μ
        =
        
          μ
          
            o
          
        
        +
        k
        ⋅
        T
        ⋅
        log
        ⁡
        (
        γ
        ⋅
        x
        )
        +
        Ω
        ⋅
        σ
      
    
    {\displaystyle \mu =\mu ^{o}+k\cdot T\cdot \log(\gamma \cdot x)+\Omega \cdot \sigma }
  
In this equation μ represents the chemical potential, with μ° being its reference value. T stands for the temperature and k the Boltzmann constant.
Congenital dermal sinus is an uncommon form of cranial or spinal dysraphism. It occurs in 1 in 2500 live births. It occurs as a dermal indentation, found along the midline of the neuraxis and often presents alongside infection and neurological deficit. Congenital dermal sinus form due to a focal failure of dysjunction between the cutaneous ectoderm and neuroectoderm during the third to eight week of gestation. Typically observed in the lumbar and lumbosacral region, congenital dermal sinus can occur from the nasion and occiput region down.Early diagnosis and treatment is crucial for cases of congenital dermal sinus. It ensures that neurological condition does not degrade and prevents infection. Diagnosis can be confirmed through the use of advanced neuroimaging to observe the tract and associated lesions. Embryogenesis
During normal development, cutaneous ectoderm separates from neuroectoderm to allow for the insertion of mesoderm. That is, the skin separates from the tissue of the spinal cord to allow proper formation of the vertebral column. In cases of congenital dermal sinus there is a failure in this process, resulting in formation of a persistent connection between the skin and neural tissue. This manifests as a tract extending from the surface of the skin to the spinal cord lined with stratified squamous epithelium, surrounded by dermal and neurological tissue. The tract may terminate in the deep fascia, or even make contact with neural elements.