Arm and Brachial plexus dissection Flashcards
How many flexor muscles are found in the anterior compartment of the arm?
3
Where are the muscles in the flexor compartment of the arm located?
One of these muscles is a flexor at the shoulder joint, one a flexor at the elbow joint, and the third is a flexor at both the shoulder and elbow joint.
Name the largest flexor muscle in the anterior compartment of the arm
Biceps brachii
How many heads does the biceps brachii have?
2
Give the origin of the long head of the biceps brachii
supraglenoid tubercle of the scapula
Give the origin of the short head of the biceps brachii
coracoid process of the scapula
Where does the long head of biceps brachii travel?
Inside the capsule of the shoulder joint and continues down the intertubercular sulcus
What do the two heads of the biceps brachii insert?
Radial tuberosity
Name an expansion of the tendon of biceps
Bicipital aponeurosis
Where does the bicipital aponeurosis cross?
crosses medially over the superficial flexors of the forearm
Where does the bicipital aponeurosis attach?
posterior border of the ulna via the deep fascia.
What action does biceps exert when it crosses the shoulder and elbow joint?
Flexor action on both joints
Name a powerful supinator muscle of the forearm
Biceps
Give the origin of coracobrachialis
from the coracoid process
What forms the conjoint tendon?
The short head of biceps and coracobrachialis
Where does coracobrachialis insert?
medial aspect of the humerus half way down the shaft.
Where does coracobrachialis lie in relation to biceps?
Medial
Give the origin of brachialis
distal half of the anterior of the humerus
Give the insertion of brachialis
ulna tuberosity
Where does brachialis lie in relation to biceps?
Deep
How many muscles are in the posterior compartment of the arm?
1
Name the muscle in the posterior compartment of the arm
Triceps brachii
How many heads does triceps brachii have?
3
Give the origin of the long head of triceps brachii
infraglenoid tubercle of the scapula
Give the origin of the lateral head of triceps brachii
posterior aspect of the humerus above the spiral (or radial) groove of the humerus
Give the origin of the medial head of triceps brachii
posterior surface of the humerus but below the spiral groove.
Give the insertion of triceps brachii
olecranon process of the ulna
What are the muscles of the arm, forearm and hand innervated by?
Brachial plexus
Describe the roots of the brachial plexus
C5-T1
What do the roots of the brachial plexus form?
Trunks - superior, middle and inferior
What do the trunks of the brachial plexus form?
Cords - lateral, posterior and medial
What are the cords of the brachial plexus related to?
Axillary artery
What does the lateral cord of brachial plexus give rise to?
lateral pectoral nerve
What does the lateral pectoral nerve supply?
Pectoralis minor/major
Name the terminal branches of the lateral cord
lateral head of the median nerve and the musculocutaneous nerve
What does the Musculocutaneous nerve pierce?
coracobrachialis approximately 5cm distal to the conjoint tendon.
Name the terminal branch of the Musculocutaneous nerve
lateral cutaneous nerve of the forearm
What does the lateral cutaneous nerve of the forearm supply?
supplies the skin of the lateral forearm on both the dorsal and ventral aspects
What does the medial cord give rise to?
medial pectoral nerve
cutaneous nerves of the arm and forearm
What does the medial pectoral nerve supply?
Pectoral muscles
Name the terminal branches of the median nerve
medial head of the median nerve and the ulnar nerve.
What does the ulnar nerve give rise to?
limited supply to the flexor muscles of the forearm and is the main supply is the small muscles of the hand.
Describe the pathway of the ulnar nerve
The nerve lies medial to the brachial artery in the arm and passes behind the medial epicondyle of the humerus at the elbow joint (the cubital tunnel) to gain access to the forearm.
What does the median nerve supply?
It supplies almost all of the muscles of the anterior compartment of the forearm.
What are the branches of the posterior cord?
upper subscapular, thoracodorsal and lower subscapular nerve
What are the terminal branches of the posterior cord
Radial nerve
Axillary
What does the radial nerve supply?
muscles and skin over the whole posterior aspect of the upper limb. The radial nerve supplies the triceps muscles and the extensor muscles of the forearm.
What does the axillary nerve supply?
The axillary nerve supplies teres minor and the deltoid muscle as well as a small area of skin over the insertion of the deltoid, known as the badge area.
What is the origin of the subclavian artery on the right
Brachiocephalic trunk
What is the origin of the subclavian artery on the left?
Aorta
Describe the course of the blood supply of the arm
As the subclavian artery passes over the first rib it changes its name to the axillary artery. In the axilla, the axillary artery is accompanied by the cords of the brachial plexus. Once the axillary artery crosses the lower border of teres major it changes its name again to become the brachial artery, which is the main artery within the arm. The brachial artery gives off many small muscular branches and also the profunda (or deep) brachii artery, which accompanies the radial nerve in the spiral groove of the humerus to supply triceps and the elbow joint. Locate the subclavian artery and follow it as it becomes the axillary artery and then the brachial artery.
