Download Scapula

Scapula
Objectives:
 To discuss the anatomical features of scapula.
 To describe the muscle attachment of scapula,
 To explain the clinical correlates of scapula.
Introduction
 The scapula forms the posterior part of the shoulder girdle.
 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.
Side determination
 The lateral side of the scapula is formed by the glenoid cavity.
 The dorsal surface of the scapula is convex and is divided by the triangular
spine.
 The costal surface is concave.
scapula
Surfaces
 Costal surface or Subscapular fossa:
 It is concave and 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.
 Dorsal surface:
 Provides attachment to the spine of scapula.
 Two fossa are present; smaller supraspinous fossa and a larger infraspinaous
fossa.
 Connected by the spinoglenoid notch.
Borders
 Superior Border:
 Thin and short
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Suprascapular notch present near the root of the corocoid process.
Lateral Border:
It is thick
Infraglenoid tubercle present at the upper end of the lateral border.
 Medial Border:
 It is thin.
 Extension is from the superior angle to the inferior angle.
Angles
 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
 Spinous process:
 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.
 Acromian process:
 2 borders; medial and lateral
 2 surfaces; superior and inferior
 A facet for the clavicle.
 Corocoid process:
 This is directed forwards and slightly laterally.
Muscle Attachments on the
Scapula
Deltoid
Origin:
 Lateral 1/3rd of the clavicle, the lower border of the crest of the spine and
the lateral border of the acromian.
 Insertion:
 Middle of the lateral surface of the shaft of the humerus.
 Supraspinatus
 Origin:
 Supraspinous fossa of the scapula.
 Insertion:
 Greater tuberosity of the humerus.
 Infraspinatus
 Origin:
 Infraspinous fossa of the scapula.
 Insertion:
 Greater tuberosity of the humerus.
 Teres major
 Origin:
 Lower third of the lateral border of the scapula.
 Insertion:
 Medial lip of the bicipital groove of the humerus.
 Teres minor
 Origin:
 Upper two thirds of the lateral border of the scapula.
Insertion:
 Greater tuberosity of the humerus.
 Dorsal Muscle Attachments
 Subscapularis
Costal Surface Muscle Attachments
Origin:
Subscapular fossa.
Insertion:
 Lesser tuberosity of the humerus.
 Costal Surface Muscle Attachments
 Serratus anterior
Origin:
Upper eight ribs.
Insertion:
 Medial border and inferior angle of the scapula (costal surface).
 Costal Surface Muscle Attachments
 Winging of Scapula
 Pectoralis minor
Origin:
3rd, 4th and 5th ribs
Insertion:
 Medial border and superior surface of the corocoid process of the scapula.
 Trapezius
 Origin:
 Occipital bone, seventh cervical vertebrae and the thoracic vertebrae.
Insertion:
 Lateral third of the clavicle, medial border of acromian and the upper
border of the crest of spine.
 Levator scapulae
Origin:
 Transverse processes of the first four cervical vertebrae.
Insertion:
 Medial border of the scapula from the superior angle to the rot of the spine.
 Rhomboid minor
Origin:
 Seventh cervical vertebrae and the first thoracic vertebrae.
Insertion:
 Medial border of the scapula opposite to the root of the spinous process.
 Rhomboid
major
Origin:
 Second to fifth thoracic vertebraes.
Insertion:
 Medial border of the scapula between the root of the spine and the inferior
angle.
 Dorsal Muscle Attachments
 Biceps brachii
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 corocoid process.
 Coracobrachialis
Origin:
 It arises from the medial part of the tip of the corocoid process.
 Triceps
Origin:
 The long head of the triceps arises from the infraglenoid tubercle.
Ligament Attachments on the Scapula
 Glenoid labrum
 This is present on the margins of the glenoid cavity and provides support to
the shoulder joint.
 Coracoacromial ligament
This is attached to the:
 Lateral border of the corocoid process, and
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The medial side of the tip of the acromian process.
Coracohumeral ligament
This is attached to the root of the corocoid process.
Coracoclavicular ligament
This is attached to the corocoid process; the trapezoid part on the superior
aspect and the conoid part near the root.
Suprascapular ligament
It bridges across the suprascapular notch and converts it into a foramen.
Spinoglenoid ligament
This ligament bridges the spinoglenoid notch.