Podcast
Questions and Answers
Which bones form the shoulder girdle?
The acromioclavicular joint is a type of synovial joint.
True
What is the primary function of the shoulder girdle?
To provide a mobile base for the attachment of the upper limbs to the trunk.
The ________ joint articulates with the humerus at the glenoid fossa.
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Which of the following ligaments reinforces the sternoclavicular joint?
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Match the shoulder girdle joints with their types:
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The scapula possesses a prominent spine on its anterior surface.
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The ________ groove acts as a barrier to distance the scapula and upper limb from the chest wall.
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Which ligament is considered the major stabilizing factor of the sternoclavicular joint?
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The acromioclavicular joint is a hinge joint.
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What are the two parts of the coracoclavicular ligament?
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The action of the pectoralis minor muscle includes _______ and _______ of the scapula.
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Match the muscles of the pectoral region with their actions:
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Which nerve supplies the serratus anterior muscle?
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Injury to the long thoracic nerve leads to weakness in abduction of the arm above 90 degrees.
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What attachment points define the subclavius muscle?
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What action does the levator scapulae muscle perform?
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The rhomboideus minor and major muscles retract the scapula.
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What nerve supplies the trapezius muscle?
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The fracture of the clavicle usually occurs in the ______ one-third.
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Which of the following muscles helps to rotate the scapula to raise the arm above 90 degrees?
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Weakness in retraction of the scapula can be a sign of trapezius muscle paralysis.
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Match the muscles with their respective actions on the scapula:
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Which muscles primarily perform medial (downward) rotation of the scapula?
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Study Notes
Shoulder Girdle
- Composed of the clavicle (collar bone) and scapula (shoulder blade)
- Provides a mobile base for attaching the upper limbs to the trunk
Clavicle
- Acts as a bar to distance the scapula and upper limb from the chest wall
- Forms articulations with the sternum and the acromion of the scapula
- Transmits forces to the axial skeleton
- Lacks marrow and ossifies in membrane
Scapula
- Triangular bone
- Articulates with the humerus at the glenoid fossa
- Possesses a prominent spine on the posterior surface
- Provides large, flat surfaces and roughened processes for muscle attachments
Sternoclavicular Joint
- Saddle synovial joint
- Articular surfaces include the sternal end of the clavicle, the clavicular notch of manubrium sterni, and 1st costal cartilage
- Articular surfaces are covered by fibrocartilage
- Enclosed by a synovial capsule reinforced by anterior and posterior sternoclavicular ligaments
- Costoclavicular ligament connects the clavicle to the 1st costal cartilage and 1st rib, the major stabilizing factor of the joint
- A fibrocartilaginous disc divides the joint into two cavities
Acromioclavicular Joint
- Plane synovial joint
- Articular surfaces include the acromial end of the clavicle and the clavicular facet of the acromion process of the scapula
- Accessory ligaments include the acromioclavicular ligament, the Coracoclavicular ligament (trapezoid and conoid parts)
Scapular Movements
- Elevation (upwards): by upper fibers of trapezius and levator scapulae
- Depression (downwards): by lower fibers of trapezius and pectoralis minor
- Protraction (forward): by serratus anterior and pectoralis minor
- Retraction (backwards): by middle fibers of trapezius, rhomboideus minor, and major
- Lateral (upward) rotation: by upper & lower fibers of trapezius and lower digitations of serratus anterior
- Medial (downward) rotation: by levator scapulae and rhomboids (minor and major)
Muscles of the Pectoral Region
- Includes pectoralis major, pectoralis minor, serratus anterior, and subclavius
- Pectoralis Minor: attaches between the upper ribs and coracoid process of the scapula, action is protraction and depression of the scapula
- Subclavius: attaches between first rib and costal cartilage and clavicle, action is stabilization of the clavicle
- Serratus Anterior: attaches from upper 8 or 9 ribs to the medial border of the scapula, action is protraction and rotation of the scapula to raise the arm above 90 degrees
Muscles of the Back
- Superficial layer: trapezius
- Deep layer: levator scapula, rhomboideus minor, and rhomboideus major
- Trapezius: attaches from skull and upper half of vertebral column to the scapula and clavicle, acts with serratus anterior to rotate the scapula, upper fibers elevate the scapula, middle fibers retract the scapula, and lower fibers depress the scapula
- Rhomboideus minor and major: attach between the vertebral column and the medial border of the scapula, action is retraction of the scapula
- Levator scapulae: attaches between the vertebral column and the medial border of the scapula, action is elevation of the scapula
Clavicle Fracture
- Most common mechanism is a fall directly on the shoulder with the arm at the side
- Usually occurs in the middle one-third of the clavicle
- Proximal piece is lifted superiorly by the sternoclastoid muscle, and the distal fragment is pulled inferiorly by the arm
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Description
Explore the intricate structure of the shoulder girdle, including the clavicle and scapula. Learn about their functions, articulations, and the important sternoclavicular joint. This quiz will enhance your understanding of how these components provide mobility and support to the upper limbs.
