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