Chapter 9, Problem 9GAQ

a.

Summary Introduction

To explain: The reason why the trapezius muscle separated into three muscles.

Introduction: The pectoral girdle muscles arise from the axial skeleton and articulate either to the scapula or the clavicle. These muscles help to stabilize the scapula and move to increase the angle of movement. The anterior thoracic muscles are pectoralis minor, serratus anterior, and subclavius. The posterior muscles are levator scapulae, rhomboid major, rhomboid minor, and trapezius.

b.

Summary Introduction

To explain: The reason why the rhomboid muscles described as one muscle.