Where is Scapula Bone located?

Scapula bone is located between second and seventh ribs. It is one of the two bones that make up the pectoral girdle. The other being clavicle or collarbone. It consists of the spine, coracoid, acromion process and glenoid cavity.

Table of Contents:

• Scapula Bone-Anatomy
• Scaplua – Functions and Disorders
• Frequently Asked Questions

Scapula Bone – Anatomy

What is a scapula? – Scapular region

Scapula is also known as the shoulder blade. It is a part of the pectoral girdle. It provides an attachment site to the head of the humerus and many muscles of shoulder and arms.

Laying foundation to the posterior of the shoulder girdle, the scapula is the connecting bone between the humerus and the clavicle. This triangular bone supports a group of muscles assisting in internal and external rotation of the joint and in abduction. The clavicle meets with the scapula at the tip of the acromion. The acromioclavicular joint is where the acromion, part of the scapula and the clavicle meet.

Characteristics of Scapula – Features

The main characteristics of the scapula are:

• It is a triangular bone.
• A pair of scapula bones are present in the pectoral girdle.
• It forms the posterior part of the shoulder girdle and is situated over the ribs posteriorly covering the second to seventh ribs.
• The dorsal surface of the scapula is convex and there is an elevated ridge, which is known as the spine of the scapula. It divides the bone into an upper smaller portion and the lower larger portion known as supraspinous fossa and infraspinous fossa, respectively.
• The spine of the scapula projects laterally forming the acromion process. The clavicle articulates with acromion by acromioclavicular joint.
• The ventral surface is concave and known as the subscapular fossa.
• There is a depression in the scapula bone laterally known as the glenoid cavity. The head of the humerus articulates with the glenoid cavity by the glenohumeral joint.
• The hook-like projection present below the clavicle and above the glenoid cavity is known as the coracoid process. It is attached to the clavicle by ligaments.
• Both the scapula bones are not attached to the axial skeleton directly. They are attached to the vertebral column and thorax by muscles, which provides a wider range of movement.
• There are various types of muscles attached to the scapula, which facilitate the different movements of the shoulder.
• The muscles that originate from the scapula region are biceps, triceps, deltoid, teres minor and major, supra and infraspinatus, etc.
• Trapezius, levator scapulae, serratus anterior and rhomboid muscles, etc. are responsible for the rotation and stabilization of the scapula.

Parts of Scapula

The main areas of the shoulder are – bones and joints, muscles, tendons and ligaments, nerves, bursae and blood vessels.

Bones of Shoulder

There are three main bones of the shoulder –

• Scapula – Shoulder blade
• Humerus – Upper arm bone
• Clavicle – Collar bone

The ceiling of the shoulder takes form by acromion – part of the scapula.

Joints of Shoulder

Shoulder is formed by four joints –

• Glenohumeral joint – ball of the humerus sits into the socket (glenoid) on the scapula
• Sternoclavicular joint – assists in connecting the arms and shoulders on the front of the chest to the main skeleton
• Acromioclavicular joint – clavicle meets the acromion
• Scapulothoracic joint (False joint) – takes form at the point where the scapula slides against the thorax

Muscles of Shoulder

Rotator cuff tendons associate with the rotator cuff muscles. The group of muscles are seen immediately outside the shoulder joint. The muscles assist in rotation in different directions, raising the arm sideways and other activities performed on a daily basis.

The rotator cuff muscles and the tendons assist in keeping the shoulder joint at a stable place by firmly folding the head of the humerus and the glenoid socket. The deltoid muscle forms the exterior layer of the shoulder, imparting the roundness of the shoulder over the glenohumeral joint. This muscle is the strongest and the largest muscle of the shoulder.

Read more: Muscles Attached to the Scapula

Spine of Scapula

The spine of scapula is a ridge of the bone, a shelf-like projection distinguishing  the posterior surface of the scapula. The posterior side of the scapula is divided into smaller supraspinous fossa (above) and a big infraspinous fossa (below) by a transverse spine of scapula. The fossae and spine provides the muscles with attachment which are functional in rotating the arm.

Root of spine of scapula: It is the triangular area of the spine of scapula.

Also check: Parts of Scapula

Scapula – Functions and Disorders

Scapula region performs some important functions that aid to induce various movements in the body which are brought together with the scapular muscles. It helps in rotation, elevation, retraction and protraction movements of various muscles. Also, after a certain age, the membranous bones such as sternum, vertebra, scapula, ribs, iliac bones and skull bones and also the ends of long bones produce RBCs. Usually, fractures or deformities of the scapula are rare due to its protective placement. 

• The scapula bone renders the main structural support
• Muscles like pectoralis minor, trapezius, deltoid, etc. are attached to the scapula bone
• Scapula also performs six different muscle actions. It enables full-functional upper extremity movement such as elevation, retraction, protraction, depression, downward and upward rotation
• It helps in elevating the upper trapezius and depresses the lower trapezius. Downward rotation of pectoralis minor and upward rotation of trapezius is possible because of scapula
• Abnormal functioning of the scapula can lead to shoulder impingement. The scapula elevates the acromion process during a serving or throwing motion. When the scapula fails to perform this function, it leads to an impingement
• Winging of the scapula is a bone deformity. It is due to the excessive prominence of the medial border of the scapula. This leads to a loss of pushing and punching actions. During attempts at pushing, there occurs winging of the scapula where the arm cannot be raised beyond 90°.

The scapula and clavicle form the pectoral girdle, which connects the upper limb to the axial skeleton.

Also Explore: Human Skeletal System

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