The sternocleidomastoid is a commonly recognized muscle of the neck; however, its contribution to an infant’s development is frequently neglected until a parent realizes that the baby keeps turning his/her head in one direction all the time. For those working as manual therapists for growing families, knowledge about this muscle can make the difference between providing unnecessary reassurance and being fully aware of when to refer. The following article provides information about its anatomy, etiology of congenital muscular torticollis, and relevant signs of assessment.
The Sternocleidomastoid at a Glance
The sternocleidomastoid is a two-headed neck muscle that runs from the sternum and clavicle up to the mastoid process behind the ear, and acting alone, it tilts the head to the same side while rotating the face to the opposite side.
The muscle has two heads. The sternal head attaches to the top of the sternum, and the clavicular head attaches to the medial third of the clavicle. Both converge and travel upward to insert on the mastoid process of the temporal bone and the lateral occiput.
Its actions depend on whether one side or both sides contract:
- Working unilaterally, it laterally flexes the head and neck to the same side and rotates the face toward the opposite side.
- Working bilaterally, it flexes the lower cervical spine and extends the upper cervical spine, producing the forward jut of the chin.
Because it is such a prominent landmark, the sternocleidomastoid is a reliable palpation reference for locating deeper structures. For a fuller map of how it sits among its neighbors, learnmuscles.com offers a detailed breakdown of the musculature of the cervical spine that places the muscle in its regional context.
How the SCM Drives Congenital Muscular Torticollis
Congenital muscular torticollis is a postural deformity present at or shortly after birth, caused by shortening or tightness of the sternocleidomastoid that tilts the head toward the affected side and rotates the chin toward the opposite side.
The word torticollis comes from the Latin for twisted neck, and that is exactly what the presentation looks like. When one sternocleidomastoid is shortened or fibrotic, it pulls the head into its characteristic position and resists correction toward the other side.
According to StatPearls from the National Library of Medicine, congenital muscular torticollis is the third most common congenital musculoskeletal condition in infants, and it is frequently associated with intrauterine positioning and birth history.
Several factors are commonly linked to the condition:
- Restricted space in the uterus during the later stages of pregnancy
- Breech positioning or a difficult delivery
- A palpable thickening or mass within the muscle belly, sometimes called a sternocleidomastoid pseudotumor
- Prolonged positioning that reinforces a preferred head turn after birth
This is important to remember when working on muscles because there are many factors involved other than just the muscle itself. These factors include the cervical joints, the fascia around the area, and how the baby positions himself or herself.
Recognizing the Pattern: Positional Preference and Plagiocephaly
Positional preference is when an infant consistently holds or turns the head to one side, and left unaddressed, it can contribute to positional plagiocephaly, a flattening of one region of the skull.
Parents can identify the pattern long before naming it. The child is able to feed better from one side, sleep with the head oriented in that same position, or follow objects with the eyes in just one half of their visual field.
The concern is that a sustained head position places uneven pressure on the soft infant skull. This can lead to positional plagiocephaly, where one area of the head flattens. The relationship runs in both directions: a tight sternocleidomastoid can drive the head preference, and an existing flat spot can reinforce the preference in turn.
Watch for these observable signs:
- A consistent head tilt toward one shoulder paired with rotation to the opposite side
- Reduced range when the head is gently guided toward the non-preferred side
- Asymmetry of the face or skull that becomes more noticeable over weeks
- A firm, olive-shaped nodule within the muscle in some cases
Palpating the Infant SCM Safely
Palpation of an infant’s sternocleidomastoid should be gentle and brief, using light fingertip contact along the muscle belly to assess for tightness, thickening, or a discrete nodule without forcing any range of motion.
The skin of an infant is very sensitive, and thus the aim of palpation should be the gathering of information and not the correction of any problem. The process becomes more efficient and less uncomfortable with a relaxed child, a parent present, and gentle contact.
A practical approach includes:
- Positioning the infant supported and settled, ideally after feeding rather than during hunger or fatigue
- Using flat, light fingertip pressure to trace the muscle from the mastoid down toward the sternal and clavicular attachments
- Noting any thickening, a palpable mass, or a difference in tension between the two sides
- Observing the infant’s tolerance and stopping if there is distress
Palpation technique is a skill that rewards repetition and a clear regional framework. learnmuscles.com provides a useful reference on palpation assessment of the neck that translates well to careful work with smaller clients.
When to Refer and Who to Involve
Manual therapy practitioners should always recommend that the infant be seen by a physician or pediatric specialist in order to ensure early diagnosis and rule out any other less common conditions causing the torticollis.
Bodywork does not happen in isolation, and torticollis is a clear example of where a care team serves the family best. Any suspected case warrants medical evaluation, both to confirm the diagnosis and to exclude the small number of cases with a non-muscular origin.
A collaborative care team often includes a pediatrician to diagnose and monitor development and a pediatric physical therapist to guide stretching and movement. Families may also consult a chiropractor Charleston SC, who focuses on pediatric care to assess movement patterns and collaborate with other healthcare providers when appropriate. If head preference affects feeding, lactation consultants can also help improve positioning and nursing.
The earlier the pattern is caught, the more responsive it tends to be, which is why the observational eye of a manual therapist can be genuinely valuable.
Frequently Asked Questions
What muscle causes infant torticollis?
According to StatPearls from the National Library of Medicine, congenital muscular torticollis is caused by shortening or tightness of the sternocleidomastoid muscle, which tilts the head toward the affected side and rotates the chin toward the opposite side.
Can infant torticollis be corrected?
Most cases of congenital muscular torticollis respond well to early conservative care, including positioning, gentle stretching, and physical therapy, especially when started in the first months of life.
What does the sternocleidomastoid do?
The sternocleidomastoid laterally flexes the head to the same side and rotates the face to the opposite side when acting on one side, and flexes the lower neck while extending the upper neck when both sides act together.
Is torticollis the same as a flat head?
No. Torticollis is a neck muscle condition that limits head movement, while positional plagiocephaly is a flattening of the skull, though a persistent head preference from torticollis can contribute to plagiocephaly over time.
When should a baby’s head tilt be checked by a professional?
A head tilt or strong head-turn preference that persists, or that comes with limited neck movement or skull asymmetry, should be evaluated by a pediatrician so that assessment and any needed care can begin early.
Conclusion
The sternocleidomastoid does much more than being a landmark for finding the carotid pulse or working with the neck. The sternocleidomastoid plays an important role in the first months of life in terms of how the baby positions its head, eats, and even how its skull grows, which is why a muscle that is so well-known to each manual therapist needs reconsideration in the context of infant development. Knowing the anatomy, the positional pattern, being careful while palpating, and understanding when to involve other specialists becomes something useful for developing families.
