Overview
Veterinary nomenclature distinguishes two groups, the superficial pectorals (mm. pectorales superficiales) and the deep pectoral (m. pectoralis profundus). In cattle the superficial pectorals have two parts:
- Descending pectoral (m. pectoralis descendens): cranial, from the manubrium to the arm.
- Transverse pectoral (m. pectoralis transversus): from the sternum to the antebrachial fascia.
The deep pectoral is much larger and spreads over the ventral thorax as far as the abdominal wall. Together with the serratus ventralis it forms the thoracic sling, which suspends the trunk between the thoracic limbs. In meat, these muscles make up the brisket.
Origin
- Descending pectoral: manubrium of the sternum.
- Transverse pectoral: ventral surface of the first sternebrae.
- Deep pectoral: ventral surface of the sternum, costal cartilages and fascia of the ventral abdominal wall.
Insertion
- Descending pectoral: crest of the humerus, together with the cleidobrachialis.
- Transverse pectoral: medial antebrachial fascia.
- Deep pectoral: greater and lesser tubercles of the humerus.
Action
Adduct the thoracic limb and support the trunk between the limbs. The deep pectoral also draws the limb caudally and, with the limb planted, pulls the trunk cranially.
Innervation
Cranial and caudal pectoral nerves (nn. pectorales) from the brachial plexus.