SCAPULA
LEARNING OBJECTIVES
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At the end of the lecture the student should be able to
Recognize the bone.
Identify the site of bone.
Mention the bony landmarks of bone like borders, surfaces & land mark
used for bone determination.
Discuss the attachment of muscles on scapula
Scapula
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The scapula forms the posterior part of the
shoulder girdle.
Connects the humerus with the clavicle
It is a flat, triangular bone, with two surfaces,
three borders, three angles and three processes.
It extends from the 2nd rib to the 7th rib
posteriorly.
Surfaces of scapula
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Costal surface or Ventral surface
Concavity is called subscapular fossa
Directed medially and forwards.
3 longitudinal ridges, and a thick ridge adjoining
the lateral border (rod like) which acts as a lever
for the action of serratus anterior muscle in
overhead abduction of the arm.
Surfaces of scapula
Dorsal surface:
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Provides attachment to the spine of scapula.
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Two fossa are present;
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Smaller supraspinous fossa.
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Larger infraspinaous fossa.
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Connected by the spinoglenoid notch.
Borders
Superior Border:
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Thin and short
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Suprascapular notch present near the root of the corocoid process.
Lateral Border: (axillary border)
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It is thick
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Infraglenoid tubercle present at the upper end of the lateral border.
Medial Border: (vertebral border)
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It is thin. Longest of the three.
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Extension is from the superior angle to the inferior angle.
Borders of scapula
Angles of scapula
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The superior angle is covered by the trapezius
muscle.
The inferior angle is covered by the latissimus
dorsi muscle.
The lateral or glenoid angle is broad and bears the
glenoid cavity.
Processes of scapula
Spinous process:
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Triangular plate of bone with 3 borders and 2 surfaces.
It divides the dorsal surface into the supraspinous and
infraspinous fossa.
Posterior border is called the crest of the spine, which
has an upper lip and a lower lip.
Processes of scapula
Acromion process:
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2 borders; medial and lateral
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2 surfaces; superior and inferior
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A facet for the clavicle.
Coracoid process:
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This is directed forwards and slightly laterally.
Muscle Attachments on the Scapula
Deltoid
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Origin:
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Lateral 1/3rd of the clavicle, the lower border of
the crest of the spine and the lateral border of
the acromian.
Insertion:
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Middle of the lateral surface of the shaft of the
humerus.
Supraspinatus
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Origin:
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Supraspinous fossa of the scapula.
Insertion:
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Greater tuberosity of the humerus.
Infraspinatus
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Origin:
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Infraspinous fossa of the scapula.
Insertion:
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Greater tuberosity of the humerus.
Teres major
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Origin:
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Lower third of the lateral border of the scapula.
Insertion:
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Medial lip of the bicipital groove of the humerus.
Teres minor
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Origin:
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Upper two thirds of the lateral border of the
scapula.
Insertion:
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Greater tuberosity of the humerus.
Muscle Attachments on the Scapula
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Subscapularis
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Origin:
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Subscapular fossa.
Insertion:
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Lesser tuberosity of the humerus.
Serratus anterior
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Origin:
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Upper eight ribs.
Insertion:
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Medial border and inferior angle of the scapula (costal
surface).
Winging of Scapula
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Pectoralis minor
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Origin:
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3rd, 4th and 5th ribs
Insertion:
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Medial border and superior surface of the corocoid
process of the scapula.
Trapezius
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Origin:
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Occipital bone, seventh cervical vertebrae and the
thoracic vertebrae.
Insertion:
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Lateral third of the clavicle, medial border of acromian
and the upper border of the crest of spine.
Levator scapulae
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Origin:
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Transverse processes of the first four cervical
vertebrae.
Insertion:
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Medial border of the scapula from the superior
angle to the rot of the spine.
Rhomboid minor
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Origin:
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Seventh cervical vertebrae and the first
thoracic vertebrae.
Insertion:
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Medial border of the scapula opposite to
the root of the spinous process.
Rhomboid major
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Origin:
– Second to fifth thoracic vertebraes.
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Insertion:
– Medial border of the scapula between
the root of the spine and the inferior
angle.
Biceps brachii
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Origin:
– The long head of the biceps brachii
arises from the supraglenoid tubercle;
and the short head from the lateral part
of the tip of the coracoid process.
Coracobrachialis
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Origin:
– It arises from the medial part of the tip of the coracoid process.
Triceps
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Origin:
– The long head of the triceps arises from the infraglenoid tubercle.
Ligament Attachments on the Scapula
Glenoid labrum
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This is present on the margins of the glenoid
cavity and provides support to the shoulder joint.
Suprascapular ligament
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It bridges across the suprascapular notch and
converts it into a foramen.
Spinoglenoid ligament
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This ligament bridges the spinoglenoid notch.
Coracoacromial ligament
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This is attached to the:
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Lateral border of the coracoid process, and
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The medial side of the tip of the acromion process.
Coracohumeral ligament
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This is attached to the root of the coracoid process.
Coracoclavicular ligament
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This is attached to the corocoid process; the
trapezoid part on the superior aspect and the conoid part near the root.
Winging of scapula
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Condition in which the medial border of a
person's scapula is abnormally positioned
outward and backward.
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The resulting appearance of the upper back is
said to be wing-like because the inferior angle
of the shoulder blade protrudes backward rather
than lying mostly flat like in people without the
condition.
References
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Gray’s textbook of anatomy.
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