Serratus Anterior

Authors

Affiliations

Nathaniel Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Serratus Anterior Schematic¹
3: SA Superior part
4: SA Intermediate part
4: SA Inferior part

Serratus Anterior (Right lateral view)¹

Muscle	Origin	Insertion	Innervation	Action
Serratus anterior	1-9 Ribs	Superior angle of Scapula (costal and dorsal surfaces) Medial border of scapula (costal surface) Medial border of scapula (costal surface) Inferior angle of Scapula (costal & dorsal surfaces)	Long thoracic n. C5 - C7	Superior part: Lowers raised arm Entire mm.: Protraction, Rib elevation (with fixed shoulder) Inferior part: Rotates scapula laterally forward

Origin

1-9th ribs¹

Insertion

• Superior part: Superior angle of Scapula (costal and dorsal surfaces)¹
• Intermediate part: Medial border of Scapula (costal surface)¹
• Inferior part: Medial border of Scapula (costal surface), Inferior angle (costal and dorsal surfaces)¹

Nerve

The Serratus Anterior is solely innervated by the Long Thoracic N. (C5, C6, C7)¹

Action

• Entire muscle: Draws scapula laterally forward, elevates ribs when shoulders are fixed¹
• Superior part: Lowers the raised arm¹
• Inferior part: Rotates inferior angle of scapula laterally forward (allows elevation of arm above 90°)¹

Function

The Serratus Anterior (along with the rhomboids) serves to aid in scapular stability during arm elevation²

Superior View of the shoulder: You can see how the rhomboids and SA both actively stabilize the scapulothoracic joint by pulling the scapula towards the thoracic wall²

Paralysis

• SCI
• peripheral nerve injury
• Nerve root?
• botox?

Functional ramifications

1.

Gilroy AM, MacPherson BR, Wikenheiser JC, Voll MM, Wesker K, Schünke M, eds. Atlas of Anatomy. 4th ed. Thieme; 2020.

2.

Dutton M. Dutton’s Orthopaedic Examination, Evaluation, and Intervention. 5th ed. McGraw Hill Education; 2020.