Musculus sternocephalicus
The sternocephalicus is a paired muscle running from the sternum to the head. It originates from the manubrium of the sternum and inserts on the mastoid process and mandible (depending on subdivision). Its actions are to flex the head and neck ventrally and draw the head toward the chest. It is innervated by the ventral branch of the accessory nerve (cranial nerve XI) and cervical nerves. It is visible as the prominent strap along the underside of the neck and is the antagonist to the dorsal neck extensors.
Origin: Manubrium of the sternum
Insertion: Mastoid process and mandible (depending on species/subdivision)
Action: Flexes the head and neck ventrally; draws the head toward the chest
Innervation: Ventral branch of the accessory nerve (CN XI) and cervical nerves
Isolated injury is uncommon. Relevant in evaluations of neck flexion and head carriage. Dysfunction can contribute to reduced ventral flexion.
## Overview The jugular groove is the depression in the neck where the jugular vein runs, bordered by muscles including the sternocephalicus. It is the landmark for blood draws and intravenous cathet
## Overview Forced deep flexion (rollkur-style work) overworks the ventral neck muscles, including the sternocephalicus. Horses develop pain on palpation of the underside of the neck, reluctance to f
Persistent difficulty flexing the neck or abnormal head carriage after trauma should be evaluated.
## Overview The jugular groove is the depression in the neck where the jugular vein runs, bordered by muscles including the sternocephalicus. It is the landmark for blood draws and intravenous catheter placement. Swelling from inflammation, thrombophlebitis, or other neck problems can obscure the groove and make venous access difficult. ## Causes Normal anatomy altered by swelling, thrombosis, or muscle inflammation. ## Diagnosis Visual and palpable assessment of the groove. Ultrasound if the vein cannot be identified. ## Treatment Address the underlying swelling or thrombosis. Alternative venous access sites may be needed temporarily. ## Recovery and Prognosis Depends on the cause of the swelling. ## Prevention Careful catheter management to avoid thrombophlebitis. Signs include: swollen ventral neck obscuring the jugular groove; difficulty raising or catheterizing the vein
## Overview Forced deep flexion (rollkur-style work) overworks the ventral neck muscles, including the sternocephalicus. Horses develop pain on palpation of the underside of the neck, reluctance to flex the poll, preference for going above the bit, and muscle hardness. ## Causes Training that forces the head behind the vertical for prolonged periods. ## Diagnosis Palpation and observation under saddle. ## Treatment Stop the aggravating work, physiotherapy, and retrain with a more natural head position. ## Recovery and Prognosis Good once the training method changes. ## Prevention Avoid prolonged forced hyperflexion. Signs include: pain on palpation of the ventral neck; reluctance to flex the poll; preference for going above the bit; muscle hardness along the underside of the neck
Isolated injury is uncommon. Relevant in evaluations of neck flexion and head carriage. Dysfunction can contribute to reduced ventral flexion.
Persistent difficulty flexing the neck or abnormal head carriage after trauma should be evaluated.
See the Sternocephalicus on our interactive 3D horse model. Open 3D Model