Foot Flashcards
How are the bones of the foot classified?
Tarsals – A set of seven irregularly shaped bones. They are situated proximally in the foot, in the ankle area.
Metatarsals – These bones connect the phalanges to the tarsals. There are five in number – one for each digit.
Phalanges – The bones of the toes. Each toe has three phalanges – a proximal, intermediate and distal (except the big toe, which only has two phalanges).
What are the proximal tarsal bones?
The proximal tarsal bones are the talus and the calcaneus.
How does the talus articulate?
The talus is the most superior of the tarsal bones. It has three articulations:
Superiorly: Ankle joint – between the talus and the bones of the leg (the tibia and fibula).
Inferiorly: Subtalar joint – between the talus and calcaneus.
Anteriorly: Talonavicular joint – between the talus and the navicular.
Describe the articulations of the calcaneus
The calcaneus lies underneath the talus, and has two articulations:
Superiorly: Subtalar joint – between the calcaneus and the talus.
Anteriorly: Calcaneocuboid joint – between the calcaneus and the cuboid.
It is thick and sturdy, acting to transmit forces from the talus to the ground. The posterior aspect of the calcaneus is marked by calcaneal tuberosity, to which the Achilles tendon attaches.
What bone is in the intermediate compartment of the tarsals?
The intermediate row of tarsal bones contains one bone, the navicular (given its name because it is shaped like a boat). It articulates with the talus posteriorly, the cuneiform bones anteriorly, and the cuboid bone laterally.
On the plantar surface of the navicular, there is a tuberosity for the attachment of the tibialis posterior tendon.
What bones are in the distal group of the tarsals?
In the distal row, there are four tarsal bones – the cuboid and the three cuneiforms. These bones articulate with the metatarsals of the foot.
The cuboid is the most lateral bone in the distal row, articulating with the calcaneus posteriorly, and two metatarsals anteriorly. As the name suggests, it is shaped like a cube. The inferior surface of the cuboid is marked by a groove for the fibularis longus muscle.
The three cuneiforms (lateral, intermediate and medial) are wedge shaped bones. They articulate with the navicular posteriorly, and the metatarsals anteriorly. The shape of the bones helps form a transverse arch across the foot.
What are the metatarsals and how do they articulate?
The metatarsals are located in the midfoot, between the tarsals and phalanges. They are numbered I-V (medial to lateral).
Each metatarsal has a similar structure. They consist of a distal head and proximal base, which are joined by a shaft of bone. They have three or four articulations:
Proximally: Tarsometatarsal joint – between the metatarsal bases and the cuneiforms or cuboid bones.
Laterally: Intermetatarsal joint(s) – between the metatarsal and the adjacent metatarsals.
Distally: Metatarsophalangeal joint – between the metatarsal head and the proximal phalanx.
What are the phalanges?
The phalanges are the bones of the toes. Most toes have three phalanges – proximal, intermediate and distal. The great toe only has proximal and distal phalanges.
What is the difference between the intrinsic and extrinsic muscles of the foot?
The extrinsic muscles arise from the anterior, posterior and lateral compartments of the leg. They are mainly responsible for actions such as eversion, inversion, plantarflexion and dorsiflexion of the foot.
The intrinsic muscles are located within the foot and are responsible for the more fine motor actions of the foot, for example movement of individual digits.
Give the attachments, innervation and actions of Extensor Digitorum Brevis
Extensor Digitorum Brevis
The extensor digitorum brevis muscle lies deep to the tendon of the extensor digitorum longus.
Attachments: Originates from the calcaneus, the interosseus talocalcaneal ligament and the inferior extensor retinaculum. It attaches to the long extensor tendons of the four lateral digits.
Actions: Aids the extensor digitorum longus in extending the medial four toes at the metatarsophalangeal and interphalangeal joints.
Innervation: Deep fibular nerve.
Give the attachments, innervation and actions of Extensor Hallucis Brevis
The extensor hallucis brevis muscle is medial to extensor digitorum longus and lateral to extensor hallucis longus.
Attachments: Originates from the calcaneus, the interosseus talocalcaneal ligament and the inferior extensor retinaculum. It attaches to the base of the proximal phalanx of the great toe.
Actions: Aids the extensor hallucis longus in extending the great toe at the metatarsophalangeal joint.
Innervation: Deep fibular nerve.
What are the plantar muscles?
There are 10 intrinsic muscles located in the sole of the foot. They act collectively to stablise the arches of the foot, and individually to control movement of the digits. All the muscles are innervated either by the medial plantar nerve or the lateral plantar nerve, which are both branches of the tibial nerve.
The muscle of the plantar aspect are described in four layers (superficial to deep).
What are the plantar muscles in the first layer?
Abductor Hallucis
Flexor Digitorum Brevis
Abductor Digiti Minimi
Give the attachments, innervation and actions of Abductor Hallucis
The abductor hallucis muscle is located on the medial side of the sole, where it contributes to a small soft tissue bulge.
Attachments: Originates from the medial tubercle of the calcaneus, the flexor retinaculum and the plantar aponeurosis. It attaches to the medial base of the proximal phalanx of the great toe.
Actions: Abducts and flexes the great toe.
Innervation: Medial plantar nerve.
Give the attachments, innervation and actions of Flexor Digitorum Brevis
The flexor digitorum brevis muscle is located laterally to the abductor hallucis. It sits in the center of the sole, sandwiched between the plantar aponeurosis and the tendons of flexor digitorum longus.
Attachments: Originates from the medial tubercle of the calcaneus and the plantar aponeurosis. It attaches to the middle phalanges of the lateral four digits.
Actions: Flexes the lateral four digits at the proximal interphalangeal joints.
Innervation: Medial plantar nerve.
Give the attachments, innervation and actions of Abductor Digiti Minimi
Attachments: Originates from the medial and lateral tubercles of the calcaneus and the plantar aponeurosis. It attaches to the lateral base of the proximal phalanx of the 5th digit.
Actions: Abducts and flexes the 5th digit.
Innervation: Lateral plantar nerve.
Give the attachments, innervation and actions of Quadratus Plantae
The quadratus plantae muscle is located superior to the flexor digitorum longus tendons. It is separated from the first layer of muscles by the lateral plantar vessels and nerve.
Attachments: Originates from the medial and lateral plantar surface of the calcaneus. It attaches to the tendons of flexor digitorum longus.
Actions: Assists flexor digitorum longus in flexing the lateral four digits.
Innervation: Lateral plantar nerve.
Give the attachments, innervation and actions of the lumbricals
There are four lumbrical muscles in the foot. They are each located medial to their respective tendon of the flexor digitorum longus.
Attachments: Originates from the tendons of flexor digitorum longus. Attaches to the extensor hoods of the lateral four digits.
Actions: Flexes at the metatarsophalangeal joints, while extending the interphalangeal joints.
Innervation: The most medial lumbrical is innervated by the medial plantar nerve. The remaining three are innervated by the lateral plantar nerve.
What are the plantar muscles in the third layer?
The third layer contains three muscles. The flexor hallucis brevis and adductor hallucis are associated with movements of the great toe. The remaining muscle, the flexor digiti minimi brevis, moves the little toe.
What are the plantar muscles in the fourth layer?
The plantar and dorsal interossei comprise the fourth and final plantar muscle layer. The plantar interossei have a unipennate morphology, while the dorsal interossei are bipennate.
