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Questions and Answers
What is the primary function of the supraspinatus muscle?
What is the primary function of the supraspinatus muscle?
Which nerve innervates the teres minor muscle?
Which nerve innervates the teres minor muscle?
The deltoid muscle is primarily responsible for which of the following movements?
The deltoid muscle is primarily responsible for which of the following movements?
What is the origin of the teres major muscle?
What is the origin of the teres major muscle?
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Which muscles are included in the rotator cuff?
Which muscles are included in the rotator cuff?
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Which component of the rotator cuff is responsible for holding the head of the humerus in the glenoid cavity?
Which component of the rotator cuff is responsible for holding the head of the humerus in the glenoid cavity?
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What is the primary action of the infraspinatus muscle?
What is the primary action of the infraspinatus muscle?
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Which nerve innervates the deltoid muscle?
Which nerve innervates the deltoid muscle?
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Which muscle is primarily responsible for lateral rotation of the humerus?
Which muscle is primarily responsible for lateral rotation of the humerus?
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Which nerve is responsible for the cutaneous innervation of the upper lateral aspect of the arm?
Which nerve is responsible for the cutaneous innervation of the upper lateral aspect of the arm?
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What is the primary action of the teres major muscle?
What is the primary action of the teres major muscle?
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Which structure is primarily responsible for holding the head of the humerus in the glenoid cavity?
Which structure is primarily responsible for holding the head of the humerus in the glenoid cavity?
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What is the origin of the supraspinatus muscle?
What is the origin of the supraspinatus muscle?
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Which muscle acts as the chief abductor of the arm?
Which muscle acts as the chief abductor of the arm?
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Which muscular action is associated with the subscapularis muscle?
Which muscular action is associated with the subscapularis muscle?
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Which muscle originates from the infraspinous fossa?
Which muscle originates from the infraspinous fossa?
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What is the function of the deltoid muscle's middle part?
What is the function of the deltoid muscle's middle part?
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Which muscle is primarily responsible for the medial rotation of the humerus?
Which muscle is primarily responsible for the medial rotation of the humerus?
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Which nerve innervates the supraspinatus muscle?
Which nerve innervates the supraspinatus muscle?
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What is the origin of the teres major muscle?
What is the origin of the teres major muscle?
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Which muscle functions to laterally rotate the humerus?
Which muscle functions to laterally rotate the humerus?
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What nerve is responsible for the cutaneous innervation of the posterior aspect of the arm?
What nerve is responsible for the cutaneous innervation of the posterior aspect of the arm?
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What is the insertion point of the supraspinatus muscle?
What is the insertion point of the supraspinatus muscle?
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Which part of the deltoid muscle is responsible for flexion and medial rotation of the arm?
Which part of the deltoid muscle is responsible for flexion and medial rotation of the arm?
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What muscle is primarily responsible for adducting and medially rotating the humerus?
What muscle is primarily responsible for adducting and medially rotating the humerus?
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Which muscle is the chief abductor of the arm?
Which muscle is the chief abductor of the arm?
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What is the primary function of the infraspinatus muscle?
What is the primary function of the infraspinatus muscle?
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What nerves innervate the upper and lower parts of the subscapularis muscle?
What nerves innervate the upper and lower parts of the subscapularis muscle?
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The rotator cuff consists of which of the following muscles?
The rotator cuff consists of which of the following muscles?
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Which muscle originates from the supraspinous fossa?
Which muscle originates from the supraspinous fossa?
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Which part of the deltoid muscle is responsible for extension and lateral rotation of the arm?
Which part of the deltoid muscle is responsible for extension and lateral rotation of the arm?
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What is the insertion point of the supraspinatus muscle?
What is the insertion point of the supraspinatus muscle?
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Study Notes
Cutaneous Innervation
- The supraclavicular nerve (cervical plexus) innervates the skin of the shoulder
- The upper lateral cutaneous nerve of the arm (axillary nerve) innervates the skin of the lateral aspect of the arm
- The medial cutaneous nerve of the arm (brachial plexus) innervates the skin of the medial aspect of the arm
- The posterior cutaneous nerve of the arm (radial nerve) innervates the skin of the posterior aspect of the arm
Deltoid Muscle
- The deltoid muscle is innervated by the axillary nerve (C5, C6)
- The deltoid muscle has three parts:
- Anterior (clavicular) part: flexes and medially rotates the arm
- Middle (acromial) part: chief abductor of the arm
- Posterior (spinous) part: extends and laterally rotates the arm
Supraspinatus Muscle
- The supraspinatus muscle is innervated by the suprascapular nerve (C4, C5, C6)
- It originates from the supraspinous fossa
- It inserts onto the superior facet of the greater tubercle of the humerus
- It abducts the humerus
Infraspinatus Muscle
- The infraspinatus muscle is innervated by the suprascapular nerve (C5, C6)
- It originates from the infraspinous fossa
- It inserts onto the middle facet of the greater tubercle of the humerus
- It laterally rotates the humerus
Teres Minor Muscle
- The teres minor muscle is innervated by the axillary nerve (C5, C6)
- It originates from the superior part of the lateral border of the scapula
- It inserts onto the inferior facet of the greater tubercle of the humerus
- It laterally rotates the humerus
Teres Major Muscle
- The teres major muscle is innervated by the lower subscapular nerve (C6, C7)
- It originates from the dorsal surface of the inferior angle of the scapula
- It inserts onto the medial lip of the intertubercular groove
- It adducts and medially rotates the humerus
Subscapularis Muscle
- The subscapularis muscle is innervated by the upper and lower subscapular nerves (C5, C6, C7)
- It originates from the subscapular fossa
- It inserts onto the lesser tubercle of the humerus
- It medially rotates the humerus
Rotator Cuff
- The rotator cuff is a group of four muscles that surround the shoulder joint
- The four muscles of the rotator cuff are:
- Supraspinatus
- Infraspinatus
- Teres Minor
- Subscapularis
- The rotator cuff muscles help to hold the head of the humerus in the glenoid cavity
- These muscles provide stability to the shoulder joint
- "SITS" is a mnemonic for remembering the muscles of the rotator cuff:
- Supraspinatus
- Infraspinatus
- Teres Minor
- Subscapularis
Muscles Inserting to the Greater Tubercle
- The supraspinatus muscle inserts onto the superior facet of the greater tubercle
- The infraspinatus muscle inserts onto the middle facet of the greater tubercle
- The teres minor muscle inserts onto the inferior facet of the greater tubercle
- These muscles are innervated by the suprascapular and axillary nerves
Cutaneous Innervation of Shoulder and Arm
- Supraclavicular nerve (cervical plexus)
- Upper lateral cutaneous nerve of arm (axillary nerve)
- Medial cutaneous nerve of arm (brachial plexus)
- Posterior cutaneous nerve of arm (radial nerve)
Deep Fascia of Shoulder and Arm
- Deltoid Fascia
Deltoid Muscle
- Originates: Lateral 1/3rd of clavicle
- Inserts: Deltoid tuberosity
- Function: Flexion and medial rotation of the arm
Deltoid Muscle (Middle/Acromial Part)
- Chief abductor of arm
Deltoid Muscle (Post/Spinous Part)
- Originates: Spine of scapula
- Inserts: Deltoid tuberosity
- Function: Extension and lateral rotation of the arm
- Innervation: Axillary nerve (C5, C6)
Supraspinatus Muscle
- Originates: Supraspinous fossa
- Inserts: Sup facet on greater tuberosity
- Function: Abducts humerus
- Innervation: Suprascapular nerve (C4,C5,C6)
Infraspinatus Muscle
- Originates: Infraspinous fossa
- Inserts: Middle facet on greater tubercle
- Function: Laterally rotates humerus
- Innervation: Suprascapular nerve (C5, C6)
Teres Minor Muscle
- Originates: Sup part of lat border of scapula
- Inserts: Inferior facet on greater tubercle
- Function: Laterally rotates humerus
- Innervation: Axillary nerve (C5, C6)
Teres major Muscle
- Originates: Dorsal surface of inf angle of scapula
- Inserts: Med lip of intertubercular groove
- Function: Adducts & medially rotates humerus
- Innervation: Lower Subscapular nerve (C6, C7)
Subscapularis Muscle
- Originates: Subscapular fossa
- Inserts: Lesser tubercle of humerus
- Function: Medially rotates humerus
- Innervation: Upper and lower subscapular nerves (C5, C6, C7)
Rotator Cuff
- Muscles: Supraspinatus, Infraspinatus, Teres minor, Subscapularis
- Function: Holds the head of the humerus in the glenoid cavity
- AKA: "SITS"
Cutaneous Innervation
- Supraclavicular Nerve: Innervates the skin of the shoulder
- Upper Lateral Cutaneous Nerve of Arm: Innervates the skin of the upper lateral aspect of the arm
- Medial Cutaneous Nerve of Arm: Innervates the skin of the medial aspect of arm
- Posterior Cutaneous Nerve of Arm: Innervates the skin of the posterior aspect of the arm
Deep Fascia
- Deltoid Fascia wraps around the Deltoid Muscle
### Deltoid Muscle
- Action: Shoulder abduction, flexion, medial and lateral rotation
- Innervation: Axillary Nerve (C5, C6)
- Components:
- Anterior/Clavicular Part: Originates from the lateral 1/3 of the clavicle, inserts into the Deltoid Tuberosity
- Middle/Acromial Part: Responsible for primary abduction
- Posterior/Spinous Part: Responsible for extension and lateral rotation of the arm.
### Supraspinatus Muscle
- Action: Abduction of the humerus
- Innervation: Suprascapular Nerve ( C4,C5,C6)
- Origin: Supraspinous Fossa
- Insertion: Superior facet on greater tubercle
Infraspinatus Muscle
- Action: Lateral rotation of the humerus
- Innervation: Suprascapular Nerve (C5,C6)
- Origin: Infraspinous Fossa
- Insertion: Middle facet on greater tubercle
### Teres Minor Muscle
- Action: Lateral rotation of the humerus
- Innervation: Axillary Nerve ( C5,C6)
- Origin: Superior of the lateral border of the scapula
- Insertion: Inferior facet on greater tubercle
### Teres Major Muscle
- Action: Adduction and medial rotation of the humerus
- Innervation: Lower Subscapular Nerve (C6,C7)
- Origin: Dorsal surface of the inferior angle of scapula
- Insertion: Medial lip of the intertubercular groove
Subscapularis Muscle
- Action: Medial rotation of the humerus
- Innervation: Upper and Lower Subscapular Nerves (C5,C6,C7)
- Origin: Subscapular Fossa
- Insertion: Lesser tubercle of humerus
Greater Tubercle
- The Supraspinatus, Infraspinatus, and Teres Minor muscles all insert onto the Greater Tubercle
Rotator Cuff
- Consists of: Supraspinatus, Infraspinatus, Teres Minor, and Subscapularis, collectively known as SITS.
- Role: Stabilizes the head of the humerus in the glenoid cavity.
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Description
Test your knowledge on cutaneous innervation and deltoid muscle anatomy. This quiz covers the innervation of various muscles and nerves in the shoulder and arm, including the supraclavicular nerve and the deltoid muscle's functions. Challenge yourself to identify the key components and their roles in arm movement.
