Musculus splenius
The splenius is a broad, flat muscle lying deep to the brachiocephalicus in the upper neck. It originates from the spinous processes of the first 3-5 thoracic vertebrae and the thoracolumbar fascia and inserts on the nuchal crest, mastoid process, and wing of the atlas (C1). Its actions are to raise the head and neck when acting bilaterally and to produce lateral flexion of the head and neck when acting unilaterally. It is innervated by dorsal branches of cervical spinal nerves. It is one of the most important muscles for head and neck elevation and is heavily used during collection and dressage work.
Origin: Spinous processes of the first 3-5 thoracic vertebrae and the thoracolumbar fascia
Insertion: Nuchal crest, mastoid process, and wing of the atlas (C1)
Action: Bilateral: raises the head and neck. Unilateral: lateral flexion of the head and neck
Innervation: Dorsal branches of cervical spinal nerves
Atrophy or dysfunction can contribute to poor head carriage or reduced neck strength. Relevant in evaluations of neck function and after trauma.
## Overview Splenius myalgia is pain and spasm in the splenius muscle from chronic overuse, often due to forced collection, heavy rein contact, or working behind the vertical. Horses resist poll flex
## Overview Nuchal bursitis, traditionally called poll evil, is inflammation of the bursa at the poll, often involving the nuchal ligament attachments. It causes swelling, extreme pain on poll flexio
Loss of neck strength or difficulty elevating the head after illness or trauma should be evaluated. Balanced work and correct head carriage help maintain function.
## Overview Splenius myalgia is pain and spasm in the splenius muscle from chronic overuse, often due to forced collection, heavy rein contact, or working behind the vertical. Horses resist poll flexion, toss the head, and show pain on palpation of the upper neck behind the poll. Signs worsen when asked to work round and through. ## Causes Training-related overuse. ## Diagnosis Palpation and observation under saddle. ## Treatment Rest from forced flexion, physiotherapy, anti-inflammatories, and retraining with lighter contact. ## Recovery and Prognosis Good when the training approach is modified. ## Prevention Balanced training that does not force poll flexion. Signs include: reluctance to flex at the poll; head tossing; resistance to bridle contact; pain on palpation of the upper neck; worse when asked to work round
## Overview Nuchal bursitis, traditionally called poll evil, is inflammation of the bursa at the poll, often involving the nuchal ligament attachments. It causes swelling, extreme pain on poll flexion, and reluctance to lower the head. Infection (including Brucella, Actinomyces, or Borrelia in some regions) or trauma can be responsible. Chronic cases become disfiguring with draining tracts. ## Causes Trauma or bacterial infection of the nuchal bursa. ## Diagnosis Clinical signs, ultrasound of the bursa, and culture or polymerase chain reaction of bursal fluid. ## Treatment Surgical debridement and prolonged antibiotics for infected cases. Traumatic cases may respond to anti-inflammatories and rest. Recurrence is possible. ## Recovery and Prognosis Guarded for infectious cases. Recovery is often prolonged. ## Prevention Avoidance of poll trauma and attention to regional infectious risks. Signs include: swelling at the poll; extreme pain on flexion; draining tract if infected; reluctance to lower the head
Atrophy or dysfunction can contribute to poor head carriage or reduced neck strength. Relevant in evaluations of neck function and after trauma.
Loss of neck strength or difficulty elevating the head after illness or trauma should be evaluated. Balanced work and correct head carriage help maintain function.
See the Splenius on our interactive 3D horse model. Open 3D Model