functional organizations of the arm and hand Flashcards
compartments
each contains one or more functional groups of muscles, deep fascia divides the arm and forearm into post and ant components
anterior/flexor compartment of arm
contains muscles that flex the elbow joint and supinate the radioulnar joint
posterior/extensor compartment of arm
contains muscles that extend the elbow joint
innervation of anterior compartment of arm
musculocutaneous: from lateral cord of the brachial plexus. C5-C7, C6 is the main contributor. Motor innervation to muscles in the anterior brachial compartment and carries sensory from the lateral portion of the forearm (C6 dermatome)
innervation of posterior compartment of arm
radial nerve: derived from pot cord of brachial plexus, C5-T1, C5-7 are the main contributors. Motor to triceps and anconeus, sensation from post lat portion of arm (C5 dermatome)
anterior compartment of the forearm
contains muscles that flex the wrist joint, pronate the radioulnar joint and flex the digits
posterior compartment of the forearm
contains muscles that extend the wrist joint, supinate the radioulnar joint, and extend and abduct the digits
innervation of the posterior compartment of the forearm
radial nerve
innervation of the anterior compartment of the forearm
ulnar and medial nerve
transition zones (3)
provide a passageway for the contents (particularly nerves and vessels) of one compartment to enter another 1. axilla 2. cubital fossa 3. wrist
muscles in the anterior compartment of the arm (3)
- biceps brachii 2. brachialis 3. coracobrachialis
blood supply to muscles in ant compartment of arm
brachial artery, branches include: 1. muscular branches to the muscles in the ant compartment of the arm 2. collateral branches in elbow anastomosis 3. deep brachial artery: extensor compartment
Muscles in the post compartment of the arm (2)
- triceps brachii 2. anconeus
Blood supply of the posterior compartment of the arm
Deep profunda brachial artery (1st brach of the brachial) gives off: -muscular branches to the muscles in the extensor compartment -collateral branches in elbow anastomosis
Veins in the arm (3)
Cephalic (lateral) Basilic (medial) Median cubital (connects the 2)
Biceps rupture
could tear the biceps from an attachment on the supraglenoid tubercle, the radial tuberosity or both. Make the bicep appear higher or lower on the arm depending on where it is torn. Sometimes if the person is not an athlete they won’t repair it, if they do, they sew the tendon back onto the bone
Cubital Fossa
region anterior to the elbow joint, passageway for nerves and vessels traveling from the arm into the forearm, venipuncture usually performed here
Cubital Fossa Boundaries
Superior: imaginary line connecting condyles Medial: pronator teres lateral: brachioradialis roof: skin, fascia, bicipital apaneurosis floor: medial: brachilis lateral: supinator
Cubital Fossa Contents (4ish)
- radial nerve 2. biceps tendon 3. brachial artery and vein terminal branches: radial and ulnar artery 4. median nerve
Ulnar Artery branches
branches off into common interossius artery which is very short and splits very quickly into the anterior and posterior interossius artery
Radius
-main articulation of the wrist -articulate with the ulna, humerus, scaphoid, and lunate bones -the tuberosity of the radius is where the biceps tendon attaches
Ulna
-more stable because it has a hook -articulates with humerus and radius -has a fibrocartilagenous disc at the wrist
Muscles of the anterior portion of the arm (characteristic)
common origin at the medial epicondyle of the humerus
Radio-ulnar pronators
cause the radius to rotate on a fixed ulna bringing the forearm and hang “palms down” 1. pronator teres 2. pronator quadratus
Wrist flexors
attach to the medial epicondyle of the humerus and bring the palm of the hand toward the elbow (flexion)
- flexor carpi radialis
- palmaris longus
- flexor carpi ulnaris
Digital Flexors
extrinsic, bellies of origin in forearm but exert actions of wrist and hand
- flexor digitorum superficialis
- flexor digitorum profundus
- flexor pollicis longus
Movement of the thumb
median motor nerve muscle supply (7)
- pronator teres
- pronator quadratus
- flexor carpi radialis
- palmaris longus
- flexor digitorum superficialis
- radial 1/2 of flexor digitorum profundus
- flexor pollicis longus
ulnar motor nerve supply (2)
- flexor carpi radialis
- ulna portion of the flexor digtorum profundus
cutaneous innervation of the forearm
Lateral/radial side
- lateral antibrachial cutaneous (C6), cutaneous branch of musculocutaneous nerve
Medial/ulna side
- medial antibrachial cutaneous carries sensory axons from T1. Branch of medial cord of brachial plexus
blood supply to flexor compartment of the forearm
provided by radial and ulnar arteries which brach from brachial artery
branches of the radial artery
- muscular branches to muscles in flexor compartment
- recurrent branch in elbow anastomosis
branches of the ulnar artery
- muscular branch to the muscle in the flexor compartment
- recurrent in elbow anastomosis
- common interosseous branch
- anterior: deep lying muscles in flexor
- posterior: main blood supply to muscles in extensor
posterior compartment of the forarm characteristic
wrist and finger extensors have a common attachment from the lateral epicondyle of the humerus
Anatomical Snuff box muscles
act on the 1st metacarpal and joints of the thumb
- abductor pollicis longus
- extensor pollicis brevis
- extensor pollicis longus
wrist extensors
- extensor carpi radialis longus
- extensor carpi radialis brevis
- extensor carpi ulnaris (weaker than other 2, why extension usually occurs along with radial deviation)
finger extensors
- extensor digitorum
- extensor digiti minimi
- extensor indicis
misc. muscles in the forearm
- supinator: weak supinator of the radioulnar joint (biceps is the strongest)
- brachioradialis: flexes elbow when the hand is in neutral position
Extensor compartments
6 tunnels that are comprised of a tendon(s) surrounded by a synovial sheath. located within tunnels bound by portions of the extensor retinaculum
Compartment 1
abductor pollicis longus and extensor pollicis brevis.
most clincally significant. repetitive movements of the thumb and wrist can result in De Quervain’s Disease
Compartment 2
extensor carpi radialis longus and brevis tendons
Compartment 3
Extensor pollicis longus tendon (wraps around tubercle on radius)
Compartment 4
extensor digitorum and etensor indicis
Compartment 5
Extensor digiti minimi
Compartment 6
extendor carpi radialis tendon
De Quervain’s Disease
caused by repetitve movents of the thumb and wrist, especially flexion of the thumb and ulnar deviation of the wrist results in pain to the dorsal aspect of wrist
asking the patient to fold their thumb under the fingers and move the wrist toward the ulna (ulnar deviation) produces a pain that tests positive for this condition
Innervation of the extensor compartment
Radial Nerve: enters the cubital fossa and winds arounf the shaft of the humerus. Branches into:
- muscular branches that supply extensor carpi radialis longus and brachioradialis
- a superficial branch that conveys sensory ONLY from the dorsum of the hand and thumb
- a deep branch: pierces the supinator muscle and supplies ECRB
blood supply of the extensor compartment of the forearm
posterior interosseus branch of the common interosseus artery to all of the muscles
tennis elbow
overuse of extensors, tearing or inflammation on or around the lateral epicondyle. common treatment is to put a strap around the tendons
also medial epicondylitis which is the same thing only on the lateral epicondyle
