Physiology x Flashcards
How to assess for acessory nerve function
Should inspect the shoulders for loss of muscle bulk, ask the patient to shrug their shoulders against resistance, and turn their head against resistance
When is the ankle reflec delayed?
It is typically delayed in L5 and S1 disk prolapses.
What nerve roots does the ankle reflex test?
The ankle reflex is elicited by tapping the Achilles tendon with a tendon hammer. It tests the S1 and S2 nerve roots
The anterior interosseous nerve (volar interosseous nerve)
A branch of the median nerve that supplies the deep muscles on the front of the forearm, except the ulnar half of the flexor digitorum profundus.
Brachial artery journey
The brachial artery begins at the lower border of teres major as a continuation of the axillary artery. It terminates in the cubital fossa at the level of the neck of the radius by dividing into the radial and ulnar arteries
How is the brachial artery seperated from the median cubital vein?
In the cubital fossa it is separated from the median cubital vein by the bicipital aponeurosis.
Mamilliary body
Function is recollective memory. Memory information begins within the hippocampus. Theta waves activate CA3 neurons in the hippocampus. Information about memory transmits through the fornix to the mammillary bodies.
Anyglada function
The main job of the amygdala is to regulate emotions, such as fear and aggression. The amygdala is also involved in tying emotional meaning to our memories. reward processing, and decision-making.
What are the cavernous sinuses?
The cavernous sinuses are paired and are situated on the body of the sphenoid bone. It runs from the superior orbital fissure to the petrous temporal bone
Where is the common pernoeal nerve derived from?
Derived from the dorsal divisions of the sacral plexus (L4, L5, S1 and S2).
Common peroneal nerve functions
This nerve supplies the skin and fascia of the anterolateral surface of the leg and the dorsum of the foot. It also innervates the muscles of the anterior and peroneal compartments of the leg, extensor digitorum brevis as well as the knee, ankle and foot joints.
Branches of the common peroneal nerve in the thigh
Nerve to the short head of biceps Articular branch (knee)
Branches of the common peroneal nerve in the popliteal fossa
Lateral cutaneous nerve of the calf
Branches of the common peroneal nerve at the neck of fibula
Superficial and deep peroneal nerves
The cranial venous sinuses
The cranial venous sinuses are located within the dura mater. They have no valves which is important in the potential for spreading sepsis. They eventually drain into the internal jugular vein.
Occulomotor nerve palsy features
Ptosis
Eye down and out
Unable to move the eye superiorly, inferiorly, medially
Pupil fixed and dilated
Trochlear nerve palsy features
Vertical diplopia (diplopia on descending the stairs) Unable to look down and in
Abducens nerve palsy features
Convergence of eyes in primary position
Lateral diplopia towards side of lesion
Eye deviates medially
Location of jugular and stylomastoid foramen
Temporal bone
Location of foramen magnum
Occipital bone
Location of Foramen ovale, spinosum, rotundum & lacerum
Sphenoid bone
Damage to what nerve causes a Trendelenberg gait?
Damage to the superior gluteal nerve will result in the patient developing a Trendelenberg gait
Superior gluteal nerve (L5, S1)
Gluteus medius
Gluteus minimis
Tensor fascia lata
Inferior gluteal nerve
Gluteus maximus
Ventromedial nucleus
Satiety centre. Lesions → hyperphagia
Paraventricular nucleus
Produces oxytocin + ADH. Lesions → diabetes insipidus
Supraoptic nucleus
Produces antidiuretic hormone (ADH). Lesions → diabetes insipidus
Suprachiasmatic nuclues
Regulars circadian rhythm
Septal nucleus
Regulates sexual desire
Posterior nucleus of hypothalamus
Heating (conservation and increased production) - damage results in poikilothermia
Stimulates sympathetic nervous system
Lateral nucleus of hypothalamus
Stimulation → increased appetite
Lesions → anorexia
Anterior nucleus of hypothalamus
Cooling by stimulation of parasympathetic nervous system
Long thoracic nerve injury
Winging of Scapula occurs in long thoracic nerve injury (most common) or from spinal accessory nerve injury (which denervates the trapezius) or a dorsal scapular nerve injury
Lumbar punctuure procedure
The supraspinous ligament which connects the tips of spinous processes and the interspinous ligaments between adjacent borders of spinous processes
Then the needle passes through the ligamentum flavum, which may cause a give as it is penetrated
A second give represents penetration of the needle through the dura mater into the subarachnoid space. Clear CSF should be obtained at this point
Median nerve motor supply in hand
Motor supply (LOAF)
Lateral 2 lumbricals
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis
Median merve sensory supply in hand
Over thumb and lateral 2 ½ fingers
Median nerve damage at wrist
carpal tunnel syndrome
paralysis and wasting of thenar eminence muscles and opponens pollicis (ape hand deformity)
sensory loss to palmar aspect of lateral (radial) 2 ½ fingers
The four infoldings of the dura mater
Falx cerebri: separates the cerebral hemispheres
Tentorium cerebelli: separates the occipital lobes from cerebellum
Falx cerebelli, vertical infolding: separates the cerebellar hemispheres
Diaphragma sellae: covers the pituitary gland and sella turcica
Musculocutaneous nerve innervations
Coracobrachialis
Biceps brachii
Brachialis
Knee reflex nerve roots
L3-L4
Biceps reflex nerve root
C5-C6
Triceps reflex nerve root
C7-C8
Lateral geniculate nucleus
visual signals
Medial geniculate nucleus
Auditory signals
Lateral portion of the ventral posterior nucleus of thalamus
Body sensation (touch, pain, proprioception, pressure, vibration)
Medial portion of the ventral posterior nucleus (VML) of thalamus
Facial sensation
What are the different nuclei of the thalamus?
Lateral geniculate nucleus
Medial geniculate nucleus
Medial portion of the ventral posterior nucleus (VML)
Ventral anterior/lateral nuclei
Lateral portion of the ventral posterior nucleus
Features or Wernicke’s encephalopathy
nystagmus (the most common ocular sign) ophthalmoplegia ataxia confusion, altered GCS peripheral sensory neuropathy
Wallerian degenaeration
Is the process that occurs when a nerve is cut or crushed.
- It occurs when the part of the axon separated from the neuron’s cell nucleus degenerates.
- It usually begins 24 hours following neuronal injury and the distal axon remains excitable up until this time.
Triptans
Triptans are specific 5-HT1B and 5-HT1D agonists used in the acute treatment of migraine. They are generally used first-line in combination therapy with an NSAID or paracetamol
Triptans side effects
triptan sensations’ - tingling, heat, tightness (e.g. throat and chest), heaviness, pressure
Triptans contraindications
patients with a history of, or significant risk factors for, ischaemic heart disease or cerebrovascular disease
Clinical presentation of neurogenic Thoracic outlet syndrome
painless muscle wasting of hand muscles, with patients complaining of hand weakness e.g. grasping
sensory symptoms such as numbness and tingling may be present
if autonomic nerves are involved, the patient may experience cold hands, blanching or swelling
Clinical presentation of vascular Thoracic outlet syndrome
subclavian vein compression leads to painful diffuse arm swelling with distended veins
subclavian artery compression leads to painful arm claudication and in severe cases, ulceration and gangrene
Subacute combined degeneration of spinal cord
due to vitamin B12 deficiency
dorsal columns + lateral corticospinal tracts are affected
joint position and vibration sense lost first then distal paraesthesia
upper motor neuron signs typically develop in the legs, classically extensor plantars, brisk knee reflexes, absent ankle jerks
if untreated stiffness and weakness persist
Syringomyelia features
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Flacid paresis (typically affecting the intrinsic hand muscles)
2. Loss of pain and temperature sensation
Anterior spinal artery occlusion
- Bilateral spastic paresis
2. Bilateral loss of pain and temperature sensation
Friedrich’s ataxia
- Bilateral spastic paresis
- Bilateral loss of proprioception and vibration sensation
- Bilateral limb ataxia
In addition cerebellar ataxia → other features e.g. intention tremor
Features of sciatic nerve lesion
motor: paralysis of knee flexion and all movements below knee
sensory: loss below knee
reflexes: ankle + plantar lost, knee jerk intact
Pathway of pupillary light reflex
afferent: retina → optic nerve → lateral geniculate body → midbrain
efferent: Edinger-Westphal nucleus (midbrain) → oculomotor nerve
A relative afferent pupillary defect
Is found by the ‘swinging light test’. It is caused by a lesion anterior to the optic chiasm i.e. optic nerve or retina
When the test is performed in an eye with an afferent pupillary defect, light directed in the affected eye will cause only mild constriction of both pupils while light in the unaffected eye will cause a normal constriction of both pupils (due to an intact efferent path, and an intact consensual pupillary reflex).
Progressive supranuclear palsy features
postural instability and falls
patients tend to have a stiff, broad-based gait
impairment of vertical gaze (down gaze worse than up gaze - patients may complain of difficultly reading or descending stairs)
parkinsonism
bradykinesia is prominent
cognitive impairment
primarily frontal lobe dysfunction
Internuclear ophthalmoplegia features
Features
impaired adduction of the eye on the same side as the lesion
horizontal nystagmus of the abducting eye on the contralateral side
Internuclear ophthalmoplegia cause
due to a lesion in the medial longitudinal fasciculus (MLF)
controls horizontal eye movements by interconnecting the IIIrd, IVth and VIth cranial nuclei
located in the paramedian area of the midbrain and pons
Miller Fisher syndrome
variant of Guillain-Barre syndrome
associated with ophthalmoplegia, areflexia and ataxia. The eye muscles are typically affected first
usually presents as a descending paralysis rather than ascending as seen in other forms of Guillain-Barre syndrome
anti-GQ1b antibodies are present in 90% of cases
Ethosuximide
Ethosuximide is an antiepileptic that is particularly indicated in patients with absence seizures
Ethosuximide mechanism of action
blocks T-type calcium channels in thalamic neurons
Enpty sella features
headaches
hypertension
rhinorrhoea
Empty sella
pituitary gland is flattened and on the posterior aspect of the sella turcica
cause unknown
more common in multiparous obese women
Chorioretinitis causes
syphilis cytomegalovirus toxoplasmosis sarcoidosis tuberculosis
Cerebellar syndrome/diseases causes
Friedreich's ataxia, ataxic telangiectasia neoplastic: cerebellar haemangioma stroke alcohol multiple sclerosis hypothyroidism drugs: phenytoin, lead poisoning paraneoplastic e.g. secondary to lung cancer
Cerebellar syndrome/disease features
D - Dysdiadochokinesia, Dysmetria (past-pointing), patients may appear ‘Drunk’
A - Ataxia (limb, truncal)
N - Nystamus (horizontal = ipsilateral hemisphere)
I - Intention tremour
S - Slurred staccato speech, Scanning dysarthria
H - Hypotonia
Frontal lobes lesions
expressive (Broca's) aphasia disinhibition perseveration anosmia inability to generate a list
Temporal lobe lesions
Wernicke’s aphasia
superior homonymous quadrantanopia
auditory agnosia
prosopagnosia (difficulty recognising faces
Parietal lobe lesions
sensory inattention apraxias astereognosis (tactile agnosia) inferior homonymous quadrantanopia Gerstmann's syndrome (lesion of dominant parietal): alexia, acalculia, finger agnosia and right-left disorientation
