Musculus quadriceps femoris -- vastus intermedius
The vastus intermedius is the deepest quadriceps head, lying directly on the cranial femur. It originates from the cranial surface of the femoral shaft and inserts on the tibial tuberosity via the patellar ligaments. The vastus lateralis is the lateral component, originating from the lateral surface of the proximal femur and inserting on the lateral patellar ligament and tibial tuberosity. The vastus medialis is the medial component, originating from the medial surface of the proximal femur and inserting on the medial patellar ligament and tibial tuberosity. All extend the stifle. The vastus medialis is particularly important for medial stabilization of the patella. All are innervated by the femoral nerve (roughly L4-L5). Together with the rectus femoris they form the major anti-gravity muscle group of the hindlimb.
Origin: Cranial surface of the femoral shaft
Insertion: Tibial tuberosity via the patellar ligaments
Action: Extends the stifle
Innervation: Femoral nerve (L4-L5)
Strain of the quadriceps can cause hindlimb lameness and reduced stifle extension. The vastus medialis is relevant in evaluations of patellar stability and upward fixation. Diagnosis is clinical and with ultrasound.
## Overview Pathology of the deep quadriceps muscles produces thigh pain and weakness of stifle extension. Because of the depth of the muscles, clinical assessment is difficult and ultrasound-guided
Sudden hindlimb lameness with swelling or pain over the front of the thigh after work should be evaluated. Rest and appropriate rehabilitation are important for recovery.
## Overview Pathology of the deep quadriceps muscles produces thigh pain and weakness of stifle extension. Because of the depth of the muscles, clinical assessment is difficult and ultrasound-guided techniques are often needed for diagnosis and treatment. It is usually part of a broader quadriceps injury rather than an isolated problem. ## Causes Strain from slipping, sudden effort, or compensatory overload. ## Diagnosis Pain on deep palpation, weakness going downhill, and ultrasound or response to diagnostic injection. ## Treatment Rest, anti-inflammatories, physiotherapy, and ultrasound-guided injection when indicated. ## Recovery and Prognosis Generally good for muscle strain with appropriate rehabilitation. ## Prevention Gradual conditioning and attention to footing. Signs include: deep thigh pain; stifle extension weakness; lameness worse downhill; response to ultrasound-guided treatment
Strain of the quadriceps can cause hindlimb lameness and reduced stifle extension. The vastus medialis is relevant in evaluations of patellar stability and upward fixation. Diagnosis is clinical and with ultrasound.
Sudden hindlimb lameness with swelling or pain over the front of the thigh after work should be evaluated. Rest and appropriate rehabilitation are important for recovery.
See the Vastus Intermedius on our interactive 3D horse model. Open 3D Model