Dr. J Anatomy - Lecture Quiz 11 (Brachial Plexus/Terminal Branches)

ape hand

Syndrome that is brought about by damage to the median nerve. This results in the loss of ability to oppose the thumb.

surface of index finger, middle finger and half of ring finger

The *median nerve* receives sensory input from the anterolateral cutaneous area of the hand, the lateral half of the ring finger and the middle and index fingers.

surface of little finger and half of the ring ringer

The *ulnar nerve* receives sensory input from the posterior and anterior medial cutaneous area of the hand, the little finger and the medial half of the ring finger.

suprascapular notch

This is an imp. landmark of the scapula b/c it is through this that the suprascapular artery and the suprascapular nerve pass. This nerve goes on to control the supraspinatus and infraspinatus muscles. The suprascapular artery is a branch of the transverse scapular artery.

extensor carpi radialis brevis muscle

This is in the posterior compartment of the forearm. It is served by the radial nerve and is an extensor and abductor of the wrist. It is found on the lateral side of the forearm, and its origin can be found on the lateral epicondyle of the humerus at the common extensor tendon.

cervical ramus 6

This is the 2nd from the most superior ramus that forms the brachial plexus. There is one on each side of the body. Gives rise to the musculocutaneous nerve, axillary nerve, median nerve, and radial nerve.

cervical ramus 7

This is the 3rd from the most superior ramus that forms the brachial plexus. There is one on each side of the body. Gives rise to the musculocutaneous nerve, median nerve, and radial nerve.

cervical ramus 8

This is the 4th from the most superior ramus that forms the brachial plexus. There is one one each side of the body. Gives rise to the median nerve, radial nerve and ulnar nerve.

belly of the biceps brachii

This is the area that the cranial humeral circumflex artery normally connects to. It is also the area where we find the musculocutaneous nerve running along.

posterior compartment of forearm

This is the distal extensor compartment of the pectoral appendage. It is served by the radial nerve. ("Big Larry Bird Lacks Undies"- brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum communis, extensor digitorum lateralis, extensor carpi ulnaris) Human: brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum communis, extensor carpi ulnaris, supinator "Big Larry Bird Coach Understands Sports"

thoracic ramus 1

This is the inferior most of the anterior rami that make up the brachial plexus. Serves median nerve, radial nerve and ulnar nerve, like C8.

cervical ramus 5

This is the most superior ramus that forms the brachial plexus. There is one on each side of the body. Gives rise to the musculocutaneous nerve, axillary nerve, and radial nerve.

lateral cutaneous nerve of forearm

This is the name of the branch of the musculocutaneous nerve that serves the skin in the forearm. It is the only nerve derived from the musculocutaneous nerve that goes into the forearm.

latero-posterior surface of the hand

This is the posterior surface of the hand served by the radial nerve. The first two and 1/2 of the 3rd digit are served by the median nerve.

lateral surface of palm

This is the surface of the hand, not including the digits, where the skin is served by the median nerve.

supracondyloid foramen (cat)

This landmark is found on the humerus of the cat but only occasionally (~1% of the population) on the humerus of a human. The brachial a. and median n. of the cat pass through this structure and are, therefore, somewhat protected by this arch of bone.

biceps brachii muscle

This muscle *originates on the supraglenoid tubercle and coracoid process of scapula* and *inserts in the radial tuberosity and bicipital aponeurosis of the forearm*. It is capable of causing *flexion of the forearm (elbow) and supination of the forearm and hand*. It is located in the anterior compartment of the arm and is served by the *musculocutaneous nerve*.

flexor carpi radialis muscle

This muscle flexes and abducts the wrist. It is served by the median nerve. It has an origin on the medial epicondyle of the humerus at common flexor tendon.

infraspinatus muscle (rotator cuff)

This muscle has its origin on the infraspinous fossa of scapula and insertion on the greater tubercle of humerus. Its action is lateral (external) rotation and horizontal abduction of the arm. It is served by the suprascapular nerve, and is one of the rotator cuff muscles. This muscle has the same action as the teres minor muscle.

supraspinatus muscle (rotator cuff)

This muscle is a rotator cuff muscle. It is the only rotator cuff muscle that is an abductor of the arm. It is served by the suprascapular nerve. It has an origin on the supraspinous fossa of the scapula and inserts on the greater tubercle of the humerus.

extensor carpi radialis longus muscle

This muscle is found in the posterior compartment of the forearm. It is one of two muscles that we studied that extends and abducts the hand or wrist. It is served by the radial nerve and originates from the lateral epicondyle of the humerus.

flexor carpi ulnaris muscle

This muscle is in the anterior compartment of the forearm. It is unusual in that it is served by the ulnar nerve. It is a flexor and adductor of the wrist. Origin: medial epicondyle of the humerus at the common flexor tendon

extensor digitorum communis muscle

This muscle is in the posterior compartment of the forearm. It is served by the radial nerve and is an extensor of the digits 2-5 and the wrist. It originates on the lateral epicondyle of the humerus at the common extensor tendon.

radial nerve

"Biggest hugest nervous of the armus." This nerve is a branch of the posterior cord containing neurons from the anterior rami of C5, C6, C7, C8 and T1. It serves the posterior compartment of the arm and forearm as well as the brachioradialis muscle. It controls all the extensor muscles found in the arm and forearm and the supinator muscle. It also receives sensory input from the posterolateral cutaneous area of the hand. When damaged it results in the clinical condition called wrist drop. input from the posterolateral cutaneous area of the hand.

dorsal scapular nerve

Although we did not see this in the lab, it is important b/c it serves the rhomboid muscles and the levator scapulae ventralis muscle.

anterior compartment of the arm

Mostly flexor muscles are located in this compartment of the pectoral appendage. A significant number of the muscles in this compartment are controlled by the musculocutaneous nerve. (coracobrachialis, brachialis, biceps brachii)

extensor digitorum lateralis muscle (cat)

Origin: lateral supracondyloid ridge of humerus distal to the origin of the extensor digitorum communis. Insertion: the three tendons on the ulnar side join the tendons of the extensor digitorum communis at their insertions. Nerve: radial. Action: extensor of the digits

axillary artery

The axillary artery begins where the subclavian artery terminates and ends where the brachial artery begins. It has three branches: ventral thoracic a., lateral (long) thoracic a., and the subscapular a. The beginning of the subscapular artery is often used to delineate the end of this artery.

brachial artery

The brachial artery begins at the distal end of the axillary artery where the subscapular artery branches from the axillary artery. The brachial artery *ends near the neck of the radius where it branches into the ulnar and radial arteries*. It *provides the main arterial blood supply to the arm*, and has 2 branches: the cranial humeral circumflex artery, and the deep brachial artery. It runs with the median nerve in the arm, and in the cat both these structures run through the supracondyloid foramen of the humerus. Approx. 1% of humans have a vestige of the supracondyloid foramen. It normally passes deep to the bicipital aponeurosis in the cubital fossa (so it is not a risk when blood is drawn there). *A brachial pulse can be taken where the brachial artery passes through the medial bicipital groove*.

branches

The cords of the brachial plexus give rise to 5 of these (musculocutaneous n., axillary n., median n., radial n., and ulnar n.) Four of them go into the arm and one goes out into the shoulder.

half of flexor digitorum profundus muscle

The flexor digitorum profundus muscle is also called the 1/2, 1/2 muscle. Half of it is served by the ulnar nerve and the other half is served by the median nerve. This muscle is a flexor of the digits 2-5, and wrist (hand).

ulnar nerve

The medial cord gives rise to the ulnar nerve in the axilla. It contains nerves from the anterior rami of C8 and T1 that come directly from the anterior divisions of the brachial plexus, as well as the anterior ramus of C7 from communication with the median nerve. We find it first running by itself on the medial surface of the arm. It the forearm it joins the ulnar artery and runs along the ulna bone. It passes into the hand on the anteromedial portion of the wrist just deep to the skin and superficial to the flexor retinaculum. B/c of that, it is often damages when the wrist is cut. Although this nerve does not innervate any muscles in the arm, it innervates 1.5 muscles in the forearm (flexor carpi ulnaris and half of flexor digitorum profundus) and 15 out of 20 muscles of the hand (except those controlling the thumb). It also receives sensory input from the posterior and anteromedial cutaneous area of the hand, the little finger (5th digit), and the medial half of the ring finger (digit 4). Damage to this nerve results in the clinical condition called "claw hand."

divisions

The three trunks of the brachial plexus give rise to these. There is an anterior and posterior structure from each trunk that are collectively called this. They are deep to the clavicle.

posterior divisions

The trunks of the brachial plexus give rise to these as well as a similar set of structures that pass anteriorly.

anterior divisions

The trunks of the brachial plexus give rise to these as well as a similar set of the structures that pass posteriorly. (musculocutaneous, median, ulnar nerves)

trunks

There are three of these and they are formed by the anterior rami of cervical spinal nerves 5,6,7,8 and T1. Each of them gives rise to an anterior and a posterior division.

cords

There are three of these structures (lateral, medial and posterior cord), and two are formed by the merging of the anterior and posterior divisions. One is formed by a single anterior division. They are named for their positions relative to the middle third of the axillary artery.

15 intrinsic muscles in the hand exept those that control the thumb

These 15 muscles are controlled by the ulnar nerve. Damage to ulnar nerve can cause claw hand.

5 muscles in the hand controlling the thumb

These 5 muscles are controlled by the median nerve. Damage to the median nerve can cause ape hand.

radial artery

This artery is a branch of the brachial artery. Its origin is in the forearm, and it runs with the median nerve on the lateral side of the forearm. It is usually found deep and medial to flexor carpi radials. (Group: radius bone, radial artery, median nerve).

ulnar artery

This artery is a branch of the brachial artery. Its origin is in the forearm, and it runs with the ulnar nerve on the medial side of the forearm. It is usually found deep and lateral to the flexor carpi ulnaris muscle. (Group: ulna bone, ulnar artery, ulnar nerve).

lateral (long) thoracic artery

This artery is a branch of the middle third of the axillary artery. (It gets its name from the fact that is passes to the lateral thoracic wall.) In humans, it serves the anterior and medial walls of the axilla. In women, it also has branches that serve the mammary gland.

caudal humeral circumflex artery

This artery is a branch of the subscapular artery. (It gets its name from the fact that it passes around the caudal side of the humerus.) It forms collateral circulation with the cranial humeral circumflex artery in the lateral region of the arm. In the cat, it serves the lateral/long heads of the triceps brachii, the acromiodeltoid, and the spinodeltoid. *In humans, it serves the deltoid muscle and the shoulder joint*.

thoracodorsal artery

This artery is a branch of the subscapular artery. It serves the latissimus dorsi muscle and can be observed on the deep side of that muscle at its humeral end where it runs w/ the thoracodorsal nerve. In the cat, it serves the teres major, the epitrochlearis and the latissimus dorsi. In humans, it serves the medial and posterior walls of the axilla.

transverse scapular artery

This artery is a branch of the thyrocervical artery. On the deep side of the scapula it runs w/ the suprascapular nerve and it then gives rise to the suprascapular artery. There is no comparable artery in humans.

deep brachial artery

This artery is a small branch (or more often two or three small branches) of the brachial artery. It runs deep into the arm with the radial nerve. In humans, it serves the posterior compartment of the arm and forms anastomoses with the posterior humeral circumflex artery. In the cat it serves the triceps brachii, epitrochlearis, and latissimus dorsi.

vental thoracic artery

This artery is the first lateral branch of the axillary artery. It serves the medial ends of the latissimus dorsi and the pectoralis muscles. It runs with the cranial ventral thoracic nerve. In humans, this vessel is called the superior thoracic artery, and it originates from the anterior surface of the proximal third of the axillary artery. It serves the anterior and medical walls of the axilla.

subscapular artery

This artery is the largest lateral branch of the axillary artery. It marks the end of the axillary artery and the beginning of the brachial artery. It arises from the distal third of the axillary on the posterior surface. In the cat it has two branches: the caudal humeral circumflex artery and the thoracodorsal artery. It continues between the subscapularis and teres major, and it sends branches to the *subscapularis, long head of the triceps brachii, and latissimus dorsi*. It then continues over the surface of the infraspinatus muscle and serves the *infraspinatus, supraspinatus, acromiotrapezius, and spinotrapezius*. Occasionally it gives rise to the cranial humeral circumflex artery, although that vessel is more often a branch of the brachial artery. *In humans this artery serves the posterior wall of the axilla and the posterior scapular region* and has just the two terminal branches: the thoracodorsal artery and the circumflex scapular artery.

cranial humeral circumflex artery

This artery is usually a branch of the brachial artery, although it has been seen branching from the subscapular artery, the caudal humeral circumflex artery, and the thoracodorsal artery. One can distinguish this artery by where it goes-the belly of the biceps brachii muscle, rather than from where it originates. It gets its name from the fact that it passes around the cranial side of the humerus. It forms collateral circulation with the caudal humeral circumflex artery in the lateral region of the arm. In the cat, it serves the biceps brachii as well as the head of the humerus. In humans, it branches from the lateral side of the distal third of the axillary artery and serves the head of the humerus and the glenohumeral (shoulder) joint.

posterior compartment of the arm

This compartment of the pectoral appendage is completely served the the radial nerve and has extensors in it. Since there are two such compartments, you also need to know that it is the proximal of the two compartments. (triceps brachii muscle - extensor of the elbow (forearm))

anterior compartment of forearm

This compartment of the pectoral appendage is primarily controlled by the median nerve, except for 1.5 muscles. It primarily has flexor muscles in it. ("Pete Rose Swings UP"- CAT: Pronator teres, flexor carpi radialis, flexor digitorum superficialis, flexor carpi ulnaris) (Human: Pronator teres, flexor carpi radialis, flexor digitorum superficialis, flexor carpi ulnaris, flexor digitorum profundus, pronator quadratus, Palmaris longus)

rhomboideus muscles

This is a group of two muscles, both which are served by the dorsal scapular nerve. They both retract, elevate, and rotate the scapula. They both insert on the medial border of the scapula and collectively originate from the spinous processes of C7 - T5.

claw hand

This is a syndrome that is brought about by damage to the ulnar nerve. The primary symptom is *partial finger flexion of the involved hand, w/ the most flexion occurring on the medial side of the hand*.

teres minor muscle

This muscle is one of the rotator cuff muscles. It is the only one that is served by the axillary nerve. If the axillary nerve is damaged and this muscle is no longer active, the individual will exhibit the condition known as head waiter's syndrome w/ medial rotation of the arm. It is a *lateral rotator of the arm*. It originates on the *lateral (axillary) border of the scapula (superior 2/3) and inserts on the greater tubercle of the humerus. same action as infraspinatus.

subscapularis muscle

This muscle is one of the rotator cuff muscles. It is the only rotator cuff muscle that is a medial rotator of the arm. It has an origin on the subscapular fossa and inserts on the lesser tubercle of the humerus. It is served by the upper and lower subscapular nerves (C5 and C6).

flexor digitorum superficialis muscle

This muscle is served by the median nerve. It flexes the wrist (hand) and digits 2-5. It is deep to the palmaris longus in humans. In the cat it is superficial to the other flexor of the digits. Origin: medial epicondyle of humerus at the common flexor tendon, coronoid process of ulna, shaft of radius.

triceps brachii muscle

This muscle is served by the radial nerve and is found in the posterior compartment of the arm. The anconeus muscle is a synergist to this muscle. It has 3 heads and crosses 2 joints, the shoulder and the elbow. ORIGIN: infraglenoid tubercle and shaft of the humerus. INSERTION: Ulna ACTION: Extends the forearm: long head extends and adducts arm (humerus)

brachioradialis muscle

This muscle is the only flexor we study that is served by the radial nerve. It is a flexor of the forearm. This muscle, although a flexor, can be seen most easily on the extensor side of the forearm. Origin: supracondylar ridge of humerus. Insertion: radius. Nerve: radial. Action: flexes forearm (stabilizes forearm for small, quick movements - "hammering muscle"). This is 1 of 5 muscles that move the forearm.

serratus anterior muscle

This muscle looks like fingers b/c it attaches to the ribs, but has nothing to attach to between the ribs. It is one of the muscles that stabilizes the scapula, and is served by the long thoracic nerve. It originates on ribs 1-9 and can Protract (ABduct) and rotate the scapula.

deltoid muscle

This muscle moves the arm. It is the *prime flexor, abductor, extensor, medial, and lateral rotator of the arm.* It is served by the axillary nerve. It is 1 of the 5 muscles that move the arm (pectoralis major, latissimus dorsi, teres major, coracobrachialis). ORIGIN: lateral 1/3 of clavicle, acromion, and spine of the scapula INSERTION: humerus

extensor carpi ulnaris muscle

This muscle of the posterior compartment of the forearm extends and adducts the wrist (hand). It is served by the radial nerve. It has its origin on the lateral epicondyle of the humerus at the common extensor tendon.

coracobrachialis muscle

This muscle originates from the coracoid process of the scapula and inserts on the middle third of the humerus near the deltoid tuberosity. It is served by the musculocutaneous nerve, and is responsible for flexion and adduction of the arm. It also helps stabilize the shoulder joint. This is 1 of 5 muscles that move the arm.

latissimus dorsi muscle

This muscle originates from the lumbar fascia, portions of the sacrum, iliac crest, ribs, and inferior angle of the scapula, and inserts on the humerus. It extends, hyperextends, medially rotates, and adducts the arm. It is served by the thoracodorsal nerve.

levator scapulae ventralis muscle

This muscle originates from the transverse processes of C1-C4. It inserts on the vertebral border of the scapula between the superior angle and the spine of the scapula. It is served by a branch of the dorsal scapular nerve as well as lateral branches of cervical spinal nerves 3 and 4. It elevates and rotates the scapula or flexes the neck laterally. We saw it in two places in the cat.

brachialis muscle

This muscle originates on the humerus and inserts on the ulna. It is located in the anterior compartment of the arm and is served by the musculocutaneous nerve. Its only action is flexion of the forearm. This is 1 of 5 muscles that move the forearm.

pronator quadratus muscle (humans)

This muscle pronates the forearm and hand and is found at the distal end of the forearm. It is served by the median nerve. We did not see this muscle in the lab. ORIGIN: distal 1/4 of the ulna INSERTION: distal 1/4 of the radius

supinator muscle

This muscle supinates the forearm and hand but does not flex the forearm. It is served by the radial nerve. ORIGIN: lateral epicondyle of the humerus and postero-lateral proximal ulna. INSERTION: anterior proximal radius.

palmaris longus muscle

This muscles is not found in cats. It is located in the anterior compartment of the forearm and is served by the median nerve. Its only action is flexion of the hand. Its tendon is the only tendon that passes into the hand that is superficial to the flexor retinaculum. 10% of the human population does not have this muscle. ORIGIN: medial epicondyle of humerus at the common flexor tendon INSERTION: palmar aponeurosis of hand.

pronator teres muscle

This muscles pronates the hand and assists elbow flexion. It is served by the median nerve. It originates from the medial epicondyle of the humerus and from the medial surface of the coroniod process of the ulna. It inserts in the lateral surface of the middle third of the radius.

axillary nerve

This nerve is a branch of the posterior cord of the brachial plexus, containing neurons from anterior rami of C5 and C6. It can be seen in the axilla adjacent to the caudal humeral circumflex artery. It runs between the subscapularis and teres major muscles. It reappears on the lateral surface of the arm where it serves the deltoids (deltoid muscle in humans) and the teres minor. It also has cutaneous branches to the shoulder joint and the skin that covers the distal half of the deltoid muscle in humans. Damage to this nerve causes a syndrome called Head Waiter's syndrome, where the sufferer displays medial rotation of the arm.

musculocutaneous nerve

This nerve is formed from the lateral cord. It contains nerves from the anterior rami of C5, C6 and C7. It serves the anterior compartment of the arm. It also receives sensory input from the lateral cutaneous area of the forearm.

median nerve

This nerve runs with the brachial artery in the arm. It passes through the supracondyloid foramen of the cat with the brachial artery, and then in the forearm it runs with the radial artery. It also passes through the carpal tunnel into the hand. This nerve is formed from branches of the medial and lateral cords. It contains neurons from the anterior rami of C6, C7, C8 and T1 that come directly from the anterior divisions of the brachial plexus, as well as the anterior rams of C5 from communication with the musculocutaneous nerve. It serves the anterior compartment of the forearm by controlling the 2 pronator muscles and all the flexor muscles except 1.5. It also controls most of the muscles of the thumb. It also receives sensory input from the anterolateral cutaneous area of the hand, the lateral half of the ring finger, and the middle and index fingers. B/c it runs deep to the flexor retinaculum, inflammation deep to the flexor retinaculum results in carpal tunnel syndrome. When damaged, it results in the clinical condition called "ape hand."

suprascapular nerve

This nerve serves the supraspinatus and infraspinatus muscles and the shoulder joint. There are both rotator cuff muscles. The origin of this nerve is the upper trunk of the brachial plexus (incl. the anterior rami form C5, C6). It runs through the suprascapular notch w/ the suprascapular artery.

upper trunk

This part of the brachial plexus is formed by the union of the anterior rami of C5 and C6. It has an anterior and posterior division.

anconeus muscle

This small muscle in the posterior compartment of the arm is a synergist to the triceps brachii. It is served by the radial nerve. ORIGIN: lateral epicondyle of humerus. INSERTION: ulna. NERVE: radial ACTION: extends forearm

medial cord

This structure is formed from the anterior division of the lower trunk of the brachial plexus. It contains neurons from the anterior rami of C8 and T1. It gives rise to the ulnar nerve as well as to part of the median nerve. It gets is name from its position relative to the middle 3rd of the axillary artery. It forms the top, left side of the "M" as you look at it in the left axilla.

lateral cord

This structure is formed from the anterior divisions of the upper and middle trunks of the brachial plexus. It contains neurons from the anterior rami of C5, C6 and C7. It gives rise to the musculocutaneous nerve, as well as to part of the median nerve. It gets its name from its position relative to the middle 3rd of the axillary artery. It forms the top, right side of the "M" as you look at it in the left axilla of the cat.

middle trunk

This structure is formed from the anterior ramus of C7. It has an anterior and posterior division.

posterior cord

This structure is formed from the posterior divisions of the upper, middle and lower trunks of the brachial plexus. It contains neurons from the anterior rami of C5, C6, C7, C8 and T1. It gives rise to the radial and axillary nerves. It gets its name from its position relative to the middle 3rd of the axillary artery. This nerve is deep in the axillary sheath and is difficult to expose w/o doing massive amounts of cat terrorism.

lower trunk

This structure is formed from the union of anterior rami of cervical spinal nerve 8 and thoracic spinal nerve 1. It has an anterior and posterior division.

medial cutaneous area of the hand

This surface of the hand is served by the ulnar nerve, both anteriorly and posteriorly. (the little finger and the medial half of the ring finger)

Head Waiter's Syndrome

This syndrome is brought about by damage to the axillary nerve. If the damage results in loss of the use of the teres minor, the arm will rotate medially so that the palm faces posteriorly.

drop wrist syndrome

This syndrome is brought about by damage to the radial nerve. This results in the loss of ability to extend the hand and fingers.

cephalic vein

This vein is observed on the superficial, lateral side of the forearm and arm. Inferior to the clavicle, it passes into the axilla where it joins the axillary vein. The axillary vein passes through the thoracic wall to become the subclavian vein. In the forearm, the cephalic vein runs with the superficial branch of the radial nerve on the surface of the brachioradialis muscle.

suprascapular artery

This vessel is a branch of the transverse scapular artery. It passes through the suprascapular notch w/ the suprascapular nerve, and it sends branches to the supraspinatus and infraspinatus muscles. In humans it is a branch of the thyrocervical trunk or it may be a branch of the subclavian artery. It passes superior to the suprascapular notch but then runs w/ the suprascapular nerve. It serves the infraspinatus, supraspinatus, and many other structures as it moves toward those muscles.

rami

When the spinal nerves leave the intervertebral foramina they divide into anterior and posterior structures. This is the name of these structures. The anterior structures from C5 to T1 form the beginning of the brachial plexus. They combine in predictable patterns to form the trunks. All plexuses are composed by what?