The term [aphasia] has Greek origins and means "without speech". This pathology was first described by Paul Broca who called it "aphemia".

Aphasia is a total and complete loss of speech. Lesser presentations of this condition should be called [dysphasias) from the prefix [dys-] meaning "abnormal", and  [phasia], meaning "speech".

Aphasia is the lack of spoken  speech due to cerebral cortex damage in the dominant brain hemisphere, usually the left side in right-handed individuals. There are two main areas of the brain involved in speech: Broca's and Wernicke's. Broca's area is responsible for speech expression (the spoken and written word). Damage to this area causes expressive or motor aphasia (or dysphasia).

Wernicke's area is responsible for the comprehension of speech, the understanding of language. Damage to this area causes receptive orsensory aphasia (or dysphasia). Broca's and Wernicke's areas are connected by an intrahemispheric tract known as the arcuate fasciculus (see image).

Broca and Wernicke's areas in the dominant brain hemisphere

• Agraphia / dysgraphia: Incapacity / difficulty in writing
• Anomia / dysnomia: Incapacity / difficulty in naming objects
• Aphrasia / dysphrasia: Incapacity / difficulty forming phrases or sentences. The patient can communicate with single words, but cannot form sentences.

Image under copyleft agreement courtesy of The Brain from Top to Bottom
Thanks to  Margaret P. Tschimperle for suggesting this word. 

The scaphoid is one of the proximal carpal bones that form the wrist. The name arises from the Greek [scaphe], meaning "boat"; and [-oid], meaning "similar to". The scaphoid bone roughly resembles a rowboat. It is also known as the navicular bone (from the Latin [navis] meaning "boat"), and os naviculare manus.

Proximally, the scaphoid bone articulates with the radius. Distally, the scaphoid articulates with the trapezium and trapezoid bones. On its medial  aspect, the scaphoid bone has two articular surfaces for the lunate and the hamate bones. The scaphoid bone also has very strong ligamentous connections with the lunate bone by way of the scapholunate interosseous ligament

The accompanying image shows the anterior (volar) surface of the wrist. Click on the image for a larger picture.

Image modified from the original: "3D Human Anatomy: Regional Edition DVD-ROM." Courtesy of Primal Pictures

Cardiac muscle is one of the three types of muscle found in the human body. It is found exclusively in the heart, where it forms the main component of its middle layer, the myocardium.  

[Myo]=combining form for "muscle"; [-card-]=heart; and [-ium]=layer or membrane. The myocardium is the muscle layer of the heart.

Cardiac muscle has distinct striations and intercalated discs (see accompanying image). The cardiac muscle acts as a functional syncytium. 

The key characteristic of cardiac muscle is its capacity to contract rhythmically in the absence of an external electrical stimulus. The other two types of muscle (smooth and skeletal) lack this characteristic, called automatism or automaticity.

The terms [medial] and [lateral] are opposing anatomical relationship terms that indicate the location of a structure or structures in relation to the midline or median plane. The accompanying image depicts the median plane.

The term "midline" is a bit of a misnomer, as this is a plane and not a line, although if you look at the median plane from the anterior or posterior aspect of an individual in the anatomical position, you would have a line, ergo, midline! Look at this article on the anatomical position to see an explanation and image of this concept.

The term [medial] means "closer to the midline". An example of the use of this term is: "the head of the clavicle is medial to the shoulder joint", that is, the head of the clavicle is closer to the midline than the shoulder joint.

The term [lateral] means "further from the midline". An example of the use of this term is: "the wrist joint is lateral to the elbow joint", that is, the wrist joint is further away from the midline than the elbow joint.

Click on the image for a visual explanation of the concepts of "medial" and "lateral".

Images property of: CAA.Inc. Artist: Victoria G. Ratcliffe

The term [inion] is Greek and originally referred to the posterior aspect of the neck, as mentioned in the Iliad.

The term fell in disuse for hundreds of years, until it was resurrected by Peter Paul Broca (1824-1880) as a craniometric point. The inion is the midline protuberance in the posteroinferior aspect of the external surface of the occipital bone. Today, in most anatomy texts the inion is referred to as the "external occipital protuberance"

The inion is found at the intersection of three bony lines that are easily palpable, the bilaterally situated superior nuchal line, and the median nuchal line (see accompanying image). There is a corresponding internal occipital protuberance in the internal aspect of the occipital bone.

Original image courtesy of Bartleby.com. Click on the image for a larger version. 

The word [sesamoid] means "similar to a sesame". First used by Galen c.180AD, he describes small ovoid bones that are "similar to a sesame seed", referencing the seed of the plant sesamum indicum, the oil of which was used as a laxative at that time. 

Sesamoid bones are found in the tendons of some muscles and are mostly inconstant. Largey and Bonnet proposed a classification for these bones as: accessory, capsuloligamentous, intratendineous, and mixed.

Of special interest to this article are the sesamoid bones found within the two tendons of the flexor hallucis brevis muscle in the base of the foot (see accompanying X-ray image). These bones, especially the medial sesamoid bone, was attributed religious, mystical, and magical powers since ancient times. This is due to the fact that this small bone is highly resistant to natural decomposition. A Hebrew medical text dated 210 BC, attributed to Ushaia presented a small bone he called "luz" as the "depository of the soul". Many other authors, including Vesalius (who called it Albadaran), believed that upon resurrection, the whole body could reform from this "seed" bone.

This belief was later reinforced by religious texts into the early Renaissance which stated that this bone was indestructible and its presence was enough to guarantee resurrection for believers. 

Sources:
1. "Les os se?samo?¨des de l’hallux : du mythe a` la fonction" Largely,A; Bonnel, BE Med Chir Pied 2008 24: 28–38
2. "Tratado de Anatomia Humana" Testut et Latarjet 8 Ed. 1931 Salvat Editores, Spain
3. "De Humani Corporis Fabrica" Vesalius, Andrea. 1543 Oporinus
Thanks to the first year medical students at the University of Cincinnati who inspired this article. Dr. Miranda 

Original image courtesy of
Wesley Norman, Ph.D.