Pectoralis Minor
Shoulder & Scapula · Upper Limb
The pectoralis minor is a thin, triangular muscle lying deep to pectoralis major on the anterior chest wall. It arises from the outer surfaces of ribs 3 to 5 near their costal cartilages and ascends to the coracoid process of the scapula. It depresses and protracts the scapula, tilting it forward, and can raise the ribs during forced inspiration when the scapula is fixed. Its nerve supply is the medial pectoral nerve (C8, T1). It is also an important surgical and clinical landmark, as the axillary artery and cords of the brachial plexus are described in relation to it.
Origin, Insertion, Action & Nerve
Origin
Ribs 3–5, near their costal cartilages
Insertion
Coracoid process of scapula
Action
Depresses and protracts scapula; elevates ribs in forced inspiration
Nerve
Medial pectoral nerve (C8, T1)
Attachments explained
The Pectoralis Minor is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Ribs 3–5, near their costal cartilages
Insertion
Coracoid process of scapula
Action & function
When the Pectoralis Minor contracts, it produces the following movements: Depresses and protracts scapula; elevates ribs in forced inspiration.
As part of the Shoulder & Scapula group of the Upper Limb, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Pectoralis Minor receives its nerve supply from the Medial pectoral nerve (C8, T1). This nerve carries fibres from spinal segment(s) C8, T1.
Because a muscle can only contract when its nerve is intact, injury to the Medial pectoral nerve or to its spinal roots (C8, T1) can weaken or paralyse the Pectoralis Minor, impairing the movements it normally produces (depresses and protracts scapula). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Pectoralis Minor (the OIANS method)
Study pectoralis minor by its single skeletal bridge: ribs 3 to 5 up to the coracoid process. Pulling the coracoid down and forward is why it depresses and protracts the scapula, and, with the scapula fixed, why it can help hoist the ribs in laboured breathing. Keeping its ribs-to-coracoid line in mind separates it cleanly from the larger pectoralis major.
Its lasting importance is as a landmark: the three cords of the brachial plexus and the parts of the axillary artery are named in relation to it. Anchoring that surgical relationship, along with its medial pectoral nerve supply, gives the muscle a role well beyond its modest size.
Frequently asked questions
Where is the Pectoralis Minor located?
The Pectoralis Minor is a muscle of the Shoulder & Scapula group, located in the Upper Limb.
What is the origin of the Pectoralis Minor?
Ribs 3–5, near their costal cartilages
What is the insertion of the Pectoralis Minor?
Coracoid process of scapula
What movements does the Pectoralis Minor produce?
Depresses and protracts scapula; elevates ribs in forced inspiration
What nerve supplies the Pectoralis Minor?
Medial pectoral nerve (C8, T1)
Is the Pectoralis Minor free to study in OIANS?
Yes. The Pectoralis Minor is free in OIANS: its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory, and because it belongs to the Upper Limb it is also covered by the free Quiz and Flashcard decks. The other regions, the "All Muscles" deck, and the Progress and Explore tools are unlocked with a one-time Lifetime purchase.
Related muscles
Study the Pectoralis Minor
Test yourself on Upper Limb muscles with interactive quizzes and flashcards in the free OIANS app.
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