33 Koti Devata are 33 Bones in Spinal Cord

33 koti devata does not mean 33 crores of gods.
Koti in sanskrit has multiple meanings and one of them is ‘type’ or ‘category’.
33 koti devata are 33 bones in spinal cord (Vertebrae)

33 main devatas of Svarga Loka are the Aadityas (12), Vasus (8), Rudras (11) and Ashvins (2). Few consider Indra and Prajapati instead of 2 Aswins.
12 Adityas (personified deities) correspond to the 12 Solar months and represent different attributes of social life. The Vedic sages especially venerated the Adityas and Vedas are full of hymns dedicated to Indra, Agni, Surya, Varun and the like. These are:
1. Indra/Shakra (eldest and the undoubted leader of other Adityas)
2. Ansh (due share),
3. Aryaman (nobility),
4. Bhaag (due inheritance),
5. Dhatri (ritual skill),
6. Tvashtar (skill in crafting),
7. Mitra (friendship),
8. Pushan/Ravi (prosperity),
9. Savitra/Parjanya (power of word),
10. Surya/Vivasvan (social law),
11. Varun (fate),
12. Vaman (cosmic law).
12 Adityas

8 Vasus are attendant deities of Indra and comprise of eight elemental gods that represent the different aspects of Nature. They are:
1. Anil (Wind),
2. Apas (Water),
3. Antariksh/Dyaus (Space),
4. Dhara (Earth),
5. Dhruv (Pole Star),
6. Anal (Fire),
7. Prabhas (Dawn),
8. Soma (Moon).

11 Rudras:
· 5 abstractions – Ānanda (bliss), Vijñāna (knowledge), Manas (thought), Prāṇa (breath/ life), Vāc (speech),
· 5 names of Śiva – Īśāna (ruler), Tatpuruṣa (that person), Aghora (not terrible), Vāmadeva (pleasant god), Sadyojāta (born at once)
· 1 – Ātmā (spiritual self)

Then thirty-three crores of Devas emanating from the rays of the flames of Sambhu in the fiery form came forth.” — Skanda Puraana, Khanda 1 (Maheshvarakhanda), Kaumarikakhanda, Adhyaaya 47, Shloka 48

There are thirty-three crores of Devas stationed in heaven. All of them came there and celebrated that auspicious rite for him.” — Skanda Puraana, Khanda 1 (Maheshvarakhanda), Arunachalamahatmya, Adhyaaya 6, Shloka 7

The Devas were thirty-three crore in number; the Ganas were one koti and two hundred thousand; there were nine kotis of Chamundas and one koti of Bhairavis.” — Skanda Puraana, Khanda 6 (Nagarakhanda), Adhyaaya 142, Shloka 26

—Skanda Mahapurana, Kaashi-Khanda, Uttarardha, Adhyaaya 62, Shloka 99

In Brihadaranyaka Upanishad, Vidagdha, the son of Sakala, questions : ‘How many gods are there ?’
Yajnavalkya says – ‘3003, 333, 33, 3, 1.5 and 1’ each time, but actually he means that there are ‘thirty-three gods; the others are only their manifestations’.
When asked, ‘Which are those thirty-three?’, The answer is ‘The eight Vasus, eleven Rudras and twelve Adityas – these come to thirty-one and Indra and Prajapati make up the thirty-three‘.

Ramayana tells there are 33 children of the sage Kashyapa and his wife Aditi, 12 Adityas, 8 Vasus and 2 Ashvins, constituting the 33 gods.
But they were named same as the cosmic adityas.
Brahma allotted to the Rudras, the 11 positions which are – heart and the 5 sensory organs (panchendriya), the 5 organs of action and the mind (Gyanendriya).

Vedas are superior to puranas and the original scriptures, which describe these in detail.

Yasya Trayastrinshad Devaa Ange Sarve Samaahitaa, Skamma Tam Bruhi Katamah Swideva Sah.Atharva Veda

Meaning : With God’s influence, these 33 (supporting devata) sustain the world (our body through we interact with this world).

Rudras ~ The ten Pranas (Praana, Apaana, Vyaana, Samaana, Udaana, Naag, Kurma, Krikal, Devadutta and Dhananjaya) i.e. nervauric forces which live in the human body.The eleventh is the human soul.
These are called rudras, because when they leave body, it generates sorrow for others related to that human body. (Rudra means, one who creates sorrow – Hari Vamsam 13/51-52).

In our body, there is a vertebral column which supports the body’s physical structure and nervous system, enabling movement and sensation. Pathology of the spine can lead to debilitating outcomes on quality of life.
In humans, it is composed of 33 vertebrae that include 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal. Along with the skull, ribs, and sternum, these vertebrae make up the axial skeletal system.
33 bones in spinal cord (Vertebrae)

Skanda or Karthikeya, is described with a weapon Velayudham, which in reality is our brain and spinal cord or rather Skull and Backbone around them.
Kartikeya holds Vel is his hand, which means that he controls the nervous system which is connected to brain and spinal cord. That is why he is Senapati (commander in chief) of devas (gods).
Karthikeya Velayudham Brain Spinalcord
For more details, refer to the article or video on Velayudham.

If people bow down and worship this goddess with devotion, it is the same as though she has been worshipped along with thirty-three types of goddesses.” – Skanda Mahapurana, Kaasi-Khanda, Uttarardha, Adhyaaya 62, Shloka 99.

Which means, when we bow in Sashtanga Namaskar or Vajranasana position, our spine bends and is aligned horizontally with the goddess, as if she is being worshipped by us along with 33 vertebrae.
Sashtanga Namaskar Spinalcord