Scapula Bone

Author: Dimitrios Mytilinaios MD, PhD

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The scapula or shoulder blade is a flat, triangular upper limb bone that lies on the posterior surface of the thorax, over the ribs 2-7. It is a part of the pectoral (shoulder) girdle, together with the clavicle and sternum.

The scapula articulates with the humerus, forming the shoulder (glenohumeral) joint. It also articulates with the clavicle via the acromioclavicular (AC) joint. This serial connection between these bones gives the scapula an important role in the mobility of the upper limb. Primarily, it supports the shoulder joint and helps in transmission of force from the upper limb to the trunk, ensuring the proper joint functioning. In addition, it provides attachment to a number of shoulder muscles.

This article will discuss the anatomical landmarks of the scapula, as well as the muscles that attach to it.

Key points about the anatomy of the scapula
SurfacesAnterior (costal): subscapular fossa
Posterior (dorsal): spine of scapula, supraspinous fossa, infraspinous fossa, acromion
AnglesLateral: glenoid process, neck of scapula
Superior
Inferior
Borders (margins)Superior, lateral, medial
Muscles that attach to the scapulaOriginate: deltoid, supraspinatus, infraspinatus, triceps brachii (long head), teres minor, teres major, latissimus dorsi, coracobrachialis, biceps brachii (long and short heads), subscapularis, omohyoid
Insert: trapezius, levator scapulae, rhomboid major, rhomboid minor, serratus anterior, pectoralis minor

Anatomy

The scapula has three borders (superior, medial and lateral) and three angles (superior, inferior and lateral). It has two surfaces, namely the anterior (costal) surface and posterior surface. The scapula also features a prominent projection that arises from its superior surface, called the acromion.

Landmarks of the scapula from an anterior view (labeled diagram)
Landmarks of the scapula from an anterior view (labeled diagram)
Landmarks of the scapula from a posterior view (labeled diagram)
Landmarks of the scapula from a posterior view (labeled diagram)
Landmarks of the scapula
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Surfaces

The anterior (costal) surface of the scapula is mostly occupied by a large, slightly depressed region called the subscapular fossa. This fossa serves as an attachment for the subscapularis muscle. The posterior (dorsal) surface features a prominent ridge called the spine of scapula, which divides the surface into two unequal parts called the supraspinous fossa and infraspinous fossa.

Keep learning the anatomy of the scapula with quizzes and labeled diagrams.

The spine crosses the dorsal surface in a superiolateral direction. Near its root, the spine features a notable bump called the deltoid tubercle, which serves as an attachment for the deltoid muscle. The spine terminates with a lateral projection called the acromion. The acromion features the articular surface called the clavicular facet, via which it participates in the joint with the clavicle (acromioclavicular joint). Since the acromion emerges from the dorsal surface of the scapula, it creates a small notch with the dorsal surface called the spinoglenoid notch.

Angles

Scapula has three angles, lateral, superior and inferior. The superior and inferior angles of the scapula are unremarkable. The lateral angle features a region called the glenoid process of scapula. The glenoid process is connected to the lateral angle via a constriction called the neck of scapula.

The glenoid process features an articular surface called the glenoid fossa, via which it articulates with the head of the humerus and forms the glenohumeral (shoulder) joint. The superior and inferior rims of the fossa feature supraglenoid and infraglenoid tubercles, respectively.

Neck of scapula bone seen from an anterior view.
Infraglenoid tubercle of the scapula bone seen from an anterior view.
Glenoid fossa of the scapula bone seen from an anterior view.
Superior angle of the scapula bone seen from an anterior view.
Inferior angle of the scapula bone seen from an anterior view.
Angles of the scapula and their associated landmarks.
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Borders

The scapula has superior, lateral and medial borders. Only the superior border contains notable bony markings: the scapular notch and coracoid process. The scapular notch is a noticeable dip in the superior border. It is closed by the suprascapular ligament, and therefore transformed into the scapular canal. This canal is traversed by the suprascapular nerve and vessels.

Laterally to the notch, there is a bony projection directed anteriorly and laterally called the coracoid process. Together with the acromion, this process serves to stabilize the shoulder joint.

Superior border of the scapula bone seen from an anterior view.
Scapular notch of the scapula bone seen from an anterior view.
Coracoid process of the scapula bone seen from an anterior view.
Medial border of the scapula bone seen from an anterior view.
Lateral border of the scapula bone seen from an anterior view.
Borders of the scapula and their landmarks.
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Muscles that attach to scapula

There are 17 muscles in total that attach to the scapula. These include the muscles that stabilize the shoulder joint (rotator cuff muscles), as well as those whose primary function is to provide it with movement. Namely, they are:

The following diagram shows all the muscles that originate from and insert to scapula:

Origins and insertions of the muscles that attach to the anterior surface of the scapula.
Origins and insertions of the muscles that attach to the anterior surface of the scapula.
Origins and insertions of the muscles that attach to the posterior surface of the scapula.
Origins and insertions of the muscles that attach to the posterior surface of the scapula.
Muscles of the scapula
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Scapula anatomy quiz

The following quiz will help you solidify your knowledge about the bony markings of the scapula, as well as the muscles that attach to the scapula:

References

  • Open Anatomy. (n.d.). TA2 Viewer. Retrieved April 5, 2023, from https://ta2viewer.openanatomy.org/
  • Moore, K. L. (2018). Clinically Oriented Anatomy (8th ed.). Philadelphia, PA: Wolters Kluwer.
  • Drake, R. L., Vogl, A. W., & Mitchell, A. W. M. (2015). Gray’s Anatomy for Students (3rd ed.). Edinburgh, Scotland: Churchill Livingstone.
  • Standring, S. (2021). Gray’s Anatomy (42tst ed.). Edinburgh: Elsevier Churchill Livingstone.