Fun Fact: Extensor Indicis

Anatomy def: Extensor indicis is a muscle of the extensor (back) forearm – its tendon extends (straightens) the index finger (pointer finger or forefinger).

Outlander def: Jamie’s pointer finger twitches madly as Claire and Jenny come face-to-face in their terse meet-and-greet. Tappity tap – a 20-year gap. Scary!

Learn about extensor indicis in Anatomy Lesson #23, Harming Hands – Helping Hands – Healing Hands.

Turns out, the index finger receives tendons from extensor indicis and extensor digitorum (covered in a earlier FF).  Both muscles lie in the back of forearm but the tendons cross the wrist and insert into bones of the index finger. The dual tendons straighten (extend) and lift the index finger, offering it greater strength in extension and more independent movement from the remaining three fingers.

Fun Fact: In US anatomy, the thumb is not counted as a finger, so index finger is the first. Across the pond, some European anatomists define the thumb as  the first finger, so index is counted as the second finger. Ergo, many surgeons prefer using: thumb, index, middle, ring and little fingers (or something similar) to omit possible mix-ups of finger numbers during surgery. Scary x2!

Rewatch Starz episode 308, First Wife, to see Jamie’s pointer finger flutter as he ponders the strain between first wife and big sista. Not good! 

Read about Jamie’s twitchy fingers in Voyager book. Actually, his tapping fingers appear in most of Diana’s books:  

I caught a quick glance passing between Ian and Jenny; and a longer stare, unreadable, exchanged between Jenny and Jamie. A stranger here in more ways than one, I kept my own eyes cast down, observing under the shelter of my lashes. Jamie sat to my left; I could feel the tiny movement between us as the two stiff fingers of his right hand drummed their small tattoo against his thigh.

See Big Red flutter his index finger in Starz episode 308, First WifeKebbie-lebbie at Lallybroch!

The deeply grateful,

Outlander Anatomist

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Photo credits: Sony/Starz

2 Replies to “Fun Fact: Extensor Indicis”

  1. Wow! Thanks. Haven’t heard this basic term in a long time (since retired). Thx. I miss it. Lynn Brechtel, PT, CHT (Ret)

    1. I see you are a PT! Glad it jogged some memory bank i don’t imagine an injured EI is a muscle you treated very often but don’t know for sure. Glad you liked hearing about it. TY for writing!

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