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Questions and Answers
Which bones are included in the hind foot?
What is comprised in the midfoot region?
In the context of foot anatomy, what does the term 'ray' refer to?
Which structure is a part of the forefoot?
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What bones are referred to collectively when discussing the hind foot?
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What is the primary action of the fibular muscles in relation to ankle stability?
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Which artery contributes to the blood supply of the ankle joint?
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Which of the following muscles is NOT involved in stabilizing the medial aspect of the ankle?
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What are the primary motions at the talocrural joint?
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Which nerve is specifically noted for innervating the ankle joint?
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Which bones are included in the fifth ray of the foot?
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What is the primary function of the deltoid ligament in the ankle?
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Which of the following ligaments is most commonly sprained?
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What structural feature of the ankle joint allows for its classification as a modified hinge joint?
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Which structures provide secondary reinforcement to the ankle outside of the primary ligaments?
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Study Notes
Subtalar Joint Structure
- Consists of two articulations between the talus and calcaneus
- Posterior articulation is the major one
- Posterior articulation is considered a planar synovial joint, but the talus is concave and the calcaneus is convex
- Anterior articulation is between the head and neck of the talus and the anterior facets of the calcaneus
- Anterior articulation is considered more with the talonavicular or calcaneonavicular joint
- Sinus tarsi space is between anterior and posterior joint surfaces, doesn't have cartilage
- Cervical ligament or interosseous talocalcaneal ligament is located within the sinus tarsi
Subtalar Joint Ligaments
- Cervical and interosseous ligaments are located within the sinus tarsi
- Cervical and interosseous ligaments anchor the talus to the calcaneus
- Plantar calcaneonavicular ligament travels from the sustentaculum tali to the navicular
Subtalar Joint Summary
- Talus is concave and articulates with the convex surface of the calcaneus
- Plantar calcaneonavicular ligament holds up the head and neck of the talus, stabilizing it on the calcaneus### Subtalar Joint
- Articulation: Between the talus and calcaneus
- Ligaments: Talocalcaneal ligaments, deltoid ligament, calcaneofibular ligament
- Motion: Inversion (turning the sole of the foot towards midline) and eversion (turning the sole of the foot away from midline). These motions are rarely done in isolation.
- Blood Supply: The talus has a limited vascular supply due to the presence of articular cartilage on most surfaces.
- Fracture Risk: Fractures to the talus are at high risk for necrosis (bone death) due to limited blood supply.
Transverse Tarsal Joint
- Function: Part of the midfoot, it acts as a connection between the hindfoot and midfoot.
- Joints: The talonavicular (spheroidal) and the calcaneocuboid (sellar) articulating together
Ligaments of the Transverse Tarsal Joint
- Long Plantar Ligament: Long, fibrous ligament, deep to the plantar fascia, extending from the calcaneus to the bases of the lateral three metatarsals.
- Plantar Calcaneonavicular Ligament (Spring Ligament): Thick, strong ligament connecting the sustentaculum tali to the navicular.
- Plantar Calcaneocuboid Ligament: Also known as the short plantar ligament, it connects the anterior inferior surface of the calcaneus to the cuboid.
- Tibialis Posterior Tendon: Connects the navicular and metatarsals.
Motions of Pronation and Supination
-
Open Chain:
-
Pronation:
- Dorsiflexion
- Eversion
- Foot Abduction
-
Supination:
- Plantar Flexion
- Inversion
- Forefoot Adduction
-
Pronation:
Arches of the Foot
- Functions: Provide shock absorption and stabilize the foot. Prevent compression of neurovascular structures and distribute weight.
- Types:
- Medial Longitudinal: A prominent arch forming from the calcaneus, talus, navicular, cuneiform 3, and metatarsals.
- Lateral Longitudinal: Less prominent, forms from the calcaneus, cuboid, and fourth and fifth metatarsals.
- Transverse Tarsal: Runs across the foot from the medial to lateral side.
Medial Longitudinal Arch Supports
- Tibialis Posterior, Flexor Hallucis Longus, Flexor Digitorum Longus, Tibialis Anterior, Abductor Hallucis, Plantar Calcaneonavicular Ligament
Plantar Foot Muscles
- The plantar surface of the foot has 4 layers of muscles.
- Knowledge of insertions and origins of these muscles is not needed, but understanding their location, layer, innervation, and primary action is essential.
-
Layer 1
- Abductor Hallucis: pulls the big toe away from midline, innervated by the medial plantar nerve
- Abductor Digiti Minimi: pulls the little toe away from midline, innervated by the lateral plantar nerve
- Flexor Digitorum Brevis: helps flex the toes, innervated by the medial plantar nerve
-
Layer 2
- Flexor Digitorum Longus: tendon goes to the toes
- Flexor Hallucis Longus: tendon goes to the toes
- Quadratus Plantae: attaches from calcaneus to flexor digitorum longus tendon, assists in aligning the pull of the tendon, innervated by the lateral plantar nerve
- Lumbricals: help to stabilize the toes, 1st lumbrical is innervated by the medial plantar nerve, the rest are innervated by the lateral plantar nerve
-
Layer 3
- Adductor Hallucis: pulls the big toe towards the midline (often referred to as the "flip-flop" muscle), innervated by the lateral plantar nerve
- Flexor Hallucis Brevis: crosses towards the medial side, innervated by the medial plantar nerve
- Flexor Digiti Minimi Brevis: innervated by the lateral plantar nerve
-
Layer 4
- Dorsal Interossei: abduct the toes, innervated by the lateral plantar nerve
- Plantar Interossei: adduct the toes, innervated by the lateral plantar nerve
Plantar Foot Nerve Supply
- The posterior tibial artery splits into the medial and lateral plantar arteries.
- Nerves that supply the plantar foot arise from the posterior tibial nerve.
- Nerve roots that innervate the plantar foot are S2 and S3.
- Medial Plantar Nerve: innervates the medial side of the foot
- Lateral Plantar Nerve: innervates the lateral side of the foot
- Calcaneal Branches: innervate the heel
Plantar Foot Blood Supply
- The posterior tibial artery splits into the medial and lateral plantar arteries.
- Tarsal Tunnel Syndrome: compression of the artery and nerve in the foot can cause numbness and tingling in the foot, and reduced blood supply.
Foot Muscles - Layer 4: Interossei
- Interossei are located between the metatarsals.
- Plantar interossei are located on the plantar side of the foot and help with toe adduction.
- Dorsal interossei are located on the dorsal side of the foot and help with toe abduction.
- Mnemonic: 'Pad' (plantar ADduct) and 'Dab' (dorsal ABduct).
- Innervation: All interossei muscles are innervated by the lateral plantar nerve.
Foot Muscles - General
- Foot muscles play a crucial role in stabilizing the toes, especially during walking.
- Focus on recognizing the layers and identifying the muscles within each layer.
- Knowing the general action and innervation of each muscle is essential.
- Detailed muscle attachments are less important for physical therapists.
- Understanding muscle function is critical for diagnosing and treating nerve injuries.
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