Surgical instruments, Crooke (1651). From 17th century Wellcome images collection. Wikimedia Commons.
Seventeenth century English surgeon, anatomist, and Court Physician to King James I of England Helkiah Crooke (1576-1648) was one of the earliest, if not the first, English writer to use fascia (albeit a Latinised version of it) as an anatomical term. This happened in this ground-breaking anatomy textbook Mikrokosmographia (1615) when he alluded (just once, on p. 922) to the “Fasciam or the swath-band,” now known as thoracolumbar fascia, and fasciam latam: which he later (1651, first published in 1631) described as a “membranous body… [that is] more like a membrane than a tendon” (Adstrum & Nicholson, 2019). Crooke’s mingling of English and Latin words to identify body parts was pretty normal back then. It still is. This can be seen, for instance, in today’s international anatomical nomenclature lists – which officially name the body’s parts in Latin and provide their equivalents in English.
Both editions of Crooke’s textbook (1615 and 1631) contained enormous amounts of anatomical information; which, as he freely admitted, was mostly derived from the work of other, possibly more eminent, anatomists – including Hippocrates, Galen, Vesalius, Laurentius, and, especially, Bauhinus. It’s therefore not surprising that some of the things Crooke says about membranes are repeated elsewhere – by, for instance, Samuel Collins (1685) and William Cowper 1694, 1698).
Crooke’s books contained several interesting woodcut illustrations, like the one above that shows the tools that were then used by surgeons (and perhaps also anatomists). The books were highly controversial because they contained knowledge that had, prior to then, only been written in Latin; hence was only available to a small and select group of university educated physicians, who could read and understand Latin. Crooke’s books being published in English meant that this formerly restricted information could be freely accessed by people who couldn’t read and understand Latin – including members of the prestigious Company of Barber-Surgeons (who Crooke taught). Crooke copped a fair bit of flak as some of the physicians objected to their financially lucrative ‘territory’ being encroached by some less socially lofty competitors.
The anatomy textbooks in this era broadly describe the body’s membranes (syn., membrana, integuments, coats, strata, skinnes, tunicles, and pannicles) as an interconnected series of soft tissue layers that are interposed between the body’s skin and bones (Adstrum & Nicholson, 2019).
Crooke (1651, p. 694-695) explained that the membranes are “sprinkled through the whole Body almost internally and externally,” although the differences between them are “manifold and are taken from their substance, magnitude, site, figure, conformation or texture, & from the nature of the parts which they invest or contain.” Close to the body’s outside, for instance, people’s bodies are “wrapped” in five body-encircling layers – i.e., “the Hairs … the Cuticle or Scarfe-skin, the Skin itself, the Fat and the fleshie membrane” (ibid, p. 47). Crooke devotes an entire chapter to the separate description of each of these layers, and frequently refers to them in the rest of the book. They are followed, deeper inside the body are the membranes that encircle and coat the body’s numerous parts, including: the Common Coat of the Muscles; the proper Coat of each muscle; the periosteum; the pleura.
Crooke divided his description of membranes into hierarchically-ordered series of taxonomic categories (see Table 1). In so doing, he distinguished between what he perceived to be true Membranes, which invest the entire body and its many parts, and their illegitimate counterparts, which condense to form a range of fibrous body parts – including tendons and ligaments. He also spoke of “an almost infinite number” of Particular Membranes that specifically envelop and help “sustain” the body’s parts and regions (1651, pp. 694-695). Despite their various labels, however, Crooke remarked that the membranes are connected to each other. In this way, the peritoneum, for example, “proceedeth from the meninges or membranes of the Brain which invest the Marrow of the Back and the Nerves” (ibid, p. 60); and in the connection between the pericranium and dura mater, which is mediated by thin, ligamentous membranes “passing through the sutures or seams of the skull” (p. 321).
Crooke’s (1651) membrane classification system
Crooke (1651) described the body’s system of membranes in relation to a number of taxonomic categories. Italics denote some of his specified examples.
Crooke cited Laurentius when defining a membrane as “a similar part, cold and dry, engendred [sic] of the slimy part of the seed, and therefore broad, thin and fast, the Organ of the sense of touching, keeping, knitting, and separating the parts under it” (ibid, p. 693). The word ‘similar’ indicates that membranes are generally uniform in appearance. The observation that they are ‘less cold and dry than a tendon, a Ligament, a Gristle, or Bone: but more cold and dry than Arteries, Veins and Sinews’ is based on Galen’s teaching about the contrary qualities of biological materials. According to Crooke, their being derived from the ‘slimy part of the seed’ (an ingredient of conception) means they can be “stretched or distended” without danger” of being damaged. He also (p. 694) explained that most membranes, depending on their “context or conformation”, also contain some fibres, which helps prevent them from “being torn every way as paper may.”
From a functional perspective, Crooke explained that the membranes’ breadth and extensibility enabled them to invest (coat), contain, and “preserve” (structurally stabilise) their underlying parts (ibid, p. 694). Their innocuous light weight, combined with their physical strength and being firmly fixed in their designated position meant they can “easily” dispel a potentially detrimental “influxion of humours.” He warns that their thin and seemingly simple appearance is deceptive, as it belies the fact that “every membrane is double”; and the space “betwixt” them provides passage to many slim “veins for nourishment, arteries to convey life, and Nerves to convey sense.” Crooke realised that nerves convey “spirits and carrieth down the Commandments of the Soul”, but do not possess “tactive qualities.” This role of sensing touch is instead the “common office” of the skin (organ of “outward touching”) and other membranes (“organs of inward touching”) that are liberally “sprinkled through the whole Body” (ibid, p. 694).
Crooke also explained that the membranes contain and give form to, connect and separate the parts that lie beneath them, collectively
“ … [fastening] one part to another, from whence proceedeth the admirable sympathy or society of the parts. So by the periostea the bones are all continued one to another; by their common Membrane all the Muscles are united: by the skin the whole body hath his connexion though it be divers in respect of the structure of parts which are of divers kinds. Finally, by the help of membranes parts are separated from parts, as we may perceive in our sections of Muscles” (p. 694).
Even though many of the ideas in Crooke’s books were borrowed from others, his exposition on the body’s system of membranes – now known by many as the fascial system – contains an extraordinary amount of information about this important body element. His books contain a great deal more information about membranes than is usually found in today’s anatomy textbooks; much of which has sadly been overlooked and lost to later generations of anatomy scholars. The 17th century language he used may seem a bit strange by today’s standards, and some of his ideas – which were developed in the days when medicine was governed by humoral theory, and before anatomists used microscopes – may also seem a bit unusual. In my opinion, Crooke’s historical contribution to the literature about fascia and fascial anatomy has been grievously underrated… a mistake that really ought not be allowed to continue.
If you are interested, you can read some more about anatomy and fascia in my recently published (2021) book, The Living Wetsuit