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Questions and Answers
What is the primary action of the rhomboid major muscle?
What is the primary action of the rhomboid major muscle?
Which nerve innervates the levator scapulae muscle?
Which nerve innervates the levator scapulae muscle?
What is the origin of the rhomboid major muscle?
What is the origin of the rhomboid major muscle?
Which of the following muscles is responsible for the downward rotation of the scapula?
Which of the following muscles is responsible for the downward rotation of the scapula?
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What is the insertion point of the levator scapulae muscle?
What is the insertion point of the levator scapulae muscle?
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What is the action of the pectoralis minor muscle?
What is the action of the pectoralis minor muscle?
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Which nerve is responsible for the innervation of the serratus anterior muscle?
Which nerve is responsible for the innervation of the serratus anterior muscle?
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What is one function of the teres minor muscle?
What is one function of the teres minor muscle?
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Which of the following best describes the origin of the subclavius muscle?
Which of the following best describes the origin of the subclavius muscle?
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What happens to the scapula during the action of the serratus anterior muscle?
What happens to the scapula during the action of the serratus anterior muscle?
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What action does the clavicular head of the pectoralis major perform?
What action does the clavicular head of the pectoralis major perform?
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What role does the subclavius muscle play in relation to the sternoclavicular joint?
What role does the subclavius muscle play in relation to the sternoclavicular joint?
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Which muscle is primarily responsible for the depression of the elevated shoulder?
Which muscle is primarily responsible for the depression of the elevated shoulder?
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Which muscle is primarily responsible for the initiation of shoulder abduction up to 15 degrees?
Which muscle is primarily responsible for the initiation of shoulder abduction up to 15 degrees?
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What is the main action of the teres major muscle?
What is the main action of the teres major muscle?
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Which part of the deltoid muscle is responsible for shoulder abduction beyond the first 15 degrees?
Which part of the deltoid muscle is responsible for shoulder abduction beyond the first 15 degrees?
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Which muscle contributes to the downward rotation of the scapula?
Which muscle contributes to the downward rotation of the scapula?
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What is the primary innervation of the subscapularis muscle?
What is the primary innervation of the subscapularis muscle?
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Which muscle is NOT part of the rotator cuff?
Which muscle is NOT part of the rotator cuff?
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Which muscle performs elevation of the shoulder girdle?
Which muscle performs elevation of the shoulder girdle?
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Which nerve innervates the deltoid muscle?
Which nerve innervates the deltoid muscle?
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The trapezius muscle has how many parts based on the direction of its fibers?
The trapezius muscle has how many parts based on the direction of its fibers?
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What action does the latissimus dorsi muscle perform?
What action does the latissimus dorsi muscle perform?
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Study Notes
Rhomboid Major Muscle
- Origin: Spinous processes of vertebrae Th2-Th5 and supraspinal ligament
- Insertion: Medial border of the scapula, below the spine
- Nerve Supply: Dorsal scapular nerve
- Actions: Elevates the scapula, retracts the shoulder, fixes the scapula to the trunk, and rotates the scapula downward
Levator Scapulae Muscle
- Origin: Transverse processes of C1-C4 vertebrae
- Insertion: Superior part of the medial border of the scapula
- Nerve Supply: Dorsal scapular nerve
- Action: Elevates the scapula
Pectoralis Major Muscle
- Sternocostal head - sternum and costal cartilages (upper 6)
- Anterior part of rectus sheath
- Convergence of fibres inserted to the crest of greater tubercle (lateral lip of the intertubercular sulcus)
- Actions:
- Adduction, medial rotation, and depression of the elevated shoulder
- Clavicular fibres flex and sternocostal fibres extend the arm from a flexed position.
- Fixation of shoulder joint
- Nerve Supply: Medial and lateral pectoral nerves from the medial and lateral cords of the brachial plexus
Pectoralis Minor Muscle
- Origin: Outer surface of ribs 2-5 (or 3-5 near costochondral junctions)
- Insertion: Coracoid process of the scapula
- Actions:
- Depression of the elevated shoulder (ventrocaudal direction)
- Elevation of the ribs, aiding inspiration
- Fixation of the shoulder joint
- Nerve Supply: Medial and lateral pectoral nerves
Serratus Anterior Muscle
- Origin:
- Horizontal part: Ribs 1 and 2
- Divergent part: Ribs 2 and 3
- Convergent part: Ribs 4-9
- Insertion: Costal surface of the scapula along the medial border (superior angle, medial border, and inferior angle)
- Actions:
- Moves the scapula on the thorax, particularly the convergent part moving the inferior angle anterolaterally (protracts scapula).
- With the scapula fixed, elevates ribs, acting as an accessory inspiratory muscle.
- Allows arm elevation above 90° when glenoid cavity faces cranially.
- Fixation of the scapula
- Nerve Supply: Long thoracic (C5-C7). Paralysis of this nerve causes winged scapula (scapula alata).
Subclavius Muscle
- Origin: Near the costochondral junction of the 1st rib
- Insertion: Groove for the subclavius muscle on the lower surface of the clavicle
- Action: Fixation of the sternoclavicular joint, preventing upward dislocation.
- Nerve Supply: Nerve to subclavius
Teres Minor Muscle
- Origin: Upper part of the dorsal aspect of the axillary border of the scapula
- Insertion: Lower impression of the greater tuberosity and adjoining part of the humerus shaft. Runs laterally behind the long head of triceps brachii.
- Actions: Lateral rotation, adduction, and fixation of the shoulder.
- Nerve Supply: Axillary nerve
Teres Major Muscle
- Origin: Back of the inferior angle and axillary border of the scapula below the teres minor.
- Insertion: Medial lip of the biceptal groove (intertubercular sulcus)
- Actions: Medial rotation, adduction, and extension of the shoulder.
- Nerve Supply: Lower subscapular nerve
Deltoid Muscle
- Shape: Triangular, divided into three parts:
- Clavicular (anterior fibres)
- Acromial (middle fibres)
- Spinal (posterior fibres)
- Origins:
- Clavicular part: Lateral 1/3 of the clavicle
- Acromial part: Acromion process of the scapula
- Spinal part: Spine of the scapula
- Insertion: Deltoid tuberosity on the outer surface of the humerus
- Actions:
- Clavicular part: Flexion, medial rotation, and trunk pulling towards a fixed arm (e.g., climbing).
- Acromial part: Abduction up to 90 degrees (not the initial 15).
- Spinal part: Extension, lateral rotation
- All parts involved in shoulder joint fixation.
- Nerve Supply: Axillary nerve (C5-C6)
Supraspinatus Muscle
- Origin: Supraspinous fossa of the scapula
- Insertion: Upper part of the greater tubercle of the humerus (upper impression)
- Actions: Abduction of the shoulder up to 90 degrees, assists in climbing, and shoulder joint fixation. Initiates abduction (first 15 degrees), then assisted by deltoid.
- Nerve Supply: Suprascapular nerve
Infraspinatus Muscle
- Origin: Infraspinous fossa of the scapula
- Insertion: Middle of the posterior part (middle impression) of the greater tubercle of the humerus
- Actions: Lateral rotation, involved in climbing, and shoulder joint fixation.
- Nerve Supply: Suprascapular nerve
Subscapularis Muscle
- Origin: Subscapular fossa on the costal surface of the scapula
- Insertion: Lesser tubercle of the humerus
- Actions: Adduction, medial rotation, slight extension; also involved in climbing and shoulder joint fixation.
- Nerve Supply: Upper and lower subscapular nerves
- Rotator Cuff: Subscapularis, supraspinatus, infraspinatus, and teres minor comprise the rotator cuff, reinforcing the shoulder capsule and stabilizing the humeral head within the glenoid cavity.
Trapezius Muscle
- Parts: Descending (superior), Transverse (middle), Ascending (inferior)
- Origins: External occipital protuberance, medial part of the superior nuchal line, ligamentum nuchae, spinous processes of all thoracic vertebrae.
- Insertions:
- Descending fibres: Lateral 1/3 of the clavicle
- Transverse fibres: Acromion process of the scapula
- Ascending fibres: Scapular spine
- Actions:
- Descending fibres: Elevation of the shoulder girdle
- Transverse fibres: Retraction of the scapula
- Ascending fibres: Depression of an elevated shoulder
- All parts together: Retract scapula
- Descending and ascending fibres: Rotate glenoid cavity superiorly
- Nerve Supply: Spinal part of the accessory nerve, cervical plexus (C3 and C4)
Latissimus Dorsi Muscle
- Shape: Fan-shaped, covering the back
- Origins: Inferior angle of the scapula, spinous processes of thoracic vertebrae 7-12, spinous processes of all lumbar vertebrae, sacrum, thoracolumbar fascia, fleshy fibers from ribs 9-12, iliac crest
- Insertion: Thoracodorsal (middle scapular) nerve from the posterior cord of the brachial plexus.
- Actions: Medial rotation, adduction, retroversion (extension) of the shoulder, raising body during climbing. Forms the inferior angle of the triangle of auscultation. Forms the posterior axillary fold with teres major.
- Triangle of auscultation: Triangular gap for clear heart and lung sound detection. Boundaries: medial – trapezius; lateral – scapula; inferior – latissimus dorsi; floor - rhomboides major
Rhomboid Minor Muscle
- Origin: Spinous process of C7, lower part of ligamentum nuchae, and spinous process of Th1
- Insertion: Medial border of the scapula above the spine and above the insertion of rhomboid major
- Innervation and Action: Similar to rhomboid major
Levator Scapulae Muscle
- Origin: Transverse processes of C1-C4 vertebrae
- Insertion: Superior part of medial border of scapula
- Innervation: Dorsal scapular nerve
- Action: Elevates scapula
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Description
Explore the anatomy and functions of the Rhomboid Major and Levator Scapulae muscles in this quiz. Learn about their origins, insertions, nerve supplies, and actions. Perfect for students studying human anatomy!
