2.10.2. Serratus Anterior
The diagram is sketched from the perspective of an anatomist looking at the right side of the thorax.
Origin: Ribs 1 – 8.
Insertion: Medial border and inferior angle of scapula.
Nerve supply: Long thoracic nerve (with a root of C5, C6 and C7).
Action: Carries scapula forward (i.e. rotates it). Used in forced inspiration.
Basically, this muscle lies in-between the scapula and the ribs. It appears to ‘fan out’ from the scapula as eight strips of muscle, as seen in the diagram, although actually the fibres are running from the ribs to the scapula.
A damanged long thoracic nerve can lead to a 'winged scapula' - a simple diagnostic test can be performed by asking a patient to push against a wall with their arms out straight - the damaged nerve will prevent the normally restrictions on serratus anterior, and so it appears 'loose' and 'winged'.