Bone Terminology: Anatomy Guide

Terminologies

• Body, the principle mass of the bone
• Shaft, the body of a long bone
• Crest, long narrow elevation
• Eminence, a relatively small projection/bump
• Line/Ridge, a thin linear elevation with a rough surface
• Malleolus, a rounded process at the end of the bone
• Process, a relatively large projection or prominent bump
• Spine, thorn-like projection, usually large
• Tubercle, small raised eminence with a roughened surface
• Tuberosity, smaller than trochanter but large & round, raised eminence with a roughened surface
• Trochanter, large, roughened projection
• Canal, tubular passage connecting different regions of the body, usually for blood vessels or nerves
• Foramen, passage through a bone
• Fossa, hollow, depressed area or shallow cavity
• Groove, elongated depression or furrow
• Notch, small indentation at the edge of a bone
• Sulcus, depression, furrow or groove
• Head, large, round articular end of long bones
• Neck, relatively narrow portion proximal to the head
• Capitulum, small, round, articular head
• Condyle, rounded, knuckle-like prominence at the end of a bone, often occurring in pairs, articular area
• Epicondyle, eminence superior or adjacent to condyle
• Facet, smooth flat area, usually covered with cartilage where a bone articulates with another bone
• Trochlea, spool-like (rounded) articular process OR process that acts as a pulley

Femur

• The condyles articulate with the tibia
• The patella surface articulates with the patella

Patella

• Sesamoid bone formed in the quadriceps femoris tendon
• Articulates with the femur posteriorly to provide additional leverage, for quadriceps and reduces friction
• Has two attachments
• Tendon attaches to the base, ligament attaches to the apex
• Has two articular surfaces for patella surface of the femur

Tibia

• The weight-bearing (larger) bone of the leg
• Medial within the leg region
• The anteromedial border is easily palpable ('shin') on the leg
• Articulates with the femur proximally and talus distally, and fibula laterally
• It has five articulations
• It has an interosseous border (connects to the fibula)
• Proximal articular surfaces, medial & lateral tibial plateaus with the femoral condyles
• Fibular articular facet with the fibular head
• Distal articular surfaces, fibular notch with the distal fibula
• Talar articular facets with the talus (tarsal bone)
• Contains muscle and ligament attachments, medial and lateral condyles
• Ligament attachments, medial malleolus, Tibial tuberosity, Intercondylar eminence
• Has muscle attachments, soleal line
• The interosseous membrane, interosseous borders between the tibia & fibula

Fibula

• Plays no role in weight-bearing of the lower limb
• Serves as a site for muscle attachment and stability to the ankle joint with two articulations
• It is the smaller bone of the leg
• It is lateral within the leg region
• It is for stability of ankle joints & muscle attachment
• Connected by the interosseous membrane
• It has two articulations, with the Tibial articular facet its fibular articular facet (tibia) and to Articular facet with talus
• Has muscle and ligament attachments, apex
• Ligament attachments, Lateral malleolus
• The interosseous membrane, interosseous border
• Has muscle attachments, shaft

Tarsal bones

• 7 bones, talus articulates with the tibia & fibula
• Proximal row: Talus & Calcaneus
• Intermediate: Navicular
• Distal row: Lateral (3), Intermediate (2) & Medial (1) Cuneiforms & Cuboid
• The talus is a weight-bearing bone, transferred from the tibia
• The tibia sits on the trochlea of the talus
• The talus forms the ankle joint (hinge joint) between the medial & lateral malleoli of the tibia & fibula
• The talus articulates with the navicular anteriorly & calcaneus inferiorly
• Has a groove posteriorly for extrinsic muscles of the foot
• The calcaneus is a weight-bearing bone, transferred from the talus
• The talus sits on multiple facets of calcaneus
• Forms the subtalar joints that permit inversion/eversion movements
• Articulates with the talus superiorly & cuboid anteriorly
• Has a groove medially for tendons (tarsal tunnel)
• Has a calcaneal tuberosity for the calcaneal tendon ('achilles' tendon)

Metatarsal & Phalangeal bones

• The foot has five metatarsal bones (numbered from medial to lateral), similar to the hand
• Each metatarsal bone has a head, body & base
• Digits 2-5 have a proximal, middle & distal phalanx
• The great toe (hallux) only has a proximal & distal phalanx

Hind-, Mid- & Forefoot

• The foot is of clinical importance considering the amount of time physicians devote to foot problems
• The foot can be considered in three anatomical & functional zones
  • Hindfoot: Talus & Calcaneus
  • Midfoot: Navicular, Cuboid & Cuneiform bones (1-3)
  • Forefoot: Metatarsals & Phalanges

Arches of the Foot

• Uses multiple bones & ligaments to provide flexibility
• Allows the foot to deform with each ground contact
• Dissipates shock forces from impact on the ground
• Distribute weight
• Curvatures on the plantar surface: Lateral longitudinal arch, Medial longitudinal arch, Transverse arch (of mid-foot & metatarsal bases)
• The arches are supported by ligaments, the plantar aponeurosis & extrinsic tendons

Knee Joint

• Articular surfaces, the tibiofemoral & patellofemoral joints = knee joint
• Consists of medial & lateral femoral condyles with the medial & lateral tibial plateaus (condyles)
• The patella (posterior) and the distal femur
• Synovial (or diarthrosis), modified hinge joint
• Movements, Flexion & extension, limited rotation can occur during flexion
• Extracapsular ligaments reinforce the joint capsule
  • Tibial collateral ligament (medial)
  • Fibular collateral ligament (lateral)
  • Patella ligament (anterior)
  • Oblique popliteal ligament (posterior)
  • Arcuate popliteal ligament (posterior)
• Intracapsular ligaments reinforce the joint internally:
  • Anterior cruciate ligament (ACL)
  • Posterior cruciate ligament (PCL)
  • Transverse ligament
• Accessory structures:
  • Fat pads (infra- & suprapatellar)
  • Fill the spaces between the ligaments/tendons & the joint capsule, reduces friction between moving parts
  • Medial & lateral menisci
  • Deepen the articular surface & act as shock absorbers
  • Bursae, there are at least 12 bursae around the knee joint, most are positioned around the patella
  • Tendons of the knee predominantly run parallel to the bones & pull lengthwise
  • Bursae are placed to reduce friction between bones & tendons

Proximal Tibiofibular Joint

• Articular surfaces, fibular articular facet of tibia & articular facet of fibula
• Synovial, plane joint
• Small gliding movements
• Joint capsule is independent of the knee joint, reinforced by the Anterior & Posterior tibiofibular ligaments

Distal Tibiofibular Joint

• Articular surfaces: Fibular notch of tibia & articular facet of fibula
• Joint type: Syndesmosis, fibrous joint
• Movement: Slight – to accommodate the talus during dorsiflexion
• Ligaments:
  • Interosseous tibiofibular ligament (deep, binds bones together)
  • Anterior tibiofibular ligament (superficial)
  • Posterior tibiofibular ligament (superficial)
• Reinforced by the interosseous membrane

Talocrural Joint

• Distal articular facets of the tibia & fibula with the trochlea of the talus (superior articular surface)
• Joint type: Synovial, hinge joint
• Flexion & Extension, talocrural (ankle) joint
• Movements at the ankle, dorsiflexion, and plantarflexion
• Ligaments:
  • Anterior talofibular ligament, attaches the lateral malleolus to the talus anteriorly
  • Posterior talofibular ligament, attaches the lateral malleolus to the talus posteriorly
  • Medial ligament, anchors the medial malleolus to the talus, calcaneus & navicular bones
  • Calcaneofibular ligament, attaches the lateral malleolus to the calcaneus bone laterally

Subtalar Joints

• Inferior facets of the talus with the superior facets of the calcaneus
• Synovial, plane joint
• Gliding movements, enables inversion & eversion of the foot

Inter-Tarsal Joints

• Uses Tarsal bones as articular surfaces
• Joint type varies, some synovial and others fibrous
• Movement varies, some are more movable than others
• Ligaments:
  • Are reinforced by the numerous intertarsal ligaments and the short & long plantar ligaments help reinforce the arches of the foot

Metatarsophalangeal Joint

• Articular surfaces, metatarsal heads with proximal phalanx bases
• Synovial, condyloid
• Movements are biaxial, flexion/extension & abduction/adduction
• Ligaments are collateral and transverse

Interphalangeal Joints

• Articular surfaces are Phalanx heads with phalanx bases
• Proximal & distal interphalangeal joints on digits 2-5 and a single interphalangeal joint on digit 1 has
• Joint types that are Synovial, hinge
• Movements, Uniaxial - flexion/extension
• Collateral ligaments