Location and topography?
The calcaneal (Achilles) tendon is an external landmark of the posterior ankle region (Regio talocruralis posterior). Grooves are located on either side of it; the lateral boundaries of the region run along the edges of the calcaneal tendon. Other external landmarks include the lateral and medial malleoli.
- Skin: thicker than on the anterior surface. Forms transverse folds during plantar flexion of the foot.
- Synovial bursae: the bursa subtendinea m. gastrocnemii lies beneath the tendon, and the bursa subcutanea calcanea lies superficial to it.
- Blood supply to the region: calcaneal branches (rr. calcanei) originating from the medial and lateral sides run through the calcaneal region, forming the calcaneal vascular network (rete calcaneum). In the lateral retromalleolar region, calcaneal branches of the fibular [peroneal] artery (rami calcanei a. fibularis [peronea]) are present.
Neurology: Achilles reflex
The Achilles reflex is elicited by striking the Achilles tendon with a neurological reflex hammer.
- Procedure: the patient's leg is flexed at the knee joint, and the foot is in a neutral position midway between flexion and extension.
- Facilitation: the examiner can slightly stretch the Achilles tendon by passively dorsiflexing the patient's foot. If lower extremity tendon reflexes cannot be elicited by standard means, the Jendrassik maneuver is used: the patient is asked to interlock the fingers of both hands and pull them apart strongly.
- Response: plantar flexion of the foot.
- Effector muscles: contraction of the gastrocnemius and soleus muscles.
- Arc reflex level: spinal cord segments S₁–S₃. When evaluating chronic inflammatory demyelinating polyneuropathy (CIDP), the Achilles reflex is designated as the Achilles tendon reflex S₁–S₂.
- Clinical significance of changes: weakening (diminution) of the reflex indicates damage to the peripheral reflex arc, including the anterior horns of the spinal cord. Exaggeration (hyperactivity) of the reflex indicates upper motor neuron damage involving the corticospinal (pyramidal) tract above the level of the reflex arc.
Clinical significance in rheumatology
The Achilles tendon is a common site for enthesopathies.
- Enthesopathies: pathology of the sites where tendons, ligaments, or joint capsules attach to bone. Manifests as spontaneous pain or tenderness upon palpation. It is a characteristic feature of spondyloarthropathies.
- Psoriatic arthritis: the bilateral Achilles tendons are included in the anatomical evaluation sites of the Leeds Enthesitis Index (LEI). The index is used to assess enthesitis dynamics and is calculated by simply summing the scores of palpation tenderness.
- Idiopathic gout: tendons, such as the Achilles tendon, are noted as a localization site for tophi.
Class and exam questions
How to properly elicit the Achilles reflex?
Strike the Achilles tendon with a neurological reflex hammer with the leg flexed at the knee and the foot in a neutral position. For facilitation, the tendon can be slightly stretched by passively dorsiflexing the foot. If necessary, the Jendrassik maneuver is applied.
What does a diminished Achilles reflex indicate?
A diminished reflex indicates damage to the peripheral reflex arc, including the anterior horns of the spinal cord.
What is Achilles tendon enthesopathy?
This is a pathology of the tendon attachment site to the bone. Enthesopathies are characterized by spontaneous pain or tenderness upon palpation; the Achilles tendon is a typical localization site.
What else to study on this topic
- Gastrocnemius muscle (m. gastrocnemius)
- Soleus muscle (m. soleus)
- Posterior ankle region (Regio talocruralis posterior)
- Lower extremity tendon reflexes
- Enthesopathies and spondyloarthropathies
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