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Questions and Answers
Which muscle is responsible for the abduction of the arm from 15⁰ to 90⁰?
Which muscle is responsible for the abduction of the arm from 15⁰ to 90⁰?
What is the primary nerve supply for the trapezius muscle?
What is the primary nerve supply for the trapezius muscle?
Which muscle originates from the external occipital protuberance?
Which muscle originates from the external occipital protuberance?
Which action is NOT performed by the deltoid muscle?
Which action is NOT performed by the deltoid muscle?
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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 nerve supply for the rhomboideus major muscle?
What is the nerve supply for the rhomboideus major muscle?
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Which muscle is responsible for the initiation of abduction of the arm from 0-15°?
Which muscle is responsible for the initiation of abduction of the arm from 0-15°?
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What action do the rhomboideus muscles perform on the scapula?
What action do the rhomboideus muscles perform on the scapula?
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What is the primary action of the subscapularis muscle?
What is the primary action of the subscapularis muscle?
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Which muscle originates from the medial two-thirds of the infraspinous fossa?
Which muscle originates from the medial two-thirds of the infraspinous fossa?
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Study Notes
Course Information
- Course Title: Anatomy I
- Course Code: FM 101
- Department: Anatomy and embryology
- Lecture Title: Muscles of the shoulder and pectoral regions
- Lecturer Name: Pr.Dr. Morsy Abdelfattah Morsy
Objectives
- Students will be able to identify the shoulder region.
- Students will be able to describe the muscles of the shoulder region.
- Students will be able to identify the pectoral region.
- Students will be able to identify the breast.
- Students will be able to describe the muscles of the pectoral region.
Shoulder Region Muscles
- Deltoid muscle
- Trapezius
- Levator scapulae
- Rhomboid minor
- Rhomboid major
- Subscapularis muscle
- Supraspinatus muscle
- Infraspinatus muscle
- Teres major
- Teres minor
Deltoid Muscle
- Origin: Anterior border of lateral 1/3 of clavicle, lateral border of acromion process, and inferior lip of crest of spine.
- Insertion: Deltoid tuberosity.
- Nerve supply: Axillary nerve.
- Action: Anterior fibers: flexion and medial rotation of the arm; Middle fibers: abducts the arm from 15° to 90°; Posterior fibers: extension and lateral rotation of the arm.
Trapezius Muscle
- Origin: External occipital protuberance and medial 1/3 of superior nuchal line, ligamentum nuchae, 7th cervical spine and all 12 thoracic spines.
- Insertion: Posterior border of the lateral 1/3 of clavicle, medial border of acromion, upper lip of crest of spine of scapula, medial part of crest of spine of scapula.
- Nerve supply: Spinal roots of accessory nerve.
- Action: Upper fibers: rotate scapula upwards and elevate the shoulder; Middle fibers: retract the scapula; Lower fibers: depress the scapula and shoulder.
Levator Scapulae Muscle
- Origin: Transverse process of upper 4 cervical vertebrae
- Insertion: Back of medial border of scapula from superior angle to root of spine.
- Nerve Supply: Dorsal scapular nerve (Nerve to rhomboids) C5
- Action: Raises the medial border of the scapula.
Rhomboideus Minor Muscle
- Origin: Ligamentum nuchae (lower part), spines of 7th cervical and 1st thoracic vertebrae.
- Insertion: Back of medial border of scapula opposite the root of spine of scapula.
- Nerve Supply: Dorsal scapular nerve (N. to Rhomboideus) C5
- Action: Raises the medial border of the scapula upwards and medially
Rhomboideus Major Muscle
- Origin: 2nd, 3rd, 4th, 5th thoracic spines
- Insertion: Back of medial border of scapula from root of spine to inferior angle
- Nerve Supply: Dorsal scapular nerve (N. to Rhomboideus) C5
- Action: Two rhomboideus muscles rotate the scapula upwards and medially.
Subscapularis Muscle
- Origin: Medial 2/3 of subscapular fossa
- Insertion: Lesser tubercle
- Nerve supply: Upper and lower subscapular nerves
- Action: Adduction and medial rotation of the arm, one of the rotator cuff muscles.
Supraspinatus Muscle
- Origin: Medial two-thirds of the supra-spinous fossa of the scapula
- Insertion: Tip of the greater tubercle of the humerus
- Nerve supply: Suprascapular nerve (C5, C6)
- Action: Rotator cuff muscle; initiation of abduction of arm from 0-15°.
Infraspinatus Muscle
- Origin: Medial two-thirds of the infra-spinous fossa of the scapula
- Insertion: Middle facet on posterior surface of the greater tubercle of the humerus
- Nerve supply: Suprascapular nerve (C5, C6)
- Action: Rotator cuff muscle; lateral rotation of arm
Teres Minor Muscle
- Origin: Upper two-thirds of posterior surface of the lateral border of the scapula
- Insertion: Inferior facet on the posterior surface of the greater tubercle of the humerus
- Nerve supply: Axillary nerve (C5, 6)
- Action: Rotator cuff muscle; lateral rotation of arm at the shoulder joint
Teres Major Muscle
- Origin: Elongated oval area on the posterior surface of the inferior angle of the scapula
- Insertion: Medial lip of the intertubercular sulcus (Bicipital groove) on the anterior surface of the humerus
- Nerve supply: Lower subscapular nerve (C5, C6, C7)
- Action: Medial rotation and extension of the arm at the shoulder joint.
Pectoral Region
- The pectoral region is external to the anterior thoracic wall and anchors the upper limb to the trunk.
- It consists of a superficial compartment (superficial fascia, breasts) and a deep compartment (muscles).
- The breasts consist of mammary glands, associated skin and connective tissues.
- Mammary glands are modified sweat glands.
Pectoralis Major Muscle
- Origin: Clavicular head from anterior surface of medial 2/3 of clavicle, Sternocostal head from upper 6 costal cartilage and anterior surface of the manubrium sterni and body of sternum, Aponeurosis of external oblique muscle
- Insertion: Lateral lip of bicipital groove
- Nerve supply: Lateral and medial Pectoral nerves.
- Action: Flexion, Adduction, and Medial rotation of the arm.
Serratus Anterior Muscle
- Origin: Upper 8 ribs
- Insertion: Inner surface of the medial border and inferior angle of the scapula
- Nerve supply: Long thoracic nerve (C5, 6, 7)
- Action: Protraction of the scapula and rotation of the scapula upwards.
Pectoralis Minor Muscle
- Origin: 3, 4, 5 ribs
- Insertion: Coracoid process (upper surface and medial border)
- Nerve supply: Medial pectoral nerve
- Action: Protraction and depression of the scapula.
Subclavius Muscle
- Origin: Upper surface of 1st rib
- Insertion: Subclavian groove on clavicle
- Nerve supply: Nerve to subclavius
- Action: Pulls clavicle medially to stabilize sternoclavicular joint.
Clavipectoral Fascia
- A strong sheet of connective tissue immediately deep to pectoralis major muscle
- Superiorly, it attaches to clavicle and Inferiorly, it encloses subclavius and pectoralis minor muscles
###Multiple Choice Questions
- Questions related to muscle insertions, nerve supply, actions, and other anatomical aspects are included in the scans (page 37). Answers are not included in the summary
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Description
This quiz focuses on the anatomy of the shoulder and pectoral regions, specifically the identification and description of key muscles such as the deltoid, trapezius, and others. Students will test their knowledge on their origins, insertions, and functions. Prepare to demonstrate your understanding of this important area in anatomy.
