Musculus scalenus
The scalenus is a deep lateral neck muscle. It originates from the transverse processes of cervical vertebrae C4-C7 and inserts on the cranial surface of the first rib. Its actions are to elevate the first rib during inspiration and to produce lateral flexion of the neck. It is innervated by ventral branches of cervical spinal nerves (roughly C5-C7). It is important for respiration and neck mobility.
Origin: Transverse processes of cervical vertebrae C4-C7
Insertion: Cranial surface of the first rib
Action: Elevates the first rib during inspiration; lateral flexion of the neck
Innervation: Ventral branches of cervical spinal nerves (C5-C7)
Isolated injury is uncommon. Relevant in evaluations of respiratory function and neck mobility after trauma.
## Overview Respiratory effort indicators are visible signs that a horse is working harder than normal to breathe. They include flared nostrils, increased respiratory rate, abdominal push during expi
Persistent neck stiffness or difficulty breathing after trauma should be evaluated.
## Overview Respiratory effort indicators are visible signs that a horse is working harder than normal to breathe. They include flared nostrils, increased respiratory rate, abdominal push during expiration, and fatigue during exercise. In horses with heaves, accessory muscles such as the scalenus contribute to the increased work. ## What It Indicates Lower-airway obstruction, pain, fever, or other causes of increased respiratory demand. ## Diagnosis Observation of breathing pattern and further work-up of the respiratory system. ## Treatment Directed at the underlying cause. ## Recovery and Prognosis Depends on the primary disease. ## Prevention Depends on etiology. Signs include: visible effort during breathing; flared nostrils; increased respiratory rate; abdominal push; exercise fatigue
Isolated injury is uncommon. Relevant in evaluations of respiratory function and neck mobility after trauma.
Persistent neck stiffness or difficulty breathing after trauma should be evaluated.
See the Scalenus on our interactive 3D horse model. Open 3D Model