Musculus quadriceps femoris -- vastus intermedius
The deepest quadriceps head, lying directly on the cranial femur. Extends the stifle and provides deep stabilization of the patellar mechanism.
Origin: Cranial surface of the femoral shaft
Insertion: Tibial tuberosity via the patellar ligaments
Action: Extends the stifle
Innervation: Femoral nerve (L4-L5)
Difficult to assess clinically due to depth. Usually involved in widespread quadriceps injury rather than isolated pathology.
Difficult to assess clinically due to depth. Usually involved in widespread quadriceps injury rather than isolated pathology. Signs include: Deep thigh pain; stifle extension weakness; lameness worse going downhill; responds to ultrasound-guided treatment.
See the Vastus Intermedius on our interactive 3D horse model. Open 3D Model