Popliteal fossa

Boundaries

• superior and medial: semitendinosus (semimembranosus is medial to the semitendinosus)
• superior and lateral: biceps femoris
• inferior and medial: medial head of gastrocnemius
• inferior and lateral: lateral head of the gastrocnemius

Contents

• popliteal artery (continuation of the femoral artery)
• popliteal vein
• tibial nerve
• common peroneal nerve
• popliteal lymph nodes embedded in the fat

References

• http://en.wikipedia.org/wiki/Popliteal_fossa
• Posterior Compartment of the Thigh, http://mywebpages.comcast.net/wnor/postthigh.htm
  

Great resource on hands

Handworld - the name says it all huh? :)

Sequestra

A sequestrum is a piece of dead bone that has become separated from normal/sound bone during the process of necrosis . It is a complication (sequelae) of osteomyelitis.

Pathological process of development of sequestra:

• infection in the bone -> inflammatory exudate -> increase in intramedullary pressure
• periosteum becomes stripped from the osteum -> vascular thrombosis
• lack of blood supply -> bone necrosis
• sequestra are formed

Due to the avascular nature of sequestra, antibiotics which travel to sites of infection via the bloodstream, poorly penetrate these tissues. Hence the difficulty in treating chronic osteomyelitis.

At the same time as sequestra are developing, new bone is forming (known as involcrum). Openings in the involcrum allow debris and exudates (including pus) to pass from the sequestrum via sinus tracts to the skin.

References:

• http://en.wikipedia.org/wiki/Sequestrum

• Image from http://www.steinergraphics.com/surgical/006_19.3.html

Peroneus tendons

Remember that ligaments are
structures that connect bone to bone wheras tendons are structures that muscle to bone.

The peroneus tendons are often involved in inversion sprains of the ankle if they are overstretched.

The peroneus longus muscle arises from the head and lateral/superior shaft of the fibula. It follows a path down the lateral side of the leg passing behind the lateral malleolus and goes under the lateral aspect of the foot to attach on the plantar surface (bottom) of the foot on the medial cuneiform and the base of the first metatarsal. It performs ankle plantarflexion and eversion.

The peroneus brevis muscle arises from the shaft of the fibular, but more distally on the shaft than peroneus longus. It also passes down the lateral aspect of the lower leg and behind the lateral malleolus to insert on the lateral tubercle of metatarsal V. Unlike peroneus longus, it does not go under the foot. It also performs plantar flexion and eversion of the ankle.

References:

• http://www.dubinchiro.com/features/PDF/16ankle.pdf
• http://www.courses.vcu.edu/DANC291-003/unit_8.htm
  

Pars defect

Spondylolysis is a condition in which the there is a defect in a portion of the spine called the pars interarticularis (a small segment of bone joining the facet joints in the back of the spine). The pars interarticularis defect can be on one side of the spine only (unilateral) or both sides (bilateral). The most common level it is found is at L5-S1, although spondylolisthesis can occur at L4-5 and rarely at a higher level.

Spondylolysis is the most common cause of isthmic spondylolisthesis, in which one vertebral body is slipped forward over another.

References:

• http://www.spine-health.com/topics/cd/spondy/spondy01.html
• http://www.chirogeek.com/005_Spondylo-Slide-Show.htm
  

Ottawa ankle rules

Online resources

• Wikipedia has a nice, short summary of these rules.
• An online version of these rules in also available.

References

• http://www.mdcalc.com/anklekneerules