What are the functions of the pectoralis major?
The pectoralis major extends across the upper part of the chest and is attached to a ridge at the rear of the humerus (the bone of the upper arm). Its major actions are adduction, or depression, of the arm (in opposition to the action of the deltoideus muscle) and rotation of the arm forward about the axis of the body.
What is the action of the pectoralis major M?
The main function of this chest muscle as a whole is the adduction and internal rotation of the arm on the shoulder joint. Acting independently, the clavicular part helps to flex the extended arm up to 90°, while the sternocostal part facilitates the extension of the flexed arm by pulling it downwards.
What is the action of the pectoralis minor m?
[3] Function The primary actions of this muscle include the stabilization, depression, abduction or protraction, internal rotation and downward rotation of the scapula. It elevates the ribs for deep inspiration when the pectoral girdle is fixed or elevated.
What is the function of the pectoralis major quizlet?
Pectoralis Major Function: Adducts and medially rotates the humerus, and draws the scapular anteroinferiorly. On its own the clavicular head flexes the humerus , and the sternocostal head extends it.
What does the pectoralis major muscle do quizlet?
What does the pectoralis major muscle do? It adducts the arm.
Does the pectoralis major flex the shoulder?
Actions of Pectoralis Major Muscle: Flex the arm at the shoulder (glenohumeral) joint. Extends the arm at the shoulder (glenohumeral) joint from a flexed position.
What is the origin insertion and function of the pectoralis major?
It makes up the bulk of the chest muscles and lies under the breast. Beneath the pectoralis major is the pectoralis minor, a thin, triangular muscle. The pectoralis major’s primary functions are flexion, adduction, and internal rotation of the humerus.
What is the difference between pectoralis major and minor?
Pectoralis minor moves from the back to the front of the body while pectoralis major moves from the outside to the inside in the front plane of the body. Unfortunately what often happens is that these muscles get glued together (a rolfing term) and begin to move as one unit.
What kind of muscle is the pectoralis major?
triangular convergent muscle
The pectoralis major (from Latin pectus ‘breast’) is a thick, fan-shaped or triangular convergent muscle, situated at the chest of the human body. It makes up the bulk of the chest muscles and lies under the breast. Beneath the pectoralis major is the pectoralis minor, a thin, triangular muscle.
Where is the pectoralis major muscle located quizlet?
The pectoralis major muscle is a large muscle in the upper chest, fanning across the chest from the shoulder to the breastbone. The two pectoralis major muscles are the muscles that create the bulk of the chest.
What part of the body does the pectoralis major move quizlet?
1. The pectoralis major muscle, which fleshes out the anterior chest(and inserts on the humerus), is a primemover of arm flexion.
How does the pectoralis major flex the arm?
Actions of Pectoralis Major Muscle: a. Medially rotate the arm at the shoulder (glenohumeral) joint. b. Adduct the arm at the shoulder (glenohumeral) joint.
Why does the pectoralis major twist?
The pectoralis major has a distinct twist near its attachment on the humerus. This feature maintains leverage in the various positions possible at the shoulder. Fully flexing the shoulder unwinds the twist and prepares the muscle to extend and internally rotate the humerus.
What is the action and innervation of pectoralis major?
| Pectoralis major | |
|---|---|
| Nerve | lateral pectoral nerve and medial pectoral nerve Clavicular head: C5 and C6 Sternocostal head: C7, C8 and T1 |
| Actions | Clavicular head: flexes the humerus Sternocostal head: horizontal and vertical adduction, extension, and internal rotation of the humerus Depression and abduction of the scapula. |
What is the function of the pectoralis minor?
Function. Pectoralis minor muscle depresses the point of the shoulder, drawing the scapula superior, towards the thorax, and throwing its inferior angle posteriorly.
Where is the pectoralis major?
anterior chest wall
The pectoralis major is the superior most and largest muscle of the anterior chest wall. It is a thick, fan-shaped muscle that lies underneath the breast tissue and forms the anterior wall of the axilla.