Musculus quadriceps femoris -- vastus lateralis
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: Lateral surface of the proximal femur
Insertion: Lateral patellar ligament and tibial tuberosity
Action: Extends the stifle (knee)
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 Quadriceps strain is injury to the large muscle group on the front of the thigh that extends the stifle. High-demand activities such as racing, jumping, or steep hill work can strain it,
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 Quadriceps strain is injury to the large muscle group on the front of the thigh that extends the stifle. High-demand activities such as racing, jumping, or steep hill work can strain it, especially in unfit horses. Signs include a shortened hind-limb stride, reluctance to extend the stifle, difficulty going downhill, and swelling or pain over the anterior thigh. ## Causes Acute overload or overuse. ## Diagnosis Palpation and ultrasound of the quadriceps. ## Treatment Rest, anti-inflammatories, and gradual rehabilitation. ## Recovery and Prognosis Good for most strains. ## Prevention Progressive conditioning. Signs include: shortened hind-limb stride; reluctance to extend the stifle; difficulty going downhill; swelling over the anterior thigh; pain on palpation
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 Lateralis on our interactive 3D horse model. Open 3D Model