Bones Flashcards
Name the groups of bones of the foot
Tarsal bones - 7 bones
Metatarsal bones - I-V
Phalanges - 14 phalanx
Name the tarsal bones
Proximal group - Talus and calcaneus (heel bone)
Intermediate tarsal bone - navicular
Distal group - laterally to medically includes: cuboid, lateral cuneiform, intermediate cuneiform, medial cuneiform
Describe the talus
When viewed from the medial or lateral sides, is snail-shaped.
most superior bone of the foot and sits on top of and is supported by the calcaneus; it articulates above with the tibia and fibula to form the ankle joint and also projects forward to articulate with the intermediate tarsal bone (navicular) on the medial side of the foot; inferiorly articulates with calcaneus
Composed of rounded (convex) head which is projected forward and medially at the end of a short broad neck, which is connected posteriorly to an expanded body
Describe the calcaneus
elongate, irregular, box-shaped bone sitting below the talus. Its long axis is oriented along the midline of the foot, but deviates lateral to the midline anteriorly
Projects behind the ankle joint to form the skeletal framework of the heel.
Posterior surface of this heel region is circular and divided into superior, middle, and inferior facets
Superior facet separated from the calcaneal tendon by the retrocalcaneal bursa
Middle facet attachment for calcaneal tendon
Inferior facet curves anteriorly and is continuous onto the plantar surface of the bone as the calcaneal tuberosity, is the weight-bearing region of the heel
Calcaneal tuberosity projects forward on plantar surface as a large medial process and a small lateral process separated from each other by a V-shaped notch
Anterior projection on plantar surface is a tubercle (the calcaneal tubercle ) for the posterior attachment of the short plantar ligament of the sole of the foot
Lateral surface - anterior to the middle of the surface is the peroneal tubercle where peroneal brevis and longus tendons pass above and below respectively
Medial surface - concave with prominence (sustentaculum tali) protruding anteromedially from upper margin, which is a shelf of bone supporting the more posterior part of the head of the talus; superiorly is middle talar facet; inferiorly is groove accommodating the FHL tendon
Describe head of talus articulations
Anteriorly, the head of the talus is domed for articulation with a corresponding circular depression on the posterior surface of the navicular bone
Inferiorly, this domed articular surface is continuous with an additional three articular facets separated by smooth ridges:
The anterior and middle facets articulate with adjacent surfaces on the calcaneus bone.
The other facet, medial to the facets for articulation with the calcaneus, articulates with a ligament - the plantar calcaneonavicular ligament (spring ligament) - which connects the calcaneus to the navicular under the head of the talus.
Describe neck of talus
Between head and body of talus
Marked by a deep groove (the sulcus tali), which passes obliquely forward across the inferior surface from medial to lateral, and expands dramatically on the lateral side
Posterior to the sulcus tali is a large facet (posterior calcaneal surface) for articulation with the calcaneus
Vulnerable to fracture - leading to avascular necrosis
Describe body of the talus
Wider anteriorly , narrower posteriorly
Superior aspect - elevated to fit into the socket formed by the distal ends of the tibia and fibula to form the ankle joint:
Upper (trochlear) surface of this elevated region articulates with the distal end of the tibia.
Medial surface articulates with the medial malleolus of the tibia
Lateral surface articulates with the lateral malleolus of the fibula - projects more inferiorly than the medial surface to correspond with inferiorly projecting lateral malleolus; inferolateral surface forms a bony projection (lateral process) to support the lower part of the lateral articulate facet
Inferior surface - a large oval concave facet (the posterior calcaneal articular facet ) for articulation with the calcaneus
The posterior aspect - consists of a backward and medially facing projection (the posterior process ). The posterior process is marked on its surface by a lateral tubercle and a medial tubercle, which bracket between them the groove for the tendon of the flexor hallucis longus as it passes from the leg into the foot
Describe the MT bones (I-V)
Long bones
Each metatarsal has a:
Head at the distal end - articulates with the proximal phalanx of a toe; plantar surface of MT 1 also articulates with 2 sesamoid bones
Elongate shaft in the middle
Proximal base - articulates with one or more of the distal group of tarsal bones; sides of the bases of metatarsals II to V also articulate with each other
Metatarsal I, associated with the great toe, is shortest and thickest. The second is the longest
Lateral side of the base of metatarsal V has a prominent tuberosity (styloid process), which projects posteriorly and is the attachment site for the peroneal brevis tendon
Describe the phalanges
Bones of the toes
Each toe has three phalanges - proximal, middle, distal; except for the great toe, which has two - proximal and distal
Each phalanx consists of a base, shaft and distal head
Base of each proximal phalanx articulates with the head of the related metatarsal
Distal head of each distal phalanx is non-articular and flattened into a crescent-shaped plantar tuberosity under the plantar pad at the end of the digit
Describe the calcaneus articulations
Superior surface of the sustentaculum tali has a facet (middle talar articular surface) for articulation with the corresponding middle facet on the head of the talus
Anterior and posterior talar articular surfaces are on the superior surface of the calcaneus itself:
○ The anterior talar articular surface is small and articulates with the corresponding anterior facet on the head of the talus
○ The posterior talar articular surface is large and is approximately near the middle of the superior surface of the calcaneus
Anterior surface has concave articulate facet for the cuboid bone
