The scalp is an essential component for healthy hair growth, housing structures like hair follicles, blood vessels, and glands. Understanding scalp and hair anatomy can help individuals gain valuable insights into the causes of their hair concerns and explore potential treatment options.
Research content is provided for informational purposes only and should not be considered a substitute for professional medical advice.
Anatomy of the Scalp
The scalp is a soft tissue structure that covers the skull (cranium), extending from the forehead to the neck. It consists of five distinct layers, summarized by the mnemonic SCALP:
- Skin: The outermost layer, consisting of three sub-layers:
- Epidermis - the outermost layer
- Dermis - the middle layer.
- Hypodermis - the innermost layer
- (Dense) Connective Tissue: This dense tissue layer connects the skin to the epicranial aponeurosis and contains the nerves, blood vessels, and lymphatic vessels responsible for nourishing the scalp.
- (Epicranial) Aponeurosis: A tough, fibrous tissue covering the top of the skull. It connects the front forehead muscles (frontalis) to the muscles at the back of the head (occipital muscles), offering structural support.
- Loose Areolar Connective Tissue: A flexible layer that allows the upper layers of the scalp to move freely while separating them from the pericranium.
- Pericranium: The innermost layer, made of irregular dense connective tissue that adheres to the surface of the skull, providing essential blood supply to support the skull beneath.
Within the skin, structures like hair follicles, sebaceous glands, sweat glands, blood vessels, and nerves play a key role in hair health.
Things you should know about the scalp: One study indicated that the scalp ages six faster than facial skin.
The underlying layer of the scalp, the dermis, contains connective tissue vital for maintaining skin strength and elasticity. However, aging weakens this tissue, leading to a condition called elastosis where the skin's barrier function deteriorates. This thinning and weakening of the scalp increases its susceptibility to various complications.
A healthy scalp is fundamental to achieving optimal hair growth.
Each hair strand originates from a follicle embedded within the upper layers of the scalp. These follicles function much like pores: they can become clogged and obstructed, hindering hair growth, or they can remain clear and stimulated, facilitating the production of strong, healthy hair strands.
The Structure Of Hair
Hair consists of two main components:
- Hair Shaft: The visible part of the hair, extending above the skin, made up of three layers:
- Outer Cuticle: Protects the hair from damage.
- Middle Cortex: Determines hair strength, colour, and texture.
- Inner Medulla: Present mostly in thick hair, providing additional support.
- Hair Follicle: Located under the skin, the follicle is a small tube where hair grows. The base contains the bulb, where cells divide and push upward to form hair. Beneath the bulb, the papilla provides nutrients and oxygen via tiny blood vessels, supporting hair growth.
- Connected to sebaceous glands that produce sebum. A natural oil that maintains scalp and hair health by preventing dryness and creating a protective barrier.
- Interesting facts about hair strands: When wet, hair can be stretched by 30% of their original length without damage.Hair greying is not the actual turning of hair colour. As we age, hair follicles produce less pigment. So, when your hair goes through its natural cycle of shedding and regeneration, it’s more likely to grow in grey. While this typically begins around age 35, genetics and overall health also play a significant role in this process.
Hair Growth Cycle
Hair follicles go through a continuous cycle, consisting of four stages: growth, regression, rest, and shedding.
- Growth (anagen) phase: The hair follicle grows a new hair shaft and the lower position of the hair follicle grows downward to form the bulb. This phase can last 2 to 6 years for scalp hair, and only a few months for eyebrows or eyelashes.
- Regression (catagen) phase: A short transitional phase where the hair follicle shrinks and stops producing hair. This hair eventually becomes a.“club hair” which is dead hair that remains attached to the follicle.
- Rest (telogen) phase: The club hair remains in the follicle without growing for approximately 100 days.
- Shedding (exogen) phase: Old hair is shed to make room for new growth, starting the cycle anew.
It should be noted that individual factors such as genetics, health, and lifestyle can influence the duration and experience of each phase
Fun facts about the hair cycle you don’t know about
On average, most people lose about 50 to 100 strands of hair each day.Cutting your hair does not influence how fast it will grow. Each strand follows the same growth cycle, regardless of how often it’s cut.
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Disclaimer: Information presented is accurate at the time of print. Websites and references listed are not endorsed by 21 Medical Aesthetics and do not necessarily reflect the views of our medical team. Information is researched and displayed for demonstrative purposes only. It should not be used for personal diagnosis or as a substitute for professional medical consultation.
External Links
| Singapore Local Medical Research Resources & Associations |
| Informed Decisions for Hair Loss: A Resource of Credible Clinical Studies |
| Navigating Hair Restoration: A Guide to Reliable International Medical Journals |
Suggestion- could liven up the article a little bit if we can include ‘fun facts’ at the end of each section.
I.e.: Things you should know about the scalp:
Maintaining a balanced microbiome is essential.
The scalp microbiome is vital for maintaining a healthy scalp and hair. It provides the first line of defense against harmful pathogens, shielding the hair follicles and the scalp from various stresses.
The scalp ages six faster than facial skin.
The underlying layer of the scalp, the dermis, contains connective tissue vital for maintaining skin strength and elasticity. However, aging weakens this tissue, leading to a condition called elastosis where the skin's barrier function deteriorates. This thinning and weakening of the scalp increases its susceptibility to various complications.
A healthy scalp is fundamental to achieving optimal hair growth.
Each hair strand originates from a follicle embedded within the upper layers of the scalp. These follicles function much like pores: they can become clogged and obstructed, hindering hair growth, or they can remain clear and stimulated, facilitating the production of strong, healthy hair strands.
I.e: Fun facts about the Hair Strand you don’t know about.
A wet strand of hair can stretch up to 30% of its normal length.
1% of the world's population has natural red hair and the second most rare hair colour is blonde (2% of the world's population).
Hair is the second fastest growing tissue in the body.
The fastest is the bone marrow.
Cutting your hair does not influence how fast it will grow. Each strand of hair goes through the same cycle.
