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RAD141 - Chap 7A
RAD141 - Chap 7A - foot, ankle
Question | Answer |
---|---|
What are the 4 main groups of bones in the lower limb? | foot, leg, femur, hip |
How many bones in the foot? What are the groups? | 26 bones in each foot -> 14 phalanges, 5 metatarsals (instep), 7 tarsals |
How are the phalanges numbered? | 1-5, starting on the medial side of the foot; distal, middle, and proximal phalanx on all but the 1st digit, which only has proximal & distal |
How do the phalanges of the foot differ from those of the hand? | the phalanges of the foot are smaller and have more limited movement |
What is difficult with the distal phalanges of the 2nd - 5th toes? | they are very small and may be difficult to identify as separate bones on a radiograph |
What are the metatarsals? | the 5 bones of the instep; numbered 1-5 from medial side; each consists of 3 parts -> distal -> head; central -> body (shaft); proximal -> base |
What is a landmark on the 5th metatarsal? | the base is expanded laterally into a prominent rought tuberosity which provides for the attachment of a tendon; it is readily visible on radiographs and is a common trauma site for the foot |
What are the joints of the phalanges? | each joint of the foot has a name derived from the 2 bones on either side of that joint; interphalangeal (IP) joint of the 1st digit, distal IP (DIP) and proximal IP (PIP) of the 2nd - 5th phalanges |
What are the joints of the metatarsals? | each of the joints at the head of the metatarsal is a metatarsophalangeal (MTP) joint; each of the joints at the base of the metatarsal is a tarsometarsal (TMT) joint |
What is the important metatarsal joint? | the base of the 3rd metatarsal (3rd tarsometarsal joint) -> this is the centering point (CR location) for an AP and oblique foot |
What are sesamoid bones? What is special about sesamoid bones in the feet? | small detatched bones, embedded in tendons; sesamoid bones tend to be larger and more significant radiographically in the lower limbs as they can be fractured, and because of their plantar location, can be very painful |
Where are sesamoid bones commonly found in the foot? | sesamoid bones are almost always present on the plantar surface at the head of 1st metatarsal near the 1st MTP joint; may also be found near other joints of the foot |
What are the tarsal bones named? | calcaneus, talus, cuboid, navicular, and 1st, 2nd, 3rd cuneiforms (Come To Colorado (the) Next 3 Christmases |
What are alternative names for the calcaneus, talus, and navicular bones? | calcaneus -> os calcis; talus -> astragalus; navicular -> scaphoid |
How do the tarsals compare to the carpals? | only 7 tarsals (8 carpals), tarsals are larger, less mobile (provides a basis of support for the boid in an erect position) |
Which is the only tarsal bone involved in the ankle joint? | the talus |
What is the largest and strongest bone of the foot? Second largest? | largest, strongest ->the calcaneus; the posterior portion is often called the heel bone; 2nd largest -> talus |
What tuberosity processes are found on the calcaneus? | thetuberosity is on the most posterior-inferior part -> large tendons attach here; at its widest points has 2 small rounded, processes -> larger = lateral process, smaller = medial process |
What other processes are on the calcaneous, unrelated to the tuberosity? | the peroneal trochlea, aka the trochlear process is visualized laterally on an axial projection; on the medial proximal aspect is a larger more prominent bony process called the sustentaculum tali |
What are the articulations of the calcaneus? | anteriorly w/the cuboid and superiorly w/the talus; the superior articulation w/the talus forms the subtalar (talocalcaneal) joint |
What 3 facets appear at the subtalar joint? | the larger posterior articular facet and the smaller anterior and middle articular facets |
What is the calcaneal sulcus? the sinus tarsi? | calcaneal sulcus -> the deep depression between the posterior and middle articular facets; sinus tarsi (aka tarsal sinus) -> opening in the middle of the subtalar joint for passing of ligaments (combo of calcaneal sulcus & depression in the talus) |
Describe the talus | It is the 2nd largest tarsal bone and is located between the lower leg and the calcaneus; the weight of the body is transmitted by this bone thru the ankle & talocalcaneal joints |
What 4 bones does the talus articulate with? | superiorly w/the tibia and fibula, inferiorly with the calcaneus, and anteriorly with the navicular |
Describe the navicular | a flattened, oval-shaped bone located on the medial side of the foot between the talus and the 3 cuneiforms |
What 4 bones does the navicular articular articulate with? | posteriorly with the talus and anteriorly with the 3 cuneiforms |
Describe the 3 cuneiforms | cuneiform means wedge-shaped; located on the medial & midaspects of the foot between the 1st 3 metatarsals distally & the navicular proximally; largest is the medial (first) cuneiform; the intermediate (2nd) cuneiform is the smallest cuneiform |
What 4 bones does the medial cuneiform articulate with? | the 1st cuneiform articulates with the navicular proximally, the 1st and 2nd (3rd?) metatarsals distally, and the intermediate cuneiform laterally |
What 4 bones does the intermediate cuneiform articulate with? | the 2nd cuneiform articulates with the navicular proximally, the 2nd metatarsal distally, and the medial & lateral cuneiforms on each side |
What 6 bones does the lateral cuneiform articulate with? | the 3rd cuneiform articulates with the navicular proximally, the 2nd, 3rd, and 4th metatarsals distally, the intermediate cuneiform medially, and the cuboid laterally |
Describe the location of the cuboid | located on the lateral aspect of the foot, distal to the calcaneus, proximal to the 4th and 5th metatarsals |
Which 4 bones does the cuboid articulate with? | the calcaneus proximally, the lateral cuneiform medially, and the 4th and 5th metatarsals distally; occasionally, it will also articulate with the navicular |
What are the 2 arches that the bones of the foot are arranged? What is their function? | the longitudinal and transverse arches -> provide a strong, shock-absobin support for the weight of the body |
Describe the longitudinal arch | it is springy and comprises a medial and lateral component, with most of the march on the medial and midaspects of the foot |
Describe the transverse arch | located primarily along the plantar surface of the distal tarsals & the tarsometatarsal joints; made up of the cuneiforms, especially the smaller 2nd & third cuneiforms in combo w/the larger 1st cuneiform & the cuboid |
Which 3 bones form the ankle joint? | tibia, fibula, and the talus |
How is the mortise of the ankle formed? What is the mortise? | from the lateral malleolus of the fibula, the medial malleolus of the tibia, & the inferior portions of the tibia (tibial plafond) & fibula; it is a 3-sided opening into which the upper talus fits |
How can the entire 3-part joint space of the aknkle mortise be viewed? | not on a true frontal view (AP projection) because of overlapping of portions of the distal fibula & tibia by the talus; a 15 deg internally rotated AP projection (mortise position) is required |
What is the anterior tubercle? | an expanded process at the distal enterior and lateral tibia, articulates with the superolateral talus & partially overlaps the fibula anteriorly |
What is the tibial plafond? | plafond = ceiling; the distal tibial joint surface forms the roof of the ankle mortise joint; certain types of fractures of the ankle in children and youth involve the distal tibial epiphysis & tibial plafond |
How can a true lateral ankle view be verified? | the lateral malleolus should be about 0.5 inches posterior to the medial malleolus; the lateral malleolus should also extend about 0.5 inches more distally than the medial malleolus |
What type of joint is the ankle joint? | synovial joint of the ginglymus (hinge) type, with flexion & extension (i.e. dorsiflexion and plantar flexion) movements only |
What prevents the ankle from moving laterally? | strong collateral ligaments extending from the medial and lateral malleoli to the calcaneus and talus |
What happens if the ankle is subject to lateral stress? | a "sprained" ankle, with stretched or torn collateral ligaments and torn muscle tendons resulting in an increase in parts of the mortise joint space |
What type of joint are the interphalangeal joints? | hinge type |
What type of joints are the metatarsotarsal joints? | condylar |
What type of joints are the intertarsal and tarsometatarsal joints? | gliding joints |
What is the ankle joint? What type? | the ankle joint is the articulation of the talus with the tibia and fibula; it is a hinge type joint |