide into the five terminal motor branches?
Within the parotid gland
the vestibulocochlear nerve splits, forming the vestibular nerve and the cochlear nerve. - what are the functions of these two nerves ?
The vestibular nerve innervates the vestibular system of the inner ear, which is responsible for detecting balance
The cochlear nerve travels to cochlea of the inner ear, forming the spiral ganglia which serve the sense of hearing.
what nerve supplies sensory innervation to the posterior part of the external auditory canal and external ear.
The auricular branch of the vagus nerve
what is a ganglion ?
collection of cell bodies outside the central nervous system
what modalities are transmitted by the DCML pathway ?
fine touch (tactile sensation), vibration and proprioception.
how does a CN VI palsy present ?
The affected eye turns medially and is unable to abduct properly
where do second order neurons in the anterolateral pathway decussate when carrying ascending sensory signals
In the spinal cord
While still intracranial, what branches come off the facial nerve ?
- Greater petrosal nerve
- nerve to stapedius
- chorda tympanii
what structure separates the cerebral hemispheres ?
Falx cerebri
a fold of dura mater that descends vertically to fill this fissure separating the two hemispheres.
how do the post ganglionic fibres leaving the ciliary ganglion reach the eye ?
via the short cilliary nerves
The oculomotor nerve splits into superior and inferior branches. what muscles are innervated by the superior branch ?
Superior rectus – elevates the eyeball
Levator palpabrae superioris – raises the upper eyelid.
Which cranial nerves are involved in the GAG reflex ?
The glossopharyngeal nerve supplies sensory innervation to the oropharynx, and thus carries the afferent information for the gag reflex. When a foreign object touches the back of the mouth, this stimulates CNIX, beginning the reflex. The efferent nerve in this process is the vagus nerve, CNX.
An absent gag reflex signifies damage to the glossopharyngeal nerve.
what is the first extracranial branch of the facial nerve
Posterior auricular nerve
All pharyngeal muscles are innervated by the vagus nerve (CN X ) except one muscle - which muscle is this ?
stylopharyngeus
what is the function of the greater petrosal nerve ? and what nerve does it branch off
- Branches off the facial nerve
- parasympathetic fibres to mucous glands and lacrimal gland.
what is the telencephalon ?
Telencephalon is another term for cerebrum. This is the largest part of the brain and contains the cerebral cortex.
what tracts carry unconscious sensory signals to the sensory cortex ?
The Spinocerebellar Tracts
The pyramidal tracts derive their name from the medullary pyramids of the medulla oblongata, which they pass through.
What are the two groups of pyramidal tracts ?
Corticospinal tracts – supplies the musculature of the body.
Corticobulbar tracts – supplies the musculature of the head and neck.
what are the intrinsic nuclei of the basal ganglia ?
- Globus pallidus external
- Subthalamic nuclei
- Pars compacta of the substantia nigra
what nerve provides afferent fibres for the corneal reflex ?
V1
Ophthalmic
where do pyramidal tracts and extrapyramidal tracts originate ?
Pyramidal tracts – These tracts originate in the cerebral cortex,
Extrapyramidal tracts – These tracts originate in the brain stem
what structures form the Lentiform nucleus ?
Globus pallidus and Putamen
what is the anatomical course of the right and left recurrent laryngeal nerve ?
Right loops under the right subclavian
Left loops under the arch of the aorta
They both ascend to innervate the majority of the intrinsic muscles of the larynx.
List the terminal branches of the mandibular nerve
BAIL
Buccal
auriculotemporal
inferior alveolar
lingual
The hypoglossal nerve innervates all intrinsic and extrinsic muscles of the tongue except which muscle ?
And what nerve innervates this muscle ?
palatoglossus
innervated by vagus nerve
C1/C1 nerve roots catch a ride on what cranial nerve ?
CN XII - Hypoglossal
List the intrinsic tongue muscles
Genioglossus
Styloglossus
Hyoglossus
Palatoglossus
In the DCML pathway, sensory signals from the UL and LL are transported in two different pathways - describe these
Signals from the upper limb (T6 and above) – travel in the fasciculus cuneatus
Signals from the lower limb (below T6) – travel in the fasciculus gracilis
The glossopharyngeal nerve provides parasympathetic (secreto-motor) function to the parotid gland. Where do the fibres synapse before they reach the parotid ?
Otic ganglion
True or false -
The posterior belly of the digastric is innervated by the facial nerve
True
*While the anterior belly is innervated by the myelohyoid nerve – a branch of the inferior alveolar nerve (itself a branch of the mandibular nerve).
From which structure is the cerebrum embryonically derived ?
Procencephalon
which branch of CN VIII is responsible for balance
Vestibular nerve
Which cranial nerve provides sensory innervation to the dura mater?
Trigeminal nerve
How is the straight sinus formed ?
The great cerebral vein combines with the inferior sagittal sinus
what is the function of the arachnoid granulations ?
allow CSF to re-enter the circulation via the dural venous sinuses.
The chorda tympanii provides special sensation (taste) to the anterior 2/3 of the tongue. What nerve provides general sensation to the anterior 2/3 of the tongue ?
V3 - Mandibular nerve
what is the function of The tectospinal tract ?
coordinates movements of the head in relation to visual stimuli.
how is the pituitary gland accessed in surgery ?
Via the sphenoid sinus
what tracts in the descending tracts pathway are responsible for involuntary movement
Extrapyramidal tracts
What two structures in the eye receive parasympathetic innervation from the oculomotor nerve ?
- Sphincter pupillae
- Ciliary muscles
where is Prolactin released from in the brain ?
Anterior pituitary
where is CSF produced ?
Cerebrospinal fluid is produced by the choroid plexus, located in the lining of the ventricles
Where in the brainstem is the hypoglossal nucleus located
Medulla
most cranial nerve nuclei receive bilateral innervation from descending coritcobulbar tracts - which are the exceptions
CN VII and CN XII
These both receive only contralateral innervation.
At what level does the common carotid artery bifurcate ?
C4
What are the 5 terminal branches of the facial nerve ?
Temporal branch
Zygomatic branch
Buccal branch
Marginal mandibular branch
Cervical branch
where do extrapyramidal tracts originate ?
Brainstem
what structure allows passage of CSF from the lateral ventricles to the 3rd ventricle ?
Foramen of Monroe
The olfactory bulb lies in the olfactory groove. Which cranial fossa is the olfactory groove located in ?
Anterior cranial fossa
what is the anatomical relationship between the C1/C2 roots and the hypoglossal nerve
The C1/C2 roots that travel with the hypoglossal nerve also have a motor function. They branch off to innervate the geniohyoid (elevates the hyoid bone) and thyrohyoid (depresses the hyoid bone) muscles.
which two nerves combine to form the submandibular ganglion ?
chorda tympani and the Lingual branch of CN V
what nerve supplies parasympathetic function to the parotid gland ?
glossopharyngeal nerve (CN IX)
What structures make up the basal ganglia ?
- Caudate nucleus
- putamen
- sub thalamic nuclei
- Globus pallidus [internus and externus]
- Sustantia Nigra
how does the hypogossal nerve (CN XII) leave the cranial fossa ?
Via the hypoglossal canal
what modalities are transmitted by the anteriolateral pathway ?
Anterior spinothalamic tract – carries the sensory modalities of crude touch and pressure.
Lateral spinothalamic tract – carries the sensory modalities of pain and temperature.
In head injuries that lead to SIADH. What nucleus is affected ?
**Supraoptic **
The supraoptic nucleus regulates ADH release.
what is onufs nucleus and where is it located ?
Onufs nucleus is located in the anterior horn of S2 and is the origin of neurones to the external urethral sphincter.
When damaged, leads to incontinence
Explained the ‘PITS’ acronym
Temporal lesions in the brain cause contralateral superior quadrantinopia’s
Parietal lesions cause contralateral inferior quadrantinopias
