Neuroanatomy Flashcards
From inferior to superior (i.e. ascending),
what is the 4th branch of the external carotid
artery in the neck?
a. Maxillary artery
b. Occipital artery
c. Facial artery
d. Lingual artery
e. Posterior auricular artery
c. Facial artery
The external carotid artery has several branches in the neck (SALFOPSI in ascending order): superior thyroid, ascending pharyngeal, lingual, facial (aka external maxillary), occipital, posterior auricular, superficial temporal, maxillary (aka internal maxil- lary). It can be distinguished on angiogram (figure) from the ICA, which has no branches in the neck. During EC/IC bypass procedures for Moya Moya disease, anastomosis of the superficial temporal artery to the middle cerebral artery (or less com- monly occipital artery to the posterior cerebral artery/posterior inferior cerebellar artery) may be performed.
The pathway best describing how sympa-
thetic fibers of the autonomic nervous system
exit the spinal cord is
a. Via the dorsal roots and white rami
communicans
b. Via the ventral roots and white rami communicans
c. Via the dorsal roots and gray rami
communicans
d. Via the ventral roots and gray rami
communicans
e. Via the ventral roots and spinal nerves
b. Via the ventral roots and white rami communicans
Via the ventral roots and white rami communicans
The left vertebral artery usually arises from the:
a. Arch of the aorta
b. Brachiocephalic trunk
c. Left common carotid
d. Left subclavian artery
e. Costocervical trunk
d. Left subclavian artery
Each vertebral artery arises from its ipsilateral subclavian artery. The aortic arch gives off three branches in order: brachiocephalic trunk (or innominate artery), left common carotid and left subclavian arteries (A). The second commonest branching pattern (termed a “bovine arch”) is where the left common carotid arises from the brachiocephalic trunk (B).
Hemiballismus results from lesioning which
basal ganglia target?
a. Globus pallidus interna
b. Subthalamic nucleus
c. Substantia nigra pars reticularis
d. Striatum
e. Pedunculopontine nucleus
b. Subthalamic nucleus
Hemiballismus is a condition characterized by unilateral, involuntary, violent flinging of the limbs. Lesion is based in the contralateral subtha- lamic nucleus or its connections and due to vascu- lar cause (PCA territory) but can occur in MS. Often settles spontaneously and drug treatment is ineffective.
Lesion of which structure increases extensor
tone?
a. Dentate nucleus
b. Pedunculopontine nucleus
c. Red nucleus
d. Ventral tegmentum
e. Superior olive
c. Red nucleus
Factors normally inhibiting extensor action in the arms and legs are:
(A) Cortical inhibition of lateral vestibular nucleus (vestibulospinal tract) and pontine reticular formation
(B) Red nucleus projections to spinal cord (rubrospinal tract; possibly arms only)
(C) Medullary reticular formation
Disconnection lesion involving red nucleus results in loss of normal inhibition of extension (rubrospinal and medullary reticular formation) and loss of cortical inhibition of extensor action of LVN and pontine RF, producing hyperreflexia and increased extensor tone (decerebrate rigid- ity). Disconnection lesions above the red nucleus result in extension in legs, but flexion in arms (decorticate rigidity). This is explained as in humans the rubrospinal tract terminates in the cervical spine, meaning intact rubrospinal input could counteract vestibulospinal (extensor) input in the arms but it remains unopposed in the legs.
Which one of the following drain into the cavernous sinus?
a. Superior ophthalmic vein
b. Superior petrosal sinus
c. Inferior petrosal sinus
d. Basal vein of Rosenthal
e. Vein of Labbe
a. Superior ophthalmic vein
The cavernous sinus receives the superior and inferior ophthalmic veins, sphenoparietal sinus and the superficial middle cerebral vein (coursing from superiorly to inferiorly in the Sylvian fis- sure). It drains via superior petrosal sinus (to the junction of the transverse and sigmoid sinuses), inferior petrosal sinus (to the internal jugular vein). Right and left cavernous sinuses are also connected across the midline anterior and posteriorly to the pituitary gland via the ante- rior and posterior intercavernous sinuses, result- ing in the circular sinus. Each cavernous sinus is also connected to the pterygoid venous plexus via small branches in the foramen Vesalii, fora- men ovale and foramen lacerum.
Persistent trigeminal artery is commonly:
a. Found in 3-5% of people
b. Found to connect to the proximal basilar
artery
c. Found to branch off from the ICA just
proximal to the meningohypophyseal
trunk
d. Found to have a vascular abnormality in
approximately 50% of cases
e. Found in conjunction with internal
carotid artery aplasia
c. Found to branch off from the ICA just
proximal to the meningohypophyseal
trunk
Found to branch off from the ICA just proximal to the meningohypophyseal trunk
After the Pcomm, persistent primitive trigeminal artery is the next commonest remnant of the fetal circulation. It is seen in 0.1-0.6% of cerebral angio- grams. It connects the cavernous ICA (just proxi- mal to meningohypophyseal trunk) to the basilar artery between superior cerebellar and anterior inferior cerebellar arteries. Its persistence is usually associated with a hypoplastic basilar and vertebral arteries proximal to the anastomosis, as well as a hypoplastic PcommA. Its frequency is explained as the order of regression during embryogenesis is otic/acoustic artery first, then hypoglossal fol- lowed by trigeminal. Vascular abnormalities (AVM, aneurysm) is seen in 25%. Characterized by the tau sign (flow void) on sagittal MRI.
The afferent loop of the Hering-Breuer inflation and deflation reflexes is mediated by:
a. CN XIII
b. CN IX
c. CN X
d. CN XI
e. C2
c. CN X
The Hering-Breuer inflation and deflation reflexes are thought to play a role in controlling the depth of breathing, although may be less important in humans at rest. Their overall effect is to prevent overinflation and extreme deflation of the lungs. The inflation reflex is mediated by pulmonary stretch receptor afferents signaling via CNX dur- ing lung inflation to inhibit medullary inspiratory center and the pontine apneustic center, as well as inhibiting cardiac vagal motor neurons resulting in sinus tachycardia. The deflation reflex also acts via CNX and directly activates medullary inspira- tory centers, stopping expiration and initiating inspiration.
Which one of the following nerves is outside the annulus of Zinn?
a. Abducens
b. Nasociliary
c. Trochlear
d. Oculomotor (superior division)
e. Oculomotor (inferior division)
c. Trochlear
The Annulus of Zinn (or annular tendon) is a fibrous ring which surrounds the optic nerve, and which is continuous with the dura of the mid- dle cranial fossa. It is divided into upper (superior tendon of Lockwood) and lower (inferior tendon of Zinn) parts which together give rise to the four recti muscles (superior, inferior, medial, lateral) and superior oblique. The remaining two extraocular muscles, inferior oblique and levator palpabrae superioris arise from the maxillary and sphenoid bones respectively. The Annulus of Zinn contains the optic nerve, ophthalmic artery, superior division of CNIII, nasociliary division of CNV1, CNVI, and the inferior division of CNIII.
The C2 vertebra has how many secondary ossification centers?
a. 2
b. 3
c. 4
d. 5
e. 6
d. 5
Development of the vertebral column occurs in three stages:
Mesenchymal stage—where somites gives rise to sclerotomes (condensation of mesenchymal cells around notochord and neural tube, divided into a loosely packed upper half and a densely pack lower half) and myo- tomes. The centrum (primordial vertebral body) forms from the lower half of a cranial sclerotome and the upper half of the imme- diately caudal sclerotome, such that the intervertebral disc forms at the level oppo- site the myotome and the vertebral body is at the level between two myotomes.
Cartilaginous stage—chondrification centers appear in the centrum and vertebral arches, causing cartilaginous fusion, and spinous and transverse processes develop from extensions of the chondrification centers in the vertebral arches. Chondrification spreads until a cartilaginous vertebral col- umn is formed.
Bony stage—By the end of the embryonic period each vertebrae usually has three primary ossi- fication centers (centrum and each half verte- bral arch), and the cartilaginous connection between the arch and centrum allows growth as the spinal cord enlarges after birth. After puberty, five secondary ossification centers appear—tip of spinous process, tip of both transverse processes and annular epiphyses of the vertebral body.
A line drawn between the highest point of the iliac crests across the back usually denotes
a. L1/2 interspace
b. L2/3 interspace
c. L3/4 interspace
d. L4/5 interspace
e. L5/S1 interspace
d. L4/5 interspace
Intercristal line (Tuffier’s line)—space between
L4 and L5 spinous process, or through L4 spi- nous process. In infants this is at the
Which one of the following is labeled X in the image below?
a. Ophthalmic division of the trigeminal nerve
b. Meckel’s cave
c. Oculomotor nerve
d. Maxillary division of trigeminal nerve
e. Abducens nerve
b. Meckel’s cave
(containing Gasserian ganglion). Axial view in T2 MRI is shown below
Which one of the following statements about the sympathetic nervous system is FALSE?
a. Innervation of thoracic viscera arises from
T1-T4 spinal segments
b. Splanchnic nerves are unmyelinated
c. Preganglionic fibers enter the sympa-
thetic chain via white rami communicans
d. Sensory afferent fibers are important for
visceral pain sensation
e. Preganglionic fibers synapse in either the
sympathetic chain or prevertebral ganglia
b. Splanchnic nerves are unmyelinated
Pre-ganglionic sympathetic fibers (myelinated) arise in the lateral horn of gray matter T1-L2 and exit the cord via the anterior (ventral) root then as white rami communicans to reach the sympathetic ganglion. Here they may synapse onto unmyelinated post-ganglionic fibers or pass through unchanged as splanchnic nerves (which later synapse in prevertebral ganglia and inner- vate the viscera). Post-ganglionic fibers exit the sympathetic chain at the same or different level (after ascending or descending), via a gray ramus communicans which relays fibers to an existing spinal nerve. Sympathetic chain runs from the skull base to coccyx on both sides of the vertebral column.
Spinal segments responsible for sympathetic innervation (e.g. vasoconstrictor to skin, pilomo- tor to hair, sudomotor to sweat glands)
T1-T2: head and neck via ICA/vertebral arteries
T2-T5: upper limb
T1-T4: thoracic viscera via cardiac/pulmo-
nary/esophageal plexus
T4-L2: abdominal viscera via splanchnic
nerves to coeliac/hypogastric plexuses (ex- cept adrenal medulla which receives a pre- ganglionic fiber which has also traversed the coeliac plexus)
T10-L2: pelvic viscera via splanchnic nerves to pelvic plexus
T11-L2: lower limb
Sympathetic sensory afferents terminate in the intermediate zone of gray matter in the cord and are important in the appreciation of visceral pain.
Nervi erigentes are responsible for:
a. Inhibition of the external anal sphincter
b. Inhibition of the internal vesicle sphincter
c. Inhibition of the internal anal sphincter
d. Inhibition of the external vesicle sphincter
e. Inhibition of the rectal muscles
b. Inhibition of the internal vesicle sphincter
Visceromotor to rectal muscles, inhibitor to internal anal sphincter
Motor to bladder wall, inhibitor to internal vesicle sphincter
Vasodilator fibers to cavernous sinuses of penis/clitoris
Parasympathetic sensory afferents terminate
in which one of the following?
a. Nucleus ambiguus
b. Solitary nucleus
c. Edinger-Westphal nucleus
d. Red nucleus
e. Superior colliculus
b. Solitary nucleus
Parasympathetic sensory afferents:
Afferent fibers from GI, respiratory, cardiac
and mouth/pharynx travelling in CN VII/ XI/X terminate in the solitary nucleus of the medulla
Sacral afferents terminate in the S2-S4 gray matter
Important in maintaining visceral reflexes
