Exam #6: Posterior Compartment Flashcards
What innervates the posterior compartment?
Posterior divisions of the brachial plexus, specifically:
- Radial nerve
- Axillary nerve
What does the axillary nerve innervate?
Motor=
- Deltoid
- Teres minor
Cutaneous= lateral arm
Review the boudaries of the quadrangular space.
Superior= teres minor Inferior= teres major Medial= long head of the triceps brachii Lateral= Surgical neck of the humerus
What are the contents of the quadrangular space?
- Axillary nerve
- Posterior circumflex humeral a.
What does fracture of the surgical neck of the humerus damage?
Quadrangular space
A patient presents in your office following trauma to the proximal humerus with atrophy of the deltoid noted on exam. What should you suspect?
Axillary nerve injury
What can glenohumeral dislocation cause?
Damage to the contents of the quadrangular space
What are the branches of the radial nerve?
Superficial branch
Deep branch
What does the superficial branch of the radial nerve provide?
Cutaneous innervation to the dorsum of the hand
What does the deep branch of the radial nerve provide?
Motor innervation to the forearm
What is the posterior interosseous nerve?
Termination of the deep branch of the radial nerve after it innervation of the supinator muscle
What are the muscles of the posterior compartment of the arm?
Triceps Brachii
- Long (all the way to the shoulder)
- Lateral
- Medial
Anconeus
What is the function of the muscles of the posterior compartment of the arm?
Extension of the elbow
- Long head can extend the shoulder as well
What nerve innervates the posterior compartment of the arm?
Radial nerve
What are the two muscles of the posterior compartment of the arm?
Triceps Brachii
Anconeus
What is the function of the anconeus?
Assists the triceps in extending the elbow & stabilizes the elbow
What is the exception to the functional rule of the muscles in the posterior compartment of the forearm?
Brachioradialis–flexor
Where do the muscles of the posterior compartment of the forearm originate?
Either the lateral epicondyle of the humerus or posterior surface of the forearm
List the muscles in the superficial group of the posterior compartment of the forearm.
- Brachioradialis
- Extensor carpi radialis longus
- Extensor carpi radialis brevis
- Extensor carpi ulnaris
- Extensor digitorum
- Extensor digiti minimi
What is the origin of the brachioradialis?
Lateral supracondylar ridge
What is the insertion of the brachioradialis?
Styloid process of the radius
What is the innervation of the brachioradialis?
Radial n.
What is the function of the brachioradialis?
Flexion of the elbow
What is the origin of the extensor carpi radialis longus?
Lateral supracondylar ridge
What is the insertion of the extensor carpi radialis longus?
Base of MC II
What is the innervation of the extensor carpi radialis longus?
Radial n.
What is the function of the extensor carpi radialis longus?
Extends & abducts the wrist
What is the origin of the extensor carpi radialis brevis?
Lateral epicondyle
What is the insertion of the extensor carpi radialis brevis?
Base of MC III
What is the innervation of the extensor carpi radialis brevis?
Deep branch of the radial n.