Formative Flashcards
In strict order from superficial to deep, name the main layers of the skin
Epidermis
Dermis
Hypodermis
In which layer/s of skin are the following normally found:
i) Melanocytes?
ii) Coiled Secretory Portion of Sweat Glands?
iii) Blood Vessels?
i) Melanocytes are found in the epidermis
ii) Sweat Glands are found in the hypodermis
iii) Blood Vessels are found both in the hypodermis and dermis
i)What is the sensory innervation of the lower lip? ii) What is the motor innervation of muscles of the lower lip?
i) Mental Branch of the Mandibular Division of the Trigeminal Nerve
ii) The Mandibular Branch of the Motor Root of the Facial Nerve
The NF infection spreads to involve the deeper layers, but remains confined to the outermost cervical fascial plane.
i) Name the outermost layer of cervical fascia.
iv) Name any 1 anatomical structure derived from:
a) Mesenchyme and
b) Somites
likely to be destroyed by this infection
i) Superficial cervical fascia
iia) Blood vessels
iib) Platysma ( Will accept orbicularis oris/ other lower lip muscles)
Apart from nerve supply, state the key difference between muscles of facial expression and other skeletal muscles
The face is lacking in deep fascia. Thus, muscles of the face insert directly into skin, meaning that when they contract this results in changes of facial expression.
Other skeletal muscles do not insert into skin.
What is the definition of a motor unit?
It is the combination of a motor nerve and all muscle fibres it supplies.
Name 1 most likely source of clicks of noise in this case of middle ear myoclonus?
Tensor tympani
Stapedius
Tensor veli palatine (Possible, but less likely)
What key observation is the doctor likely to have seen on examining this patient’s ears, leading to the diagnosis of middle ear myoclonus?
Spontaneous movements of the tympanic membrane in response to myclonic contractions of middle ear muscles.
i) What general strategy would you suggest in the treatment of middle ear myoclonus in such a case?
ii) Suggest a drug or substance that might be administered to control this patient’s problem.
ia) Paralyse the muscle(s) undergoing the myoclonus
ib) Cut the middle ear muscles causing the discomfort.
ii) a) Botulinum toxin injected into the muscle undergoing the myclonus. This is the preferred substance of choice owing to the fact that it exerts its actions over a long term. (1 mark)
ii) a) Any muscle relaxant . (Example such as tubocurarine or succinyl choline injected directly into the muscle undergoing the myclonus. Not to forget that Muscle relaxants work only for short periods
What is i) the stapedius reflex and ii) the function of a stapedius reflex?
i) Also known as the acoustic reflex, it is an involuntary muscle contraction that occurs in the middle ear in response to highintensity sound stimuli.
ii) The reflex is triggered by high intensity of noise energy reaching the ear. The reflex contraction of the muscle decreases transmission of vibrational energy to the cochlea, where it is converted into electrical impulses to be processed by the brain
Comment: Did you know of this reflex? Some of you may have only known that the function of the stapedius is to reduce the range of movement of tympanic membrane?
By what other common name is forward displacement of the eye known as?
Exophthalmos
Had this patient presented with bilateral proptosis, what
i) Conclusions would you draw about the underlying cause and
ii) State the most likely diagnosis.
i) Generalised systemic cause or disease
ii) Grave’s Disease
Comment: Only Grave’s disease causes exophthalmos; other causes of hyperthyroidism e.g. Toxic nodule etc. do not give eye signs
Apart from a tumor, what other pathologies may cause unilateral proptosis?
i) Retrobulbar haemorrhage
ii) Swelling of soft tissues of the orbit
Name any 2 risks of leaving severe proptosis untreated in a patient with a history such as that in this scenario
i) The eyelids will fail to close during sleep, leading to the cornea drying and therefore vulnerable to damage.
ii) The underlying cause of increased pressure within the orbit might lead to compression damage of the optic nerve, leading to blindness
iii) The underlying cause of increased pressure within the orbit might lead to compression of the central retinal artery which in turn would lead to ischemic damage of the retina, hence blindness due to retinal scarring
iv) The underlying cause of increased pressure within the orbit might lead to compression of the central retinal vein which in turn would lead to papilloedema, and venostasis (hence risk of central venous thrombosis) within the eye.
What is the most likely source of an orbital schwannoma as in this case?
A Schwannoma in the orbit would arise from Schwann cells of a typical peripheral nerve, most likely the ophthalmic division of the trigeminal nerve. Given that the optic nerve is embryologically a derivative of the central nervous system, its myelin sheaths would be derived from oligodendrocytes. Thus, the optic nerve will not be the source of the Schwannoma
On a diagram, shade the C8 dermatome
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Below is a picture of a vertebra implicated in brachialgia in this case scenario.
i) Identify its vertebral level & Justify your answer
ii) Label anatomical structures A-F;
iii) What anatomical structure is normally found in D?
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What is the most likely explanation for the patient experiencing C8 brachialgia?
Compression of the C8 Nerve Root at the level of the intervertebral foramen
