Upper Limb muscles Flashcards
Where does the trapezius muscle arise from?
-from external occipital protuberance + medial third of the superior nuchal line of the occipital bone, ligamentum nuchae, and spinous processes of the 7th cervical vertebra and all 12 thoracic vertebrae.
Where do the superior fibres of the trapezius muscle insert?
Superior fibers of the trapezius muscle insert into the posterior border of the lateral third of the clavicle
Where do the middle fibres insert?
Middle fibers insert into the medial margin of the acromion and posterior border of the scapular spine
Where do the inferior fibres converge?
Inferior fibers converge to end in an aponeurosis inserted into the scapular spine
How do the upper and lower fibres of trapezius muscle act?
primarily to rotate the scapula for full abduction of the upper extremity
How upper fibres act?
The upper fibers, acting alone, elevate the shoulder and brace the shoulder girdle when a weight is being carried by the shoulder or hand
How do the central fibre act?
Central fibers run horizontally and retract the shoulder
How do lower fibres act?
- Lower fibers draw the scapula downward
- When both muscles act together, the scapula can be adducted and the head drawn directly backwar
What is the innervation of the shoulder muscles?
- Motor supply is from the accessory nerve (CN XI)
2. Proprioceptive fibers are from the 3rd and 4th cervical nerves
Does the trapezius muscle receive nerve fibres from the brachial plexus?
he trapezius, in contrast to the other shoulder muscles, does not receive nerve fibers from the brachial plexus.
How can the trapezius muscle be tested?
- The trapezius can be tested by having a patient elevate the shoulder against resistance (the upper portion of the contracting muscle can be felt)
- This tests the integrity of the accessory nerve (CN XI) innervating this muscle.
What is the origin of the latissimus dorsi muscle?
- Latissimus dorsi muscle arises from a broad aponeurosis of the posterior layer of the thoracolumbar fascia, from the spinous processes of the lower 6 thoracic vertebrae, and by fleshy digitations of the caudal-most 3 or 4 ribs
- The muscle also may attach to the iliac crest.
What are the fibres of the latissimus dorsi working?
- The fibers of the latissimus dorsi muscle converge as the muscle curves around the lower border of the teres major and twists on itself.
- They end as a tendon that inserts into the intertubercular groove of the humerus
What is the action of the latissimus dorsi?
Extends, adducts, and medially rotates the humerus (arm)
What is the innervation of the latissimus dorsi?
Thoracodorsal nerve (C6-C8)
What is the blood supply for latissimus dorsi?
by the thoracodorsal artery, a branch of the subscapular artery (which arises from the axillary artery)
What is the clinical test for the latissimus dorsi?
- The latissimus dorsi is tested clinically by having the patient raise the arm horizontal to the body with the elbow flexed, as if signaling someone to “stop.”
- Then the patient is asked to adduct the arm against resistance to test the muscle’s strength and the integrity of the thoracodorsal nerve
- The muscle can also be felt to contract over the patient’s back when the patient is asked to cough.
What is the origin of the levator scapulae muscle?
Levator scapulae muscle arises from the transverse processes of the first 4 cervical vertebrae.
What is the insertion of the levator scapulae muscle?
Inserts into the superior portion of the medial (vertebral) border of the scapula
What is the action of the levator scapulae muscle?
- Elevates the superior angle of the scapula and tends to draw it medially
- Also rotates the scapula so that the glenoid cavity is tilted inferioly
- When the scapula is held in a fixed position, the levator scapulae bends the neck laterally and rotates it slightly toward the same side
What is the innervation of the levator scapulae muscle?
By the 3rd and 4th cervical nerves from the cervical plexus and by a branch from the dorsal scapular nerve (C5) to the muscle’s lower fibers.
What is the blood supply to the levator scapulae muscle?
- Contraction of the levator scapulae helps shrug the shoulders
- The blood supply to the muscle comes largely from the transverse cervical artery of the thyrocervical trunk.
How can you test the levator scapulae muscle?
- One can easily test the levator scapulae muscle by asking the patient to shrug his or her shoulders against resistance
- Weakness in this action would require a more specific examination to determine to what degree the trapezius may also be affected or compensating, since both muscles elevate the scapula
What is the origin of the deltoid muscle?
Arises from the lateral third of the clavicle, the superior surface of the acromion, and the spine of the scapula
What is the insertion of the deltoid muscle?
The fibers converge in a thick tendon that is attached to the deltoid tuberosity on the lateral aspect of the shaft of the humerus
What is the action of the deltoid muscle?
- The principal function is abduction of the arm at the shoulder in a movement initiated together with the supraspinatus muscle
- The clavicular portion of the muscle rotates the arm medially and helps the pectoralis major flex the arm at the shoulder
- The spinous portion rotates the arm laterally and helps the latissimus dorsi extend the arm at the shoulder
What is the innervation of the deltoid muscle?
Axillary nerve (C5 and C6)
What is the blood supply of the deltoid muscle?
- The deltoid is a thick, triangular muscle with coarse fibers. It covers the shoulder joint anteriorly, posteriorly, and laterally.
- The multipennate central portion of the muscle is most active in abduction.
1. The blood supply is largely via the thoracoacromial artery and also via the anterior and posterior humeral circumflex arteries, which arise from the axillary artery.
How do you test the deltoid muscle and axillary nerve?
- have the patient abduct the upper limb against resistance (the middle fibers of the muscle should be seen to contract)
- The posterior fibers can be seen to contract if the patient tries to retract the abducted upper limb against resistance
What is origin of the supraspinatus muscle?
The supraspinatus muscle occupies the supraspinous fossa, originating from the medial two-thirds and arising from the strong supraspinatus fascia
What is the origin of the infraspinatus muscle?
The infraspinatus muscle occupies most of the infraspinous fossa; it arises from the medial two-thirds and from the infraspinatus fascia
What is the insertion of the supraspinatus muscle?
Fibers of the supraspinatus converge to form a tendon that inserts into the superior facet on the greater tubercle of the humerus
What is the insertion of the infraspinatus muscle?
- The infraspinatus fibers also converge to form a tendon, which inserts into the middle facet on the greater tubercle of the humerus
- The tendons of the 2 muscles adhere to each other
What is the action of the suprapsinatus muscle?
The supraspinatus strengthens the shoulder joint by drawing the humerus toward the glenoid fossa. With help from the deltoid, it initiates abduction at the shoulder and is a lateral rotator of the humerus (arm).
What is the action of infrapsiantus muscle?
The infraspinatus strengthens the shoulder joint by bracing the head of the humerus in the glenoid fossa. It is also a lateral rotator of the humerus.
What is the innervation of both the supraspinatus muscle and the infraspinatus muscle?
Both by the suprascapular nerve (C5 and C6
What is the clinical test for the supra and infra spinatus muscle?
- Repeated abduction and flexion of the shoulder (as in the throwing motion) may cause wear and tear on the tendons as they rub on the acromion and coracoacromial ligament
- This action can lead to rotator cuff tears or ruptures
- The tendon of the supraspinatus is the most vulnerable to injury.
What is the origin of the teres major muscle?
The teres major arises from the dorsal surface of the inferior angle of the scapula
What is the origin of the teres minor muscle?
The teres minor originates from the lateral border of the scapula
What is the insertion of the teres major muscle?
The teres major inserts into the medial lip of the intertubercular groove of the humerus
What is the insertion of the teres minor muscle?
The teres minor inserts into the inferior facet on the greater tubercle of the humerus
What is the action of the teres major?
The teres major helps extend the arm from the flexed position, and it adducts and medially rotates the arm at the shoulder.
What is the action of the teres minor?
The teres minor rotates the arm laterally and weakly adducts the arm at the shoulder. Similar to the other 3 rotator cuff muscles, it draws the humerus toward the glenoid fossa, strengthening the shoulder joint
What is the innervation of the teres minor?
The teres minor is supplied by the axillary nerve (C5 and C6)
What is the innervation of the teres major?
the teres major is innervated by the lower subscapular nerve (C6 and C7)
What is the teres minor part of?
- The teres minor is 1 of the 4 rotator cuff muscles, and it helps stabilize the shoulder joint
- Often, it is inseparable from the infraspinatus muscle
What is the clinical test of the teres major?
- The teres major is tested clinically by having the patient adduct the horizontally elevated arm against resistance while viewing the contraction of the muscle as it passes from the scapula to the humerus
- The integrity of the subscapular nerve is also tested by this action.
What is the origin of the scapularis muscle?
-Arises from the medial two-thirds of the subscapular fossa and from the lower two-thirds of the lateral border of the scapula
What is the insertion of the scapularis muscle?
The fibers converge in a tendon that is inserted into the lesser tubercle of the humerus and the anterior portion of the shoulder joint capsule
What is the action of the scapularis muscle?
- As a rotator cuff muscle, the subscapularis helps stabilize the shoulder joint and prevents anterior displacement of the humerus
- It also medially rotates and adducts the humerus (arm) at the shoulder
What is the innervation of the scapularis muscle?
Upper and lower subscapular nerves (C5 and C6)
What are the muscles in the rotator cuff?
- supraspinatus
- infraspinatus
- teres minor muscle
- the subscapularis
What forms the scapulothoracic joint?
- The subscapularis and serratus anterior muscles together form a functional (physiological) articulation of the shoulder called the scapulothoracic joint. -The joint is between the muscles, the scapula, and the loose connective tissue trapped between these 2 muscles, which permits a gliding movement of the scapula on the chest wall.
- Scapular movements at this joint include elevation, depression, protraction, retraction, and rotation.
What is the blood supply to the scapularis muscle?
- The tendon of the muscle is separated from the neck of the scapula by the subscapular bursa
- The blood supply to the muscle is by the subscapular artery, a branch of the axillary artery
What does weakness of the serratus anterior lead to?
Weakness of the serratus anterior leads to “winging” of the scapula
What is the origin of the pectrolais major?
Arises from the sternal half of the clavicle, the upper half of the sternum, and the aponeurosis of the external abdominal oblique muscle
What is the insertion of the pectoralis major?
- The fibers converge toward the anterior wall of the axilla
- All 3 parts of the muscle (clavicular, sternal, and abdominal) end as a flat tendon inserted into the intertubercular groove of the humerus
What is the action of the pectroalis major?
- Primary action adduction of arm at shoulder
- Medial rotator of humerus
- Its clavicular portions help fell shoulder and adduct the humerus medially across the midline
- The sternocostal portion along with latissimus dorsi and teres major muscles can extend against resistance, the flexed humerus to the side of the trunk
What is the innervation of the pectoralis major?
Medial and lateral pectoral nerves (C5-C8 and T1)
How does the pectoralis major help form the axilla?
-The converging fibres of this fan shaped muscle course toward the insertion on the humerus, forming the anterior boundary of the axilla
What is the artery supply for the pectoralIs major?
Thoracoacromial and lateral thoracic arteries
How do you test the pectoralis major?
- The pectoralis major (sternocostal portion) is tested clinically by having the patient adduct (move toward the body) the arm from a position of 45 ° lateral to the body wall with the elbow flexed
- One can place a hand on the elbow and provide resistance against this adduction to test the muscle’s strength and the integrity of the pectoral nerves
