May24 M3-Arm, elbow and cubital fossa Flashcards
movements the forearm can do
- flexion and extension
- pronation and supination (supination = anat position)
what nerve innervates the anterior compartment of muscles in the arm and what n. for posterior + function of each compartment + one exception
- anterior = musculocutaneous n. = flexion of arm
- posterior = radial n. = extension of arm
- brachioradialis = posterior compt of arm to anterior of forearm = radial n. = flexion*
compartment definition
muscle grouping sharing a closed fascia (CT)
number of muscles in ant and post forearm
ant = 3 muscles
post = 1 muscle
+ brachioradialis post arm to anterior forearm
compartment syndrome definition + what’s the problem
hematoma or trauma results in muscle swelling and this compresses the vessels going to muscles. get muscle dying. inflammation and pain
3 muscles in ant compt of arm
- biceps brachii m.
- coracobrachialis m.
- brachialis m.
biceps brachii how many heads and where tendons go on top (origin)
2 heads (biceps)
- tendon of the long head (LATERAL) crosses the glenohumeral joint and goes to SCAPULA
- tendon of short head (MEDIAL) attaches to coracoid process of the SCAPULA
biceps brachii insertion
- one tendon on radius (lateral bone forearm)
- an aponeurosis inserts on the ulna (medial bone forearm)
names of the aponeurosis of biceps brachii inserting on the ulna
- bicipital aponeurosis
- flat tendon of the biceps brachii m.
biceps brachii functions (2) + inn.
- flexion of arm and forearm (crosses glenohumeral joint and elbow joint)
- supination of forearm
- inn = musculocutaneous n.*
brachialis m. origin, insertion, function and inn.
- humerus to ulna
- flexion of forearm
- musculocutaneous n.
coracobrachialis m. origin, insertion, function and inn.
- scapula to humerus
- flexion of ARM and ADDuction of the arm
- musculocutaneous n.
other name for arm
brachium
supination and pronation is what movement
pronation = radius crossing over the ulna on top of it supination = radius back on side (lat) of ulna
full training of biceps brachii = what mvmts
- supination of forearm
- flexion of forearm
- arm flexion
only muscle in posterior compt of arm + how many heads and tendons
triceps brachii. 3 heads and 3 tendons on top (origin)
3 heads (on top) of the triceps brachii m. and where they originate from + location
- long head (medial): from scapula (allows ADDuction)
- lateral head (lateral): from humerus
- medial head (deep between long and lateral heads: from humerus
where triceps brachii m. inserts (the 3 heads insert where)
ulna
note: origin was scapula + humerus
function and innervation of triceps brachii m.
- extension of the arm (bc of long head) and forearm
- ADDuction of the arm
- radial n.*
what brachial artery becomes
- same name all along the humerus
- crosses elbow joint
- after crosses elbow joint, splits in radial a. (lat) and ulnar a. (medial)
what cephalic and basilic v become
- cephalic stays lat. and continues in forearm
- basilic stays medial and continues in forearm
- both connect at cubital fossa to form the median cubital vein
cubital fossa is what
anterior interior fold of the elbow
mechanism to prevent backflow of blood in veins of arm and forearm
valves
competent valve = functioning well
how to check if a valve is functional
- ID vein
- put finger on vein and move distally until see a portion of the vein that is white (no blood there proximally valve blocking = one you’re checking and distally your finger is blocking)
arteriovenous fistula links what vessels
radial artery and cephalic vein laterally
musculocutaneous n. comes from what cord + spinal levels + to what muscles
- from lateral cord
- C5,6,7
- to ant compt of arm
musculocutaneous n. travels how
- pierces coracobrachialis to go anterior to it
- travels anterior to coracobrachialis, between coracobrachialis and biceps + brachialis m.
where radial n is located (don’t have to locate in anat lab)
- posterior compt. cut lateral head of triceps
* crosses the triangular interval
important concepts in sensory info coming back from limbs
- is cutaneous + non cutaneous (feedback on muscle contraction and length)
- in general**, n. innervating a m. also inn. the skin over this m.
3 components of the cutaneous innervation of the arm
- axillary n.
- radial n.
- cutaneous branches of the brachial plexus or of the intercostal nerves (medial brachial and antebrachial cutaneous n.)
sensory inn. of axillary n.
skin over deltoid m.
sensory inn. of radial n.
skin over triceps brachii m.
sensory inn. of musculocutaneous n.
skin over the lateral surface of the FOREARM (not skin over biceps)
sensory inn. of cutaneous branches of brachial plexus or of intercostal n. (medial brachial cutaneous n. and antebrachial cutaneous n.)
skin over the biceps
shape of the cubital fossa and borders
triangle pointing downwards
- lat border = brachioradialis m.
- medial border = pronator teres m.
- superior border = imaginary line between epicondyles of the humerus
most superficial structure in the cubital fossa
median cubital vein
3 structures deep to median cubital vein in the cubital fossa
lateral to medial:
- biceps tendon (lat)
- brachial artery
- median nerve (most medial)
2 places to feel brachial pulse
- medial surface of biceps (find the brachial a. under the biceps brachii m.)
- in the cubital fossa (+ also where you hear if taking manual BP)
body landmarks on the surface of the elbow
- lateral and medial epicondyles of the humerus
- olecranon of the ulna
what is the funny bone
medial epicondyle of the humerus
ulna and radius relation to each other
- parallel in supination
- opposite shapes. as you go distally, radius becomes wider but ulna becomes narrower
- interosseus membrane between the two bones
what’s the interosseus membrane between the forearm bones
CT fibers oriented medially and in a proximal-distal direction
how the arm absorbs a shock
- hand receives force
- force transmitted from hand to RADIUS (wide distally)
- radius transfers force to ulna via interosseus membrane
- ulna (wider proximally) transfers force to humerus
name given to absorption of shock by the arm + most fragile point in the system
- circumvoluted dissipation of force
- wrist to radius transmission is most fragile
how humerus, radius and ulna articulate
humerus has 2 surfaces
- capitulum (lat) for radius
- trochlea for ulna (medial)
type of joint the elbow joint is
synovial joint (fluid in it): for more movement and less friction
structures supporting the elbow joint
- capsule (around the joint)
- radial collateral ligament (lat epicondyle of humerus to radius)
- ulnar collateral ligament (medial epicondyle of humerus to ulna)
- annulus ligament (circle around the 3 bones at their articulation + gives a hole for the radius to fit in)
2 important structures (supporting structures) in pronation and supination
- annular ligament allows radius ROTATION ON THE SURFACE OF THE HUMERUS (capitulum) in pronation-supination
- interosseus membrane prevents radius dislocation during pronation-supination
ulna movement in pronation-supination
doesn’t move at all. well articulated with humerus
why the ulna doesn’t move in pronation-supination, is well articulated with the humerus and can only do flexion-extension
the ulna wraps around the humerus (and not the opposite).
- interior part wrapping around = coronoid process of the ulna
- exterior part wrapping around = olecranon of the ulna
what’s a pulled elbow
- a dislocation of the radius from the annular ligament
- dislocation of arm downwards
- can happen in children held in the air by their hands (more likely in children bc their annular ligament is loose)
clinical case: 1. rupture of biceps tendon on right side (right upper extremity)
- no fractures or dislocation
- swelling and pain
- numbness on lateral surface of right forearm
- diminished radial pulse on the right upper extremity
- weakness on elbow flexion
* *Q: how do you account for the symptoms**: compt syndrome affecting median or ulnar or radial or musculocutaneous n. ?
compartment syndrome affecting the musculocutaneous nerve
