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The Scapula - Surfaces - Fractures - Winging - TeachMeAnatomy

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The Scapula

Home / The Upper Limb / Bones of the Upper Limb / The Scapula

Original Author(s): Oliver Jones

Last updated: October 29, 2020

Revisions: 30

The scapula is also known as the shoulder blade. It articulates with the humerus at the glenohumeral joint, and with the clavicle at the acromioclavicular
joint. In doing so, the scapula connects the upper limb to the trunk.

It is a triangular, flat bone, which serves as a site for attachment for many (17!) muscles.

In this article, we shall look at the anatomy of the scapula – its bony landmarks, articulations, and clinical correlations.

Costal Surface
The costal (anterior) surface of the scapula faces the ribcage.

It contains a large concave depression over most of its surface, known as the subscapular fossa. The subscapularis (rotator cuff muscle) originates from
this fossa.

Originating from the superolateral surface of the costal scapula is the coracoid process. It is a hook-like projection, which lies just underneath the
clavicle. Three muscles attach to the coracoid process: the pectoralis minor, coracobrachialis, and the short head of the biceps brachii.

© By TeachMeSeries Ltd (2022)

Fig 1 – The costal surface of the scapula.

Lateral Surface
The lateral surface of the scapula faces the humerus. It is the site of the glenohumeral joint, and of various muscle attachments. Its important bony
landmarks include:

Glenoid fossa – a shallow cavity, located superiorly on the lateral border.


It articulates with the head of the humerus to form the glenohumeral (shoulder) joint.

Supraglenoid tubercle – a roughening immediately superior to the glenoid fossa.


The place of attachment of the long head of the biceps brachii.

Infraglenoid tubercle – a roughening immediately inferior to the glenoid fossa.


The place of attachment of the long head of the triceps brachii.
© By TeachMeSeries Ltd (2022)

Fig 2 – Lateral view of the scapula.

Posterior Surface
The posterior surface of the scapula faces outwards. It is a site of origin for the majority of the rotator cuff muscles of the shoulder.

It is marked by:

Spine – the most prominent feature of the posterior scapula. It runs transversely across the scapula, dividing the surface into two.

Acromion – projection of the spine that arches over the glenohumeral joint and articulates with the clavicle at the acromioclavicular joint.

Infraspinous fossa – the area below the spine of the scapula, it displays a convex shape.
The infraspinatus muscle originates from this area.

Supraspinous fossa – the area above the spine of the scapula, it is much smaller than the infraspinous fossa, and is more convex in shape.
The supraspinatus muscle originates from this area.

© By TeachMeSeries Ltd (2022)

Fig 3 – The posterior surface of the scapula.


Articulations
The scapula has two main articulations:

Glenohumeral joint – between the glenoid fossa of the scapula and the head of the humerus.

Acromioclavicular joint – between the acromion of the scapula and the clavicle.

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Clinical Relevance
Fractures of the Scapula
Fractures of the scapula are relatively uncommon, and if they do occur, it is an indication of severe chest trauma. They are frequently seen in high
speed road collisions, crushing injuries, or sports injuries.

The fractured scapula does not typically require fixation as the tone of the surrounding muscles holds the pieces in place for healing to occur.

Winging of the Scapula


The serratus anterior muscle originates from ribs 1-8, and attaches the costal face of the scapula, pulling it against the ribcage. The long thoracic
nerve innervates the serratus anterior.

If this nerve becomes damaged, the scapula protrudes out of the back when pushing with the arm. The long thoracic nerve can become damaged
by trauma to the shoulder, repetitive movements involving the shoulder or by structures becoming inflamed and pressing on the nerve.

© By Dwaipayanc [CC BY-SA 3.0], via Wikimedia Commons

Fig 4 – Injury to the long thoracic nerve produces a winged appearance

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