Critical Understanding of Shiras Shareeram from Perspective of Nervous System

Introduction

Shiras (head) is the superior most and vital part of the body. It is the seat of intelligence and cognisance. Shiras is termed as Moolam (root) of human existence. The Indriya (sense organs) and their Pranavaha Srotases (channels that carry vital air) encompass Shiras like the light rays of sun. Shiras is considered as one among the Maha Marma (important vital point) and most important among all parts of the body. Acharya Susruta has considered Hrudaya (heart) and Basti (renal system) among 107 Marma (vital point) but didn’t consider Shiras as a separate Marma. With the concept of Trimarma, Acharya Charaka established importance of these parts as Marma, especially Shiro Marma. Any injury to Trimarmas leads to death immediately causing Tridosha Kopa (vitiation of three regulators of the body). All the three Doshas have well defined roles to play in Shiras, though it is said to be Shleshma Dhama (abode of Kapha).

Etymology of Shiras

The term Shiras means head, top part or highest part. The word Shiras is derived from the root “Shri + Shrayate Swange”¹ i.e all the body parts depend on Shiras for their functioning. Various synonyms of Shiras include Mastakam (the summit or highest peak), Shikharam (point, peak, top), Uttamanga (important or best part of body), Moordha (site where something is tied like turban).

Definition of Shiras

The term Shiras is defined as the location of Prana (most vital entity) and seat of all Indriyas (sense organs). Shiras controls all the sensory and motor activities.

Extent of Shiras

The part which is present above the Jatru (the collar bone - clavicle) and Skandha Sandhi (shoulder joint) is Jatrurdhwa (part of body above clavicle; head and neck) region.² The extension of head is from the lower border of mandible, above to the line extending from the angle of mandible to the mastoid process, posteriorly superior nuchal line and external occipital protuberance.

Origin of Shiras

Embryological origin

Development of body parts is a natural phenomenon.³ By the third month of gestation, the head and four limbs appear as masses or buds.⁴ Vata Dosha controls formation of Akruti in Garbha by controlling cell division. Pravyakta Tara (clear manifestation) of all parts including head occurs during the seventh month of gestation.⁵

Panchamahabhoota origin

Like all organs, ‘Shiras’ is also developed from Panchamahabhootas (five basic elements)- Prithvi (earth element), Ap (water element), Tejas (fire element), Vayu (air element) and Akasha (sky element).⁶ Shiras is the seat of all five Indriyas and predominance of each Mahabhoota is seen with respect to each sense organ situated in Shiras. They are sense of hearing with Akasha Mahabhoota predominance, the sense of touch in which the element Vayu Mahabhoota is predominant, the sense of vision in which the Agni Mahabhoota is dominant, the sense of taste in which Jala Mahabhoota is dominant and the sense of smell in which the element Prithvi Mahabhoota is predominant.

Shiras – Anatomical Aspect

Anguli pramana of shiras

Sixteen Angula (finger measure) Utsedha (height) and thirty-two Angula Parinama (circumference) are the Pramanas (measurement) of Shiras described by Acharya Charaka. ⁷

Mastulunga - Brain

In Ayurvedic texts, the term Mastulunga which is situated inside head describes brain. Chakrapani opines Mastulunga is Shirogata Sneha (unctuous part inside head).⁸ Dalhana commented Mastaka Majja (marrow inside head) is Avileena Ghrutakara (solidified ghee).⁹

Ashtanga Sangrahakara in Shareera Sthana clearly differentiates between Majja (marrow tissue) and Mastulunga Majja (brain). He says Majja which is present inside the Kapala Asthi (cranial bones) and covered by Medodhara Kala (sheath of fat) is Masthishka / Mastulunga (brain) and which is present inside Sthula Asthi (long bones) is Majja (bone marrow). ¹⁰ Acharya Charaka mentions the Pramana of Mastulunga as Ardhaanjali (half anjali).¹¹

Majja (marrow) is usually seen in bone- marrow (Asthi - Majja). However, the term has become synonymous with the nervous system. Here the Mastulunga Majja is encased in skull bones. 900 Snayu emerging from Mastulunga¹² can be understood as various peripheral nerves connected to the central nervous system.

Shiro Hrudaya - Brain

The word Hrudaya (core part) is derived from Harati Dadaati Eti – that which receives, processes and gives.¹³ This derivation is equally applicable to heart as well as brain. Heart receives impure blood from whole body and after purification by lungs pumps to all the organs of the body and never stops functioning. Similarly brain also receives all sensory stimuli through ascending nerve fibers, processes, and gives away motor stimulus for carrying out all the activities. In Atharva Veda, the description of Shiro Hrudaya (brain) clearly indicates that various controlling and regulating centers are situated in brain, which also regulates functioning of heart.¹⁴

Manas - Brain

Manas (mind) is considered as Ubhayendriya – both Jnanendriya (sense organ) and Karmendriya (motor organ). All Indriyas are said to be located in Shiras.¹⁵

In Unmada Chikitsa chapter, Manas is said to be located between Shiras and Talu (palate). ¹⁶ Shiras is upper part of cranium and Talu is base of skull. Based on Acharya Bhela’s opinion on Sthana (location) of Manas, Manas can be considered as Mastulunga or brain – area covered between head and palate and carries out functions of thinking, understanding, memory that are attributed to Manas. Acharya Susruta’s opinion substantiates this point. During the degeneration of Mastulunga, Vata Dosha puts pressure of Talu. ¹⁷

Marmas in Shiras

Vidhura Marma¹⁷

It is a Snayu Marma which is half Anguli in measurement. It is located behind ear, one on each side constituting two in number. Any injury will lead to Badhirya (deafness). Viddha Lakshanas (symptoms of injury) like deafness shows the involvement of structures such as vestibular and cochlear nerve related to internal ear.

Phana Marma¹⁷

Phana Marma is structurally Sira Marma which is half Anguli in measurement. It is located inside the nose, one on each side. The Lakshanas of injury to Phana Marma are Gandha Ajnanata (anosmia) which is carried out by olfactory bulb and olfactory nerve.

Avarta Marma¹⁷

It is a Sandhi Marma located above and middle of eyes. It is Ardhanguli in measurement and two in number, one on each side. Injury to Avarta Marma causes blindness. Injury represents the involvement of structures in visual pathway and those which help in the perception of vision.

Apanga Marma¹⁷

Apanga Marma is made up of Sira and is Ardhanguli in measurement. It is two in number, one on each side of outer canthus of eye. Any injury will lead to disability – blindness or impairment of vision. There is vision impairment or blindness based on severity of injury. Structures around Apanga Marma are involved in perception of vision.

Shankha Marma¹⁷

It is Marma formed from Asthi as Marma Vastu (tissue which constitutes marma). It is Sadya Prana Hara Marma. Shankha Marma is located between ear and eye brow just above the termination of the eyebrow – Shankha Marma may be considered as temple region. Injury leads to immediate death.

Utkshepa Marma¹⁷

It is a Snayu Marma which is Ardhanguli in measurement. It is just above the temporal region which is Vishalyaghna Marma. If any sharp instrument pierces from here, the person dies soon after its removal. If that sharp object falls off by itself, person will survive.

The areas of Shankha and Utkshepa Marma are location near temporal side of head where the bone is comparatively thin. Depending on the severity, injury may extend to brain parenchyma easily and damages nerves and other vascular structures.

Sthapani Marma¹⁷

It is a Sira Marma which is one in number. It is Vishalyaghna type of Marma which lies at the glabellar region between the eyebrows. Sthapani Marma is Ardhanguli in size. Sthapani Marma is also Vishalyagna Marma, injury similar to that of Utkshepa Marma. The spot Bru Madhya is called glabella. The structures here are superior sagittal sinus, supra trochlear vessels, nasal arch, frontal air sinuses and frontal lobe of cerebrum.

Seemanta Marma¹⁷

It is a Sandhi Marma with prognosis of Kalantara Prana Haratva. Seemanta Marma is in the measure of Karatala Pramana. Injury causes psychosis, fear, loss of mental functions and even death. Various sensory and motor areas are located near sutures. The structures are coronal, sagittal, lambdoid and parieto-temporal sutures. Injury causes various neuro-psychological conditions.

Sringaataka Marma¹⁷

These are four in number, structurally made of Sira. These are Karatala in measurement. Sringaataka Marmas are located deeper into Nasa where the Siras supplying nose, eyes, ears and tongue meet. These are Sadya Pranahara which causes immediate death on injury. Sringaataka Marma is located deeper to nostrils. Nasal medications reach up to Shringaataka Marma and spread to whole area of head. Main structure in this area is cavernous sinus and various nerves related to nose, eyes etc. pass through these sinuses. For example, occulomotor and trochlear nerve through lateral wall of cavernous sinus, abducent nerve on medial wall of cavernous sinus.

Adhipathi Marma¹⁷

It is a Sandhi Marma which is union of Siras- Sira Sannipata in Mastaka Abhyantara (interior aspect of head). Adhipathi is Sadya Pranahara Marma which is located at external occipital protuberance. Hindus will have a tuft of hair here for protection. It may be related to occipital protuberance. Underneath it, there is confluence of sinuses of head which correlates the Sira Sannipata of Mastaka Abhyantara.

Shiro Marma¹⁸

Acharya Susruta elaborated Marmas or vital points in head, while Acharya Charaka put forth the concept of Trimarma - three vital organs considered as Marma. Head as whole is considered vital part along with Hrudaya and Basti in Trimarmas.

Acharya Charaka explained Dosha Abhighataja Lakshana (injury to vital part due to internal causes) of Shiras. If head is afflicted with Vatadi Tridosha, there will be stiffness of carotid region, facial paralysis, rolling of eyeballs, mental confusion, cramps, loss of movement, cough, dyspnea, lock jaw, muteness, stammering, ptosis, quivering of cheeks, yawning, salivation, loss of voice, crookedness of face arise. The features of Dosha Abhighataja Lakshanas are various neurological presentations seen in acute cases of haemorrhagic and ischemic stroke, commonly seen as medical emergencies.

Dhamani Shareera from View of Nervous System

According to Charaka, Dhamani (pulsating channels) is termed so because they pulsate.¹⁹ Chakrapani comments that Dhamana means to be filled from the exterior with body fluid etc. In accordance with the concept of Atharva Veda, the book Paarishadyam Sabdaartha Shareeram defines that Dhamani is termed so as they respire and fill and nourish the body.

Acharya Susruta gave a detailed description about Dhamani in Dhamani Vyakaranam Shareeram chapter of Shareera Sthana. Twenty-four Dhamani arise from Nabhi (umbilicus/centre of origin), among which ten move Urdhwaga (upwards), ten move Adhoga (downwards) and four move Tiryag (obliquely).²⁰ The ten upward moving Dhamani arising from Nabhi sustain the body by carrying sensation of sound, touch, sight, taste, smell and also acts of respiration, yawning, sneezing, laughing, speaking, weeping etc. While reaching the cardiac region, they divide into three ways, making a total of thirty.²¹ Among the thirty, 10 are for carrying Dosha (regulatory factors of body) and Dhatu (structural tissues) where, two each carry Vata, Pitta, Kapha, Rasa and Rakta. With the eight Dhamani, one perceives sound, vision, taste and smell. Other functions include Bhashana (speaks), Ghosham Karoti (unmanifest sound), sleep and wake-up, crying, carry breast milk in women, and semen from breast in men.

Ten Adhoga Dhamani form channels of downward transport of Vayu (flatus), Mootra (urine), Pureesha (fecal matter), Shukra (semen), and Artava (menstrual blood).²² Tiryag-Gata Dhamani are distributed as network all over the body and their external apertures are attached to the roots of hair. They have a major role in sensing pleasant or painful touch as experienced through the Indriya. ²³ Some of the functions of Urdhwaga, Adhoga and Tiryag-Gata Dhamani resembles the functions of nervous system.

Vatavaha Sira from View of Central Nervous System

Concept of Sira is explained in detail in Susruta Samhita. All Siras are said to have origin in Nabhi, spread through the entire body upwards, downwards and obliquely, like the water spreading from rhizome of lotus plant to its stalk. These Siras arranged like minute fibres/ veinlets in a leaf, arise from large central vein. These Siras help in nourishing the body constantly, keeping it lubricated / moistened to performs various actions like flexion, extension etc.²⁴

Total Siras are 700, while Moola Siras (at the site of origin) are 40. Among these forty Sira, ten each are for each Dosha - Vata, Pitta, Kapha and Rakta. Acharya mentions that all Siras carry all Doshas together and not separately. These 10 Moola Siras divide and become 175 minute Siras of each Doshas when they reach their respective Sthanas (location).²⁵

The functions of this normal Vata Vaha Sira are to carry out bodily actions like flexion, extension, and other movements, speech and Indriya Karmas (perception of senses). These sensations are carried up to the mind and act as the cause for Amoha (state of alertness).²⁶ These functions resemble with the functions of central nervous system.

Sensations of body can be grouped into general and special senses. The special senses are olfaction, vision, taste, hearing and vestibular functions. The afferent impulses from specialised sense organs are transmitted to brain through cranial nerves – olfactory, optic, facial, trigeminal, vestibulocochlear and glossopharyngeal nerves. These explain Indriya Karmas of Vata Vaha Siras.

The ascending sensory projections consists of sequence of three neurons that extend from peripheral receptor to contra-lateral cerebral cortex. These are primary, secondary and tertiary neurons or first, second, thirdorder neurons. Primary afferents are peripherally located sensory endings and cell bodies that lie in dorsal root ganglia or the sensory ganglia associated with certain cranial nerves. The axons of second-order neurons decussate and ascend to contralateral thalamus as spinothalamic tract. The third order neuronal cell bodies located in thalamus and axons pass through internal capsule to terminate in primary somatosensory cortex in parietal lobe.

This arrangement of neurons is similar to description of Sira. The origin of Sira is described as Hrudaya (centre of origin) instead of Nabhi by Acharya Vagbhata. ²⁷ Here, Hrudaya may be considered as Shiro Hrudaya - cerebral cortex of brain and arrangement of sensory pathways similar to pattern of arrangement of Sira.

Kandara & Snayu from the View of Peripheral Nerves

Kandaras are defined as Maha Snayu by Dalhana. ²⁸ These are 16 in number in which four are in Hasta, four in Paada, four in Greeva and four in Prushtha. The Agra Praroha (lower extend of these Kandaras) are described as Nakha (nails) in Hasta and Paada, Medra for Greeva Gata and Nitambha for Prushtha Gata Kandara. The Agra Praroha (upper extension) are Uru in Paada, Amsa pinda in Hasta, Vaksha in Prushta Gata and Moordha in Greeva Gata. ²⁹ All the Kandara depend on four main Bimbamandala (round shape) where Bimba refers to a hollow structure and Mandala refers to complex network of things that are circularly arranged according to Harana Chandra. Bimbamandala refers to upper extension or roots of Kandara which emerge out of a hollow structure and form a network of Kandaras and spread to different areas of body. Bimbamandala are four in number. These four mandalas which give rise to 16 Kandara may be considered as major nerves arising from four nerve plexus such as cervical, brachial, lumbar and sacral plexus.

Kandara may be also understood as peripheral nerves as well as cranial nerves from these descriptions. Urdhwa Agra Praroha here can also be considered as spinal roots and cranium through which peripheral spinal nerves and cranial nerves emerge. Snayu which arise from Mastaka Majja may be considered as peripheral nerves connected to the central nervous system.

Physiological Aspect

Relation between Doshas with Shiras

Among the Dosha Sthanas in the body, Kapha is located predominantly in Moordha (head region), Pitta in Hrudaya (chest region) and Vata in Basti (below umbilical region). ³⁰ Each of the Doshas have five subtypes and these are distributed in whole body at different Sthana (site). Srotra (sense organ of hearing) and Sparshanendriya (sense organ of touch) is Vata Sthana (sites of vata). Drik (sense organ of vision) and Sparshana (sense organ of touch) are told as site of Pitta. Shiras particularly Ghrana (sense organ of smell) and Jihwa (sense organ of taste) are considered as Sthana of Kapha. ³¹ All three Doshas control various functions of Shiras.

Vata Dosha

Vata dosha controls all the movements occurring in the body. Minute nerve impulses originating in brain and transmitted to whole body within seconds are also controlled by Vata Dosha. Prana Vata (sub type) controls functioning of cortical areas of brain and carry out higher mental functions. It also plays major role in ascending sensory pathway carrying sensory impulses from periphery to brain.

Udana vata (subtype located in chest region) performs the functions of speech production, stimulates physical movements, valour, strength, colour, nourishing tissue pores, discrimination, intellect, memory and awakening of mind. It also provides Bala (strength) to whole body. These functions of Udana Vata also resemble to that of various neural controls of body.

Vyana Vata controls the transmission of nerve impulses to whole body and functions like peripheral nerves which carry out movements like Gati (movements). Analysing functions of Vyana Vata, most of activities are controlled and have extend in whole body including sensory, motor, visceral control. Here, Hridaya as a controlling centre of bodily functions may be correlated as brain. Acharyas have given the terms Mahajava and Krtsna Deha-chari to Vyana Vata as it can move in whole body swiftly.

Pitta Dosha

Alochaka Pitta in eyes performs the perception of vision.³² The peripheral receptors for light are situated in the retina. Nerve fibers arising in the retina constitute the optic nerve. Light has to pass through several layers of retina. The pigment cells in optic pathway are important in spacing the rods and cones and providing them with mechanical support. They absorb light and prevent back reflection. A nutritive and phagocytic role has also been attributed to them.

The Sadhaka Pitta is located in the heart region. It performs Budhi (intelligence), Medha (discrimination), pride and enthusiasm²² which are the higher mental and cortical functions.

Kapha Dosha

Tarpaka Sleshma is located in Shiras and carries out functions like nourishment of Chakshuradi Indriyas (sense organs).³² The blood and nutrient supply to sense organs is provided by Tarpaka Sleshma. The fluid compartment of brain is constituted by cerebro spinal fluid (CSF). Tarpaka Sleshma located in head and nourishing the Indriyas resemble with CSF. CSF assists the brain by providing protection, nourishment and waste removal.

Bodhaka Sleshma is mainly located in Rasanendriya which performs the specific function of taste perception.³² Saliva is the fluid component in external environment of taste receptor cells. It protects these receptors and some salivary constituents can continuously stimulate the taste receptors. Bodhaka Sleshma resembles the saliva in mouth which plays a role in taste perception. Further sensory impulses are carried by Prana Vata as taste perception in anterior 2/3rd of tongue is through sensory afferent fibres of facial nerve and that of posterior 1/3rd of tongue is by glossopharyngeal nerve.

Relation Between Dhatus with Shiras

Rasa and Raktha Dhatu

Vyana Vata does the circulation of Rasa and Rakta Dhatu from Hrudaya to all parts of the body.46 Rasa and Raktha Dhatu which are Drava Dhatus move together,²⁹ performs Preenana and Jeevana (nourishment) of Mastishka Majja.

Mamsa Dhatu

Mamsa Dhatu does Lepana Karma in the body. Mamsa Vaha Srotas originate from Snayu and Twak. ⁴⁸ All efferent nerve fibres end in a muscle group or a single muscle. Along with efferent nerve fibres, vascular supply to Mamsa Dhatu keeps it alive.

Medo Dhatu

Medas is situated in abdomen and in small bones of foetus in intrauterine life. After few weeks of birth, s lowly Sarakta Medas or Majja which is red in colour is formed inside the Asthi. Mastaka Majja has the consistency of Avileena Ghruthaakara which is nothing but Sneha. Medo Dhatu plays a role in Snehana Karma (oleation) in nervous tissue. The axons are often ensheathed in lipid-rich sheaths of myelin. Myelin sheath helps in faster conduction of nerve impulses.

Asthi Dhatu

When Medo Dhatu comes in contact with Asthi Dhatwagni, the qualities are digested and with the effect of Prithvi, Ap, Agni and Vayu Bhuta, Medas becomes solid to form Asthi Dhatu. Kapalasthi or flat bones are the type of Asthi seen in head which does the Dharana (supporting) of the body.

Majja Dhatu

The Vata makes hollowness in Asthi where the Majja Dhatu resides. Majja located in Shiras is called as Mastulunga. ⁴⁹ Functions of Majja include maintaining consciousness, and strength of the body. Kapala Asthi forms the structural framework of Shiras. Majja Dhatu is involved in the formation of Masthishka Majja.

Sukra Dhatu

The descriptions of Sukra Dhara Kala and its existence in whole body represent the cellular division which takes place in all cells. Shukra Dhatu acts in both sexes as Bala Varna Upachaya, development of secondary sexual characters, reproductive organs, spermatogenesis in males and oogenesis in females. Considering these aspects, Shukra seems to represent the entire neuroendocrine orchestra, particularly hypothalamicpituitary- gonadal axis.

Discussion

Shiras is called Uttamanga (superior part) because it is situated on top part of the body. Importance of Shiras is explained as – injury to Shiras causes severe illness or even death.²⁹

Shiroroga is a broad term encompassing various diseases of the head. Shiroroga involves Raktha Dushti due to Kupita Doshas with Sthanasamsraya (localization) at Shiras resulting in different neurovascular presentations; it is comparable with the vascular pathology of stroke. Acharya Charaka begins Rogachatushka with the description of Shiroroga, one among which is Ardita, the description of which closely resembles the clinical features of cerebrovascular accident (CVA). The Majja Dushti Lakshanas like Tama pravesha (loss of consciousness), Bhrama (giddiness), can be considered as Masthishka Majja Dushti (brain pathologies seen in nervous system disorders).

The clinical features of Ardita and Pakshaghata are similar to stroke of different etiology. Different opinions exist in Ayurveda regarding clinical presentation of Pakshaghata, especially the involvement of motor functions, sensory symptoms and varying level of consciousness. Ardita Lakshanas explain more in detail about cranial nerves involved in stroke. The importance of Shiras as site of Sthana Samshraya is evident from understanding of normal anatomy and physiology of Shiras. The terms like Dhamani, Sira are interchangeable with functions of circulatory system and nervous system based on the description of their Karma.

Conclusion

Shiras Shareeram explains anatomical and physiological aspects of Shiras and other terms described in Ayurveda which explains the anatomy and physiology of nervous system. We observe involvement of nervous system and manifestation of neurological features in Viddha Lakshanas (symptoms of injury) of both Marmas in Shiras and Shiras as Marma. Shiras or Jatrurdhwa (region above clavicle) is considered as Sthana of Kapha Dosha. But Vata Dosha and its sub-types predominantly carry out functions of nervous system. Pitta and Kapha including its sub types perform supportive role for neurons in nervous system. Shiras being the most important organ of body is required for sustaining the life.

Conflict of Interest

None