Human Movement Science & Functional Anatomy of the:

Pectoralis Minor

by Brent Brookbush DPT, PT, MS, PES, CES, CSCS, ACSM H/FS

Pectoralis Minor - http://upload.wikimedia.org/wikipedia/commons/7/75/Pectoralis_minor_muscle_and_shoulder_blade.png

What’s in a name

  • pectoral (n.) early 15c., “ornament worn on the breast,” from Middle French pectoral and directly from Latin pectorale “breastplate,” noun use of neuter of adjective pectoralis (see pectoral (adj.)). – As a shortened form of pectoral muscle, attested from 1758. Slang shortening pec for this is first recorded 1966. Related: Pectorals; pecs. (Etymology Online)
  • minor (adj.) early 13c., menour “Franciscan” (see minor (n.)), from Latin minor “less, lesser, smaller, junior,” figuratively “inferior, less important,” formed as a masculine/feminine form of minus on the mistaken assumption that minus was a neuter comparative, from PIE root *mei- (2) “small” (see minus). (Etymology Online)

    • “Smaller" of the muscles “worn” on the chest

Pectoralis Minor with Pectoralis Major removed (Cadaver) - http://classconnection.s3.amazonaws.com/751/flashcards/2200751/jpg/21351644564500.jpg

Pectoralis Minor:

Origin: Superior margins; outer surfaces of the third, fourth and fifth ribs near the costal cartilages; and fascia over corresponding intercostal muscles (11),

Insertion: Medial border, superior surface of the coracoid process of the scapula (11), in some individuals the pectoralis minor extends beyond the coracoid process to reinforce the coracohumeral ligament (8).

Nerve: Medial pectoral nerve with communicating branches from the lateral pectoral nerve arising from the medial and lateral cords of the brachial plexus, and nerve roots C7 - C8, with potential communicating branches from C6 and T1.

Pectoralis Minor Cadaver - http://www.thebodyonline.net/thorax/medial_pectoral_n_pin.jpg

Action:

  • Scapula: Protraction, downward rotation, depression, and anterior tipping (8, 10, 11, 17).
  • Respiration: With the arm and scapula fixed, the pectoralis minor can aid in forceful inspiration by elevating ribs 3, 4 and 5 (8, 10, 11).