Pectoralis Minor (P.Mn)
By : Fahad Al-BakNaming: -
/PEK-to-ra-lis MY-nor/
The name is from Pectoral (meaning chest) and minor refers to its size (also means that there is a major one [bigger]).
The name is from Pectoral (meaning chest) and minor refers to its size (also means that there is a major one [bigger]).
General: -
It is a thin triangular muscle in the anterior part of the chest (the thoracic wall), it is posterior to the pectoralis major and superior to the Serratus Anterior. It starts on the chest and cross over to the axilla to connect to the arm thus it is part of the Muscles of the Shoulder Girdle Joint.
.svg)
Supply: -
-The Blood supply of the P.Mn comes from The Pectoral Branches of the Thoracoacromial Trunk
(a branch of the Axillary Artery) and the Posterior Intercostal Arteries (branches of the Aorta) and the Lateral Thoracic Artery (a branch of the Axillary Artery).
(a branch of the Axillary Artery) and the Posterior Intercostal Arteries (branches of the Aorta) and the Lateral Thoracic Artery (a branch of the Axillary Artery).
-The nerve supply of the P.Mn comes from The Medial and Lateral Pectoral Nerves (C5, C6, C7, C8, T1).
Origin & Insertion: -
-Origin: it located to the outer surfaces of the third, fourth and fifth ribs close to their costal cartilages and the intervening intercostal fascia. There might be an additional attachment to the second or sixth rib or to both ( rare cases only).
-Insertion: The fibers change to a short, flat tendon as they pass superolaterally to go to the upper surface and medial border of the coracoid process of the scapula.
Motion & Action: -
( Protracts the scapula at the scapulocostal joint, depresses the scapula at the scapulocostal joint and Downwardly rotates the scapula at the scapulocostal joint )
By exerting a powerful pull on the coracoid process, the scapula can be pulled forwards and downwards during pushing and punching movements. When putting pressure on the hands it helps to transfer the weight of the trunk to the upper limb. Its attachment to the coracoid process assists pectoralis minor to help produce medial rotation of the scapula against resistance. With the scapula and upper limb fixed in place, pectoralis minor may be used as a helpful muscle of inspiration during respiratory distress.
By exerting a powerful pull on the coracoid process, the scapula can be pulled forwards and downwards during pushing and punching movements. When putting pressure on the hands it helps to transfer the weight of the trunk to the upper limb. Its attachment to the coracoid process assists pectoralis minor to help produce medial rotation of the scapula against resistance. With the scapula and upper limb fixed in place, pectoralis minor may be used as a helpful muscle of inspiration during respiratory distress.
In The Field Notes: -
Testing the P.Mn: Due to the location of the muscle and it being covered by the pectoralis major it cannot be tested
Clinical Note: -
Pectoralis minor injury: the isolated tear or rupture of P.Mn is rare and often in weightlifters or contact sports and should be included in the differential when evaluating athletes with anterior shoulder pain. These injuries are often mistaken for pectoralis major muscle stains and tears.
Relations: -
Relations: -
-The pectoralis minor is deep to the pectoralis major.
-Deep to the pectoralis minor are the serratus anterior and the rib cage.
-The superior attachment of the pectoralis minor is the coracoid process.
-The short head of the biceps brachii and the coracobrachialis also attach onto the coracoid process of the scapula.
-The pectoral minor is located within the deep front arm line myofascial meridian.
-The pectoralis minor is deep to the pectoralis major.
-Deep to the pectoralis minor are the serratus anterior and the rib cage.
-The superior attachment of the pectoralis minor is the coracoid process.
-The short head of the biceps brachii and the coracobrachialis also attach onto the coracoid process of the scapula.
-The pectoral minor is located within the deep front arm line myofascial meridian.
Sources: -
- Joseph E Muscolino - The Muscular System Manual: The Skeletal Muscles of the Human Body 4th edition Book (107-108).
-Nigel Palastanga & Roger Soames Anatomy and Human Movement Structure and Function 6th edition (56).
- Rare Isolated Pectoralis Minor Tear from a Noncontact Injury: Case Report and Review of the Literature – NLH
-Nigel Palastanga & Roger Soames Anatomy and Human Movement Structure and Function 6th edition (56).
- Rare Isolated Pectoralis Minor Tear from a Noncontact Injury: Case Report and Review of the Literature – NLH
