Week 5 Flashcards
Approximately how big are lymph nodes?
<0.5cm in length
In which position is it best to feel for a patient’s lymph nodes in the head/neck?
Standing behind the patient using both hands to lightly palpate
How can the areas draining to the upper and lower lymph nodes of the head/neck be distinguished?
Imaginary line from the medial aspect of the eye to the angle of the mandible
Why might the occipital lymph nodes become enlarged?
Head lice infection
What is the location of the submental lymph nodes and what areas do they drain?
Under the chin
Tip of the tongue, anterior floor of the mouth, lower lip, incisors
What is the location of the submandibular lymph nodes and what areas do they drain?
Medial side of mandible, close to submandibular gland
Most of the mouth, nasal cavity, maxillary sinus, skin of the face
What is the location of the parotid/pre-auricular lymph nodes and what areas do they drain?
Surface of parotid gland, in front of the ear
Upper face, forehead, scalp
What is the location of the posterior auricular lymph nodes and what areas do they drain?
Behind the ear
Scalp behind the ear
What is the location of the occipital lymph nodes and what areas do they drain?
Upper neck
Posterior scalp
What is the location of the deep cervical lymph nodes and what areas do they drain?
In line with internal jugular vein in the neck
Other nodes, thyroid gland, larynx, posterior tongue, pharynx, inner ear
What is the location of the superficial cervical lymph nodes and what areas do they drain?
Posterior triangle
Local skin
What is the location of the jugulo-digastric lymph nodes and what areas do they drain?
Where digastric muscle crosses internal jugular vein
Palatine tonsil
What is the location of the jugulo-omohyoid lymph nodes and what areas do they drain?
Where omohyoid muscle crosses internal jugular vein
Lingual tonsil
What is the location of the supraclavicular lymph nodes and what areas do they drain?
Posterior triangle, above clavicle
Lower neck, chest/thorax/upper abdomen (oesophagus and stomach)
What is the lymphatic drainage of the tongue?
Front - submental nodes
Back - deep cervical nodes
What is the lymphatic drainage of the maxillary sinus?
Submandibular nodes
What is the lymphatic drainage of the pharynx and larynx?
Deep cervical nodes
What is the lymphatic drainage of the palatine tonsil?
Jugulo-digastric node
What is the lymphatic drainage of the lingual tonsil?
Jugulo-omohyoid node
What are the features, attachments and function of the digastric muscle?
2 bellies with central tendon
Attached to hyoid bone via fascia and posterior belly to mastoid process
Lifts hyoid bone, opens the mouth
What are the features, attachments and function of the omohyoid muscle?
2 bellies with central tendon
Attached to clavicle via fascia and posterior bell to scapula
What infections affect the lymphatic system itself?
Glandular fever
Lymphoma
Which cartilage in the neck is the only complete ring?
Cricoid cartilage
What type of cartilage are thyroid, cricoid and arytenoid cartilage?
Hyaline cartilage
What parts of the body are elastic cartilage?
Pinna of the ear
Epiglottis
What is the vocal fold and where does it extend to?
Fold in the mucosa inside the larynx which contains elastic fibres at its core
Arises from arytenoid cartilage and spans towards thyroid cartilage at the laryngeal prominence
Where do thyroid and cricoid cartilage meet?
At the inferior horn of the thyroid cartilage - cricothyroid joint
What type of joint is the cricothyroid joint?
Synovial
What is the cricothyroid muscle and what is its function?
Small muscle from side of the cricoid cartilage to the thyroid cartilage
Contracts to pull thyroid cartilage slightly upwards towards cricoid cartilage with simultaneous rotation at the cricothyroid joint which causes laryngeal prominence to tilt forwards slightly, tensing the vocal cords to increase the pitch of the voice by increasing the frequency
Where is the cricothyroid ligament/membrane found?
Between thyroid cartilage and cricoid cartilage anteriorly (thicker at the front)
How is an emergency airway placed?
Needle inserted between cricoid cartilage and thyroid cartilage, through cricothyroid ligament
How is a planned/elective airway placed?
Horizontal incision along skin tension lines, push aside strap muscles, find isthmus of thyroid gland, clamp/divide/tie off gland, incision between 2nd/3rd/4th tracheal ring for ventilation tube
When placing an elective airway, why do surgeons avoid the 1st tracheal ring?
Risk of scar tissue and stricture formation
What important structure lies over the 2nd-4th tracheal rings?
Isthmus of the thyroid gland
What shape is the cricoid cartilage?
Signet ring - narrow at the front, wider at the back
How can aspiration of vomit be prevented clinically?
Pressing on cricoid (transcricoid pressure) closes lower pharynx to prevent vomit coming up
Which muscle attaches the back of the tongue to the hyoid bone?
Hypoglossus muscle
Which muscle attaches the side of the tongue to the mandible?
Genioglossus muscle
Which muscle attaches the top of the tongue to the styloid process?
Styloglossus muscle
Which nerve innervates all extrinsic muscles of the tongue (except palatoglossus)?
Hypoglossal nerve
Which nerve innervated the palatoglossus muscle?
Vagus nerve
Which extrinsic tongue muscle does the vagus nerve innervate?
Palatoglossus
Where might fish bones become lodged in the neck?
Piriform fossa
Vallecula
What is the glottis?
Part of the airway between the vocal folds
Where is the sinus/ventricle of the larynx and what is its function?
Between vocal and vestigial folds
Provides mucus lubrication for vocal folds
What is the anatomical basis of a cough?
Irritation of larynx mucosa → vagal afferents → deep breath in, glottis closes, diaphragm relaxes, abdominal and pelvic floor muscles contract → vocal folds move apart → dislodgement of irritant
At what vertebral level is the cricoid cartilage?
C6
What is the function of the mylohyoid muscle?
Supports structures in the floor of the mouth and separates it from the submandibular region
What 2 factors prevent food from entering the larynx?
Epiglottis sphincter mechanism
Larynx moves up and forwards to meet epiglottis
Where does the parotid gland open in the mouth?
Next to the 2nd upper molar
Where does the submandibular gland open in the mouth?
Floor, under the front of the tongue
Where does the sublingual gland open in the mouth?
Floor
What are the intrinsic tongue muscles responsible for?
Changing the shape of the tongue
What are the extrinsic muscles of the tongue responsible for?
Tongue movement
What nerve provides sensation to the larynx?
Vagus nerve (recurrent laryngeal, internal and external branches of superior laryngeal)
At which vertebral level does the trachea bifurcate?
T4
Where would a muscle graft for the tongue be taken from?
Unattached - wrist (palmaris longus) or thigh
Attached - pectoralis or platysma
What is the function of a tracheostomy cuff?
Keeps the ventilation tube open and prevents blood/secretions entering the airway and air from escaping
What is the normal function of the tongue?
Move and taste food
Make and direct sound
What epithelium is present on the tongue?
Non-keratinised stratified squamous epithelium
What is the optic disc?
Optic nerve head - point of exit for ganglion cell axons leaving the eye; blind spot; no rods or cones overlying
What is the macula?
Functional central area of retina; 20/20 and best colour vision
What is the fovea?
Central part of macula (500 microns)
What cell type is found in the macula?
Cone photoreceptors
What is the blood supply of the macula?
None - dependent on choroid for O2 and metabolic support
What are the 2 types of age-related macular degeneration?
Exudative (wet)
Atrophic (dry)
What is the pathology in exudative age-related macular degeneration?
New blood vessels growing under retina from choroid; rapid, distorted vision
What is the pathology in atrophic age-related macular degeneration?
Atrophy of outer retina; slow, blurring
What is metamorphopsia?
Distorted vision
How is visual acuity recorded? Give examples
As the distance chart is read/distance at which it should be read
E.g. 6/6 - normal (reads at 6 metres what should be seen at 6)
6/12 - reads at 6 metres what should be seen at 12
How is visual acuity <6/60 tested?
Count fingers, hand motions, light perception
How do fundus fluorescein angiograms work?
Inject fluorescein intravenously; fluorescein bound to albumin (remains within normal capillaries because of blood-retinal barrier); use blue flash and yellow filter to see details of retinal circulation
What is optical coherence tomography and what images can be taken using it?
Low-powered laser interferometry
Generates detailed cross-sectional image of retina
How does AMD lead to blindness?
Blood vessels and scar tissue grow under retina → leaking vessels cause retinal oedema → block transport of O2 and nutrients from choroid → eventual scarring causes destruction of photoreceptors
How is AMD initiated?
Photoreceptors continue to produce photosensitive pigment throughout life → ends of photoreceptor cells decay and are removed by retinal pigment epithelium → end products accumulate, causing drusen
What are drusen?
Yellow deposits under the retina made up of lipids
What are the major risk factors for AMD?
Smoking Age (>70) Diet Family history Genetics
How is diet implicated in AMD?
High doses of vitamin A and C and zinc may be protective
What genetic components are implicated in AMD?
Polymorphisms in complement factor H gene strongly linked (7.4x increased risk)
Complement genes (CFB, CF1, C2 and C3)
Lipids (genes for HDL and LDL)
Extracellular matrix (collagen and matrix metalloproteinase)
What is the normal function of complement factor H?
Regulates inflammation, prevents complement-mediated attack on own cells
What pathological changes are seen in AMD?
Thickening and elevation of macula Retinal distortion Intraretinal haemorrhage Intraretinal fluid Subretinal haemorrhage Choroidal neovascularisation
What treatments are available for AMD?
Anti-VEGF drugs – ranibizumab, bevacizumab, aflibercept
What is VEGF?
Vascular endothelial growth factor
Up-regulation of VEGF promotes growth of new vessels
How are anti-VEGF drugs administered?
Given locally via intra-vitreal injections, sterile procedure, needs clean room, repeated monthly for three doses (then as required)
What is the IVAN trial and what were its findings?
Comparison of ranibizumab (expensive, monthly) and bevacizumab (cheap, as required) - no major difference in efficacy at 12 months
Why is ranibizumab used instead of bevacizumab despite it being more expensive and inconvenient?
Bevacizumab is not licensed
What are the major causes of blindness/visual impairment?
Cataract Glaucoma AMD Corneal scarring Diabetic retinopathy
What is the psychosocial impact of blindness/visual impairment?
Economic (unable to work, increased care, health risks)
Loss of independence (domestic, shopping, finance, navigation)
Communication (hearing impairment, non-verbal, social interaction, TV/film/media)
Social/psychological (increased isolation, anxiety, depression)
What can peripheral neuropathy lead to?
Selective proprioceptive loss
What is the consequence of selective large fibre sensory neuronopathy?
No sensory feed-back from muscle, skin or joint from below the neck
What is proprioception?
Signals contributing to conscious and subconscious mechanisms of motor control
What is position sense?
Conscious awareness of the relative positions of our body parts in space
What is kinaesthesia?
Sense of movement, speed of movement, direction of movement (heaviness or sense of effort)
What receptors provide important proprioceptive signals?
Joint receptors
Cutaneous receptors
Golgi tendon organ receptors
Muscle spindle receptors
What joint receptors are slowly adapting?
Type I - Ruffini endings
Type III - Golgi endings
Type IV - free nerve endings
What joint receptors are rapidly adapting?
Type II - Panciniform endings
What sensory endings do muscle spindles have and what do they respond to?
Primary and secondary
Both respond to stretch of the muscle and signal changes in length
Primary ending also has high dynamic sensitivity and responds to changing length and tapping/vibrating
What do primary endings of muscle spindles respond to?
Muscle stretch
Changing length, tapping, vibrating
What muscle efferent (motor) axons are there?
α - skeletomotor
γ - fusimotor
What muscle afferent (sensory) axons are there?
Ia - muscle spindle (primary)
Ib - tendon organ
II - muscle spindle (secondary)
III - pressure/pain receptors
What cutaneous afferent axons are there?
II - touch, temperature
III - pain, temperature
What is the maximum conduction velocity of sensory axons in humans?
87 m/s
What is Hursh’s conversion factor?
total fibre diameter in μm
What is the relation between fibre diameter and conduction velocity for large myelinated fibres?
6
What is the relation between fibre diameter and conduction velocity for small myelinated fibres?
4.5
What constitutes the total diameter of a fibre?
Diameter of axon plus myelin sheath
What descending pathway is activated in transcranial magnetic stimulation?
Corticospinal
What principle is used by transcranial magnetic stimulation?
Electromagnetic induction
Briefly outline the process of TMS
Magnetic stimuli applied to motor cortex → activation of descending motor pathway (corticospinal tract) → magnetic field produced within cortex which leads to current flow (electromagnetic induction) → APs produced in pyramidal neurons with long axons to spinal cord → connect directly/indirectly with motoneurons → twitch contractions are elicited in skeletal muscles
How is TMS being researched for therapeutic use?
Repetitive rhythmic TMS (rTMS) for depression and stroke
What are platinum grid array electrodes used for?
Seizure monitoring and brain mapping on subdural cortical surfaces in conscious patients
What happens to proprioception when the tendon is vibrated?
Impaired
What is a muscle twitch?
Brief contraction
How can muscle contraction be controlled?
Adjustment of number of motor axons firing at any one time - recruitment
Varying frequency of action potentials in motor axons - summation
At what stimulation interval is intracellular calcium able to revert to baseline levels, maintaining separate muscle twitches?
200ms
At what stimulation interval is intracellular calcium unable to revert to baseline levels, causing a stronger contraction due to summation?
200-75ms
At what stimulation interval is intracellular calcium unable to revert to baseline levels and relaxation prevented, causing tetany?
<75ms
What muscles are responsible for movement of the thumb towards the fingers?
Adductor pollicus
Flexor muscles of thumb
What muscles are responsible for bending of the wrist?
Flexor carpi radialis and ulnaris
What muscles are responsible for movement of all fingers and pulling of thumb towards index finger? What nerve innervates these?
Intrinsic hand muscles
Ulnar nerve
Fell asleep with hand over the back of a chair. Numbness in the back of the hand and weakness of the wrist. Wrist drop. Weakness of wrist and finger extension. Sensory loss over the radial aspect of the posterior surface of the hand and the posterior surface of the forearm. What is the diagnosis?
Saturday night palsy
What nerve is affected in Saturday night palsy and how?
Radial
Nerve becomes compressed in radial groove/spiral groove of humerus
What nerves can be injured by compression?
Sciatic nerve - disc prolapse
Median nerve - carpal tunnel syndrome
