Upper limb and back: Deltoid m.

Question 1

Briefly discuss the specificity of dermatomes with regards to the cutaneous nerves and spinal nerves.

Answer 1

-Dermatomes become less specific when one spinal nerve serves many cutaneous nerves,
-but the become more specific as one cutaneous nerve is derived from many spinal nerves.

Question 2

Explain how the cephalic vein ascends and where it drains? (5)

Answer 2

-Arises from the lateral side of the dorsal venous network.
-Ascends towards the lateral border of the forearm.
-Runs along the lateral side of biceps brachii m.
-Pierces into the deep fascia between the deltoid and pectoralis major m (deltopectoral triangle).
-Drains into the axillary vein.

Question 3

Explain how the basilic vein ascends until it forms the axillary vein. (6)

Answer 3

-Arises from the medial side of the dorsal venous network.
-Ascends at the posterior surface of forearm.
-Inclines forward and reaches the cubital fossa.
-Ascends medial to the biceps brachii m.
-Pierces the deep fascia in the middle of arm.
-Joins venae comitantes of the brachial artery to form the axillary vein.

Question 4

Which vein is formed at the cubital fossa, where blood is usually drawn from?

Answer 4

Median cubital vein

Question 5

What is the origin, insertion, action and innervation of the deltoid muscle?

Answer 5

ORIGIN
-ANT. -Anterior border of 1/3 of clavicle.
-MID. -Lateral border pf the acromion.
-POST. -Inferior lip of scapula spine.
INSERTION
-Deltoid tuberosity of humerus.
ACTION
-ANT. fibers -Flexion and medial rotation.
-MID. fibers- Major abductor of arm.
-POST. fibers- Extension and lateral rotation.
INNERVATION
-Axillary nerve

Question 6

What are the four rotator cuff muscles?

Answer 6

-Supraspinatus
-Infraspinatus
-Teres minor
-Subscapularis

Question 7

What is the origin, insertion, action and innervation of the supraspinatus muscle?

Answer 7

ORIGIN
-Supraspinous fossa
INSERTION
-Superior facet of greater tubercle of humerus.
ACTION
-Initiates abduction of arm.
-Rotator cuff: stabilizes the shoulder joint.
INNERVATION
-Suprascapular nerve

Question 8

What is the origin, insertion, action and innervation of the infraspinatus muscle?

Answer 8

ORIGIN
-Infraspinous fossa
INSERTION
-Middle facet of greater tubercle of humerus.
ACTION
-Lateral rotation of arm
-Rotator cuff
INNERVATION
-Suprascapular nerve

Question 8

What is the origin, insertion, action and innervation of the teres minor muscle?

Answer 8

ORIGIN
-Lateral border of the scapula.
INSERTION
-Inferior facet of greater tubercle of humerus.
ACTION
-Lateral rotation of arm.
-Rotator cuff
INNERVATION
-Axillary nerve