Lecture 3: The arm and elbow Flashcards
what does brachium mean?
Arm
What does plexus mean?
braid
what is the brachial plexus?
The brachial plexus = nerve network that innervates the upper limb
Where is the brachial plexus located?
Located in the neck and axilla (armpit)
Where does the brachial plexus originate from?
It comes from the spinal cord
What does the brachial plexus give rise to?
It gives rise to 5 major branches that provide the motor and sensory innervation of the upper limb
What is the brachial plexus composed of?
The brachial plexus is composed of the ventral rami of the spinal nerves from the spinal cord segments C5 to T1
Which anterior rami come together to form the brachial plexus?
Anterior rami of C5, C6, C7, C8, and T1 come together to form the brachial plexus = innervates the muscles, skin and joints of the upper limbs
Define the arm region?
The ‘arm’ = region between the shoulder and elbow. The bone of this region is the humerus
what does the head of the humerus articulate with?
Glenoid fossa of scapula to form the shoulder joint.
What inserts itself into the proximal humerus and move the shoulder?
Several muscles
What does the distal humerus articulate with ?
The distal humerus articulates with the ulna and radius to form the elbow joint
What joint positions the hand?
The elbow joints
What is the clinical importance of the humerus?
Clinical importance: fractures common; close proximity of vessels and nerves
What bones are involved in the elbow joint?
3 bones involved:HumerusUlnaRadius
What are the two articulations of the elbow joint?
Humero-ulnar = between trochlea and trochlear notch Humero-radial = between capitulum and radial head
What does good congruity mean?
Very stable
What reinforces the joint capsule laterally?
Radial collateral ligament
What reinforces the joint capsule medially?
Ulnar collateral ligament
Is the joint capsule thick and tight?
No, Capsule is thin and loose anteriorly and posteriorly
What joint does the capsule of the joint contain?
the proximal radioulnar joint
Describe the proximal radioulnar joint.
This is an articulation between the radial head and the radial notch of the ulna – pivot joint
What type of joint is the elbow joint?
Hinge joint
What is the range of movements the elbow can make?
-Flexion - Extension
When can a muscle move a joint?
A muscle can only move a joint if it (or its tendon) crosses that joint
What are the two muscle compartments in the arm?
AnteriorPosterior
What does the anterior compartment of the arm do?
Bends the elbow
What does the posterior compartment of the arm do?
Straightens the elbow.
What is supination?
Palms to the sky
What is pronation?
Palm to the floor.
What are the 3 muscles of the anterior arm?
-Bicep brachi- Brachialis- Coracobrachialis
What are the 3 muscles in the anterior arm innervated by?
Musculocutaneous n. (C5-7)
Characteristics of the Biceps brachii?
has 2 heads. Short head is attached to the coracoid process; long head to the supraglenoid tubercle. Distal attachment = radial tuberosity. Flexes the elbow and shoulder
Characteristics of the brachialis?
deep to biceps. Proximal attachment = humeral shaft; distal attachment = ulna. Flexes the elbow
Characteristics of the coracobrachialis?
Coracobrachialis: small, attached to the coracoid process and inserts on the humeral shaft. Weakly flexes the shoulder
What are the 2 muscles of the posterior arm?
- Triceps brachii- Anconeus
What are the muscles of the posterior arm innervated by?
Radial n. (C5-T1)
Characteristics of the triceps brachii?
Triceps brachii = 3 heads – all insert via a common tendon onto the olecranon of the ulna. Extends the elbow Long head = attaches to the infraglenoid tubercle on the scapula, so contributes to shoulder extension Lateral head = attaches proximally to the posterior shaft of the humerusMedial head = deep to the long and lateral heads, attached to the shaft of the humerus
Characteristics of Anconeus?
= Extends elbow and stabilizes joint. Lateral epicondyle of humerus > lateral olecranon surface and posterior ulna
What does the axillary artery continue down the arm as?
Brachial artery
What does the brachial artery give rise to?
the deep artery of the arm (profunda brachii) > into the posterior compartment
What does the basilic vein of the arm continue as?
Axillary vein.
What are major tributaries of the axillary vein?
- Deep veins- Cephalic vein
What are the 4 terminal branches found of the brachial plexus in the arm?
- Musculocutaneous- Radial- Median-Ulnar
What do 3 of the terminal branches of the brachial plexus run close to?
Humerus
Where does the axillary nerve run along?
Surgical neck of the humerus
Where does the radial nerve run along?
Radial groove of the humerus
Where does the Ulnar nerve run along?
Medial epicondyle
What must you do to assess nerve damage?
To assess whether there has been any nerve damage you need to know the muscles the nerve innervates and the skin it supplies) and then test the function of those muscles and sensation in those regions.
What is pulled elbow in children?
Radial head subluxes from the annular ligamentUsual mechanism is upward force on a abducted armPainful and the child will not move their armRadial head can be palpated
What is medial epicondylitis?
= inflammation at the medial epicondyle = ‘golfer’s elbow
What is Lateral epicondylitis?
inflammation at the lateral epicondyle = ‘tennis elbow
Symptoms and treatments of Medial and lateral epicondylitis?
Pain radiates into forearm along the musclesTreatment: rest +/- injection of corticosteroids
What bursitis?
fluid-filled sacs located around joints - areas of potential friction, e.g. between a muscle and bone
How common is Bursitis?
Quite common
Symptoms of Bursitis?
Excessive, repeated pressure, and friction over the olecranon can cause inflammation of the olecranon bursa = the bursa swells (may be visible) and is often painful when touched
What does the humeral supracondylar cause?
A humeral supracondylar fracture may injure the median n. = impaired function of the forearm muscles and sensory disturbance in skin innervated by the median n.
What does injury to the brachial artery do?
ischaemia of the forearm muscles
