Pecs

We usually call our pectoral muscles “pecs”.  The first thing we need to know is that pectoral muscles are a group of muscles.

The pectoralis major makes up the bulk of the chest muscles in the male and lies under the breast in the female.

Origin:

1. Medial 1/3 of the clavicle.
2. Anterior aspect of manubrium & length of the body of the sternum.
3. Cartilaginous attachments of upper 6 ribs.
4. External oblique’s aponeurosis.

Insertion:

1. Lateral lip of bicipital groove to the crest of the greater tubercle.
2. Clavicular fibers insert more distally; sternal fibers more proximally.

It performs four actions:

1. Flexion of the humerus, as in throwing a ball side-arm, and in lifting a child.
2. Adducts the humerus, as when flapping the arms.
3. Rotates the humerus medially, as occurs when arm-wrestling.
4. Keeps the arm attached to the trunk of the body.

The pectoralis minor is a thin, triangular muscle, situated at the upper part of the chest, beneath the pectoralis major. The pectoralis minor depresses the point of the shoulder, drawing the scapula inferior, towards the thorax, and throwing its inferior angle posteriorly.

Origin:

The outer surface of ribs 2-5 or 3-5 or 6.

Insertion:

Medial aspect of the coracoid process of the scapula.

The subclavius is a small triangular muscle, placed between the clavicle and the first rib. Along with the pectoralis major and pectoralis minor muscles, the subclavius muscle makes up the anterior wall of the axilla.

Origin:

First rib about the junction of bone and cartilage.

Insertion:

The lower surface of the clavicle.

The subclavius depresses the shoulder, carrying it downward and forward. It draws the clavicle inferiorly as well as anteriorly. Also, protects the underlying brachial plexus and subclavian vessels from a broken clavicle (the most frequently broken long bone).

Pain and symptoms associated with the subclavius muscle

– Pain below the collarbone
– Pain in the upper arm
– Sends pain down the forearm into the thumb, forefinger, and middle finger
– A reliable indicator of subclavius muscle dysfunction is a pain on the outside of the upper arm that skips over the elbow then extends into the forearm. Pain can also extend to the thumb, index, and middle finger while skipping over the wrist.
– The muscle can tighten restricting circulation to the arm and hand causing tingling and numbness

Activities that cause subclavius pain and symptoms

– Lifting heavy objects
– Working with your arms out in front of you (computer, driving)
– Keeping your shoulders rolled forward
– Sleeping on your side with your arm above your head
– Broken clavicle

The serratus anterior is found more laterally in the chest and, forms the medial wall of the axilla.

Origin:

Fleshy slips from the outer surface of upper 8 or 9 ribs.

Insertion:

The costal aspect of medial margin of the scapula.

The main action of the serratus anterior is to rotate the scapula, allowing the arm to be raised over 90 degrees. It also holds the scapula against the rib cage – this is particularly useful when upper limb reaches anteriorly (e.g punching).

Pain and symptoms associated with the Serratus anterior

– Pain on the side of the chest toward the middle of the ribcage
– Pain down the arm to the fourth and fifth fingers
– Pain below the shoulder blade
– Difficulty breathing
– Inability to take a deep breath
– Sharp pain in the side (side stitch)
– Pain and difficulty reaching behind the body
– Pain and difficulty when pulling shoulders back
– Sensitivity in and around the area of the breast

Activities that cause serratus anterior pain and symptoms

– Swimming
– Tennis
– Chin ups, Push ups
– Weightlifting
– Gymnastics
– Hyperventilation
– Severe coughing