Archive for the ‘Anatomy’ Category
The Brain
July 22nd, 2011 | 
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The Brain develops from five primordia. Later, as certain divisions become greatly enlarged, they overgrow other regions of the developing brain so that the adult brain, on a cursory inspection, presents only three divisions: the cerebral hemispheres, the cerebellum, and the brainstem. The largest portion of the adult brain is the cerebral hemispheres, which are generally responsible for analyzing sensory input, memory, learning, motor function, etc.
The cerebellum is generally responsible for coordination, balance, and influences on muscle. The brainstem, the third part, is responsible for many basic vital life functions such as heartbeat, breathing, blood pressure, etc. Additionally, all of the cranial nerves emanate from the brainstem.
Haemoptysis
Haemoptysis should always be taken seriously and patients should be placed under close observation and investigated. Only a very careful history can differentiate haemoptysis from haematemesis, oropharyngeal bleeding, or a posterior epistaxis, and sometimes it needs to be witnessed to be sure. Patients with haemoptysis will continue to expectorate blood for 24 h after the acute event.
Severe haemoptysis is an emergency — maintain a clear airway, as patients die of aspiration rather than exsanguination.
Common causes of haemoptysis
TB, bronchiectasis, mitral stenosis, carcinoma of the bronchus, acute pneumonia, pulmonary embolism (with infarction), acute bronchitis.
Other causes of haemoptysis
• Infections: lung abscess, parasitic disease (e.g. paragonimiasis), fungal disease (e.g. aspergillosis), pleuro-pulmonary amoebiasis, leptospirosis.
• Trauma: lung contusions, foreign body aspiration, post endotracheal intubation or following aggressive endotracheal suctioning.
• Diffuse pulmonary parenchymal disease: Goodpastures syndrome, Wegeners granulomatosis, systemic vasculitides.
• Cardiovascular disease: pulmonary oedema, pulmonary hypertension, aortic aneurysm.
• Bleeding tendency: sepsis, DIC, snake bite, haemorrhagic fevers.
Branchial cleft fistulas
Branchial cleft fistulas (BCF) originate from the 1st to 3rd branchial apparatus during embryogenesis
of the head and neck. Anomalies of the 2nd branchial cleft are by far the most commonly found. They can be
a cyst, a sinus tract or fistulas. Fistulas (or sinus tract if they end blindly) display themselves as small cutaneous opening along the anterior lower third border of the sternocleidomastoid muscle, communicates proximally with the tonsillar fossae, and can drain saliva or a mucoid secretion. Management consists of excision since inefficient drainage may lead to infection. I have found that dissection along the tract (up to the tonsillar fossa!) can be safely and easily accomplished after probing the tract with a small guide wire in-place. This will prevent injury to nerves, vessels and accomplish a pleasantly smaller scar. Occasionally a second stepladder incision in the neck will be required. 1st BCF are uncommon, located at the angle of the mandible, and communicating with the external auditory canal. They have a close association with the fascial nerve. 3rd BCF are very rare, run into the piriform sinus and may be a cause of acute thyroiditis or recurrent neck infections.
What is the most likely cause of the hypotension in this patient?
The hypotension in this patient is most likely due to the cumulative effects of the medications he has been given (morphine and NTG). The accumulation and potentiation of medications, especially in the elderly, is a common clinical problem in the acute care setting. The combination of morphine and NTG in this patient may have induced sufficient vasodilation to cause hypotension.
Bleeding is also a possible cause of the hypotension. The administration of IV heparin, aspirin, and platelet glycoprotein IIb-IIIa inhibitor agents may result in gastrointestinal bleeding and melanotic stools. The absence of jugular venous distention and a paradoxical pulse argues against tamponade, but these findings may be absent with vasodilation or volume depletion. A more worrisome possibility is hemorrhagic pericarditis, especially because a new friction rub is heard. If the hypotension does not resolve quickly with discontinuation of NTG and morphine, an echocardiogram is indicated to exclude cardiac tamponade.