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The popliteal fossa is diamond-shaped and its borders are formed by the semimembranosus and semitendinosus muscles superiomedially, the biceps femoris muscle superiolaterally, the medial head of the gastrocnemius muscle inferiomedially, and the lateral head of the gastrocnemius muscle inferiolaterally. It contains the popliteal artery and vein, the tibial and common peroneal nerves, and is covered by subcutaneous tissue and skin.
The popliteal artery is the continuation of the superficial femoral artery after it passes through the adductor canal, an opening in the adductor magnus muscle, in the lower thirds of the thigh. It courses downward and laterally to the midline of the knee between the two condyles of the femur, into the popliteal fossa.
The popliteal artery has three segments: suprageniculate (above knee), midpopliteal (behind knee), and infrageniculate (below knee). Exposure to each segment of the popliteal artery is distinct.
The popliteal artery has superior and inferior genicular branches, which provide blood supply to the tissues surrounding the knee joint and provide important collaterals when there are occlusions of the superficial femoral or popliteal artery.
Below the knee, the popliteal artery branches into the anterior tibial artery, followed by the peroneal branch about 2–3 cm lower, which itself then branches into the peroneal and posterior tibial arteries.
The anterior tibial artery pierces the upper part of the interosseous membrane, courses in front of the membrane, under the extensor muscles of the anterior muscle compartment, and distally becomes the dorsalis pedis artery.
The tibioperoneal trunk is the direct continuation of the popliteal artery and, after approximately 3 cm, branches to form the peroneal artery laterally and the posterior tibial artery medially. The peroneal and posterior tibial arteries lie in the deep posterior compartment of the leg posteriorly of the fibula and tibia, respectively.
The posterior tibial artery continues directly to the ankle and lies superficially posterior to the medial malleolus, while the peroneal artery branches above the ankle to form collaterals to the dorsalis pedis and plantar branches of the posterior tibial artery in the foot.
The popliteal vein lies posterior to the artery (more laterally superiorly to more medially inferiorly). The tibial nerve is lateral and posterior to the artery.
The lower leg venous system consists of the superficial (greater saphenous vein) and deep (femoral vein) systems. Duplicated saphenous systems exist in the calf and thigh in approximately 25% of patients.
Distally, the greater saphenous vein can be found anterior to the medial malleolus. It crosses the tibia, runs medial to the knee, and ascends into the medial and posterior segment of the thigh as it descends medially into the common femoral vein in the groin (saphenofemoral junction).
In the thigh, the greater saphenous vein lies deep to the fascia (unlike accessory veins or tributaries). This may help discriminate the veins of the thigh during dissection.
In the proximal aspect of the thigh, the greater saphenous vein runs into the confluence of the superficial circumflex iliac vein, superficial inferior epigastric vein, and external pudendal veins to create the saphenofemoral junction. A useful anatomic landmark for the saphenofemoral junction is two fingerbreadths inferior and medial to the pubic tubercle.
For vascular trauma purposes the abdomen is divided into four retroperitoneal anatomical areas:
Zone 1: The midline retroperitoneum from the aortic hiatus to the sacral promontory is broken into supramesocolic and inframesocolic areas. The supramesocolic area contains the suprarenal aorta and its major branches (celiac artery, superior mesenteric artery, and renal arteries), the supramesocolic segment of the inferior vena cava with its major branches, and the superior mesenteric vein. The inframesocolic area contains the infrarenal aorta and infrarenal inferior vena cava.
Zone 2 (left and right): This is the paired right and left region lateral of Zone 1 containing the kidneys and renal vessels.
Zone 3: The pelvic retroperitoneum, which contains the iliac vessels.
The abdominal aorta originates between the two crura of the diaphragm at the level of T12–L1 and bifurcates into the common iliac arteries at the level of L4–5. The umbilicus is an approximate external landmark for the aortic bifurcation. The first large branch is the celiac trunk, followed by the superior mesenteric artery 1–2 cm inferiorly, and both course anteriorly and inferiorly. The renal arteries originate 1–2 cm below the origin of the superior mesenteric artery at the level of L2 and course laterally. Finally, the inferior mesenteric artery originates 2–5 cm above the aortic bifurcation on the left anterior aspect of the aorta.
Celiac artery: The main trunk originates on the anterior surface of the aorta at the level of T12–L1. It is 1–2 cm long and divides into three branches at the upper border of the pancreas—the common hepatic, left gastric, and splenic arteries. The celiac is encased in extensive fibrous, ganglionic, and lymphatic tissues, which makes surgical dissection of the celiac artery difficult. In 10–20% of patients, the left gastric artery gives off a replaced left hepatic artery that courses through the gastrohepatic omentum and can be injured while mobilizing the left lobe of the liver or lesser curve of the stomach.
Superior mesenteric artery (SMA): The SMA originates from the anterior surface of the aorta at the level of L1, 1–2 cm below the celiac artery. It courses posterior to the neck of the pancreas and anterior to the third part of the duodenum, beyond which it enters the root of the mesentery. SMA branches include the inferior pancreaticoduodenal artery, the middle colic artery, an arterial arcade with 12–18 intestinal branches, the right colic artery, and the ileocolic artery. In 10–20% of patients, the SMA gives off a replaced right hepatic artery, which courses posterior to the head of the pancreas and runs posteriorly and to the right of the portal vein.
Renal arteries: The right renal artery emerges at a slightly higher level and is longer than the left and courses posteriorly to the inferior vena cava. Approximately 30% of patients have more than one renal artery, usually an accessory artery supplying the lower pole of the kidney. Both renal veins lie anteriorly of their accompanying renal arteries. The left renal vein is significantly longer than the right and courses anteriorly to the aorta. The left renal vein drains the left gonadal vein inferiorly, the left adrenal vein superiorly, and the renolumbar vein posteriorly. The right gonadal vein drains directly into the IVC.
Inferior mesenteric artery (IMA): The IMA provides blood supply to the left colon, sigmoid, and the rectum. It communicates with the SMA through the marginal artery of Drummond and arc of Riolan.
1) To evaluate whether transient ischemic attack (TIA) management in emergency departments (EDs) of the Nova Scotia Capital District Health Authority followed Canadian Best Practice Recommendations, and 2) to assess the impact of being followed up in a dedicated outpatient neurovascular clinic.
Retrospective chart review of all patients discharged from EDs in our district from January 1, 2011 to December 31, 2012 with a diagnosis of TIA. Cox proportional hazards models, Kaplan-Meier survival curve, and propensity matched analyses were used to evaluate 90-day mortality and readmission.
Of the 686 patients seen in the ED for TIA, 88.3% received computed tomography (CT) scanning, 86.3% received an electrocardiogram (ECG), 35% received vascular imaging within 24 hours of triage, 36% were seen in a neurovascular clinic, and 4.2% experienced stroke, myocardial infarction, or vascular death within 90 days. Rates of antithrombotic use were increased in patients seen in a neurovascular clinic compared to those who were not (94% v. 86.3%, p<0.0001). After adjustment for age, sex, vascular disease risk factors, and stroke symptoms, the risk of readmission for stroke, myocardial infarction, or vascular death was lower for those seen in a neurovascular clinic compared to those who were not (adjusted hazard ratio 0.28; 95% confidence interval 0.08–0.99, p=0.048).
The majority of patients in our study were treated with antithrombotic agents in the ED and investigated with CT and ECG within 24 hours; however, vascular imaging and neurovascular clinic follow-up were underutilized. For those with neurovascular clinic follow-up, there was an association with reduced risk of subsequent stroke, myocardial infarction, or vascular death.