The Structure of Hair - Part 3: The Medulla ©

Modula

It is the empty intermittent space that exists in the middle of the fiber and is called medulla. The function of the medulla is not well known and very little research is conducted on the chemistry and other properties of medulla. It is believed to contribute in higher volume/ body to the hair. The medulla may provide thermo-regulatory properties to hair with regard to the airspaces within the medulla (p.9) (30). The hair fiber that is fine in texture seems to have very little medulla or no medulla and tends to have very little body. The hair fiber that is coarse in texture seems to have higher degree of medulla and consequently has lots of body. Therefore, the size of the medulla determines the degree of the body (volume) of the hair fiber. The shape of the medulla of human hair fiber is shown in SEM Micrograph in Figure 17.

 

Figure17: The shape of modula in coarse hair. Source: Courtesy of Avlon Research Center, Melrose Park, IL.USA.

 

 

 The properties of hair fibers related to its shapes, diameter, physical strength (elasticity), combing and brushing, moisture contents, impact of humidity, static charge, friction, swelling, porosity, thermal stability, shine, and pH will be discussed later.

References 

The Structure of Hair Part 1 - The Cortex 

[1] Swift, J.A. 1999. Human hair cuticle: biologically conspired to the owner’s advantage. J Cosmet Sci. Vol 50: 23-47.

 [2] Leon, N.H. 1972. Structural Aspects of keratin fibers. J. Soc. Cosmet. Chem. Vol 23. 432.

 [3] Leslie, J.N., D.E. Rivett and D.J. Tucker. 2007. Wool and Related Mammalian Fibers. Editor Menachem Lewin. In: Handbook of Fiber Chemistry. 3rd Ed. CRC Press, Boca Raton, Fl., p. 341.

 [4] Franbourg, A. and F. Leroy. 2005. Hair Structure, function, and physiochemical Properties. In Ed: Bouillon, C. and J. Wilkinson. The Science Of Hair Care, 2nd Ed., CRC Press Taylor & Francis Group, Boca Raton, Fl. p. 4.

 [5] Swift, J.A. 1999. Human hair cuticle: Biologically conspired to the owner’s advantage. J. Cosmet. Sci., 50, p. 23.

 [6] Ibid. p.24.

 [7] Leon, N.H. 1972. Structural Aspects of keratin fibers. J. Soc. Cosmet. Chem. Vol 23. 435.

 [8] DJ Evans, JD Leeder, JA Rippon, and DE Rivett. (1985). Separation and analysis of  surface lipids of the wool fibre. In Proc. 7th Int. Wool Tex. Res. Conf. I, Tokyo, Japan, pp.135-142.

 [9] LN Jones, et al. (1996). Hairs from the patients with maple syrup urine disease show a structural defect in the fiber cuticle, J. Invest. Dermatol. 106, 461-464.

[10] C Robbins. (2009). The cell membrane complex: Three related but different cellular cohesion componenets of mammalian hair fibers. J. Cosmet. Sci., 60, 437-465.

[11] C Robbins. (2009). The cell membrane complex:Three related but different cellular cohesion components of mammalian hair fibers. J. Cosmet. Sci., 60, 437-465.

 [12] ibid, p. 446.

 [13] JD Leeder, et al. (1985). Use of the transmission electron microscope to study dyeing an diffusion processes, Proc. 7th IWTRC, Tokyo, V, 99-108.

 [14] C Robbins. (2009). The cell membrane complex:Three related but different cellular cohesion components of mammalian hair fibers. J. Cosmet. Sci., 60, p. 447.

 [15] Franbourg, A. and F. Leroy. 2005. Hair Structure, function, and physiochemical Properties. In Ed: Bouillon, C. and J. Wilkinson. The Science Of Hair Care, 2nd Ed., CRC Press Taylor & Francis Group, Boca Raton, Fl. p. 15.

[16] Feughelman, M. 1997. Mechanical properties and structure of alpha – keratin fibres: Wool human hair and related fibres. Sydney: UNSW Press, p. 3.

[17] Negri, AP, Cornell HJ, Rivett DE.(1993). The modification of the surface diffusion barrier of wool. J Soc Dyers Col, 109, pp. 296-300

 [18] Breakspear, S., Smith, J.R., Luengo, G. (2005). Effect of the covalently linked fatty acid 18 – MEA on the nanotribology of hair’s outermost surface. Journal of structural Biology, 149: 235-242.

 [19] Ibid

 [20] Feugheleman, M. (1997). Mechanical Properties and Structure of Alpha – Keratin Fibers Wool, Human Hair and Related Fibres. University of New South Wales Press, Sidney: Australia. p. 2.

 [21] Swift, J.A. (1999). Human hair cuticle: Biologically conspired to the owner’s advantage. J. Cosmet. Sci., 50, p. 28.

 [22] Wortmann, F.J., & Kure, N. (1994). Effects of the cuticle on the permanent wave set of human hair. J. oc. Cosmet., Chem., 45, p. 149.

 [23] Swift, J.A. (2000). Letter to the Editor: The cuticle controls bending stiffness of hair. J. Cosmet. Sci., 51, p. 38.

The Structure of the Hair Part 2 - The Cuticle  

[24] A Franbourg, and F Leroy. (2005). Hair Structure, function, and physiochemical Properties. In Ed: Bouillon, C., Wilkinson, J. The Science Of Hair Care, 2nd Ed., CRC Press Taylor & Francis Group, Boca Raton, Fl. p.7.

 [25] M Feughelman. (1997. Mechanical properties and structure of alpha – keratin fibres: Wool human hair and related fibres. Sydney: UNSW Press, p. 3.

 [26] Ibid, p. 3

 [27] AN Syed, TN Ventura, and MN Syed. (2013). Hair ethnicity and ellipticity: A preliminary study. Cos & Toil, 128, (4), 250-259.

[28] ibid, p. 59, and Figure 12 p. 60.

 [29] Leon, N.H. 1972. Structural Aspects of keratin fibers. J. Soc. 

The Structure of the Hair Part 3 - The Medulla 

[30] Zviak, C. (1986). The Science of Haircare. New York: Marcel Dekker,