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A tendon is dense connective tissue transmitting force from muscle to an attachment, commonly a bone. Parallel organization of its matrix supports tensile loading. Elasticity and geometry affect force transmission, so a tendon is not an absolutely rigid connector.

A tetrapod limb is a paired appendage of a tetrapod, such as a forelimb or hindlimb, organized around a shared inherited skeletal pattern. In a familiar forelimb, one proximal bone, the humerus, is followed by the radius bone and ulna, then more distal elements and limb digits. The corresponding structures can differ greatly in proportions and use. Comparing their relationships, rather than just their overall shape, is central to recognizing homology.

The transition from a fin to a limb was not an instantaneous appearance of an entire new skeleton. A 2006 study of Tiktaalik described a pectoral fin with an expanded distal internal skeleton and articulations permitting a substrate-supported posture. The reconstructed joint configurations included flexed shoulder and elbow regions and an extended distal region. This indicates precursors of limb-like support in a finned animal; it does not make every distal fin element a limb digit.^[ref]

A useful comparison traces the humerus, radius bone and ulna in two differently shaped forelimbs, then asks which elements contact one another. A wing and a walking appendage can preserve corresponding elements while redistributing their lengths and mechanical roles. Shared ancestry and present function are related questions, but one cannot be read directly from the other.

Use of ultrasound to investigate structures of the chest. Fluid and superficial interfaces can be examined directly, whereas air and bone restrict access to deeper structures.

One of the principal lower-leg bones, paired with the fibula.

T. K. Greenlee is a coauthor of the 1971 study of bonding between a glass-ceramic biomaterial and bone. The publisher’s byline lists Greenlee at the Veterans Administration Hospital in Gainesville, Florida.^[ref]

The study connected an interfacial chemical model with observations in biological tissue. Laboratory studies of material solubility and hydroxyapatite crystallization were compared with histology and ultrastructure around implants in rat femurs. This comparison addresses a concrete problem: a material can have suitable bulk mechanical properties while developing an unsuitable interface with living bone. Microscopic observations of that interface help test a proposed bonding mechanism instead of inferring it from bulk strength alone.^[ref]

In his historical account, Larry L. Hench identifies Greenlee as an orthopaedic surgeon involved in the early work.^[ref]

One of the principal forearm bones, paired with the radius bone.

A median palatal bone whose form and contacts contribute to comparisons of avian cranial kinesis.

W. C. Allen is a coauthor of the 1971 paper on a bone-bonding glass-ceramic. The primary publisher record associates Allen with the College of Engineering at the University of Florida.^[ref]

The joint work examined how a biomaterial could develop a bond with bone, combining glass-ceramic solubility and interfacial hydroxyapatite crystallization studies with implant histology and ultrastructure. The example illustrates why designing a biomaterial requires more than selecting a high-strength material: interfacial reactions and the surrounding biological response can control how a mechanical load is transmitted. The publication compares laboratory interfacial evidence with tissue observations rather than treating every implant interface as chemically inert.^[ref]

Hench’s retrospective describes the collaborator Bill Allen as an orthopaedic surgeon; the 1971 source byline is retained here as W. C. Allen.^[ref]

W. F. Finney, published in full as William F. Finney, collaborated with M. D. Morris on using Raman spectroscopy to study bone under mechanical loading. Their experiment connected a change in a Raman spectrum to deformation of a living material's mineral component, rather than merely identifying its chemical ingredients.^[ref]

The apparatus held hydrated mouse femora in a mechanical tester on a Raman spectroscopy microprobe stage. A load cell monitored the applied loading, which stayed below yielding, while the experiment followed shifts of a phosphate vibrational band. This joined a mechanical measurement to a molecular-scale probe of the loaded bone.^[ref]

For an original illustration of the mechanical scale, a specimen segment of initial length $10\mathrm{mm}$ that extends by $0.02\mathrm{mm}$ has engineering strain $\epsilon =0.02/10=0.002$, or $0.2\%$. A simultaneous Raman shift measurement could track how a molecular vibration changes during that extension. The numerical extension is illustrative; it is not a reported value from Finney's experiment.

The zygomatic bone forms part of the cheek prominence and lateral orbital boundary. Its connections with neighboring bones help transmit forces through the face. Its external prominence and contribution to the orbit are different aspects of one structural element.