The splenium is a paired muscle located in the posterior region of the neck and upper back, located below the trapezius and sternocleidomastoid muscles. Some authors describe it as part of the superficial muscles of the back.
It is made up of two muscular bellies with a common origin and different final insertions. For this reason it is described as two muscles: splenium of the neck and splenium of the head.
Route of the splenium muscle. From Mikael Häggström.When using this image in external works, it may be cited as: Häggström, Mikael (2014). "Medical gallery of Mikael Häggström 2014". WikiJournal of Medicine 1 (2). DOI: 10.15347 / wjm / 2014.008. ISSN 2002-4436. Public Domain.orBy Mikael Häggström, used with permission. - Image: Gray409.png, Public Domain, Each of the splenium bodies can act in isolation or together to achieve specific movements. Individually they act in the rotation and lateral flexion of the neck. However, contracting synchronously, they are cervical extensors.
Together with the trapezius muscles and the deep muscles of the neck and back, they play an important role in maintaining the stability of the head.
Splenium contracture, especially of its cephalic portion, is associated with chronic pain in the neck and head that is often confused with the pain produced by migraine.
Once the diagnosis is confirmed, the patient must receive a physical therapy and rehabilitation treatment that includes massages, rest and, in some cases, infiltration with analgesics and steroids.
Anatomy
The splenium is a long and broad muscle that is located on each side of the cervical midline, occupying the back of the neck and the upper part of the back. For some it is considered a superficial muscle of the back and, for others, a deep muscle of the neck.
It is made up of two bundles that have a common origin in the cervical spine, but are separated to insert individually into the skull and spine. Thus, they are distinguished as two different muscles, the splenium of the head and the cervical splenium.
Both muscle bundles of the splenium are located below the trapezius and sternocleidomastoid, and above the supraspinatus of the head and the longus cervical.
Splenium muscle below the trapezius and sternocleidomastoid. By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See «Book» section below) Bartleby.com: Gray's Anatomy, Plate 385, Public Domain, https://commons.wikimedia.org/w/index. php? curid = 512953
The splenii on each side form a triangular anatomical area called the splenius triangle that contains the so-called complex muscles, which are the semi-spinous of the head (complexo major) and the longus of the head (complexo minor).
Origin
The site where the splenius muscle begins its course can be variable, however in most cases its fibers are found in the spinous processes of the fourth thoracic vertebra (T4) to the seventh cervical (C7). It also has fibers that originate from the lower half of the nuchal ligament.
From there the muscular body begins an upward and oblique path outward. At the level of the third cervical vertebra (C3) it divides into two muscular bodies that have different end attachments.
By Anatomography - Anatomography (setteing page of this image.), CC BY-SA 2.1 jp, The belly, wider and flattened, is directed towards the head while the slimmer follows the path parallel to the cervical spine.
It is important to note that some authors consider the splenium muscle of the head and cervical as two completely different bodies, citing their origin separately.
In this case, the splenium of the head is formed by the most superior fibers (from the nuchal ligament and the seventh cervical vertebra) and the cervical splenium from the sixth to the third thoracic vertebra (T6 to T3).
Insertion
The splenium of the head ends its course in the lateral third of the nuchal line of the occipital bone, below the sternocleidomastoid muscle, and on the lateral aspect of the mastoid process of the temporal bone.
For its part, the cervical splenium ends up inserting into the transverse process of the atlas and the axis (first and second cervical vertebrae, respectively) and in the posterior tubercle of the third cervical vertebra (C3), posterior to the levator scapula muscle.
Irrigation
The supply of the splenium in its entirety is ensured by the occipital artery, which is a branch of the external carotid artery.
By Mikael Häggström. When using this image in external works, it may be cited as: Häggström, Mikael (2014). "Medical gallery of Mikael Häggström 2014". WikiJournal of Medicine 1 (2). DOI: 10.15347 / wjm / 2014.008. ISSN 2002-4436. Public Domain.orBy Mikael Häggström, used with permission. - Image: External_carotid_a.gif, Public Domain, Similarly, the deep cervical artery, a branch of the costocervical trunk of the subclavian artery, provides blood supply to this muscle group.
The posterior jugular plexus is the venous network that is responsible for draining the blood in this area, both from the superficial and deep muscles.
Innervation
The splenium of the head is innervated by lateral branches of the posterior division of spinal nerves C1 to C3, while the cervical portion of the splenium receives neurological branches from the posterior division of spinal nerves C6 to T1.
Features
Both the cervical and cephalic portions of the splenium can perform individual movements, but they also work together by contracting synchronously.
When acting individually, the splenium of the head is a lateral flexion muscle of the neck and the cervical splenium is responsible for rotating the head to the same side of the muscle.
When they are contracted at the same time, they achieve the movement of cervical extension and hyperextension, working together with the trapezius, semi-spinous muscles of the head and very long of the head. It is one of the main muscles involved in cervical extension and in head stability.
Cervical extension X-ray. By Stillwaterising - own medical image, work for hire, CC0,
Injuries
Splenium contracture is a common pathology that is difficult to diagnose since it is often confused with others that cause similar symptoms.
In patients who have suffered motor vehicle accidents, spectacular falls or in which posture problems are observed, whether due to work or while sleeping, splenium injury should be suspected.
The clinical manifestations are chronic headache that begins in the neck and extends to the temporal region causing pain behind the eyes and, in some cases, chewing discomfort, nausea, vomiting, and pain in the shoulders.
The diagnosis is purely clinical, so the doctor must be meticulous at the time of the questioning and physical examination.
Passive neck flexion and extension, as well as lateral rotation and flexion, may be limited in patients with splenic contracture. Rectification of the physiological curvature of the cervical spine can be seen on the cervical radiograph.
Passive neck mobilization. By Muthu.G - Own work, CC BY-SA 4.0, Once the condition is diagnosed, the treatment is outpatient and includes physical rehabilitation therapy in which the patient learns to perform massage of the affected region and relaxation exercises for the cervical musculature.
If after 3 weeks of physical therapy the patient does not report improvement, the muscle insertion point is infiltrated with local anesthesia and steroid. This treatment is effective and definitive in relieving symptoms.
References
- Henson, B; Edens, MA (2018). Anatomy, Back, Muscles StatPearls. Treasure Island (FL). Taken from: ncbi.nlm.nih.gov
- Ferrés, E; Agreda, V. S; Montesinos, M. (1991). Manual of embryology and general anatomy. Valencia, Spain: Publications of the University of Valencia
- Latarjet, M; Liard, AR (2004). Human anatomy. Buenos Aires, Argentina: Editorial Médica Panamericana
- Lee, T. H; Lee, J. H; Lee, Y. S; Kim, M. K; Kim, SG (2015). Changes in the activity of the muscles surrounding the neck according to the angles of movement of the neck in adults in their 20s. Journal of physical therapy science. Taken from: ncbi.nlm.nih.gov
- Hall, T; Briffa, K; Hopper, D. (2008). Clinical evaluation of cervicogenic headache: a clinical perspective. The Journal of manual & manipulative therapy. Taken from: ncbi.nlm.nih.gov