Lecture 8 calcaneum

Lower Limb

1. LECTURE 8: CALCANEUM BONE external features and attachments Dr. EIMAAN SUMAYYAH DPT (IPMR-KMU) MS NEUROLOGY (KMU)

2. Side Determination of Calcaneus The anterior surface is small and bears a concavocovex articular facet for the cuboid. The posterior surface is large and rough. The dorsal or superior has a large convex articular surface in the middle. The plantar surface is large and triangular. The lateral surface is flat The medial surface concave from above downwards.

3. CALCANEUS Calcaneus is bone of the hind foot and is the largest tarsal bone. Calcaneus forms the prominence of the heel. Calcaneus is roughly cuboidal in shape. It is directed forwards, upwards and laterally.

4. Structure of Calcaneus It has six surfaces. Anterior Surface The anterior surface is the smallest surface of the bone. It is covered by a concavoconvex , sloping articular surface to the calcaneocuboid joint and is roughly triangular.

5. POSTERIOR SURFACE The posterior calcaneal surface is convex, dome shaped, wider inferiorly, and has 3 distinct areas – upper, middle and lower. The upper area is smooth, slopes anteriorly, and supports a bursa, which lies between it and the Achilles tendon. The middle part gives insertion to the Achilles tendon The lower part is covered by fibrofatty tissue of the plantar heel pad

6. SUPERIOR SURFACE The superior calcaneal surface of the calcaneus has 2 parts: articular and nonarticular . The nonarticular part has variable length and extends posteriorly to form the heel. It is about one third of total superior surface. It is convex from side to side, is concave in the anteroposterior axis, and supports a fat pad situated anterior to the Achilles tendon. Anterior to this nonarticular part is articular which has an oval facet facing superiorly and is tilted anteriorly. The articular portion of the superior surface is convex in the anteroposterior axis and articulates with the posterior calcaneal facet on the undersurface of the talus.

7. SUPERIOR SURFACE Calcaneus sulcus is deep groove anterior to posterior facet and directed posteromedially It matches the inferior similar sulcus on lower surface of the talus, and both these grooves form a canal in the hindfoot called the sinus tarsi. Anteromedial to the calcaneal sulcus is an articular area, elongated and concave in its long axis and directed anterolaterally . A transverse notch divides this into larger middle facet posteriorly and anterior facet. The middle facet lies on a medially projecting process of the calcaneus called the sustentaculum tali . It articulates with the middle calcaneal facet on the under surface of the talus.

8. The anterior facet lies on the anterior process of the calcaneus and articulates with the anterior calcaneal facet on the talus. The upper rough surface, anterior and lateral to the facets, is rough for the attachment of ligaments and for the origin of the extensor digitorum brevis .

9. INFERIOR/PLANTAR SURFACE The inferior or plantar surface is wider posteriorly and convex from side to side. It has a prominence at the back, called the calcaneal tuberosity. Calcaneal tuberosity has a central longitudinal depression dividing it into a smaller lateral and larger broader medial process. Lateral process gives rise to part of the abductor digiti minimi whereas medial process that gives attachment to the abductor hallucis , front to the flexor digitorum brevis and the plantar aponeurosis .

10. LATERAL SURFACE The lateral surface is rough and almost flat, broader posteriorly and narrower anteriorly. Anteriorly, a small elevation termed the peroneal fibular] tubercle or trochlea is present. It is a ridge that separates two grooves. Superior groove is for peroneus brevis tendon and inferior is for peroneus longus tendon. A small tubercle in the middle of lateral surface give attachment to the calcaneofibular ligament.

11. MEDIAL SURFACE Medial surface is concave from above downwards. The concavity is accentuated by the presence of medially oriented shelf-like projection of bone, called the sustentaculum tali , which projects medially from its anterosuperior border. The sustentaculum tali has an articular surface for the middle calcaneal facet and is grooved inferiorly to house the flexor hallucis longus tendon

12. ATTACHMENTS AND RELATIONS OF THE CALCANEUS

13. Attachments on Posterior Surface The middle rough area on the posterior surface receives the insertion of the tendocalcaneus and of the plantaris . The upper area is covered by a bursa. The lower area is covered by dense fibrofatty tissue and supports the body weight while standing.

14. Attachments on Dorsal or Superior Surface The lateral part of the nonarticular area on the anterior part of the dorsal surface provides; Origin to the extensor digitorum brevis Attachment to the inferior extensor retinaculam Attachment to the bifurcate ligament . Sulcus calcanei provides attachment to the interosseus talo-calcanean ligament medially, and the cervical ligament laterally.

15. NFERIOR SURFACE The medial tubercle: Medially: Origin for the abductor hallucis Attachment to the flexor retinculum Anteriorly: Flexor digitorum brevis Attachment to the plantar aponeurosis The lateral tubercle: Origin to the abductor digiti minimi , the origin extending to the front of the tubercle. The anterior tubercle Along with the rough area in front – short plantar ligament. Rough strip between the three tubercle – Long plantar ligament.

16. Attachments on Lateral Surface The peroneal tubercle – Slip from the inferior peroneal rentinaculum . The calcaneofibular ligament is attached about I cm behind the peroneal trochlea

17. Attachments on Medial Surface The groove on the lower surface of the sustentaculum tali is occupied by the tendon of the flexor hallucis longus . The medial margin of the sustentaculum tali Spring ligament Slip from the tibialis posterior in the middle Superficial fibers of the deltoid ligament along the length Medial talocaneal ligament posteriorly. Below the groove for the flexor hallucis longus ,the medial surface gives origin to the fleshy fibres of the medial head of the accessory flexor digitorum .

18. Clinical Significance of Calcaneum Gastrocnemius, soleus, and plantaris are posterior compartment muscles of the leg and aid in walking, running and jumping. Their specific functions include plantarflexion of the foot, flexion of the knee, and steadying the leg on the ankle during standing. Calcaneal is frequently injured bone especially in fall from height. Most of calcaneal fractures are treated by non operative means but surgery for displaced fractures is required. Calcaneal is surrounded by minimal soft tissue and surgical incisions need to be carefully planned because of wound healing problems in the area.