Flashcards in Prac flash cards- block 6.csv - Prac flash cards- block 6.csv Deck (294):
Name the 3 thenar muscles and comment on their innervation (nerve and roots)
Abductor pollicis brevis, flexor pollicis brevis and opponens pollicis. Median nerve, C8
Name the 3 hypothenar muscles and comment on their innervation (nerve and roots)
1. Abductor digiti minimi, flexor digiti minimi and opponens digiti minimi. Ulnar nerve, T1
Name the 3 groups of intermediate intrinsic hand muscles and comment on their innervation (nerve and roots)
All innervated by the ulnar nerve (excepts 1-2 lumbricals by median nerve). All supplied by T1 nerve root.
Which artery crosses the snuffbox?
Which arteries of the forearm form the superficial vs deep palmar arch?
Superficial = ulnar artery, Deep = radial artery
Name the 3 superficial (large) veins of the forearm
Dorsal venous arch, cephalic (lateral) and basilic (medial)
The ulnar nerve originates from which cord of the brachial plexus? What are the associated nerve roots?
Medial cord (C8, T1)
The median nerve originates from which cord of the brachial plexus? What are the associated nerve roots?
Medial and lateral cords (C6-T1)
The radial nerve originates from which cord of the brachial plexus? What are the associated nerve roots?
Posterior cord (C5-T1)
What is the ulnar nerve motor to? What is it sensory to?
Motor to intrinsic hand muscles, flexor carpi ulnaris and flexor digitorum profundus. Sensory to medial palm.
What is the median nerve motor to? What is it sensory to?
Motor to forearm flexors, thenar muscles and 1-2 lumbricals. Sensory to lateral palm.
What is the radial nerve motor to? What is it sensory to?
Motor to the arm extensors. Sensory to the posterior arm, forearm and hand
The primary curvatures of the spine (thoracic and sacral) are caused by differences in height between anterior and posterior ______, whereas the secondary curvatures (cervical and lumbar) are caused by differences in _____ betwteen anterior and posterior parts of the _____.
Parts of vertebrae, thickenss of intervertebral discs
What is the other name given to the facet joints of the vertebral column?
What are the 3 pillars of the vertebrae?
Body and 2 x facet joints
Which factors determine the movements allowed by the spine?
1. Intervertebral discs to body ratio in thickness 2. Facet joints
Name the vertebra that have a bifid spinos process
In which direction do the superior articular facets of the cervical vertebrae face?
Backward and up
List a couple of the defining features of a cervical vertebra
Bifid spinous process, large vertebral foramen compared to smaller vertebral body and presence of transverse foramen, anterior and posterior tubercles of transverse process
List the movements allowed by the cervical vertebra
Flexion, extension, lateral flexion and rotation
List the 3 x atypical cervical vertebrae
Atlas, axis and vertebra prominens (C7)
What makes the atlas unique?
No body, no spinous process, lateral mass and posterior and anterior arches
What makes the axis unique?
Presence of dens (odontoid process)
Which vessels run through the transverse processes of the cervical vertebra?
Vertebral artery (but only C1-6), vertebral vein and cervical extension of the sympathetic trunk
What is unique about the thoracic vertebra?
Has superior and inferior costal demifacets (articulate with the head of each rib), transverse processes have costal facets to artciulate with tubercle of a rib
In which direction do the superior articular facets of the thoracic vertebrae face?
Which movements are allowed by the thoracic vertebrae?
Lateral flexion and rotation
In which direction do the superior articular facets of the lumbar vertebrae face?
Which movements are allowed by the lumbar vertebrae?
Flexion, extension, and some lateral flexion
The sacroiliac joints are covered with _____ cartilage and are ____ joints
The sacrum contains both anterior and posterior _____
How many anterior and posterior foramina are present in the sacrum?
4 on each side
What structure/s run through the foramina of the sacrum?
The anterior and posterior rami of S1-S4 spinal nerves
The sacral canal contains which structures?
Nerve roots of cauda equina
The coccyx provides attachments of which muscles?
Gluteus maximus and coccygeus
What are the 2 types of intervetebral articulations?
1. Facet joints 2. Cartilaginous joints (discs)
The movement of facet joints are determined by what key anatomical feature?
Orientation of facets
The ligamentum flavum connects which structures of adjacent vertebrae?
List the 7 ligaments of the vertebral column
1. Anterior longitudinal ligament 2. Posterior longitudinal ligament 3. Ligamentum flavum 4. Supraspinous ligament 5. Interspinous lig 6. Intertransverse lig 7. Intervertebral discs
If added, the total length of all intervetebral discs = _____ of the length of the entire vertebral column
Which characteristic of the vertebral anatomy contributes to loss of height with age?
Water loss from the nucleus propulsus of the intervetebral discs
Superficial and intermediate groups of back muscles are all ____ muscles of the back
What is the main purpose of the extrinsic back muscles?
Connect the upper limbs to the trunk and control limb movements
List the 4 main superficial muscles of the back
Trapezius, latissimus dorsi, levator scapulae and rhomboids
Name the large ligament that runs longitudinally down the back from the skull
Deep/intrinsic back muscles are innervated by?
The dorsal rami of spinal nerves
What is the purpose of the intrinsic muscles of the back?
Maintain posture and control movements of the vertebral column
The intrinsic back muscles extend from the ____ to the ____
Pelvis to the skull
The intrinsic back muscles are enclosed by the _______ fascia
Name the back muscle/s in the superficial layer of intrinsic muscles
Splenius (cervicis and capitis)
Describe the location of the splenius muscle
Arises from midline and extends superolaterally to cervical vertebrae (splenius cervicus) and skull (splenius capitus)
Which back muscles are in the intermediate layer of intrinsic back muscles?
Erector spinae (spinalis, longissimus and iliocostalis)
What is the origin and insertion of the erector spinae muscles?
Sacrum, lumbar spinous processes and iliac crest (spinalis inserts on spinous processes, longissimus inserts on transverse processes and iliocostalis inserts onto ribs)
Name the back muscles in the deep layer of intrinsic muscles
Transverseospinalis, interspinalis, intertransverarius and levator costarium
Which 3 muscles make up the transversospinalis muscle?
Semispinalis, multifidus and rotatores
The fibres of transversospinalis run from the ____ process to the superior ____ process
List the 2 reasons why 2 xray projections are required for imaging the spine?
1. Superimposition of anatomic structures means that some pathological conditions may not be visible on one projection 2. To determine the exact location of pathology 3. To visualise a fracture and determine the alignment of the fractures parts
Why are 3 projections required when imaging joints?
Enables multiple surfaces and angles of the bones comprising the joint to be visualised to ensure that pathology is not missed
List the standard projections used to assess the cervical spine
1. AP 2. Lateral 3. Anterior-posterior open mouth (APON) or odontoid peg
In a cervical spine imagine, if the vertebrae down to T1 are not visible on the lateral view, which additional view may be taken?
"Swimmer's view" on a repeat lateral with the arms lowered
List the standard projections used to assess the thoracic spine
AP and lateral
On a thoracic spinal xray, if the upper thoracic spine is not visible on the lateral view and an injury is suspected, which other specialised view may be required?
Which ribs articulate with the thoracic vertebra in 3 places? Name the 3 places
Ribs 2-9. Head of rib has 2 articular facets (sup and inf) which articulate with the inferior and superior costal facets of the corresponding vertebral body. The rib also contains a tubercle on it's posterior aspect with another facet. This facet articulates with the transverse costal facet located on the verebral transverse psocess
How is the 10th rib different to the others in it's articulation with the vertebrae?
Only articulates with one vertebral body (by means of the inferior articular facet). It still has a tubercle and articulates with the vertebral transverse process
Ribs 11 and 12 only articulate with 1 ______ and do not have a _____
Vertebral body, tubercle
Rib 1 articulates with the ____ vertebra only by an inferior _____ _____.
T1 by inferior vertebral facet
List the standard projections used to assess the lumbar spine
AP and lateral
Which specialised view of the lumbar spine may be used in addition to the AP and lateral standard views?
Lumbosacral (with the xray beam centred at the level of the lumbosacral junction)
Name a cancer than affects the meninges
CSF is produced by filtration of ____ within the brain within the _____, which circulates back to the vascular system via the ______
Blood; ventricles; meninges
What is hydroencephalus?
Enlargement of the ventricles causing raised ICP
Areas of the skull where the dura is folded back onto itself results in the formation of which features?
Venous dural sinuses
What is the falx cerebri?
Large, crescent-shaped fold of meningeal layer of dura mater that descends vertically in the longitudinal fissure between the cerebral hemispheres
What is the tentorium cerebelli?
An extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes
What is the diaphragm sellae?
flat piece of dura mater with a circular hole allowing the vertical passage of the pituitary stalk. It retains the pituitary gland beneath it in the fossa hypophyseos as it almost completely roofs the fossa hypophyseos of the sella turcica, a part of the sphenoid bone
List the venous sinuses of the brain
Sagittal (superior and inferior), straight sinus, cavernous sinus, transverse, petrosal and signmoid
Where does the falx cerebri attach to the anterior skull?
The falx cerebri attaches anteriorly at the crista galli in proximity to the cribriform plate and to the frontal and ethmoid sinuses
Where does the falx cerebri attach to the posterior skull?
Posteriorly, it is connected with the upper surface of the tentorium cerebelli
Which sinus is contained in the superior margin of the falx cerebri and overlies the longitudinal fissure of the brain?
The diaphragma sellae is innervated by which nerve?
V1 of the cranial trigeminal nerve
What is the final dumping ground for all fluid leaving the skull?
The anterior meningeal artery is a branch of which other artery?
Internal carotid > ophthalmic artery > internal ethmoidal artery > anterior meningel artery
Where does the anterior meningeal artery enter the cranium?
Lateral part of cribriform plate, from the orbit
The middle meningeal artery is a branch of which other artery?
Maxillary artery (terminal branch of external carotid)
Where does the middle meningeal artery enter the cranium?
The posterior meningeal artery is a branch of which other artery?
Ascending pharyngeal artery
Where does the posterior meningeal artery enter the cranium?
Could be jugular foramen, foramen mangnum, hypoglossal canal (or all 3)
Which is the largest vessel supplying the dura region of the posterior fossa?
Posterior meningeal artery
Which major vessel that supplies the dura mater is epidural?
Why is the middle meningeal artery much more likley to cause haemorrhage than the anterior and posterior meningeal arteries? Why is this type of haemorrhage particularly dangerous?
Lies embedded within the skull bone directly behind the weak point between the temporal and parietal bones (pterygoid). Even a light blow to the side of the head can dissect the artery, causing an epidural bleed. This is dangerous because the patient may not know it is happening, which is why someone with a concussion should be advised to stay awake, so that their consciousness can be monitored. If they were to go to sleep and then develop so much bleeding that they become unconscious, they would never wake up and you would never know the difference
What structures are formed when the arachnoid mater skils from gyrus to gyrus and around the brainstem, leaving large spaces between the pia and arachnois mater?
Anatomically, how are the cerebral artery vessels separated from the neural environemnt? What is the advantage of this arrangement?
As they invaginate into the brain, they take the pia mater with them, which forms the barrier between the vessel and the brain. This helps to minimise passive diffusion of blood-born substances into the neural tissues
What is the purpsoe of tight junctions between endothelial cells in the BBB?
Prevent blood cells and large molecules from squeezing between cells and entering the neural microenvironment (i.e., physical barrier)
What are some of the mechanistic adaptations of the BBB?
Virtual absence of vesiscular transport across the membranes f vascular endothelial cells of the cerebral vessels
Unknown factors derived from _____ appear to play a role in maintaining the integrity of the blood brain, and blood retinal, barriers
Mechanistic adaptations of the BBB are maintained via what signals? What disrupts these signals?
Cell-cell signals; disrupted by inflammatory events
Astrocytes are located in the neural environment and define a _____ space
Which major artery do the vertebral arteries branch from? Where does this originally branch?
Subclavian; as it loops over the first rib
What region does the anterior spinal artery supply? What are some of the important structures in this region?
Anterior 2/3 spinal cord, and anterior medial brainstem below the open medulla. Important structures in this area of the brainstem include the pyramids (corticospinal tracs) and some of the medial lemniscus (some sensory) etc.
What region does the posterior spinal artery supply? What are some of the important structures in this region?
Posterior 1/3 of spinal cord, posterolateral midbrain. Important structures = dorsal column pathway
At what level do the vertebral arteries unit to form the basilar artery?
What do the paramedian branches of the basilar artery supply?
Pons adjacent to the midline (including corticospinal tracts)
What do the short circumferential branches of the basilar artery supply?
Supply more lateral regions of pons
What do the long circumferential branches of the basilar artery supply?
Perforate the brainstem and supply the region between the pontocerebellar fibres and the 4th ventricle
Which 3 branches of the basillar artery supply the pons and region between the pontocerebrallar fibres and 4th ventricle?
Paramedian branches (midline), short circumferential (lateral pons) and long circumferential (region betweeen pontocerebellar fibres and fourth ventricle)
What region is supplied by the posterior inferior cerebellar artery?
Most of the inferior surface of the cerebellum, lateral upper medulla including the inferior cerebellar peduncle
What regions are supplied by the anterior inferior cerebellar artery? What are the important structures in this area?
Anterior segment of inferior cerebellar surface,middle cerebellar peduncles and inferolateral parts of the pons' ponto-cerebellar fibres
What regions are supplied by the superior cerebellar artery? What important structures lie in this region?
Superior surface of the cerebellum, superior cerebellar peuncle; mainly efferent fibres of cerebellothalamic tract, cerebellorubral tract. Also has afferent tracts tectocerebellar etc.
What are the terminal branches of the basilar artery?
Posterior cerebral arteries (L and R)
What structures in the brainstem are supplied by the posterior cerebral arteries?
Most of cerebral peduncles and almost all of the tectum
Unilateral infarction of the posterior cererbral artery causes what visual field defect?
List the 3 stroke syndromes of the midbrain
Webers, Benedikt, Claude syndromes
What is Weber syndrome? What is the likley presentation
Midbrain stroke syndrome that involves the occulomotor nerve resultin in ipsilateral CNIII palsy and contralateral hemiplegia or hemiparesis
What is Benedikt syndrome? What is the likley presentation
Midbrain stroke syndrome that involves the occulomotor nerve and red nucleus. Results in an ipsilateral CNIII palsy and crossed hemitaxia and chorea
What is Claude syndrome? What is the likley presentation
Midbrain stroke syndrome where there is infarction to the dorsomedial aspect of the midbrain secondary to occlusion of small perforating branches of the posterior cerebral arteries. Infarction involved red nucleus, CNIII nucleus and superior cerebellar peduncle. Clinical picture includes ipsilateral CNIII nerve palsy and contralateral upper and lower limb ataxia
Which nerves traverse the lateral wall of the cavernous sinus, and which lies closes to the internal carotid artery?
1. CN III, IV, V1, V2; the nerve closes to the internal carotid is abducens (VI)
After winding around the ____ peduncles, the Pca crosses the gap between the brainstem and the _____ lobe, where is branches into the ______ and _____ PCA.
Cerebral; temporal lobe; lateral and medial PCA
The ACA winds laterally around the ___ ____ then passes medially towards the medial aspect of the _____ lobe
Optic chiasm; frontal
The medial cerebral artery enters the lateral _______
Which cortical territories are supplied by the anterior cerebral artery?
Superior parietal lobule, superior frontal gyrus,medial strip of the cortex from the frontal lobe bakc to the beginning of the occipital lobe, and basically all of the inner parietal lobes (extending up and over the ventricles)
Which cortical territories are supplied by the middle cerebral artery?
Inferior frontal gyrus, superior temporal gyrus, most of the temporal lbe, precentral and post central gyri, inferior parietal lobule, inferior parietal lobe
Which cortical territories are supplied by the posterior cerebral artery?
Occipital lobe, inferior temporal gyrus, inferior part of the temporal lobe
The deep cerebral structures of the brain are supplied by which vessels?
1. Perforating branches of the cerebral arteries on the base of the brain 2. Communicating arteries of the circle of willis
Which vessel supplies the hippocampus and amygdala?
Anterior choroidal artery (branch of internal carotid or sometimes the middle cerebral)
Which deep territories of the brain are supplied by the perforating branches of the anterior cerebral artery?
Anterior limb of the internal capsule, the inferior portions fo the head of the caudate and anterior globus pallidus
From which cerebral artery do the medial and lateral striate arteries originate?
What deep structures of the cortex do the lateral and medial striate branches of the medial cerebral ateries supply?
Internal capsule and reticular formation
What strcuctures are supplied by the anterior choroidal artery (branch of internal carotid)?
Choroid plexus of lateral and third ventricles, optic chiasm and tract, internal capsule, lateral geniculate body, globus pallidus, tail of caudate nucleus, hippocampus, amygdala, substantial nigra, red nucleus and crus cerebri
List the 3 main features of system of venous drainage of the brain. What is the purpose of this organisation?
1. A limited number of large veins that make contact with brain matter 2. Direct course of veins into venous dural sinuses 3. Dural sinuses separated from the brain surface by CSF in the subarachnoid space (helps prevent brain from overheating)
Describe the venous drainage of deep cortical structures
Composed of dural venous sinuses. Most prominent is the superior saggital sinus, which forms the confluence of sinuses where it meets the sinus that drains the deep structures. From here, 2 transverse sinuses bifurcate and travel laterally and inferiorly in a S-cruve that form the sigmoid sinuses, which then go on to form the jugular veins.
Describe the venous drainage of superficial cortical structures
Primarily composed of traditional veins inside the deep structures of the brain, which join behind the midbrain to form the vein of Galen (great cerebral vein). This vein merges with the inferior saggital sinus to form the straight sinus, which then joins the superficial venous system at the confluence of sinuses. Blood then collects into the transverse sinuses > sigmoid sinuses > jugular veins > SVC
The apex of the knee is directed _____
Which nerve supplies the muscles in the posterior compartment of the thigh?
List the 4 muscles in the posterior compartment of the thigh and comment on their similar origins
Hamstrings (x3) and adductor magnus - all originate from the ischial tuberosity
What are the origins and insertions of the long and short head of the biceps femoris?
Long head originates at the ischial tuberosity and short head from the linea aspera - two belliws unite and insert laterally to the knee joint into the head of the fibula and lateral condyle of the tibia
The short head of the biceps femoris inserts into the linea aspera between which 2 other muscles?
Adductor magnus and vastus lateralis
Which muscle inserts into the medial surface of the tibia, distal to the gracillis tendon?
What is the most posterior attachment in the knee joint on the upper end of the tibia?
Posterior cruciate ligament
The lateral collateral ligament of the knee stands free of the ____ ____, separated from it by the tendon of the _____ muscle
Joint capsule, popliteus
Which ligament is located on the posterior knee?
Oblique posterior ligament (lateral femur to medial tibia)
Which bones form the ankle joint? What is the other name for this joint?
The combined articular surfaces of the tibia and fibula and the broadly curved anterior surface of the talus (talocrural joint)
What is the sustententaculum talus?
Medial projection of the calcaneus that provides an antero-superior facet for the talus
On the medial side of the foot, the talus articulates with the _____
On the lateral side of the foot, the calcaneum articulates anteriorly with the _____. This is known as the ______ joint and is supported by deep ligaments on the sole of the foot
Cuboid, talo-calcaneo-navicular joint
List the 3 muscles in the anterior compartment of the lower leg/ankle/foot. What is the action of this group?
Extend/dorsiflex the ankle and toes. 1. Tibialis anterior 2. Extensor digitorum longus 3. Extensor hallicus longus
What are the 2 actions of the tibialis anterior?
Dorsiflexion of the ankle and inversion
Which nerve innervates the extensor muscles in the anterior compartment of the lower leg?
Peroneal nerve (deep)
List the 3 mucles in the lateral compartment of the lower leg. Which nerve innervates this group?
Peroneus longus, peroneus brevis and peroneus tertius. Innervated by peroneal nerve (superficial)
List the 6 muscles in the posterior compartment of the lower leg. Which nerve innervates this group?
1. Soleus 2. Gastrocnemius 3. Popliteus. Innervated by the tibial nerve 4. Flexor digitorum longus 5. Flexor hallicus longus 6. Tibialis posterior
What is the function of the popliteus?
Unlocks the knee joint by laterally rotating the femur against the tibia
The tibialis posterior attaches to the tuberosity of the ____, and adjacent tarsal bones
What is the main intrinsic muscle on the dorsum of the foot? What is it's innervation?
Extensor digitorum brevis - deep peroneal nerve S1, S2
The ___ ____ artery passes forwards over the top of the _____ membrane to enter the anterior compartment of the leg
Anterior tibial artery, interosseus
The anterior artery gives off which brances to the ankle joint?
Medial and lateral malleolar branches
Which vein drains the toes?
Dorsal venous arch
The lateral end of the dorsal venous arch becomes the ___ ___ vein, whilst th emedial end becomes the ____ ____ vein
Short saphenous, long saphenous
Branches of which nerve root supply the lower abdominal wall, pelvis brim and skin of external genitalia?
Which is the main nerve to the anterior and lateral thigh?
Which nerve innervates the medial thigh?
Which nerve innervates the posterior thigh, leg and foot?
The peroneal branch of the sciatic nerve winds around which structure before giving off a branch which is joined by the tibial nerve. What is the name of the resultant nerve?
Head of the fibula, forms the sural nerve
What is suprathreshold stimulation in an evoked EMG stimulation study?
The point at which the response reaches a maximum beyond which an increase in stimulus duration and/or amplitude does not increase the evoved EMG response. With increaseing stimulus strengths, more and ore motor axons are stimulated. Once all axons are stimulated, the muscle response will be maximal and a further increase in stimulus strength does not affect the muscle response
What is the size principle in the normal physiology of motor neuron recruitment?
Small motor units are recruited first and bigger ones last (because smaller units have less membrane surface area, so they impose more resistance and thus the biggest voltage change occurs here first)
Loss in nerve conduction velocity is a result of _____
Which 3 factors contribute to the latency of nerve conduction velocity?
1. Stimulation 2. Neuromuscular transmission 3. Generation of muscle action potential
What are the typical values for conduction velocities for motor nerves?
How is conduction velocity calculated in a nerve conduction study?
Distance between elbow and wrist electrodes (in mm) divided by the time difference between two consecutive action potentials (in ms)
Briefly describe how summation of stimulation in a nerve conduction study can lead to increased muscle force production
Muscle relaxes over 100ms. If the interval between the stimulation is shorter than the time to relax, the second contraction adds to the remaining force from the first. During relaxation, calcium is cleared from the cytosol. At intervals < 50ms, the calcium released from the sarcoplastic reticulum adds to the residucal calcium in the cytosol = stronger muscle contraction
Which 2 structures are considered to make up the protective layer of the eye?
Cornea and sclera
Which 3 structures are considered to make up the vascularlayer of the eye?
Choroid, ciliary body and iris (and pupil)
What is the ora serrata?
The anterior peripheral margin of the retina
What is the aqueous chamber of the eye and where is it located?
Anterior to the lens and ciliary body - divided into anterior and posterior components. Anterior chamber is anterior ot the iris and the posterior is behind the irius but in front of the lens
What are the 2 roles of the ciliary body of the eye?
1. Accommodation/adjusting of lens for near vision 2. Secretion of aqueous humour is achieved through a filtration process that occurs in the fine capillary beds of the ciliary body
Which ligaments of the lens are inserted in the ciliary body?
When the ciliary body fo the eye moves anteriorly, tension on the lense capsule is _____. What is the end result of this?
Relaxed - lense bulges thereby increasing it's power (dioptre value) and bending light more effectively
What controls that anterior-posterior position of the ciliary body and lens, and thereby accommodation?
Ciliary muscles within the ciliary body
Aqueous humor is secreted into the ____ chamber and flows through the ____ into the ______ chamber.
Posterior chamber, pupil, anterior chamber
Aqueous humor in the anterior chamber is cleared through which canal? Where is this located?
Canal of Schlemm at the corneal-scleral junction
What is the vitreous chamber of the eye?
A large chamber behind the ciliary body and lens, loosely attached to the inner surface of the retina, helping to hols it in place
What is short-sightedness?
also known as short-sightedness and myopia, is a condition of the eye where light focuses in front, instead of on the retina. This causes distant objects to be blurry while close objects appear normal
Desribe the neural pathway of the corneal reflex
Trigeminal primary afferent senses irritation via free nerve endings in the cornea (trigeminal nerve, ganglion, root, and spinal trigeminal tract), which end on secondary trigeminal afferents in the spinal trigeminal nucleus. Some of these send their axons to interneurons in the reticular formation which then send axons bilaterally to the facial morot neurons in the facial nucleus, which then send facial nerve axons to the obicularis occuli to lower the eye lid (blink)
What is presbyopia and who is most likley to be affected?
Presbyopia is a natural part of the aging process. It is due to hardening of the lens causing the eye to focus light behind rather than on the retina when looking at close objects. It is a type of refractive error along with nearsightedness, farsightedness, and astigmatism
What is dry macular degeneration?
Pigment epithelium and photoreceptors of macula die, leaving the retina thin and homogenous looking. Druen are a feature of this disease and are detectable well before any overt degeneration
What is wet macular degeneration?
Loss of vision in the centreal visual field occurs suddenly as a result of haemorrhage. The extrusion of blood cells into the retinal results in scar tissue formation and permanent loss of vision
List the 4 types of ganglion cells in the eye that send axons to the brain
1. Magnocellular (Parasol) 2. Parvocellular (Midget) 3. Koniocellular 4. Melanopsin-containing GCs
Where do axons of magnocellular (parasol) cells terminate?
In the LG and superior colliculus
What are parasol cells (magonocellular) responsible for?
Large, thick, fast conducting axons that get converging input from large numbers of photoreceptors and are sensitive to contrast, and movement in the periphery of the visual field
What are parvocellular (midget) cells responsible for?
Represent responses of individual cones in light frequencies of red/green range and encode fine detail and colour responses
Which ganglion cell type is responsible for detecting yellow/blue frequencies?
What is the pretectum responsible for?
Pupillary reflexes and coordination of eye movements
The optic tract takes ganglion cell axons to which 3 major structures?
Tectum, hypothalamus or thalamus
The superior colliculus plays what role in the visual system?
Sacacdic eye movements that orient the eyes towards stimulus and coordinates head and body reflexes to bring the external stimuli into the centre fo vision and onto foeva. Also provides input to medial longitudinal fasisculus to control neck muscles.
Which nucleus of the hypothalamus forms part of the visual system? Where does it get it's inputs from?
Suprachiasmatic nucleus, main input from melanopsin containing GCs (to regulate circadian rhythm)
Lesions to the suprachiasmatic nucleus of the hypothalamus have what effect?
Diruption of circadian rhythms and production of the pineal gland hormone melatonin
Layers 1 and 2 of the lateral geniculate nuclei receive information from ___ cells, whilst layers 3-6 get input from ___ celks
Magnocellular ganglion cells (parasol), parvocellular cells (midget)
The lateral geniculate nucleus relays information from the retina to area ___ of the cortex
17 - primary visual cortex
Describe the pattern of macular vision loss seen in a patient with a lesion rostral to the optic tract
Macula sparing due to pojections from geniculate being 'spread out' with a great many fibres originating from the macular region
Describe the pattern of vision loss in bitemporal hemianopia and comment on what sort of lesion could cause this
Loss of both temporal fields in each eye from lesion in the pituitary or optic chaism
The loop of Meyer in the visual system comprises fibres that represent the _____ visual field
Meyer's loop fibres loop around the ____ horn of the ____ ventricle
Anterior horn of lateral ventricle
What sort of vision loss would be likley if there was a lesion in the temporal lobe
Affect Meyer's loop (superior visual field) = causes vision loss in contralateral superior visual field
Describe the neural pathway of the direct and consensual pupillary reflexes
Light shone in the eye travels through the retina, optic nerve, optic chiasm, and the optic tract fibers. These fibres travel to the superior colliclus and terminate in the pretectal area of the midbrain. From here, most axons are sent bilaterally in the posterior commissure to the Edinger-Westphal nucleus of the occulomotor complex, which contains parasympathetic preganglionic neurons. Axons are sent to the occulomotor nerve to terminate in the ciliary gangion, which sends parasympathetic postganglionic axons in the short ciliary nerve, which ends on the iris sphincter. Because the optic tract carries visual information from both eyes and the pretectal area projects bilaterally to both Edinger-Westphal nuclei: the normal pupillary response to light is consensual. That is, a light directed in one eye results in constriction of the pupils of both eyes
What is a saccade?
A rapid movement of the eye between fixation points
What is the MLF and what does it do?
The medial longitudinal fasciculus carries information about the direction that the eyes should move. It connects the cranial nerve nuclei III (Oculomotor nerve), IV (Trochlear nerve) and VI (Abducens nerve) together, and integrates movements directed by the gaze centers (frontal eye field) and information about head movement (from cranial nerve VIII, Vestibulocochlear nerve). It is an integral component of saccadic eye movements as well as vestibulo-ocular and optokinetic reflexes.
What would be the result of a lesion of the MLF?
A lesion of the MLF produces slowed or absent adduction of the ipsilateral eye, usually associated with involuntary jerk eye movements (nystagmus) of the abducting eye, a syndrome called internuclear ophthalmoplegia
What is parallel processing? What does it mean in terms of the visual system?
Parallel processing is the ability of the brain to simultaneously process incoming stimuli of differing quality. Parallel processing becomes most important in vision, as the brain divides what it sees into four components: color, motion, shape, and depth
What is the functional significance of the pyramids?
Contain descending fibres from motor cortex
What is the functional significance of the pons?
Contains fibres that cross the midline to enter the cerebellum
What is the functional significance of the cerebral peduncles?
Contains descending fibres from all over the cortex, which terminate in the brainstem (corticobulbar) or spinal cord (corticospinal)
What is the functional significance of the mamillary bodies?
Part of the hypothalamus
What is the functional significance of the occulomotor nerve?
Supplies motor fibres to 4 out 6 extra ocular muscles, and includes parasympathetic fibres to the iris and ciliary body
What is the functional significance of the facial nerve?
Innervates muscles of facial expression
What is the functional significance of the trigeminal nerve?
Sensory nerve to the face
What is the functional significance of the thalamus?
All fibres on their way to cerebral neocortex pass through the thalamus.
What is the functional significance of the optic tract?
Carries axons from both eyes, that encode information from the opposite visual hemifield
What is the functional significance of the pineal gland?
Endocrine gland that regulates our circadian rhythms by releasing melatonin
What is the functional significance of the trochlear nerve?
Fourth cranial nerve which provides motor innervation to the superior oblique muscle
What is the functional significance of the superior colliculus?
Receives a mapped input from the retina, which guides reflexes responses to stimuli of auditory (e.g. scary sound), somatosensory (e.g.,creepy crawlies on the skin), or visual (e.g. ducking to avoid a fast moving /dangerous object coming towards you unexpectedly) origin
What is the functional significance of the dorsal columns?
Carry pressure and fine touch fibres from the body surface (proprioception)
What is the functional significance of the middle cerebellar peduncle?
Comprises the major descending input from cortex to cerebellum: cortico-pontine > ponto-cerebellar fibres
The lateral horn of the spinal cord is only present at which spinal cord levels?
What are the 3 divisions of CN V?
V1: ophthalmic division V2: Maxillary division V3: Mandibular division
What are the main functions of V1 (CN V)?
Ophthalmic division: sensory to upper face and eye, anterior nasal cavity and some sinuses
What are the main functions of V2 (CN V)?
Maxillary division: sensory to the middle face, maxillary sinus and nasopharynx
What are the main functions of V3 (CN V)?
Mandibular division: sensory to the lower face, motor supply to msucles of mastication
What are the main functions of CN VII (facial)?
Motor to muscles of facial expression. Parasympathetic/secretomotor supply to lacrimal, sublingual and submandibular glands. Taste (special sense) to anterior 2/3 of tongue
What are the main functions of CV VIII?
Vestibulocochlear: special senses hearing (cochlear) and balance (vestibular apparatus)
What are the main functions of CN X?
Vagus - Visceromotos fibres (from dorsal motor nucleus of vagus - parasympathetic) to heart and bronchi, digestive tract as far as the left colic flexure. Sensory to external acoustic meatus and part of auricle. Carries motor fibres to striated muscles of larynx and pharynx (derived from nucleus ambigulous via cranial accessory nerve)
What are the main functions of CN XII?
Hypoglossal: motor fibres to the intrinsic muscles of the tongue (four paired intrinsic muscles of the tongue originate and insert within the tongue, running along its length. They are the superior longitudinal muscle, the inferior longitudinal muscle, the vertical muscle, and the transverse muscle)
List the name of the nuclei, location and function of the occulomotor nerve
1. Motor nucleus at level of superior colliculus - controls SR, MR, IR and IO muscles of the eye. 2. Edinger Westphal nucleus at level of superior colliculus - controls ciliary and pupillary muscles
What ganglion serves the Edinger Westphal nucleus of the occulomotor nerve?
List the name of the nuclei, location and function of the trochelar nerve
Motor nucleus at level of inferior colliculus - controls the SO muscle
List the name of the nuclei, location and function of the trigeminal nerve
1. Motor nucleus at level of superior colliculus - pons: controls muscles of mastication, tensor vali palinitin, tensor tympani and anterior digastric 2. Principal V nucleus at the level of the pons: controls sensation (touch) to the face 3. Spinal V nucleus at the level of the medulla - upper spinal cord: controls sensation (pain and temperature) of the face 4. Mesencephalic nucleus at the level of the superior colliculus - upper pons: controls sensation (proprioception) of face
Which ganglion serves the Principal V and spinal V nuclei of the trigeminal nerve?
List the name of the nuclei, location and function of the abducens nerve
Motor nucleus at level of the pons - controls LR muscle of the eye
List the name of the nuclei, location and function of the facial nerve
1. Motor nucleus at lower pons - muscles of facial expression, stapedius, posterior digastric and stylohyoid 2. Super salivatory nucleus at lower pons - lacrimal, submandibular and sublingual glands 3. Solitary nucleus (taste) in medulla for taste to anterior 2/3 tongue 4. Spinal V nucleus in medulla - upper spinal cord for somatic sensation around the ear
Which ganglion serves the super salivatory nucleus of the facial nerve?
Pterygoipalatine and submandibular (parasympathetic)
Which ganglion serves the solitary nucleus and spinal V nucleus of the facial nerve?
List the name of the nuclei, location and function of the vestibulocochlear nerve
1. Superior, lateral, medial and inferior vestibular nuclei at the ponto-medullary junction for balance 2. Cochlear nucleu at the ponto-medullary junction for hearing
Which ganglion serves the vestibular nuclei of the vestibulocochlear nerve?
Which ganglion serves the cochelar nuclei of the vestibulocochlear nerve?
Spiral ganlgion (sensory)
Where are the rostral and caudal solitary nuclei of the glossopharyngeal nerve located, what ganglion are they served by, and what is the function of each?
Located within open and closed medulla and served by inferior ganglion of IX (in jugular foramen). Rostral is responsible for taste in the posterior 1/3 of tongue and caudal is responsible for baroreceptors and chemoreceptors (carotid)
List the 5 nuclei of the glossopharyngeal nerve
1. Solitary (rostral) 2. Solitary (caudal) 3. Spinal V 4. Nucleus ambigulous 5. Inferior salivary
Which ganglion serves the spinal V nucleus of the glossopharyngeal nerve?
Superior ganglion of IX (in jugular foramen)
Which ganglion serves the inferior salivatory nucleus of the glossopharyngeal nerve?
Where is the spinal V nuclei of the glossopharyngeal nerve located and what is it's function?
Medulla - upper spinal cord, responsible for somatic sensation behind auricle of ear
Where is the nucleus ambiguous of the glossopharyngeal nerve located and what is it's function?
Open and closed medulla - responsible for branchiomeric muscles of the pharynx and larynx
Where is the inferior salivatory nucleus of the glossopharyngeal nerve located and what is it's function?
Open medulla and responsible for action of parotid gland
List the name of the nuclei, location and function of the vagus nerve
1. Dorsal motor nucleus of X in open medulla - thoracic and abdominal organs (visceral afferent) 2. Spinal V nucleus in medulla - upper spinal cord for somatic sensation to external ear, external auditory canal, external surface of tympanic membrane 3. Solitary nucleus in open and closed medualla for taste (epiglottis); pharynx, larynx, trachea, esophagus, thoracic and abdominal viscera (visceral afferent)
Which ganglion serves the dorsal motor nucleus of X (vagus)?
Walls of viscera (parasympathetic)
Which ganglion serves the Spinal V nucleus of the vagus nerve?
Superior ganglion of X (in jugular foramen)
Which ganglion serves the solitary nucleus of the vagus nerve?
Inferior ganglion of X (in jugular foramen)
List the name of the nuclei, location and function of the accessory nerve (cranial)
Nucleus ambiguous in open and closed medulla - responsible for intrinsic muscles of the larynx
List the name of the nuclei, location and function of the hypoglossal nerve
XII motor nucleus in open and closed medulla - responsible for muscles of the tongue except that palatoglossus
The hypoglossal nerve is responsible for all muscles of the tongue EXCEPT for which one?
What are the main functions of the medulla?
contains theÊcardiac,Êrespiratory,ÊvomitingÊandÊvasomotorÊcenters and therefore deals with the autonomic functions ofbreathing,Êheart rateÊandÊblood pressure
What are the open and closed parts of the medulla?
Superior part is openÊwhere the dorsal surface is formed by theÊfourth ventricle (creates the caudal half of the rhomboid fossa (floor of the 4th ventricle). The inferior part is closed, where the fourth ventricle has narrowed and surrounds part of theÊcentral canal.
Describe the location of the tectum
On the dorsal surface of the midbrain
Which CNs exit from the midbrain?
III (occulomotor) and IV (trochlear). Note that the trochlear nerve is the only nerve to exit dorsally from the brainstem
Which CNs exit from the pons?
V (trigeminal), VI (abducens) and VII (facial)
Which CNs exit from the medulla?
VIII (vestibulocochlear), IX (glossopharyngeal), X (vagus) and XII (hypoglossal)
What is the clivus, and what brain structure is it closely related with?
part of theÊcraniumÊat the skull base, a shallow depression behind theÊdorsum sell¾Êthat slopes obliquely backward. The pons sits on the clivus.
What is the sella turcica, and what brain structure is it closely related with?
a depression in the sphenoid bone, containing the pituitary gland
What is the optic groove (chiasmatic groove), and what brain structure is it closely related with?
Ridge on the superior body of the sphenoid that forms the anterior border of a narrow, transverse groove, theÊchiasmatic groove, above and behind which lies theÊoptic chiasmaÊof cranial nerve 2 (the optic nerve)
Consider CNI: What is the site of nerve attachment and the site of exit from the skull?
Olfactory bulb; cribiform plate
Consider CNII: What is the site of nerve attachment and the site of exit from the skull?
Lateral geniculate nucleus (thalamus) and midbrain; optic canal
Consider CNIII: What is the site of nerve attachment and the site of exit from the skull?
Interpeduncular fossa; superior orbital fissure
Consider CNIV: What is the site of nerve attachment and the site of exit from the skull?
Midbrain tectum inferior to inferior colliculus; superior orbital fissure
Consider CNV: What is the site of nerve attachment and the site of exit from the skull?
Lateral margin of the mid-pons; V1 exits at superior orbital fissure, V2 exits at foramen rotundum and V3 exits at foramen ovale
Consider CNVI: What is the site of nerve attachment and the site of exit from the skull?
Medial edge of pontomedullary sulcus; superior orbital fissure
Consider CNVII: What is the site of nerve attachment and the site of exit from the skull?
Lateral edge of pontomedullary sulcus; internal acoustic meatus
Consider CNVIII: What is the site of nerve attachment and the site of exit from the skull?
Lateral edge of pontomedullary sulcus (lateral to CN VII); internal acoustic meatus
Consider CNIX: What is the site of nerve attachment and the site of exit from the skull?
Lateral to the olive of the medulla; jugular foramen
Consider CNX: What is the site of nerve attachment and the site of exit from the skull?
Lateral to the olive of the medulla; jugular foramen
Consider CNXI: What is the site of nerve attachment and the site of exit from the skull?
Lateral surface of the upper vercial spinal cord; jugular foramen
Consider CNXII: What is the site of nerve attachment and the site of exit from the skull?
Between pyramid and olive of medulla; hypoglossa canal
Which 3 CNs exit the skull through the superior orbital fissure?
III, IV and V1
Which 2 CNs exit the skull thorugh the interal acoustic meatus?
VII and VIII
Which 3 CNs exit the skull through the jugular foramen?
IX, X, XI
Describe where the first, second and third order neurons of themedial lemniscal pathway (dorsal column system) arise and synapse
First-order neurons reside in dorsal root ganglia and send their axons through theÊfasciculusÊgracilis andÊcuneatous. The first-order axons make contact with second order neurons at the gracilis and cuneate nuclei in the lowerÊ(closed) medulla. The second-order neurons send their axons to theÊthalamus. The third order neurons arise from thalamus to the postcentral gyrus
Fibres from which other nerve join with the dorsal column system information is it travels upwards as the medial lemniscus?
Fibres from the trigeminal nerve
Describe where the first, second and third order neurons of the spinothalamic pathways arise and synapse
First order have cell bodies in dorsal root ganglion and synapses in dorsal root of spinal cord on the ipsilateral side. Second order neurons cross the cord and send fibres upward to synpase in the thalamus. Third order neurons are sent up to the somatosensory cortex in the post-central gyrus
What information do the spinocerebellar tracts convey?
information to the cerebellum about length and tension of muscle fibers (i.e., unconscious proprioceptive sensation)
The dorsal spinocerebellar tracts carries information from which receptor types?
Muscle spindles and golgi tendon organs (i.e., information about skeletal muscle and joint proprioception)
Briefly describe the dorsal spinocerebellar tract
Proprioceptive information is taken to the spinal cord via dorsal root gangliaÊ(first order neurons). Central processes travel through theÊdorsal horn, where they synapse with second order neurons ofÊClarke's nucleus. Fibres from Clarke's Nucleus convey information in the spinal cord in the peripheral region of theÊfuniculus posteriorÊipsilaterally. The fibers continue to course through the medulla oblongataÊand theÊponsÊof theÊbrainstem, at which point they pass through theÊinferior cerebellar peduncleÊand into the cerebellum. This tract involves twoÊneuronsÊand ends up on the same side of the body
What information do the dorsal spinocerebellar and cuneocerebellar tracts relay?
Both relay proprioceptive information, but the former is more concerned with forearm, trunk and lower limb, which cuneate is concerned with the arm
Vry briefly describe the ventral spinocerebellar tract
The ventral spinocerebellar tract will cross to the opposite side of the body first in the spinal cord as part of theÊanterior white commissureÊand then cross again to end in the cerebellum (referred to as a "double cross")
CSF is produced by the ____ lexuses, located in the ___ and ___ ventricles
Choroid, lateral and fourth
The anterior choroidal artery is a branch of the ____ artery, and enters the ____ horn of the lateral ventricle
Internal carotid, inferior horn
The anterior choroidal artery supplies the optic tract as far as which structure?
Dorsal lateral geniculate nulceus
The plexuses of each lateral ventricle are continuous with each other via which structure?
Intraventricular foramen (of Munro)
From the 4th ventricle, most CSF leaves the ventricular system via which 2 foramen? Where does the CSF then flow?
Luschka (lateral) and Magendie (medial). CSF then enters the subarachnoid cisterns that surround the cerebellum
List the 4 places that CSF flows after entering the cerebello-medullary cistern
1. Down and around the spinal cord 2. Anteriorly and up into the pontine and interpeduncular cisterns 3. Upwards and backwards around the cerebellum and into a cistern posterior to the midbrain 4. Around the tentorium cerebelli into the subarachnoid space of the middle and anterior cranial fossa