Pelvis & lower limb
Interphalangeal joints of the foot
Hinge-type synovial joints between the phalanges of the toes. The great toe has a single interphalangeal joint because it has only two phalanges; toes two to five each have a proximal (PIP) and a distal (DIP) interphalangeal joint. They allow only flexion and extension and help the toes grip the ground.
- Structural
- Synovial joints
- Functional
- Diarthrosis
- Synovial type
- Hinge
- Axes
- Uniaxial: flexion and extension about a transverse axis
Tap a bone or ligament on the model, or choose one from the list. Hide the capsule to see what lies inside it.
3D model: Z-Anatomy (CC BY-SA 4.0), derived from BodyParts3D © DBCLS (CC BY-SA 2.1 JP). Adapted by PharmaWallah. Credits & licence
Structures
Choose one to highlight it. Grey dots are taught here but not modelled.
Bones
Special structures
Ligaments
Identification
Location: Within the toes, between successive phalanges: one joint in the great toe and two (proximal and distal) in each of the other four toes.
Bones taking part
- Proximal phalanx of great toe
- Distal phalanx of great toe
- Proximal phalanx of second toe
- Middle phalanx of second toe
- Distal phalanx of second toe
- Proximal phalanx of third toe
- Middle phalanx of third toe
- Distal phalanx of third toe
- Proximal phalanx of fourth toe
- Middle phalanx of fourth toe
- Distal phalanx of fourth toe
- Proximal phalanx of fifth toe
- Middle phalanx of fifth toe
- Distal phalanx of fifth toe
Articulating surfaces
- Great toe: the pulley-shaped head of the proximal phalanx with the base of the distal phalanx.
- Toes 2–5, proximal interphalangeal joint: the head of the proximal phalanx with the base of the middle phalanx.
- Toes 2–5, distal interphalangeal joint: the head of the middle phalanx with the base of the distal phalanx.
- Each head is pulley-shaped (bicondylar) and fits a base with two shallow facets separated by a ridge.
Classification & structure
- Structural
- Synovial joints.
- Functional
- Diarthrosis (freely movable).
- Synovial subtype
- Hinge.
- Axes
- Uniaxial: flexion and extension about a transverse axis.
- Capsule & cavity
- Each joint has its own fibrous capsule lined by synovial membrane, strengthened on each side by collateral ligaments and on the plantar side by a plantar ligament. Dorsally the capsule is covered by the extensor expansion.
Its parts, one by one
Interphalangeal joint of the great toe
Synovial, hinge
Bones: Proximal and distal phalanges of the great toe
Only one joint, because the great toe has two phalanges; flexed by flexor hallucis longus and extended by extensor hallucis longus.
Proximal interphalangeal joints (toes 2–5)
Synovial, hinge
Bones: Proximal and middle phalanges
Flexed by flexor digitorum brevis (and flexor digitorum longus).
Distal interphalangeal joints (toes 2–5)
Synovial, hinge
Bones: Middle and distal phalanges
Flexed by flexor digitorum longus. In the fifth toe the middle and distal phalanges are often fused, so this joint may be absent.
Ligaments & supporting structures
| Structure | Attachments / position | Role |
|---|---|---|
| Capsule of the interphalangeal joint of the great toe | Around the articular margins of the proximal and distal phalanges of the great toe. | Encloses the single interphalangeal joint of the great toe. |
| Capsules of the proximal interphalangeal joints | Around the joints between the proximal and middle phalanges of toes 2–5. | Enclose the proximal interphalangeal joints. |
| Capsules of the distal interphalangeal joints | Around the joints between the middle and distal phalanges of toes 2–5. | Enclose the distal interphalangeal joints. |
| Collateral interphalangeal ligaments | On each side of each joint, from the side of the head of the more proximal phalanx to the side of the base of the more distal phalanx. | Prevent side-to-side movement, so the joint moves only as a hinge. |
| Plantar interphalangeal ligaments | Thick plates on the plantar side of each joint, grooved for the long flexor tendons. | Form the floor of each joint and resist over-extension. |
Movements
Flexion
The toes curl downward toward the sole, bending at the interphalangeal joints.
Main muscles: Flexor digitorum longus, Flexor digitorum brevis, Flexor hallucis longus
Extension
The toes straighten at the interphalangeal joints.
Main muscles: Extensor digitorum longus, Extensor digitorum brevis, Extensor hallucis longus, Lumbricals
Not at this joint
- Abduction and adduction of the toes occur at the metatarsophalangeal joints, not the interphalangeal joints.
- Dorsiflexion and plantarflexion of the foot occur at the ankle (talocrural) joint.
- Inversion and eversion occur mainly at the subtalar and transverse tarsal joints.
Function
- Standing: flexion of the toes presses the toe pads into the ground, widening the base of support.
- Walking: the toes grip the ground and help steady the foot as weight moves forward to push-off.
- Balance: small toe flexor contractions correct sway, especially when standing on one leg.
- Locomotion: the great toe's flexors give the final part of push-off.
Stability vs mobility: Stable hinges: collateral ligaments prevent sideways movement and the plantar ligaments resist over-extension. Mobility is limited to flexion and extension and is less than in the fingers.
Clinical correlations
- Hammer toe: the metatarsophalangeal joint is extended and the proximal interphalangeal joint flexed, often with a painful callus on top of the toe.
- Claw toe: the metatarsophalangeal joint is extended while both interphalangeal joints are flexed.
- Mallet toe: the distal interphalangeal joint is held flexed.
- Tight footwear and imbalance between toe flexors and extensors contribute to these deformities.
What examiners look for
- Hinge synovial joints; uniaxial; flexion and extension only.
- Great toe: one IP joint; toes 2–5: PIP and DIP.
- Fifth toe: middle and distal phalanges often fused.
- Flexor digitorum brevis flexes the PIP joints; flexor digitorum longus the DIP (and PIP) joints; flexor hallucis longus the IP joint of the great toe.
- Abduction/adduction occur at the MTP joints, not here.
- Distinguish hammer toe, claw toe and mallet toe by which joints are flexed.
Common mistakes
- Giving the great toe two interphalangeal joints.
- Saying abduction and adduction occur at the interphalangeal joints.
- Saying flexor digitorum brevis reaches the distal phalanx — it inserts on the middle phalanges.
- Calling these joints condylar — they are hinges.
Viva questions
What type of joint are the interphalangeal joints of the foot?Show answer
Hinge-type synovial joints, uniaxial.
How many interphalangeal joints does the great toe have, and why?Show answer
One, because it has only two phalanges (proximal and distal).
Which muscle flexes the distal interphalangeal joints of the lateral four toes?Show answer
Flexor digitorum longus, which inserts into the distal phalanges.
Which muscle flexes the interphalangeal joint of the great toe?Show answer
Flexor hallucis longus.
Which movements are possible at these joints?Show answer
Flexion and extension only.
What is a hammer toe?Show answer
Extension at the metatarsophalangeal joint with flexion at the proximal interphalangeal joint.
Revision notes
- Hinge synovial; uniaxial; flexion and extension.
- Great toe: one IP joint. Toes 2–5: PIP and DIP.
- Ligaments: collateral and plantar.
- Flexors: FDL (distal phalanges), FDB (middle phalanges), FHL (great toe).
- Extensors: EDL, EDB, EHL (great toe).
- Fifth toe: middle and distal phalanges often fused.
- Hammer, claw and mallet toe deformities.
Related joints
References
- Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. 5th ed. Philadelphia: Elsevier; 2023.
- Moore KL, Dalley AF, Agur AMR. Moore's Clinically Oriented Anatomy. 9th ed. Philadelphia: Wolters Kluwer; 2023.
- Federative International Programme for Anatomical Terminology (FIPAT). Terminologia Anatomica. 2nd ed. FIPAT.library.dal.ca; 2019. fipat.library.dal.ca/TA2
- Kervyn G, Zielinski M, Vinent L, et al. Z-Anatomy: the libre 3D atlas of anatomy. Models derived from BodyParts3D, The Database Center for Life Science (CC BY-SA 2.1 JP). CC BY-SA 4.0. www.z-anatomy.com/
Prepared by the PharmaWallah student team. Verify results with your textbook or instructor. Report an error · Editorial policy