Human Movement Science & Functional Anatomy of the:

Flexor Hallucis Longus (FHL) &

Flexor Digitorum Longus (FDL)

by Dr. Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS,

By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See "Book" section below)Bartleby.com: Gray's Anatomy, Plate 439, Public Domain, https://commons.wikimedia.org/w/index.php?curid=529088 By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See "Book" section below)Bartleby.com: Gray's Anatomy, Plate 439, Public Domain, https://commons.wikimedia.org/w/index.php?curid=529088

H/FS

 

 

What's in a name:

  • Flexor - 1610s, Modern Latin, short for musculus flexor "a bending muscle," agent noun from past participle stem of Latin flectere "to bend" (see flexible) - Etymology Online
  • Hallucis - mid 19th century: modern Latin alteration of medieval Latin allex, Latin hallus (referring to big toe) - Oxford Dictionary
  • Digitorum - From the latin digitus - refering to a finger or toe - Oxford Dictionary
  • Longus - late 17th century: longus is the Latin word for 'long' - Oxford Dictionary

Dissection of deep posterior compartment of the lower leg - https://upload.wikimedia.org/wikipedia/commons/d/d2/Slide2ACA.JPG

Flexor Hallucis Longus (FHL):

  • Origin: Posterior surface of the distal 2/3rds of the fibula, interosseous membrane, and adjacent intermuscular septa and fascia (8,11).
  • Insertion: Base of the distal phalanx of the great toe, plantar surface (11).
  • Nerve: Tibial nerve arising from the sciatic nerve via the sacral plexus, originating from nerve roots L5, S1, and S2.
  •  Action:

    • Phalanges: flexion of the interphalangeal joint of the great toe and assists in flexion of the metatarsophalangeal joint (15, 16, 17).

      • In most individuals fascial slips