Basic Sciences Flashcards
(118 cards)
1
Q
Where are sarcomas most likely to be found?
A
In the extremities
2
Q
What are sarcomas?
A
Malignant tumours fo mesenchymal origin.
3
Q
What are the origins of sarcomas? (3)
A
- Bone
- Soft tissue
- Malignant fibrous histocytoma - sarcoma that may arise in both soft tissues and bone
4
Q
Types of bone sarcoma? (3)
A
- Osteosarcoma.
- Ewings sarcoma (although non bony sites also recognised)
- Chondrosarcoma - originates from chondrycytes.
5
Q
Types of soft tissue sarcoma? (4)
A
- Liposarcoma (adipocytes)
- Rhabdomyosaroma (striated muscle)
- Leiomyosarcoma (smooth muscle)
- Synovial sarcomas (close to joints - cell fo origin not known, but NOT synovium)
6
Q
General clinical features of sarcomas? (4)
A
- Large (>5cm) soft tissue mass.
- Deep tissue location or intra muscular location.
- Rapid growth.
- Painful lump.
7
Q
Assessment of sarcomas?
A
Imaging of suspicious masses should utilise a combination fo MRI, CT and ultrasound.
Blind biopsy should not be performed prior to imaging and where required should be done in such a way that the biopsy tract can be subsequently included in any resection.
8
Q
Epidemiology of Ewings sarcoma? (3)
A
- Commoner in males.
- Incidence of 0.3/1,000,000
- Onset typically between 10-20 years.
9
Q
Commonest site of Ewings sarcoma?
A
Location by femoral diaphysis is commonest site.
10
Q
Histology of Ewings sarcoma?
A
Small round tumour.
11
Q
Management of Ewings sarcoma?
A
Blood borne metastasis is common and chemotherapy is often combined with surgery.
12
Q
Pathophysiology of osteosarcoma?
A
Mesenchymal cells with osteoblastic differentiation.
13
Q
Epidemiology of osteosarcoma? (4)
A
- 20% of all primary bone tumours.
- Incidence of 5/1,000,000
- Peak age 15-30.
- Commoner in males.
14
Q
Management of osteosarcoma?
A
Limb preserving surgery may be possible and many patients will receive chemotherapy.
15
Q
Origins of liposarcoma?
A
Adipocytes
16
Q
Epidemiology of liposarcoma? (3)
A
- Rare - 2.5/1,000,000.
- They are the most common soft tissue sarcoma.
- Affect older age group - usually >40 years of age.
17
Q
Pathophysiology of liposarcoma? (3)
A
- Located in deep locations such as retroperitoneum.
- May be well differentiated and thus slow growing although may undergo de-differentiation and disease progression.
- Many tumours will have a pseudocapsule that can misleadingly allow surgeons to feel that they can ‘shell out’ these lesions. In reality, tumour may invade at the edge of the pseudocapsule and result in local recurrence if this strategy is adopted.
18
Q
Management of liposarcoma?
A
Usually resistant to radiotherapy, although this is often used in a palliative setting.
19
Q
Pathology of malignant fibrous histiocytoma?
A
Tumour with large number of histiocytes.
Also described as undifferentated pleomorphic sarcoma NOS (i.e. cell of origin is not known).
20
Q
Subtypes of malignant fibrous histocytoma? (4)
A
- Storiform- pleomorphic (70%)
- Myxoid (less aggressive)
- Giant cell
- Inflammatory
21
Q
Management of malignant fibrous histiocytoma?
A
Treatment is usually with surgical resection and adjuvant radiotherapy as this reduces the likelihood of local recurrence.
22
Q
A 10 year old boy is admitted to the emergency department following a fall. On examination, there is deformity and swelling of the forearm. The ability to flex the fingers of the affected limb is impaired. However, there is no sensory impairment. Imaging confirms a displaced forearm fracture. Which of the nerves listed below is likely to have been affected?
A
Anterior interosseous nerve.
Forearm fractures may be complicated by neurovascular compromise. The anterior interosseous nerve may be affected. It has no sensory supply, so the defect is motor alone.
23
Q
Features of the anterior interosseous nerve?
A
- A branch of the median nerve that supplies the deep muscles of the front of the forearm - except the ulnar half of the flexor digitorum profundus.
- It accompanies the anterior interosseous artery along the anterior of the interosseous membrane of the forearm - in the interval between the flexor pollicis longus and flexor digitorum profundus, supplying the whole of the former and (most commonly) the radial half of the latter, and ending below in the pronator quadratus and wrist joint.
24
Q
Innervation of the anterior interosseous nerve? (3)
A
It classically innervates 2.5 muscles:
- Flexor pollicis longus
- Pronator quadratus
- Radial half of the flexor digitorum profundus (the lateral two out of the four tendons).
These muscles are in the deep level of the anterior compartment of the forearm.
25
Which nerve supplies the majority of the skin on the palmar aspect of the thumb?
Median nerve supplies the cutaneous sensation to this region.
26
Features of the median nerve?
Path of median nerve?
It is formed by the union of a lateral and medial root respectively from the lateral (C5,6,7) and medial (C8, T1) cords of the brachial plexus.
The medial root passes anterior to the third part of the axillary artery.
The nerve descends lateral to the brachial artery, crosses to its medial side (usually passing anterior to the artery).
It passes deep to the bicepital aponeurosis and the median cubital vein at the elbow.
It passes between the two heads of the pronator teres muscle and runs on the deep surface of the flexor digitorum superficialis (within its fascial sheath)
Near the wrist it becomes superficial between the tendons of flexor digitorum superficialis and flexor carpi radialis, deep to the palmaris longus tendon.
It passes deep to the flexor retinaculum to enter the palm, but lies anterior to the long flexor tendons within the carpal tunnel.
27
Upper arm branches of median nerve?
No branches, although the nerve commonly communicates with the musculocutaneous nerve.
28
Innervation of median nerve in forearm? (7)
1. Pronator teres.
2. Pronator quadratus.
3. Flexor carpi radialis.
4. Palmaris longus.
5. Flexor digitorum superficialis.
6. Flexor pollicis longus.
7. Flexor digitorum profundus (only the radial half)
29
Branch of median nerve in distal forearm?
Palmar cutaneous branch
30
Motor supply of median nerve in hand? (4)
LOAF
1. Lateral 2 lumbricals
2. Opponens pollicis
3. Abductor pollicis brevis
4. Flexor pollicis brevis
31
Sensory supple of median nerve in hand?
Over thumb and lateral 2.5 fingers.
On the palmar aspect this projects proximally, on the dorsal aspect only the distal regions are innervated with the radial enrve providing the more proximal cutaneous innervation.
32
Features of median nerve damage at wrist? (3)
1. Paralysis and wasting of thenar eminence muscles and opponens pollicis (ape hand deformity)
2. Sensory loss to palmar aspect of lateral (radial) 2.5 fingers.
E.g. carpal tunnel syndrome
33
Features of median nerve damage at elbow? (4)
Same as for damage at wrist:
1. Paralysis and wasting of thenar eminence muscles and opponens pollicis (ape hand deformity)
2. Sensory loss to palmar aspect of lateral (radial) 2.5 fingers.
ALSO:
1. Unable to pronate forearm.
2. Weak wrist flexion.
3. Ulnar deviation of wrist.
34
Features of damage to anterior interosseous nerve?
It is a branch of the median nerve. Leaves just below the elbow.
1. Results in loss of pronation of forearm and weakness of long flexors of thumb and index finger.
35
Which drug increases the rate of gastric emptying in the vagotomised stomach?
Erythromycin - it enhances gastric emptying by acting via the motilin receptor in the gut.
Vagotomy seriously compromises gastris emptying which is why either a pyloroplasty of a gastro-emterostomy is routinely performed at the same time.
Ondansetron slows gastric emptying slightly.
Metoclopramide increases the rate of gastric emptying but its effects are mediated via the vagus nerve.
36
Features of gastric emptying?
The stomach serves both a mechanical and immunological function. Solid and liquid are retained in the stomach during which time repeated peristalitic activity against a closed pyloric sphincter will cause fragmentation of food bolus material. Contact with gastric acid will help to neutralise any pathogens present.
The amount of time material spends in the stomach is related to its composition and volume.
The presence of amino acids and fat will all serve to delay gastric emptying.
37
Hormones with increase gastric emptying? (1)
1. Gastrin
38
Hormones which delay gastric emptying? (3)
1. Gastric inhibitory peptide.
2. Cholecytokinin.
3. Enteroglucagon.
39
Features of nervous system control of gastric emptying?
Neuronal stimuation of the stomach is mediated via the vagus and the parasympathetic nervous system will tend to favour an increase in gastric motility.
It is for this reason that individuals who have undergone truncal vagotomy will tend to routinely require either a pyloroplasty or gastro-enterostomy as they would otherwise have delayed gastric emptying.
40
Diseases affecting gastric emptying? (4)
1. Iatrogenic
2. Diabetic gastroparesis
3. Malignancies
4. COngenital hypertrophic pyloric stenosis
41
Features of iatrogenic causes affecting gastric emptying?
Gastric surgery can have profound effects on gastric emptying.
Any procedure that disrupts the vagus can cause delayed emptying.
Particularly true of vagotomy (but now rarely performed)
Surgeons are divided on the importance of vagal disruption that occurs during an oesophagectomy, some will routinely perform a pyloroplasty and others will not.
When a distal gastrectomy is performed, the type of anastemosis performed will impact on emptying. When a gastro-enterostomy is constructed, a posterior, retrocolic gastroenterostomy will empty better than an anterior one.
42
Features of diabetic gastroparesis affecting gastric emptying?
Predominantly due to neuropathy affecting the vagus nerve.
The stomach empties poorly and patients may have episodes of repeated and protracted vomiting.
Diagnosis is made by upper GI endoscopy and contrast studies, in some cases a radio nucleotide scan is needed to demonstrate the abnormality more clearly.
In treating these conditions, drugs such as metoclopramide will be less effective as they exert their effect via the vagus nerve. One of the few prokinetic drugs that do not work in this way is the antibiotic erythromycin.
43
Features of how malignancies can affect gastric emptying?
Obviously a distal gastric cancer may obstruct the pylorus and delay emptying.
In addition, malignancies of the pancreas may cause extrinsic compression of the duodenum and delay emptying.
Treatment in these cases is by gastric decompression using a wide bore nasogastric tube and insertion of a stent or, if that is not possible, by a surgical gastroenterostomy.
As a general rule gastroenterostomies constructed for bypass of malignancy are usually placed on the anterior wall of the stomach (in spite of the fact that they empty less well).
A Roux en Y bypass may also be undertaken, but the increased number of anastomoses for this, in malignant disease that is being palliated, is probably not justified.
44
Features of how congenital hypertrophic pyloric stenosis can affect gastric emptying?
This is typically a disease of infancy.
Most babies will present around 6 weeks of age with projectile non bile stained vomiting.
It has an incidence of 2.4 per 1000 live births and is more common in males.
Diagnosis is usually made by careful history and examination and a mass may be palpable in the epigastrium (often cited seldom felt!).
The most important diagnostic test is an ultrasound that usually demonstrates the hypertrophied pylorus.
Blood tests may reveal a hypochloraemic metabolic alkalosis if the vomiting is long standing.
Once the diagnosis is made the infant is resuscitated and a pyloromyotomy is performed (either open or laparoscopically).
Once treated there are no long term sequelae.
45
What branches of the brachial plexus form the median nerve?
It is formed by the union of a lateral and medial root respectively from the lateral (C5,6,7) and medial (C8, T1) cords of the brachial plexus.
46
What is the relationship between the median nerve and the axillary artery?
The medial root passes anterior to the third part of the axillary artery.
47
What is the relationship between the median nerve and the brachial artery?
The nerve descends lateral to the brachial artery, crosses to its medial side (usually passing anterior to the artery).
48
What is the path of the median nerve at the elbow?
It passes deep to the bicepital aponeurosis and the median cubital vein at the elbow.
49
What is the relationship between the median nerve and pronator teres?
It passes between the two heads of the pronator teres muscle and runs on the deep surface of the flexor digitorum superficialis (within its fascial sheath)
50
What is the relationship between the median nerve and flexor digitorum superficialis?
It passes between the two heads of the pronator teres muscle and runs on the deep surface of the flexor digitorum superficialis (within its fascial sheath)
51
What is the path of the median nerve in the wrist?
Near the wrist it becomes superficial between the tendons of flexor digitorum superficialis and flexor carpi radialis, deep to the palmaris longus tendon.
It passes deep to the flexor retinaculum to enter the palm, but lies anterior to the long flexor tendons within the carpal tunnel.
52
What is the lymph node drainage for the upper aspect of the vagina?
Interior illiac nodes
The lymph vessels from the superior aspect of the vagina join the internal and external iliac nodes.
Those from the inferior aspect of the vagina drain to the superficial inguinal nodes.
53
Which of the following structures is not transmitted by the jugular foramen?
1. Hypoglossal nerve.
2. Accessory nerve.
3. Internal jugular vein.
4. Inferior petrosal sinus.
5. Vagus nerve.
Hypoglossal nerve is not transmitted by the jugular foramen.
The contents of the jugular foramen:
Anterior: inferior petrosal sinus.
Intermediate: glossopharyngeal, vagus and accessory nerves.
Posterior: sigmoid sinus (becoming the internal jugular vein) and some meningeal branches from the occipital and ascending pharyngeal arteries.
54
What are the contents of the jugular foramen?
Anterior: inferior petrosal sinus.
Intermediate: glossopharyngeal, vagus and accessory nerves.
Posterior: sigmoid sinus (becoming the internal jugular vein) and some meningeal branches from the occipital and ascending pharyngeal arteries.
55
Where is the jugular foramen located?
Temporal bone
56
What are the contents of the foramen ovale? (5)
1. Otic ganglion
2. V3 (Mandibular nerve -3rd branch of trigeminal)
3. Accessory meningeal artery
4. Lesser petrosal nerve
5. Emissary veins
57
Where is the foramen ovale located?
Sphenoid bone
58
What are the contents of the foramen spinosum? (2)
1. Middle meningeal artery
| 2. Meningeal branch of the mandibular nerve
59
Where is the foramen spinosum located?
Sphenoid bone
60
What are the contents of the foramen rotundum? (1)
Maxillary nerve (V2)
61
WHere is the foramen rotundum located?
Sphenoid bone
62
What are the contents of the foramen lacerum/ carotid canal? (3)
1. Base of the medial pterygoid plate.
2. Internal carotid artery*
3. Nerve and artery of the pterygoid canal
*= In life the foramen lacerum is occluded by a cartilagenous plug. The ICA initially passes into the carotid canal which ascends superomedially to enter the cranial cavity through the foramen lacerum.
63
What are the contents of the foramen magnum? (3)
1. Anterior and posterior spinal arteries
2. Vertebral arteries
3. Medulla oblongata
64
Where is the foramen magnum located?
Occipital bone
65
What are the contents of the stylomastoid foramen? (2)
1. Stylomastoid artery
| 2. Facial nerve
66
What are the contents of the superior orbital fissure? (6)
1. Oculomotor nerve (III)
2. Recurrent meningeal artery
3. Trochlear nerve (IV)
4. Lacrimal, frontal and nasociliary branches of ophthalmic nerve (V1)
5. Abducens nerve (VI)
6. Superior ophthalmic vein
67
A 19 year old female is admitted with suspected meningitis. The House Officer is due to perform a lumbar puncture. What is the most likely structure first encountered when the needle is inserted?
Supraspinatus ligament
68
Why are lumbar punctures performed?
To obtain CSF fluid
69
At what level is a LP performed in adults?
L3/4 or L4/5
These levels are below the termination of the spinal cord at L1
70
What structures does the needle pass through when doing a LP? (3)
1. Suprapinatus ligament - which connects the tips of spinous processes and the interspinous ligaments between adjacent borders of spinous processes.
2. Ligamentum flavum, which may cause a give as it is penetrated.
3. A second give represents penetration of the needle through the dura mater into the subarachnoid space - clear CSF should be obtained at this point
71
Which of the following is not secreted by the parietal cells?
```
Hydrochloric acid
Mucus
Magnesium
Intrinsic factor
Calcium
```
Mucus
Chief of Pepsi Cola = Chief cells secrete PEPSInogen
72
What do parietal cells secrete? (5)
1. HCl
2. Calcium
3. Sodium
4. Magnesium
5. Intrinsic factor
73
What do chief cells secrete?
Pepsinogen
74
What do surface mucosal cells secrete? (2)
1. Mucus
| 2. Bicarbonate
75
What is the pH of gastric acid?
Around 2
76
How is the acidity of the stomach maintained?
H/K ATPase pump
As part of the process bicarbonate ions will be secreted into the surrounding vessels
Sodium and chloride ions are actively secreted from the parietal ell into the canaliculus. This sets up a negative potential across the membrane and as a result sodium and potassium ions diffuse across into the canaliculus.
Carbonic anhydrase forms carbonic acid which dissociates and the hydrogen ions formed by dissociation leave the cell via the H/K antiporter pump. At the same time sodium ions are actively absorbed. This leaves hydrogen and chloride ions in the canaliculus these mix and are secreted into the lumen of the oxyntic gland.
77
What are the three phases of gastric acid secretion?
1. Cephalic phase (smell/taste of food)
2. Gastric phase (distension of stomach)
3. Intestinal phase (food in duodenum)
78
What are the features of the cephalic phase of gastric acid secretion? (2)
30% acid production
Vagal cholinergic stimulation causing secretion of HCl and gastrin release from G cells
79
What are the features of the gastric phase of gastric acid secretion? (2)
60% acid production
Stomach distension/low H/ peptides causes gastrin release
80
What are the features of the intestinal phase of gastric acid production? (2)
10% acid production
High acidity/ distension/ hypertonic solutions in the duodenum inhibits gastric acid secretion via enterogastrones (CCK, secretin) and neural reflexes
81
What factors increase gastric acid production? (3)
1. Vagal nerve stumulation
2. Gastrin release
3. Histamine release (indirectly following gastrin release) from enterchromaffin like cells
82
What factors decrease gastric acid production? (3)
1. Somatostatin (inhibits histamine release)
2. Cholecytokinin
3. Secretin
83
What are the major hormones involved in food digestion? (5)
1. Gastrin
2. CCK
3. Secretin
4. VIP
5. Somatostatin
84
What is the source of gastrin?
G cells in the antrum of the stomach
85
What are the stimuli for gastrin production? (2)
1. Distension of the stomach
| 2. Extrinsic nerves
86
What factors inhibit gastrin production? (2)
1. Low antral pH
| 2. Somatostatin
87
What is the action of gastrin? (3)
1. Increases HCl, pepsinogen, and IF secretion.
2. Increases gastric motility
3. Trophic effect on gastric mucosa
88
What is the source of CCK?
I cells in upper small intestine
89
What is the stimulus for CCK production?
Partially digested proteins and triglycerides
90
What are the actions of CCK? (5)
1. Increases secretion of enzyme-rich fluid from pancreas.
2. Contraction of gallbladder and relaxation of sphincter of Oddi.
3. Decreases gastric emptying.
4. Trophic effect on pancreatic acinar cells.
5. Induces satiety.
91
What is the source of secretin?
S cells in upper small intestine
92
What are the stimuli for secretin production? (2)
1. Acidic chyme
| 2. Fatty acids
93
What are the actions of secretin? (3)
1. Increases secretion of bicarbonate rich fluid from pancreas and hepatic duct cells.
2. Decreases gastric acid secretion.
3. Trophic effect on pancreatic acinar cells.
94
What is the source of VIP? (2)
1. Small intestine
| 2. Pancreas
95
What is the stimulus for VIP production?
Neural
96
What are the actions of VIP? (2)
1. Stimulates secretion by pancreas and intestines
| 2. Inhibits acid and pepsinogen secretion
97
What is the source of somatostatin?
D cells in the pancreas and stomach
98
What are the stimuli for somatostatin production? 3)
1. Fat
2. Bile salts
3. Glucose
All in the intestinal lumen
99
What are the actions of somatostatin? (6)
1. Decreases acid and pepsin secretion.
2. Decreases gastrin secretion.
3. Decreases pancreatic enzyme secretion.
4. Decreases insulin and glucagon secretion.
5. Inhibits trophic effects of gastrin.
6. Stimulates gastric mucous production.
100
Which is the most important suspensory muscle of the duodenum?
Ligament of Trietz
101
Where is the ligament of Treves located?
Between the ileum and caecum
102
Features of the duodenum? (5)
1. The first and widest part of the small bowel.
2. Diameter of 4-5cm.
3. Its commencement is immediately distal to the pylorus and it runs for around 25cm where it becomes the jejunum at the region of the duodenojejunal flexure.
4. It has 4 parts: superior, descebding, horizontal and ascending. Of these, the horizontal is the longest segment.
5. The first 2-3cm of the superior duodenum are intraperitoneal, the remainder is largely retroperitoneal with the exception of the final 1-2cm.
103
Parts of the duodenum? (4)
1. Superior
2. Descending
3. Horizontal
4. Ascending
104
Longest segment of the duodenum?
Horizontal segment
105
Is the duodenum intraperitoneal or retroperitoneal?
The first 2-3cm of the superior duodenum are intraperitoneal.
The remainder is largely retroperitoneal, with the exception of the final 1-2cm.
106
What are the medial relations of the duodenum? (2)
1. Superior pancreatico-duodenal artery
| 2. Pancreatic head
107
What are the structures related to the descending duodenum?
Closely related to the commencement of the transverse colon which has little in the way of mesentary at this area.
108
What structures are posterior the duodenum?
Right kidney lies posterior to the descending duodenum.
109
What structures is the horizontal part of the duodenum related to? (5) (2)
The horizontal part passes transversely to the left with an upward deflection as it does so.
From right to left it crosses: in front of:
1. Right ureter
2. Right psoas major
3. Right gonadal vessels
4. IVC
It terminates anterior to the aorta.
Anteriorly, its relations include:
1. Superior mesenteric vessels
2. Root of the small bowel
110
What are the relations of the ascending part of the duodenum? (3) (3)
Ascending part runs to the left of the aorta and upwards to the level of L2.
Terminates by binding abruptly forwards at the duodenojejunal flexure.
Anteriorly:
1. Gives attachment to the root of the mesentery
2. Left kidney lies laterally
3. Uncinate process of the pancreas lies medially
Posteriorly:
1. Left sympathetic trunk
2. Left psoas major
3. Left gonasal vessels
111
What is the ligament of Trietz?
The suspensory muscle of the duodenum.
This is a fibromuscular band which blends with the musculature of the flexure and passes upwards deep to the pancreas to gain attachment to the right crus of the diaphragm.
112
A 45 year old motor cyclist sustains a tibial fracture and is noted to have anaesthesia of the web space between his first and second toes. Which nerve is most likely to be compromised?
Deep peroneal nerve.
THe deep peroneal nerve lies in the anterior muscular compartment of the lower leg and can be compromised by compartment syndrome affecting this area.
It provides cutaneous sensation to the first web space.
The superficial peroneal nerve provides more lateral cutaneous innervation.
113
What is the origin of the deep peroneal nerve?
From the common peroneal nerve, at the lateral aspect of the fibula, deep to peroneus longus.
114
What are the nerve root origns of the deep peroneal nerve?
L4, L5, S1, S2
115
Where does the deep peroneal nerve terminate?
In the dorsum of the foot.
116
What is the course of the deep peroneal nerve?
Pierces the anterior intermuscular septum to enter the anterior compartment of the lower leg.
Passes anteriorly down to the ankle joint, midway between the two malleoli.
After its bifurcation past the ankle joint, the lateral branch of the deep peroneal nerve innervates the extensor digitorum brevis and the extensor hallucis brevis.
THe medial branch supplies the web space between the first and second digits.
117
What muscles are innervated by the deep peroneal nerve? (5)
1. Tibialis anterior.
2. Extensor hallucis longus
3. Extensor digitorum longus
4. Peroneous tertius
5. Extensor digitorum brevis
118
What are the actions of the deep peroneal nerve? (3)
1. Dorsiflexion of ankle joint.
2. Extension of all toes (extensor hallucis longus adn extensor digitorum longus)
3. Eversion of the foot.
