Serratus posterior muscles: anatomy, clinical relevance, and function

Pictorial Essay on Ultrasound and Magnetic Resonance Imaging of Paraspinal Muscles for Myofascial Pain Syndrome

The paraspinal muscles of the cervical, thoracic, and lumbar spine are important pain generators because muscle strains or myofascial pain syndrome caused by trigger points are common during clinical practice. Ultrasonography is the most convenient imaging tool for evaluating these muscles due to its advantages, such as providing good delineation of soft tissues, easy accessibility, and zero radiation. Additionally, ultrasound can serve as a useful guiding tool for paraspinal muscle intervention to prevent inadvertent injuries to vital axial neurovascular structures. This pictorial essay presents ultrasound scanning protocols for the paraspinal and other associated muscles as well as a discussion of their clinical relevance. Axial magnetic resonance imaging has also been used to elucidate reciprocal anatomy. In conclusion, ultrasound imaging proves to be a valuable tool that facilitates the differentiation of individual paraspinal muscles. This capability significantly enhances the precision of interventions designed to address myofascial pain syndrome.

Consideration of the thoracic phenotype of cerebro-costo-mandibular syndrome

Cerebro-costo-mandibular syndrome (CCMS) is a congenital condition with skeletal and orofacial abnormalities that often results in respiratory distress in neonates. The three main phenotypes in the thorax are posterior rib gaps, abnormal costovertebral articulation and absent ribs. Although the condition can be lethal, accurate diagnosis, and subsequent management help improve the survival rate. Mutations in the causative gene SNRPB have been identified, however, the mechanism whereby the skeletal phenotypes affect respiratory function is not well-studied due to the multiple skeletal phenotypes, lack of anatomy-based studies into the condition and rarity of CCMS cases. This review aims to clarify the extent to which the three main skeletal phenotypes in the thorax contribute to respiratory distress in neonates with CCMS. Despite the posterior rib gaps being unique to this condition and visually striking on radiographic images, anatomical consideration, and meta-analyses suggested that they might not be the significant factor in causing respiratory distress in neonates. Rather, the increase in chest wall compliance due to the rib gaps and the decrease in compliance at the costovertebral complex was considered to result in an equilibrium, minimizing the impact of these abnormalities. The absence of floating ribs is likely insignificant as seen in the general population; however, a further absence of ribs or vestigial rib formation is associated with respiratory distress and increased lethality. Based on these, we propose to evaluate the number of absent or vestigial ribs as a priority indicator to develop a personalized treatment plan based on the phenotypes exhibited.

Identification and characterization of a potentially novel dorsal cutaneous muscle in rodents

In the course of performing a detailed dissection of adult rat to map the cutaneous nerves of cervical, thoracic, and lumbar levels a small and unexpected structure was isolated. It appeared to be a cutaneous striated muscle and was observed in both male and female rats and in mice but absent from cats and humans. With the skin reflected laterally from midline, the muscle lies closely apposed to the lateral border of the Thoracic Trapezius (Spinotrapezius) muscle and is easily missed in standard gross dissections. Focussed prosections were performed to identify the origin, insertion, and course of gross innervation. Identification of each of these elements showed them to be distinct from the nearby Trapezius and Cutaneous Trunci (Cutaneous Maximus in mouse) muscles. The striated muscle nature of the structure was validated with whole-mount microscopy. Consulting a range of published rodent anatomical atlases and gross anatomical experts revealed no prior descriptions. This preliminary report is an opportunity for the anatomical and research communities to provide input to either confirm the novelty of this muscle or refer to prior published descriptions in rodents or other species while the muscle, its innervation, and function are further characterized. Presuming this muscle is indeed novel, the name "Cutaneous Scapularis muscle" is proposed in accord with general principles of the anatomical field.

The unilateral muscular slip of the two-bellied Serratus Posterior Inferior muscle: a case report and a review of literature

PURPOSE

The two-bellied serratus posterior inferior (SPI) muscle with a muscular slip is a rare variation of the back region, which can cause significant discomfort to patients. Patients typically present with symptoms of chronic pain syndrome, radiating back pain, myofascial pain, or lower back pain. This report describes a case of a female cadaver with a two-headed SPI muscle and a right muscular slip, along with a literature review.

METHODS

A case of an unusual back muscle was observed in a female cadaver during advanced cadaver dissection of the back region. The SPI muscle was found deep to the latissimus dorsi muscle and superficial to the erector spinae and thoracolumbar fascia. Its oblique arrangement and insertion onto the 8th-11th costae were consistent with its known anatomy, but the presence of two separate fibrotendinous heads and an uncommon variance between the erector spinae and latissimus dorsi muscles was observed.

RESULTS

The SPI muscle fibers were found to be attached to the 8th costa on the right side and displayed two heads on both sides. In our study, the presence of muscular and tendinous digitations towards the twelfth rib was not detected, which aligns with the characteristics described for types D and E. However, we observed a separation between the digitations. Therefore, it is appropriate to classify our findings as type E according to the established categorization. Simultaneously, an anomalous muscular slip, which did not conform to any of the aforementioned classifications, was identified as extending towards the 8th rib.

CONCLUSION

The underlying cause of unilateral oblique muscular fiber extension is thought to result from aberrant muscle migration during embryonic development or alterations in tendon attachment sites. Differential diagnosis of unidentified lower back pain should consider the various types and alterations of the SPI muscle.

Prediction model of rhomboid major and pleura depth based on anthropometric features to decrease the risk of pneumothorax during dry needling

BACKGROUND

Although most common adverse events associated with dry needling can be considered minor, serious adverse events including induced pneumothorax cannot be excluded, and safety instructions for reducing the risk of pleura puncture are needed.

OBJECTIVE

To investigate if anthropometric features can predict the rhomboid major muscle and pleura depth in a sample of healthy subjects to avoid the risk of pneumothorax during dry needling.

METHODS

A diagnostic study was conducted on 59 healthy subjects (52.5% male) involving a total of 236 measurements (both sides in maximum inspiration and expiration), to calculate the accuracy of a prediction model for both pleura and rhomboid depth, as assessed with ultrasound imaging, based on sex, age, height, weight, body mass index (BMI), breathing and chest circumference. A correlation matrix and a multiple linear regression analyses were used to detect those variables contributing significantly to the variance in both locations.

RESULTS

Men showed greater height, weight, BMI, thorax circumference and skin-to-rhomboid, rhomboid-to-pleura and skin-to-pleura distances (P < .001). Sex, BMI, and thorax circumference explained 51.5% of the variance of the rhomboid (P < .001) and 69.7% of pleura (P < .001) depth limit. In general, inserting a maximum length of 19 mm is recommended to reach the deep limit of rhomboid major decreasing the risk of passing through the pleura.

CONCLUSION

This study identified that gender, BMI and thorax circumference can predict both rhomboid and pleura depth, as assessed with ultrasonography, in healthy subjects. Our findings could assist clinicians in the needle length election in avoiding the risk of induced pneumothorax during dry needling.

An Unusual Back Muscle Identified Bilaterally: Case Report

Most muscular structures in the human body are named based on their function, origin/insertion, or shape. During routine dissection of the back, an unusual muscle was found deep to the rhomboid muscles. The details of this case and a review of the extant literature are provided.

Skin, fascias, and scars: symptoms and systemic connections

Every element or cell in the human body produces substances that communicate and respond in an autocrine or paracrine mode, consequently affecting organs and structures that are seemingly far from each other. The same also applies to the skin. In fact, when the integrity of the skin has been altered, or when its healing process is disturbed, it becomes a source of symptoms that are not merely cutaneous. The skin is an organ, and similar to any other structure, it has different functions in addition to connections with the central and peripheral nervous system. This article examines pathological responses produced by scars, analyzing definitions and differences. At the same time, it considers the subcutaneous fascias, as this connective structure is altered when there is a discontinuous cutaneous surface. The consequence is an ample symptomatology, which is not limited to the body area where the scar is located, such as a postural or trigeminal disorder.

An anatomic investigation of the serratus posterior superior and serratus posterior inferior muscles

In classical anatomy textbooks the serratus posterior superior muscle was said to elevate the superior four ribs, thus increasing the AP diameter of the thorax and raising the sternum. However, electromyographic and other studies do not support its role in respiration. In order to help resolve this controversy and provide some insight into their possible functionality, the present study aimed at examining the morphology, topography and morphometry of serratus posterior superior and inferior muscles in both normal specimens and those derived from patients with a history of chronic obstructive pulmonary disorder (COPD). These muscles were examined in 50 human cadavers with an age range of 58-82 years. In 18 of the cadavers their histories revealed that they were suffering from COPD. There was no significant difference between right and left sides, race, gender and age and positive COPD history in regard to dimensions and nerves supply of serratus posterior superior and inferior muscles (P > 0.05). Based upon our findings that no morphometric differences exist between the of serratus posterior superior and inferior muscles of COPD patients versus controls, we are suggesting that no respiratory function be attributed to either of the serratus posterior superior and inferior muscles.

The costotransverse ligaments in human: a detailed anatomical study

This study provides a more detailed description of the costotransverse ligaments in human, aimed at investigating some controversial data and disclosing some lacking information concerning the anatomy of such ligaments. Complete spinal segments from the seventh cervical to the first lumbar vertebra were removed from 15 human cadavers (8 males, 7 females) with a mean age of 55 years. The costotransverse ligaments were exposed, bilaterally, at each vertebral level, using a posterior and an anterior approach to the spine. The lateral costotransverse, the superior costotransverse, and the costotransverse ligaments were identified and described. A rudimentary superior costotransverse ligament related to the first rib was also identified. In addition, two thick ligamentous bands were clearly observed in all dissected specimens and were referred to in the study as inferior and posterior costotransverse ligaments. Both bands were subjected to a detailed anatomical study. The importance of such ligaments in maintaining stability of the spine was also discussed.