Human Anatomy - Arm

Median nerve innervates _____

elbow joint -no branches in the arm

Triceps brachii origin

infraglenoid tubercle

The contents

terminal part of the brachial artery and its branches, radial and ulnar arteries. Accompanying deep veins. Biceps brachii tendon. Median nerve. Radial nerve branches

To test triceps brachii

the arm needs to be abducted 90 first, then extend elbow joint against resistance

Brachial Artery Insertion

the cubital fossa undercover the bicipital aponeurosis -divides into radial and ulnar arteries

Biceps brachii function

-flexes the arm and forearm -supinate the forearm when elbow is flexed at 90 degrees (e.g., drive a screw)

Brachialis

-lies deep to the biceps, the major elbow flexors -from distal half of humorous to the coroniod process and tuberosity of ulna

Muscles of the arm are divided into ________

2 compartments: -anterior -posterior (the arm is the shoulder to the elbow) (connective tissue fascia wrap around muscles and continue with the connective tissue wrapping around the bones (pariostium) and keep the muscle together - but separate the muscles into different compartments)

Musculocutaneous nerve injury

Cause: -weapons Appearance: -paralysis of coracobrachialis, biceps, and brachialis. Weakened forearm flexion and supination. Loss of sensation on the lateral surface of the forearm

Musculocutaneous nerve

Comes from: -the lateral cord of the brachial plexus. Begins at : the inferior border of the pectoralis minor, pierces the coracobrachialis, runs in between the biceps and the brachialis, innervates all three anterior flexors of the arm, ends as the lateral cutaneous nerve of the forearm that supplies a large area of the forearm

Median nerve runs ______

Runs together with but lateral to the brachial artery until the middle of the arm. Crosses to the medial side of brachial artery and descends to the cubital fossa, where it runs under the bicipital aponeurosis

Biceps brachii - proximal attachments: Long head

The long head runs into the glenoid joint, over the head of the humerus, inside the intertubercular groove where it is fixed in place by the transverse humeral ligament and surrounded by synovial membrane, attaches to the supraglenoid tubercle.

-Compressing the brachial artery

To stop bleeding, the best place is near the middle of the arm before the deep artery of the arm branches out, compress against the humerus. After the deep artery of the arm, the anastomoses allow collateral circulation.

Posterior Compartment

Two muscles (triceps brachii and anconeus), functions as extensors of shoulder and elbow joint. All innervated by radial nerve

bicipital aponeurosis

a membranous band that runs from the biceps tendon across the cubital fossa and merges with the ante brachial (deep) fascia on the top of the flexor muscles in the medial side of the forearm

Deep veins

runs along with the arteries. They anastomose with each other freely and they all have valves that allow one direction blood flow

Laterally

the brachioradialis

Rupture of the tendon of the long head of the biceps: Cause

wear and tear of an inflamed tendon (older aged athletes), forceful flexion of the arm (weight lifting).

The "Crazy Bone"

when ulnar nerve runs posterior to the epicondyle, it is superficial, easily palpable, and vulnerable to injury

Biceps tendinitis testing and diagnosis

wrestling for pain

Fracture - dislocation of the proximal humeral epiphysis

Happens to children or adolescents when the arm or shoulder is directly hit by a blow (causing axillary nerve injury)

Triceps brachii function

In addition to extend the forearm, its long head also functions to stabilize the adducted glenohumeral joint by preventing inferior displacement of the head of the humerus. Triceps also help in extension and adduction of the arm (push on a chair to try to stand up)

-Occlusion or laceration of the brachial artery

Ischemia will result, involves forearm flexor muscles. (ischemia: shortage of blood (oxygen and nutrients) to keep tissue alive)

Triceps brachii attachment

Its distal attachment passes over the subtendinous olecranon bursa, which reduces the friction between the tendon and olecranon.

Cephalic vein

Located along the anterolateral surface of the proximal forearm and arm, visible through the skin, pass superiorly between the deltoid and pectoralis major in the deltopectoral groove, also pass through the deltopectoral triangle where it empties into the axillary vein.

Branches of the brachial artery

Multiple unnamed muscular and humeral nutrient branches, arise from the lateral side. Four named branches all arise from the medial side. -deep artery of the arm (profunda brachii) (superior ulnar collateral artery, inferior ulnar collateral artery) - comes off the ulnar artery

The two muscle compartments are separated by _____

dense connective tissue -lateral intermuscular septum -medial intermuscular septum (Muscle atrophy or swelling of muscle and have nowhere to go because of compartment - tremendous amount of pressure - presses on muscle cells = muscle death if you don't relieve the pressure (earthquakes - people compressed between concrete) - treatment is simple - just cut it open)

Ulnar nerve innervates _____

elbow joint -no branches to the arm

Superficial veins

runs in the subcutaneous tissue -cephalic vein -basilica vein -median cubital vein

At the beginning the brachial artery _____

runs medial to the humerus, anterior to the triceps and brachialis, then turn anterior to the humerus

Bicipital myotatic reflex tests for ____

deep tendon reflex

Rupture of the tendon of the long head of the biceps: Appearance

"Popeye deformity" - The detached muscle belly forms a ball near the center of the distal part of the anterior aspect of the arm.

Radial nerve injury: after the branches to the triceps

(in the radial groove) - same symptoms as above except the triceps may not be completely paralyzed

Veins of the Arm: 2 groups

-superficial veins -deep veins

Cubital Fossa

A hollow area on the anterior aspect of the elbow. The boundaries are: -superiorly -medially -laterally -the floor -the roof -the contents (always go superficial to draw blood cause you don't want to go too deep into an artery)

Coracobrachialis

A landmark for the musculocutaneous nerve (which pierces through this muscle) and the nutrient foramen of the humerus (at its distal end).

Deep artery of the arm (profunda brachii)

Branch out most superiorly, the largest branch, accompanies the radial nerve through the radial groove and divides into anterior and posterior descending branches (may give out branches of radial collateral and medial collateral)

-Measuring blood pressure

In the brachial artery

-Palpation of the brachial artery

Maybe difficult, has to push the biceps laterally

Basilica vein

Pass on the medial side of the inferior part of the arm, penetrate the brachial fascia at the junction of the middle and the lower third of the arm, merge with veins accompanying the brachial artery to form the axillary vein.

Median cubital vein

The two veins forms anastomoses in the forearm and communicate in the cubital fossa

Nerves of the Arm

There are four (4) major nerves pass through the arm. Two of them have branches (musculocutaneous and radial) in this section and two of them (median and ulnar) have no branches in the arm

Anterior Compartment

Three muscles (biceps brachii, brachialis, and coracobrachialis), all function as flexors of shoulder and elbow joint. Innervated by musculocutaneous nerve

Radial nerve descends with the _____ and passes _____

deep artery of the arm around the humerus in the radial groove

Superiorly

an imaginary line connecting the medial and lateral epicondyles.

Radial nerve enters the arm ______

anterior to the long head of the triceps, posterior to the brachial artery, medial to the humerus.

Ulnar nerve passes ______

anterior to the triceps, on the medial side of the brachial artery. -In the middle of the arm, it pierces the medial intermuscular septum with the superior ulnar collateral artery and descends between the septum and the medial head of the triceps. -At distal arm, it passes posterior to the medial epicondyle and medial to the olecranon to enter the forearm

Triceps and Anconeus Function (don't need to know much)

arm extensors are particularly needed when one wants to standup from an armchair or a wheel chair

Ex:

arm wrestling uses the biceps a lot

Biceps brachii - proximal attachments: Short head

attaches to coracoid process of the scapula (2 heads proximally and 2 heads distally Short head on medial side origin: coracoid process of the scapula Long head on lateral side - inserts on supraglenoid tubercle)

the distal end continues as the _____

bicipital aponeurosis

Venipuncture

common location of blood sampling, infusion, intravenous, injection, and catheterization

The brachial artery is a _____

continuation of the axillary artery once it passes the teres major

Coracobrachilais origin

coracoid process of scapula

Superficial branch

cutaneous, supplies the skin of the dorsum of the hand and digits

Coracobrachialis function

flexes and adducts the arm

The floor

formed by brachialis and supinator muscles of the forearm

The roof

formed by deep fascia and the bicipital aponeurosis

Coracobrachialis stabilizes the ______

glenohumeral joint by resisting the downward dislocation of the head of humerus. This task is accomplished in cooperation with the deltoid and the long head of the triceps

Biceps tendinitis

happens to the tendon of the long head of the biceps which is enclosed by a synovial sheath and lies in the inter tubercular groove

If a baseball bat swung and hit the humerus right in the middle you would have a _____

humeral fracture and damage to the radial nerve (wrist-drop sign)

At the level of the ________, the radial nerve divides into ______

lateral epicondyle of the humerus two branches

At the distal portion of the arm, the radial nerve pierces the ______

lateral intermuscular septum, runs in the anterior compartment of the arm between the brachialis and the brachioradialis, and reaches the lateral epicondyle of the humerus

Ulnar nerve comes from the ______

medial cord of the brachial plexus

superior vena cava to the subclavian artery to the axillary artery to brachial artery - which branches - ulnar artery and radial artery

medial cutaneous vein branches in the cubital fossa to the basilic vein on the medial side and the cephalic vein on the lateral side

Where do doctors usually take blood from

median cubital vein

The ______ and the _______ run deep to the coracobrachialis

median nerve humeral artery

The brachial artery runs with the _____

median nerve in the arm

Coracobrachialis insertion

mid 1/3 of humerus

Cuntaneous innervation of the _____

nerve

Triceps brachii insertion

olecranon of ulna

The brachial artery is ______

palpatable throughout its course

Radial nerve injury: before the branches to the triceps

paralysis of the triceps, brachioradialis, supinator and extensor muscles of the wrist and digits. Loss of sensation in the dorsum hand and digits

Radial nerve is a direct continuation of the ______

posterior cord of the brachial plexus

Biceps tendinitis is caused by ____

repetitive micro trauma from certain motions such as throwing or using a racquet

Deep branch

supplies forearm muscles and the elbow joint

Biceps tendinitis symptoms are _____

tenderness and crackling sound (crepitus) in the region

Dislocation of the tendon of the long head of the biceps may be caused by _____

tendinitis and a traumatic separation of the proximal epiphysis of the humorous -a popping or catching sensation can be felt (Ligament broken and tendon (head of biceps) jumps out of the intertubercle groove Forced movement of the biceps)

Brachial Artery Origin

the inferior border of the teres major

Medially

the pronator teres

bicipital aponeurosis function

to protect the brachial artery and the median nerve in the cubital fossa -it also helps lesson the pressure on the biceps tendon on the radial tuberosity during pronation and supination of the forearm (Flexor for two joints; shoulder and elbow Biceps are a supinator only when elbow bent at 90 degrees Biceps muscle contracted you will pull in (this direction) to supinate)

Radial nerve innervates the _____

triceps (entire arm and forearm extensors)

Biceps brachii - distal end: attaches to the ____

tuberosity of the radius (because it has two origins it is more powerful)

Wrist-drop sign

typical radial nerve injury, unable to extend at the metacarpophalangeal joints

Swing a bat and hit the back of the medial epicondyle of the humerus you would damage the ______

ulnar nerve

Median nerve comes from the ______

union of a lateral cord and a medial cord of the brachial plexus