Glossary · Muscle
Pectoralis minor
A small chest muscle tucked under the pectoralis major. It is blamed for rounded shoulders, and the research supports part of that story.
The pectoralis minor is a smaller chest muscle that sits underneath the pectoralis major. It connects three of your ribs to the front of the shoulder blade, and how short or long it is affects where the shoulder blade sits on your back.
Where is the pectoralis minor?
It lies directly beneath the pectoralis major, and the two muscles together form the front wall of the armpit (Kenhub). It starts from the third, fourth and fifth ribs and attaches to the coracoid process, a small projection on the front of the shoulder blade. Its nerve is the medial pectoral nerve (TeachMeAnatomy).
One detail matters for symptoms in the arm: the main nerves to the arm (the cords of the brachial plexus) and the large artery and vein of the armpit all run underneath it (Kenhub).
What does the pectoralis minor do?
It holds the shoulder blade against the chest wall by drawing it forwards and downwards (TeachMeAnatomy). Together with the serratus anterior it moves the shoulder blade forward around the ribcage, and it helps rotate the shoulder blade downwards. When the shoulder blade is fixed, it can also lift the third to fifth ribs during deep, forced breaths in (Kenhub).
On the back, the rhomboids pull the shoulder blade the other way, towards the spine.
Why does the pectoralis minor get tight at a desk?
Anatomy references state that long periods with the shoulder blades drawn forward, as when you work with your arms in front of you, will shorten the pectoralis minor (Kenhub). The research has looked mostly at the next step: what a short pectoralis minor does to the shoulder blade.
- In 50 people without shoulder pain, those with a shorter pectoralis minor had shoulder blades that stayed tipped forward as they raised their arms, and turned further inwards at lower arm angles. That pattern is similar to the one seen in people with shoulder impingement (Borstad & Ludewig, 2005).
- In a similar group, people with a shorter pectoralis minor differed from those with a longer one in how rounded their upper back was and how far their shoulder blades turned inwards (Borstad, 2006).
Two limits matter. These studies were in people without pain, and they show associations: they don’t prove that desk work shortens the muscle, or that a short muscle causes pain. Muscle length also doesn’t explain everything. In 50 people with and without shoulder pain, pectoralis minor length was not strongly linked with how far the shoulder could rotate outwards (Rosa et al., 2019).
Which conditions involve the pectoralis minor?
- A rounded upper back and shoulders. A short pectoralis minor is part of the rounded upper back picture, linked with the curve of the upper back, the thoracic kyphosis. Tight pectoral muscles are also one of the features of upper crossed syndrome (Russin et al., 2026).
- Shoulder pain. The link with impingement-like shoulder blade movement is why it comes up in shoulder pain from computer work.
- Pectoralis minor syndrome. Rarely, the nerves to the arm are compressed where they pass under the muscle. It is diagnosed mainly from the history and examination, sometimes with an injection into the muscle to confirm it (Sanders & Annest, 2017). It is related to thoracic outlet syndrome, a group of conditions in which the nerves and blood vessels heading for the arm are compressed between the neck and the armpit (Kaplan & Kanwal, 2023).
Posture correctors are designed to pull the shoulders back. What the evidence says about them is in Do posture correctors work?, and the wall posture test is a quick self-check of your upper back.
When should you see a doctor?
Ask for an urgent GP appointment or contact NHS 111 if you have pins and needles that don’t go away, no feeling in your arm, an arm or shoulder that is hot or cold to touch, or sudden, very bad shoulder pain (NHS). Never put chest pain down to a tight muscle without getting it checked: call 999 if chest pain spreads to your arms, neck or jaw. Feeling short of breath, sick or sweaty can come with it (NHS).
Stretches for the chest and the front of the shoulder, where the pectoralis minor sits, are part of Bavelu’s shoulder and upper back sessions, designed and filmed by physiotherapists.
Questions people ask
Where is the pectoralis minor?
It lies on the front of the chest, directly underneath the pectoralis major. It runs from the third, fourth and fifth ribs up to the coracoid process, a small projection on the front of the shoulder blade.
Does sitting at a desk shorten the pectoralis minor?
Anatomy references say long periods with the shoulder blades drawn forward shorten it. Studies show that a short pectoralis minor goes with a forward-tipped shoulder blade and a rounder upper back, but they were done in people without pain and do not prove that desk work causes the change.
Can a tight pectoralis minor cause pins and needles in the arm?
Rarely. The nerves to the arm run under this muscle, and in pectoralis minor syndrome they are compressed there. Pins and needles that don't go away, or an arm that feels numb, hot or cold, should be checked urgently by a GP or NHS 111.
Could chest pain be a tight pec minor?
Don't assume so. Chest pain that spreads to the arms, neck or jaw needs a 999 call, especially with breathlessness, sweating or feeling sick. Only once serious causes are ruled out does a muscle explanation make sense.
Terms on this page
- RhomboidsTwo flat muscles between the spine and the shoulder blades that pull the blades back and hold them steady.
- Thoracic kyphosisThe natural outward curve of the upper back, and when it becomes hyperkyphosis.
- Upper crossed syndromeA proposed pattern of tight and weak neck, chest and shoulder muscles behind a forward-head, round-shouldered posture.
Sources
- Kenhub. Pectoralis minor muscle.
- TeachMeAnatomy. Muscles of the pectoral region.
- Borstad JD, Ludewig PM. The effect of long versus short pectoralis minor resting length on scapular kinematics in healthy individuals. Journal of Orthopaedic and Sports Physical Therapy, 2005.
- Borstad JD. Resting position variables at the shoulder: evidence to support a posture-impairment association. Physical Therapy, 2006.
- Rosa DP et al. Shoulder external rotation range of motion and pectoralis minor length in individuals with and without shoulder pain. Physiotherapy Theory and Practice, 2019.
- Russin NH, Robertson C, Montalvo A. Upper crossed syndrome in the workplace: a narrative review with clinical recommendations for non-pharmacologic management. International Journal of Environmental Research and Public Health, 2026.
- Sanders RJ, Annest SJ. Pectoralis minor syndrome: subclavicular brachial plexus compression. Diagnostics, 2017.
- Kaplan J, Kanwal A. Thoracic Outlet Syndrome. StatPearls (NCBI Bookshelf), 2023.
- NHS. Shoulder pain.
- NHS. Heart attack.
This page explains a topic in general terms. It is not a diagnosis and does not replace a doctor or physiotherapist. If something hurts badly, keeps getting worse or comes with numbness, weakness or fever, see a doctor.
