Flashcards in Formative Deck (45)
In strict order from superficial to deep, name the main layers of the skin
In which layer/s of skin are the following normally found:
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
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 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?
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
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?
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
What is the most likely explanation for the patient recently developing dysphagia consequent upon long-standing C8 brachialgia?
The mass responsible for lesioning the vertebral column in this patient is invading the vertebrae anteriorly, leading to compression of the pharynx, hence its irritation and resulting dysphagia
Name the boundaries of the anterior triangle of the neck.
Posteriorly-Anterior Border of Sternocleidomastoid
Superiorly-Inferior Border of Mandible
Define the term “shock” and briefly explain why it is likely to have occurred in this patient.
Failure to adequately perfuse tissues (1 Mark)
In this case shock has resulted from loss of circulating volume due to haemorrhage from the neck wound (likely damage to major arteries or veins
What bony structure is the carotid pulse palpated against?
Transverse process of C6 Vertebra (termed the carotid tubercle)
At what vertebral level does the common carotid artery bifurcate?
Outline the renal compensatory mechanisms in response to hypoperfusion
Increased production of rennin from JGA; conversion of angiotensinogen to AT1 by rennin; conversion of AT1 to AT2 by ACE
Vasoconstriction due to AT2
Retention of Na+ and water due to increased aldesterone secretion
Post-operatively the patient is moved to ITU where his clinical condition improves. He is examined by the surgical team who note that his tongue has deviated to the right.
Suggest what structure may have been damaged and explain how this has occurred.
Right hypoglossal nerve injury (1 mark; ½ mark only if Right not specified) Hypoglossal nerve curves around internal and external carotid arteries after exiting from hypoglossal canal. Damage to hypoglossal nerve may be directly as a result of the stab wound or as a result of subsequent surgery (1 mark)
Name 3 factors which affect wound healing after surgery
Patient Age Site of Wound Surgical Technique Wound infection Presence of haematoma Co-morbidities predisposing to reduced perfusion (e.g. diabetes) Nutritional State Etc
On examination, the doctor diagnosed infection of one of the right upper premolar teeth that had spread to the maxillary sinus
Name specifically; i) the cranial nerve and ii) specific branch that the dentist would have to anaesthetize before carrying out the treatment.
Maxillary division of the trigeminal nerve ii)
Superior alveolar nerve
Assuming the infected premolar/molar tooth was in the mandible,
Name specifically; i) the cranial nerve and ii) specific branch that the dentist would have to anaesthetize before carrying out the treatment.
Mandibular division of the trigeminal nerve iv) Inferior alveolar nerve
i) Explain the development of unilateral sinusitis in this patient.
ii) Why might treatment of this case of sinusitis be problematic?
iii) Account for the yellowish discharge through the nostrils on on bending the head in this case
The roots of the maxillary premolar/molar teeth project into the floor of the maxillary sinus (½ mark); infection from the root may perforate the bone and affect the sinus.(½ mark)
The yellowish discharge is that of puss from the infection accumulating within the maxillary sinus.
The maxillary sinus has a particular drainage problem that arises from the high location of its ostium (½ mark) is located on the medial wall of the maxilla. This ostium becomes easily blocked (½ mark) during maxillary congestion, meaning that drainage of puss will be slow.
Name the bony boundaries of the maxillary air- sinus
Superior -floor of the orbit Medial- lateral wall of the nasal cavity Lateral - body of maxilla Inferior - alveolar process of maxilla
i) What is the histological classification of the epithelium lining paranasal sinuses?
ii) Which type of nerves cause mucous secretion from the paranasal sinus mucosa?
iii) Name two sources of sensory nerve supply to the paranasal sinuses.
Pseudostratified ciliated columnar epithelium (½ mark) – do not accept respiratory epithelium – must state pseudostratified + (ciliated or columnar)
(ii) parasympathetic nerve fibres (½ mark)
(iii) Ophthalmic (½) and maxillary (½) division of the trigeminal nerve
His thyroid function tests show that he is hyperthyroid. Give 3 causes of hyperthyroidism
Toxic Multinodular Goitre
Name 4 histological features of normal thyroid tissue
Thyroid follicles (1/2 mark) are lined by simple cuboidal epithelium (1/2) which produces and secretes thyroid hormones (1/2 mark).Thyroid follicles are filled with a glycoprotein called thyroglobulin or thyroid colloid (1/2 mark).
Also C cells of the thyroid gland secrete calcitonin (1/2 mark)
Describe the arterial blood supply to the thyroid gland. (2 marks)
The thyroid has a rich supply from the paired superior and inferior thyroid arteries. The superior thyroid artery is the first branch of the external carotid (1 mark) and the inferior thyroid artery is the largest branch of the thyrocervical trunk (1 mark)
The thyoid ima artery, and accessory artery present in 10% of people may also contribute to this rich anastomosis
A small amount of post-operative bleeding in this patient may produce life-threatening airway compromise. Explain why this may occur, with reference to layers in the neck
This is because the thyroid and parathyroid glands along with the trachea are enclosed by the pretracheal layer of cervical fascia, which is relatively inelastic, thus a small haematoma in the thyroid may cause a large amount of compression over the trachea, causing airway obstruction (2 marks). This presents in the first 24 hours after surgery with stridor and respiratory distress and needs urgent decompression.
State the anatomical relations of the middle ear cavity
Anterior- Eustachian tube and internal carotid artery Inferior- Internal Jugular Vein Posterior- Mastoid Air-Cells Superior- Tegmen Tympanum Lateral Tympanic Membrane
Why might a patient cough on suctioning of the external acoustic meatus?
Suctioning the external auditory meatus in such a case activates endings of the vagus nerve leading to reflex coughing.
State the name of the reflex responsible for coughing in (B) above. (1/2 mark)
What nerves are responsible for this reflex? (1/2 mark)
This is the ear-cough reflex
Afferent Limb of the reflex - Auricular branch of the Vagus Nerve also know as Alderman’s nerve or Arnold’s nerve
Efferent limb of the reflex - The vagus nerve, superior laryngeal nerve and the phrenic nerve
Name 3 common micro-organisms which are responsible for causing otitis externa.
Name two bacteria which are commonly responsible for causing otitis media
The patient was informed that BRAO is often self-limiting in Susac’s syndrome and in his case, it was bilateral with a single branch of the artery affected in each of the eyes. Given this information, comment on the likelihood of blindness in this patient. (1mark)
The patient is likely to experience only visual field blindness but not complete blindness because arterial occlusion in this case occurred distally along the central retinal artery after it had divided to give rise to for branches. Retinal arterial occlusion in this case is limited to only one of the 4 branches of the central retinal artery, which is also commonly referred to as an end artery. Visual field deficits would be restricted only to those peripheral fields served by the patch of the retina supplied by the occluded branch of the retinal artery.
The patient reported seeing flashes of light and stars during episodes of migraine headaches. What is the explanation for this experience?
The patient’s headaches are likely to originate from irritation of the meninges of the brain (or blood vessels). Since the meninges of the brain continue to envelope the optic nerve, irritation of brain meninges would radiate to the meninges of the optic nerve which would in turn inadvertently trigger pathological action potentials in the optic nerve, thereby giving rise to flashes of light or stars.
i) In strict sequential order from inside-to-out, name the three connective tissue layers that envelope any typical peripheral nerve (11/2 marks). ii) Would you expect connective tissue envelopes of the optic nerve to be different from those you listed in i) above or not? Justify your answer 1/2 mark)
i)Endoneurium, perineurium, epineurium (1mark)
ii) The optic nerve is embryologically derived from brain tissue and is therefore not similar to a typical peripheral nerve. The optic nerve is therefore, attended by meninges for its connective tissue envelopes (1mark)
In this patient, sensorineural deafness resulted from damage to the cochlear itself. i) In which portion of the temporal bone is the cochlear found? (1 mark) ii) Name one other portion of the temporal bone and identify its clinical significance (1 mark)
i)Petrous part of the temporal bone (1mark)
ii) a) Mastoid process-contains mastoid air-cells b) Squamous process- is involved in the formation of the ptyerion c) Styloid process-the facial nerve is found within its vicinity d) Zygomatic process-its distal process forms one of the boundaries of the ocular orbit e) Tympanic process-it forms the opening of the acoustic meatus