Musculus serratus ventralis thoracis
The serratus ventralis consists of cervical and thoracic portions that together form the muscular sling suspending the thorax between the forelimbs. The serratus ventralis cervicis originates from the transverse processes of cervical vertebrae C3-C7 and inserts on the cranial medial surface of the scapula. The serratus ventralis thoracis is a massive fan-shaped muscle that originates from the lateral surfaces of ribs 1-9 and inserts on the medial surface of the scapula. Their actions are to support the trunk between the forelimbs, draw the trunk forward, elevate the base of the neck, rotate the scapula during locomotion, and absorb concussion. They are innervated by the long thoracic nerve and ventral branches of cervical nerves (roughly C5-C7). Because horses have no clavicle, these muscles bear the full weight of the thorax.
Origin: Lateral surfaces of ribs 1-9 (serrated, saw-tooth pattern)
Insertion: Serrated face of the scapula (medial surface)
Action: Supports the trunk between the forelimbs; rotates the scapula during locomotion; absorbs concussion
Innervation: Long thoracic nerve and ventral branches of cervical nerves (C5-C7)
Dysfunction or atrophy can contribute to reduced thoracic support and altered shoulder biomechanics. Relevant in evaluations of shoulder function and after trauma. They are critical for suspending the thorax.
## Overview Compensatory overload occurs when a horse shifts weight or alters gait to protect a painful forelimb, thereby increasing stress on the opposite forelimb, the hind limbs, or the back and n
## Overview A saddle that restricts scapular rotation can compress the serratus ventralis, the muscle that helps suspend the trunk and allow free shoulder movement. This shortens the forelimb stride,
Weakness of the serratus ventralis allows the thorax to drop between the forelimbs, creating a hollow behind the withers and affecting the entire posture of the horse. This is the core of the 'core' i
Persistent shoulder asymmetry or reduced thoracic support after trauma should be evaluated. Correct saddle fit and balanced work help maintain function.
## Overview Compensatory overload occurs when a horse shifts weight or alters gait to protect a painful forelimb, thereby increasing stress on the opposite forelimb, the hind limbs, or the back and neck. This can produce secondary lameness, muscle strain, or joint inflammation that persists even after the primary problem is treated. ## Causes Any significant forelimb lameness (foot pain, tendon injury, joint disease) that causes prolonged weight redistribution. ## Diagnosis Recognition of a primary lameness plus secondary signs in other limbs or the axial skeleton. Sequential blocking and imaging identify both the original and compensatory lesions. ## Treatment Treat the primary lameness aggressively and support the overloaded structures with rest, anti-inflammatories, and rehabilitation. Corrective shoeing may help redistribute load. ## Recovery and Prognosis Good if the primary problem is resolved before secondary damage becomes severe. Chronic compensation can leave lasting issues. ## Prevention Early diagnosis and treatment of forelimb lameness. Signs include: primary forelimb lameness plus secondary lameness or stiffness in other limbs or the back; muscle soreness; altered posture
## Overview A saddle that restricts scapular rotation can compress the serratus ventralis, the muscle that helps suspend the trunk and allow free shoulder movement. This shortens the forelimb stride, causes muscle atrophy behind the shoulder, and makes the horse move better without the saddle. Stumbling and resistance to downward transitions may occur. ## Causes Poorly fitted saddle limiting scapular motion. ## Diagnosis Comparison of movement with and without the saddle, and evaluation of saddle fit. ## Treatment Refit or replace the saddle. Allow the muscle to recover with correct work. ## Recovery and Prognosis Good once saddle fit is corrected. ## Prevention Professional saddle fitting that allows free scapular rotation. Signs include: shortened forelimb stride; muscle atrophy behind the shoulder; moves better without saddle; resistance to downward transitions; stumbling
Weakness of the serratus ventralis allows the thorax to drop between the forelimbs, creating a hollow behind the withers and affecting the entire posture of the horse. This is the core of the 'core' in equine rehabilitation. Signs include: Hollow behind the withers; withers appear more prominent than they should; horse falls on the forehand; heavy in the hand; difficulty engaging the hindquarters; stumbling on the forehand.; Low withers appearance; stumbling and tripping; heavy on the forehand; reduced shock absorption (jarring trot); forelimb lameness from increased concussive loading.; Stumbling; withers appear to sink between the shoulders; premature fatigue during work; poor shock absorption at the trot.
Dysfunction or atrophy can contribute to reduced thoracic support and altered shoulder biomechanics. Relevant in evaluations of shoulder function and after trauma. They are critical for suspending the thorax.
Persistent shoulder asymmetry or reduced thoracic support after trauma should be evaluated. Correct saddle fit and balanced work help maintain function.
See the Serratus Ventralis Thoracis on our interactive 3D horse model. Open 3D Model