Slanting neck is a deformity in which one side of the neck is shorter than the opposite side, so that the head is skewed to the affected side and the chin is moved up to the normal side. If the oblique neck has existed for a long time, it can cause significant deformities such as the shoulder on the affected side being higher than the normal side, facial development and asymmetry in the level of eye fissures on both sides. The main key to this deformity is the shortening of the sternocleidomastoid muscle on the affected side due to fibrosis of the muscle tissue. The causes of muscle fibrosis are congenital and acquired. The causes of congenital squint include shortening of the muscles (mainly sternocleidomastoid muscle) and abnormal development of the cervical spine. In acquired cases, the causes are trauma, infection (which can spread to other adjacent muscles), muscle spasm or neurological causes. A small number of cases of oblique neck may be due to congenital causes. It has been reported in the literature that infants born by cesarean section can develop a squamous neck deformity. This may be due to ischemic contracture caused by compression of the neck muscles due to the abnormal position of the fetus in the uterus, and genetics is also a possible cause. Plagiocephaly has been thought to be associated with a hematoma within the sternocleidomastoid muscle of the infant due to inadvertent application of forceps by the mother during delivery, but in fact no definite hematoma has been found within this muscle to date. A more plausible explanation may be due to obstruction of venous return following injury to this muscle. Extensive and deep infection of the neck in early childhood can cause shortening and adhesions of the muscle, which can interfere with normal development and may result in a sloping neck. A severe developmental deformity of the neck can cause a squint, but a severe squint can also cause a secondary bending deformity of the cervical spine over time. What is the main cause between the two can be distinguished by X-ray. Strabismus can also cause lateral deviation of the head, which can be easily confused with strabismus, but obviously there is no lesion in the sternocleidomastoid muscle at this time, which can be differentiated. The diagnosis of strabismus is usually not difficult. In the first few days of life, the infant’s head is often tilted to one side, which is easier for the family to detect. On examination, a stiff shortening of the sternocleidomastoid muscle on the affected side can be detected. The degree of stiffness and shortening varies depending on the severity of the condition. In most cases, it is a shortening of the clavicular segment, but in severe cases, there is also a significant shortening of the sternal segment. If left untreated, the affected side and cervical vertebrae may develop severe secondary deformities after growth, such as asymmetrical eye fissures on both sides, oblique face toward the affected side, significantly enlarged auricles on the affected side, and higher shoulders than the healthy side. In severe cases of oblique neck, the head is tilted downward in addition to the affected side, which can sometimes be misdiagnosed and operated on the normal side. We have seen a case where an inexperienced surgeon misdiagnosed the problem and caused a surgical error. In addition, a differential diagnosis should be made with the above-mentioned cases of oblique neck not caused by sternocleidomastoid contracture. The surgical treatment of the sternocleidomastoid should be performed at an early age to avoid secondary facial deformities, usually at the age of 4 to 5 years. In adult cases with secondary deformities, it is also desirable to perform surgery in a timely manner to correct the deformities, as they are expected to improve to varying degrees after surgery. The surgery is performed under general or local anesthesia. The typical surgical approach is to make a short transverse incision at the upper border of the affected clavicle, separate the subcutaneous tissue above the incision, and sever the supraclavicular attachment of the sternocleidomastoid muscle. The head and neck are continually deflected to the healthy side to tense the affected muscle and facilitate the severance and release of the contracture. Care is taken not to damage the underlying carotid sheath and phrenic nerve. In more severe cases, the suprasternal attachment point of the muscle should be severed as well. In addition, the adjacent fascial tissues should also be dissected and released until the head and neck can be fully repositioned in the neutral position. After careful hemostasis, the supraclavicular skin incision is sutured. However, when the muscle is severely fibrotic and adheres to the surrounding tissues, cutting the supraclavicular muscle attachment point alone is often insufficient to obtain adequate release. Therefore, we often make a small transverse incision in the middle section of the fibrotic muscle and one below the mastoid. The supraclavicular attachment point is cut first, and a blunt dissection is used along the fibrotic muscle to make a peripheral dissection, then the muscle is cut below the mastoid process, and the majority of the fibrotic muscle is removed. The result of this surgical operation is often better than simply cutting the supraclavicular attachment. If the detachment is complete and overcorrected during the surgery, it can generally be restored to its normal form after 3 months of post-operative bracing.