Lecture 7
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The talus bone is located in the hindfoot and articulates with 4 other bones to form parts of the ankle and subtalar joints. It has a body, neck, and head. The superior surface of the body forms part of the ankle joint with the tibia. The inferior surface forms part of the subtalar joint with the calcaneus. Ligaments attach to surfaces of the talus, but no muscles insert on it. The talus transmits weight from the leg to the foot.
Lecture 7
- 1. LECTURE 7: TARSAL BONES external features and attachments Dr. EIMAAN SUMAYYAH DPT (IPMR-KMU) MS NEUROLOGY (KMU)
- 2. TALUS BONE: • Talus is a tarsal bone of hindfoot. There are about 26 bones in the human foot grouped into 3 parts – tarsal bones, metatarsal bones and phalanges. • The foot itself can be divided into 3 parts • Hindfoot or rearfoot • Midfoot • Forefoot
- 4. • Hind foot is formed by talus and calcaneus, two of the seven tarsal bones. • Rest of the five tarsal bones form midfoot. Forefoot contains the metatarsals and the phalanges. • The talus is the second largest tarsal bone, and is situated above the calcaneus in the hindfoot.
- 5. • Talus is a unique bone. Two thirds of the talar surface is covered with articular cartilage. Neither tendons nor muscles insert or originate from this bone. • The talus articulates with 4 bones: the tibia, fibula, calcaneus, and navicular.
- 7. SIDE DETERMINATION OF TALUS • The rounded head is directed forwards. • The trochlear articular surface of the body is directed upwards, and the concave articular surface downwards. • The body bears a large triangular facet laterally, and a comma-shaped facet medially.
- 8. Structure of Talus • Talus is composed of body, neck and head. It also has two processes- the lateral and posterior. • Body of Talus • The body is cuboidal in shape and has five surfaces. • Superior Surface • Inferior Surface • Medial Surface • Lateral surface • Posterior Surface
- 9. SUPERIOR SURFACE • The superior surface is also called trochlear surface and bears an articular surface, which articulates with the lower end of the tibia to form the ankle joint. • It is convex from before backwards and concave from side to side. • It is wider anteriorly than posteriorly. • In front, it is continuous with the upper surface of the neck of the bone.
- 11. INFERIOR SURFACE • It bears an oval, concave articular surface called posterior facet or posterior calcaneal articular surface which articulates with the posterior facet of the calcaneum to form the subtalar joint.
- 13. MEDIAL SURFACE • It has two parts. Upper comma shaped part is articular above and the lower part is non-articular. The Articular surface articulates with the medial malleolus. • Under the tail of the medial malleolar facet, the posterior half of the inferior portion consists of a large oval area that provides insertion for the deep component of the deltoid ligament.
- 14. LEFT MEDIAL VIEW
- 15. LATERAL SURFACE • The lateral surface bears a triangular articular surface for the lateral malleolus. The surface is concave from above downwards, and its apex forms the lateral tubercle of the talus . • It is continuous above with the superior articular surface with posterior part of the being separated from the trochlea by an ill-defined, small triangular area which articulates with the inferior transverse tibiofibular ligament. • Along the anterior, inferior, and posterior boundary of articular surface is the lateral process, a nonarticular component of the talus. • Along the posteroinferior border of this lateral surface lies a groove for the attachment of the posterior talofibular ligament. • The lateral talocalcaneal ligament inserts at the inferior tip of the lateral process. • The anterior talofibular ligament inserts at anterior border of the triangular lateral process. •
- 17. POSTERIOR SURFACE • The posterior surface is small and is marked by an oblique groove. The groove is bounded by medial and lateral tubercles. Tendon of flexor hallucis longus passes through the groove. • A posterior tubercle is also present . Sometimes it is separate and in such cases, it is called os trigonum. • The posterolateral tubercle is more prominent of the two and gives attachment to the posterior talofibular ligament.
- 18. Os trigonum.
- 19. NECK OF THE TALUS • This is the constricted part of the bone between the head and the body. It is set obliquely on the body. • The neck-body angle is 130 to 140 degrees in infants and 150 degrees in adults. • This portion of the talus is most vulnerable to fracture. • The neck has 4 surfaces- superior, lateral, medial, and inferior.
- 20. SUPERIOR SURFACES • The superior surface of the neck is limited posteriorly by the anterior border of the trochlea of the talus (the dome or body) and anteriorly by the articular surface of the talar head. • The tibiotalar capsule inserts along this superior surface just proximal to the insertion of the capsule of the talonavicular joint.
- 21. LATERAL SURFACE • The lateral surface of the neck is concave and is continuous below with the deep groove for the interosseous talocalcaneal ligament. It provides an insertion for the medial aspect of the inferior extensor retinaculum.
- 22. INFERIOR SURFACE • The inferior surface of the neck forms the roof of the sinus tarsi and sinus canal. It forms a deep groove called sulcus tali which separates the posterior facet of body and middle facets on the head. • The groove runs obliquely forward and lateralward, becoming gradually broader and deeper in front. A similar groove is on upon the upper surface of the calcaneus, and both the grooves together form a tarsal canal termed the sinus tarsi. It contains interosseous talocalcaneal ligament. • Inferior surface of the neck contains numerous holes for nutrient arteries.
- 23. MEDIAL SURFACE • The medial surface provides an area for insertion of the talonavicular ligamentS.
- 24. HEAD OF THE TALUS • Head of the talus is directed forwards and slightly downwards and medially. Its anterior articular surface is oval and convex. The long axis of this surface is directed downwards and medially. It articulates with the posterior surface of the navicular bone. • The inferior surface is marked by three articular areas separated by indistinct ridges. The middle facet is largest,oval and gently convex; it articulates with the middle facet of the calcaneum. The anterolateral facet articulates with the anterior facet of the calcaneum, and the medial facet with the spring ligament. • The head of the talus nests within an articulation known as the acetabulum pedis, or foot socket formed by the calcaneal middle and anterior surfaces connected to the large navicular articular surface by the inferior and superomedial calcaneonavicular ligaments.
- 25. ATTACHMENTS OF TALUS BONE • The talus is devoid of muscular attachments, but numerous ligaments are attached to it because it takes part in three joints. • The lower, non-articular part of the medial surface of the body gives attachment to the deep fibres of the deltoid ligament. • The groove on the posterior surface lodges the tendon of the flexor hallucis longus. • The medial tubercle provides attachment to the superficial fibres of the deltoid ligament above and the posterior talocalcanean ligament. • The following ligaments are attached to the neck: • The distal part of the dorsal surface provides attachment to the capsular ligament of the ankle joint and to the dorsal talonavicular ligament. The proximal part of the dorsal surface lies within the ankle joint. • The inferior surface provides attachments to the interosseus talo-calcanean and cervical ligaments. • The lateral part of the neck provides attachment to the anterior talofibular ligament.