Lecture 2: Upper Limb

The upper limb is specialized for mobility and fine motor manipulations. What are the 4 segments of the upper limb?

1. Shoulder (girdle) = scapula and clavicle with associated muscles

2. Arm - longest segment, formed by humerus

3. Forearm - connects elbow to wrist, form around radius and ulna

4. Hand = carpals, metacarpals, and phalanges; Consist of sensory nerve endings for touch, pain, and temp

Describe the clavicle with its function as well.

• Clavicle has an acromial end (flat, forms joint with scapula)

• Sternal end - forms sternoclavicular joint with manubrium

• Functions:

  • Support scapula and upper extremity from axial skeleton

  • Protects large nerve trucks (brachial plexus) and vessels passing from neck to upper extremity

Where is the clavicle frequently broken?

• the middle and lateral 1/3 area where the bone “changes direction”; subclavian groove

Describe the following parts of the shoulder osteology

1. Acromion

2. Coracoid process

3. Spine of Scapula

4. Suprascapular notch

1. Acromion - highest point of the shoulder and forms the acromioclavicular joint with the clavicle.

2. Coracoid process (Kaw!) - attachment site for coracoclavicular ligament that suspends the upper limb from the clavicle

3. Spine of scapula separates posterior side into supraspinous and infraspinous fossas

4. Suprascapular notch - a grove on the scapula that allows passage of the suprascapular nerve and vessels.

T/F: borders and angles serve as sites of muscle attachment

true

Which joint is considered a physiological joint in the shoulder between the thorax and scapula?

Scapulothoracic joint - serves as articulation between the shoulder blade (scapula) and the rib cage (thorax)

Review radiology of the shoulder

…

What are the 3 groups of shoulder muscles and the muscles that reside in each?

Posterior Axioappendicular

• Trapezius

• Latissiumus dorsi

• Levator Scapulae

• Rhomboid major and mind

Anterior Axioappendicular

• Pectoralis Major

• Pectoralis Minor

• Subclavius

• Serratus Anterior

Scapulohumeral mm (6 muscles that attach the scapula and humuers)

• Deltoid

• Teres Major

• Teres Minor

• Supraspinatus

• Infraspinatus

• Subscapularis

Which of the three muscle groups functions to attach the scapula to the humerus?

a. Posterior axioappendicular

b. Anterior axioappendicular mm

c. scapulohumeral mm

c. scapulohumeral mm

Describe the muscles of the Anterior axioappendicular shoulder muscle group.

• Action, Innervation, and possible blood supply

Pectoralis Major

• Action: adduct and medially rotate arm

• innervated by medial and lateral pectoral nerves

Pectoralis Minor

• Action: Stabilizes scapula

• Innervated by medial pectoral nerve (nerve goes through the muscle_

• side: attaches coracoid process to ribs 3-5

Subclavius

• Action: protects the nerves under the clavicle and anchors and depresses clavicle

• Innervated by nerve to subclavius

• side: attaches the clavicle to the 1st rib (sits on inferior side of clavicle)

Serratus Anterior

• Action: protract and rotate scapula

• Innervated by long thoracic nerve

• Blood supply: long thoracic artery

Describe the muscles of the Scapulohumeral muscle group of the shoulder.

• Action, Innervation, and possible blood supply

Deltoid

• Actions: Abducts arm (medial side), flex and medially rotates arm (anterior side), and extend and lateral rotation (posterior side)

• Innervated by axillary nerve

• Blood supply: posterior circumflex humeral artery

Teres Major

• Action: Adducts, and medially rotates the arm

• Innervated by subscapular nerve

• Blood supply: circumflex scapular artery

Teres Minor

• Action: Laterally rotates arm

• Innervated by axillary nerve

Supraspinatus

• Action: Abducts arm from full adduction

• Innervated by suprascapular nerve

• Blood supply: suprascapular artery

Infraspinatus

• Action: Laterally rotates arm

• Innervated by suprascapular nerve

• Blood supply: suprascapular artery

Subscapularis

• Action: adducts and Medially rotates arm

• Innervated by upper and lower subscapular nerves

What are the Scapulohumeral muscles of the rotator cuff superior to inferior?

1. Supraspinatus (related to rotator cuff disolations)

2. Infraspinatus

3. Teres Minor

4. Subscapularis

SITS

In the arm, describe the anatomical neck, surgical neck, and radial groove and their importrance.

Anatomical neck - the groove surrounding the head of the humerus and indicates limit of joint.

Surgical neck - The narrow part of the humerus and site of fractures

• importance: related to axillary nerve damage as neck fractures

Radial groove - a groove on the posterior humeral shaft

• importance: holds radial nerves adn deep branch of brachial artery

Damage to which nerve in the upper limb will cause hand drop?

A. Ulnar

B. Radial

C. Axillary

D. Basilic

B. Radial

Differentiate between the medial epicondyles and lateral epicondyles

Medial epicondyle - Attachment site for flexor muscles; ulnar nerves passes through here

Lateral epicondyle - attachment site for extensors of forearm

Label the Upper Extremity in the photo provided.

Label the Upper Extremity in the photo provided.

What is the Intermuscular septa?

Separates the arm into compartments

• Anterior (flexors)

  • Biceps brachii

  • Brachialis

  • Coracobrachialis - attaches corocoid to arm

• Posterior (extensors)

  • Triceps brachii

  • Anconeus

Describe the muscles of the anterior compartment of the arm with their action and innervation

Biceps Brachii

• action: supination and flexion - put the cork in and pull out

• innervation: musculocutaneous nerve

Brachialis

• action: flexion of the elbow

• innervation: musculocutaneous nerve

Coracobrachialis

• action: flexion and adduction of the shoulder

• innervation: musculocutaneous nerve

T/F: the biceps brachii attaches to the humerus

false

In the biceps brachii there are two heads. Which one is lateral and medial?

Describe the muscles of the posterior compartment of the arm with their action and innervation

Triceps brachii

• 3 heads (long, medial, and lateral)

• action: extend forearm and resist dislocation

• Innv: radial n

• Artery: deep branch of brachial artery

Anconeus

• action: assist extension of forearm and protects the bony structures under

• Innv: radial n

What is the role of the ulnar bone?

Stablize forearm

What is the olecranon?

• In ulnar bone

• attaches and levers triceps

What is the styloid process of the ulnar bone?

at the distal end of the ulnar bone that provides attachment for the ulnar collateral ligament and stabilizes the wrist.

What is the interosseous membrane?

• between the radial and ulnar bones - connects them together

• prevents separation while bones are moving (ex: supination)

Which bone of the forearm is shorter? Radial or Ulnar?

Radial

Anterior Muscles of the forearm are arranged into 3 layers: Superficial, Intermediate, and Deep. Name the muscles in each section

Superficial

• Pronator Teres

• Flexor Carpi Radialis

• Palmaris Longus

• Flexor Carpi Ulnaris

Intermediate

• Flexor digitorum superficialis

Deep

• Flexor pollicis (thumb) longus

• Flexor digitorum profundus

• Pronator quadratus

Describe the superficial anterior muscles of the forearm including action and innervation

Pronator Teres

• Action: pronates arm

• Inn: Median nerve

Flexor carpi radialis

• Action: Flexes and abducts the wrist

  Inn: Median nerve

Palmaris longus

• Action: Wrist flexor (sometimes absent)

• Inn: Median nerve

Flexor carpi ulnaris

• Action: Flexes and adducts wrist

• Inn: Ulnar nerve

Describe the intermediate anterior muscle of the forearm including action and innervation

Flexor digitorum superficialis

• Action: Flexes middle phalanges of fingers. Flexes wrist as well

• Inn: Median nerve

Describe the deep anterior muscles of the forearm including action and innervation.

Flexor pollicis longus

• Action: Flexes the thumb

• Inn: Median nerve

Flexor digitorum profundus

• flexes the distal phalanges of the fingers

  • muscle runs to end of fingers

• Inn: Median nerve (digits 2 and 3) and Ulnar nerve (digits 4 and 5)

  • able to “come in peace”

• Blood supply: anterior interosseous artery

Pronator quadratus

• Action: Pronates the forearm

• Inn: Median nerve

• Blood supply: anterior interosseous artery

What do the tendons of the flexor digitorum superficialis and profundus have in common that is unique?

• run in common flexor sheath through the palm = the tendons run in digital synovial sheaths to individual digits

  • allows flexion of digits and to anchor them by reducing friction and support

Where does the flexor digitorum superficialis split an insert in relation to the digital synovial sheath?

What about the flexor digitorum profundus?

1. splits and inserts on middle phalanx

2. inserts on distal phalanx

Which two tendons in the hands allow for grip strength together?

Superficialis tendon and profundus tendon

Name the posterior muscles of the forearm and the layers they reside in.

ALL INNERVATED BY THE RADIAL NERVE

Superficial layer - *proximal attachment at lateral epicondyle (around elbow)

• Extensor carpi longus

• Brachioradialis

• Extensor carpi radialis brevis *

• Extensor carpi ulnaris*

• Extensor digitorum*

• Extensor digiti minimi*

Deep layer

• Supinator

• Extensor pollicis longus

• Extensor pollicis brevis

• Abductor pollicis longus

• Extensor indicis

What are the functions of the posterior superficial layer of the forearm?

ALL INNERVATED BY THE RADIAL NERVE

• Extensor carpi longus - Extend and abduct wrist

• Brachioradialis - Elbow flexor

• Extensor carpi radialis brevis - Extend and abduct wrist

• Extensor carpi ulnaris - Extends and adducts wrist

• Extensor digitorum - Main extensor of fingers

• Extensor digiti minimi - Extensor of digit 5

What are the functions of the posterior deep layer of the forearm?

ALL INNERVATED BY THE RADIAL NERVE

• Supinator - Supinates

• Extensor pollicis longus - Extends (laterally) the distal phalanx of thumb and other joints it crosses

• Extensor pollicis brevis - Extends (medially) the proximal phalanx of thumb and other joints it crosses

• Abductor pollicis longus - Abductor of thumb

  • thumb moves away from the body

• Extensor indicis - Extends 2nd difit

1. Which digits do the extensor indices tendon cover?

1. Index finger and not connected to intertendinous connection

Which bone in the forearm is the most action of the wrist correlated with?

Radius

Define the function and placement of the Scaphoid, lunate, and Triquetrium bones of the wrist.

All 3 bones allow for abduction of the wrist

Describe the osteology of the hand.

1. Metacarpals

2. Proximal phalax

3. Middle phalanx

4. distal phalanx

From the base of the finger:

1. Metacarpal - In digits 1-5 beginning with thumb and articulates with carpals and phalanges

2. Proximal phalanx - largest; articulate with metacarpals

3. Middle phalanx

4. Distal phalanx - expanded and flattened distally for nails

Identify the Scaphoid, lunate, triquetrium and Midcarpal joint in the x-ray.

The deep fascia of the arm and forearm continue down toward the wrist and thicken in what four areas?

1. Bicipital Aponeurosis

2. Retinacula (Extensor and Flexor) -function is to act like straps to prevent “bowstringing” - when tendons pop up away from the bones as you move

3. Palmar Aponeurosis

4. Digital Sheaths

What are the Flexor Retinaculum and the Extensor Retinaculum?

1. Flexor R - aka transverse carpal ligament; forms the roof of the carpal tunnel

   1. Medial nerve and flexor tendons pass underneath it

2. Extensor R - on back of the wrist and secures tendons so they don’t pop up when extending the hand

   1. ties tendons to wrist bones

*Extend from the deep fascia

What is the Palmar aponeurosis?

What is the Palmaris brevis?

1. The palmar aponeurosis is a thick, fibrous layer of tissue in the palm of the hand that provides support and helps anchor the skin. It serves as a protective covering for the underlying flexor tendons and structures of the hand.

2. Serves to protect the underlying ulnar nerve and artery

What are the functions of the digital (flexor) sheaths?

prevent bowstringing of tendons

The Intrinsic Hand Muscles consist of several groups: Thenar, Hypothenar, Adductor Pollicis, Lumbricals, and Interossei.

• Describe the Thenar group

• On the thumb side

• all innervated by the Median nerve (except the flexor pollicis brevis)

• Muscles

  • Abductor pollicis brevis

  • Flexor pollicis brevis

  • Opponens pollicis

The Intrinsic Hand Muscles consist of several groups: Thenar, Hypothenar, Adductor Pollicis, Lumbricals, and Interossei.

• Describe the hypothenar group

• act on 5th digit

• innervated by ulnar nerve

• Muscles

  • Abductor digiti minimi

  • Flexor digiti minimi brevis

  • Opponens digiti minimi

The Intrinsic Hand Muscles consist of several groups: Thenar, Hypothenar, Adductor Pollicis, Lumbricals, and Interossei.

• Describe the Adductor pollicis “group”

• so deep it sits against the bone

• adducts the thumb

• innervatedby the ulnar nerve

The Intrinsic Hand Muscles consist of several groups: Thenar, Hypothenar, Adductor Pollicis, Lumbricals, and Interossei.

• Describe the Lumbricals group

• Four small worm-like muscles on digits 2-5

• action: flex metacarpophalangeal joints

• Innervation: 1 and 2 are by median; 3 and 4 are by ulnar

• allow full extension of fingers

The Intrinsic Hand Muscles consist of several groups: Thenar, Hypothenar, Adductor Pollicis, Lumbricals, and Interossei.

• Describe the Interossei group

• 7 total with 3 palmar (for adduction of fingers) and 4 dorsal (for abduction of fingers)

• all innervated by ulnar nerve

Which area of the arm is considered the “distribution center” because it is a space in which all major nerves, lymph nodes and vessels pass through and communicate with the arm, shoulder and chest?

Axilla

Elements of the axilla are embedded in _____ and surrounded with fascia for protection.

A. Superficial Muscle

B. Deep Muscle

C. Lymph nodes

D. Adipose tissue

D. Adipose tissue

Describe the contents of the axilla

• Arteries - axillary artery and branches

• Veins - axillary veins and tributaries

• Brachial plexus

• Axillary sheath - CT sheath that invetsts and protects neurovascular structures in the axilla

• Axillary lymph nodes

Describe the Brachial Plexus (overview)

• Major nerve supply all segments of the upper extremity

• Begins in neck from ventral rami of C5-T1 and runs through axila

• Divided into 5 parts: Roots, Trunks, Divisions, Cords, Terminal Branches (Nerves)

  • Randy Travis Drinks Cold Beers (branches)

What kind of injuries can occur when injured at the ventral rami of C5-T1 (beginning of brachial plexus)?

Injuries at the ventral rami of C5-T1 can lead to upper trunk injuries, resulting in conditions such as Erb's Palsy, characterized by weakness in the shoulder and arm due to the affected nerve supply. These injuries often occur from trauma such as birth injuries or accidents.

The Roots of the brachial plexus each give off important nerves. What are the two and what do they innervate?

Dorsal Scapular Nerve (C5)

• Rhomboids, Levator Scapular

Long Thoracic Nerve (C5-C7)

• Serratus Anterior

  • Frequent Damage here is called “winged scapula”

In the Brachial Plexus, roots will combine to form trunks. Describe the 3 trunks.

Upper Trunk (C5-C6)

• Suprascapular nerve innervates supraspinatus and infraspinatus

• Subclavius nerve - innervates Subclavian

Middle Trunk (C7)

Lower Trunk (C8-T1)

In the brachial plexus, what can be expected after the trunks?

Hint: Randy Travis Drinks Cold Beers

Divisions (anterior and posterior)

• each trunk splits into anterior and posterior divisions

In the Brachial plexus, from the divisions, cords will form. Describe the 3 cords

Lateral Cord (C5-C7)

• Lateral Pectoral nerve

  • innervates Pectoralis major

Posterior Cord (C5-T1)

• Upper Subscapular nerve

  • innervates upper Subscapularis

• Thoracodorsal Nerve

  • innervates Latissimus Dorsi

• Lower Subscapular nerve

  • innervates subscapularis and teres major

Medial cord (C8-T1)

• Medial pectoral nerve

  • innervates both pectoralis major and minor

From the cords of the brachial plexus, terminal branches will form. Describe them

1. Musculocutaneous nerve (C5-C7)

   • Biceps brachii, Brachialis, and Coracobrachialis

2. Axillary Nerve (C5-C6)

   • Deltoid, Teres Minor

3. Median Nerve (C5-T1)

   • All anterior forearm muscles EXCEPT flexor carpi ulnaris and medial half of flexor digitorum profundus

   • Thenar muscles and 1st two lumbricals

4. Ulnar Nerve (C8-T1)

   • Flexor carpi ulnaris

   • medial half of flexor digitorum profundus

   • All intrinsic muscles of the hand except Thenar and 1st and 2nd lumbricals

5. Radial Nerve (C5-T1)

   • all muscles of the posterior arm and forearm

   MARMU (Most Alcoholics Really Must Urinate) mneumonic

   1. Musculocutaneous, Axillary, Radial, Median, Ulnar

The terminal branches of the brachial plexus are the major _____ nerves that continue into the upper limb.

A. Sensory

B. Motor

C. Mixed

B. Motor

A mastectomy is used to remove a cancerous tumor. The procedure involves excision of the breast tissue to the pec major muscle, associated fascia, and into the medial axillary wall. After the procedure, the woman as a noticeable winged scapula. Which nerve was most likely damanged?

A. Spinal accessory n.

B. Long thoracic n.

C. Dorsal scapular n.

D. Nerve to the subclavius

E. Lateral pectoral

B. Long thoracic n.

Winged scapula is associated with the serratus anterior muscle which is innervated by the long thoracic n.

What are the nerves of the scapular region?

• Suprascapular

  • runs under the superior transverse scapular ligament

  • supplies the supraspinatus and infraspinatus muscles

• Upper Subscapular

• Lower Subscapular

• Thoracodorsal/Middle Subscapular

  • nerve to latissimus dorsi

• Axillary Nerve

  • enters the quadrangular space along with the posterior circumflex humeral artery

Which of the scapular nerve(s) originate from the posterior cord and descend across the subscapularis to the target muscle?

Upper, Lower, and middle (thoracodorsal) subscapular nerves

What are the branches of the axillary nerve?

• articular branch to the shoulder joint

• anterior terminal branch, winds around the surgical neck of the humerus and supplies deltoid

• the posterior terminal branch gives a branch to the teres minor and then branches to the deltoid becoming the upper lateral cutaneous nerve

A fracture to the proximal humerus may injure which nerve? It would produce loss of sensation over the skin of the shoulder and difficulty abducting the arm.

Axillary nerve

• supplies deltoid which assists in abduction of the arm

Define the Quadrangular space

A border made of the teres minor, teres major, triceps long head, and the surgical neck of the humerus

• contains the axillary nerve and posterior circumflex humeral vessels

Define the Triangular space

Made by the teres minor, teres major, and triceps long head

• contains the circumflex scapular artery

What are the 4 main nerves of the arm and where do they arise from?

*Which two pass through the arm but do not innervate the arm?

• musculocutaneous - from lateral cord of brachial plexus

• radial - from posterior cord

• ulnar* - from medial cord

• median* - from lateral and medial cord

The musculocutaneous nerve pierces through which muscle of the arm?

A. Coracobrachialis

B. Brachialis

C. Biceps Brachii

D. Triceps brachii long head

A. Coracobrachialis

The musculocutaneous nerve of the arm will emerge lateral to the biceps brachii and pierce the deep fascia becoming the ______ nerve

lateral cutaneous nerve

Describe the radial nerve of the arm

• Arises from the posterior cord

• supplies all muscles of the posterior arm and forearm

• Branches to all heads of the triceps and anconeus

Which nerve of the arm will descend from the deep brachial artery and pass through the radial groove?

A. Musculocutaneous

B. Radial

C. Median

D. Ulnar

B. Radial nerve

_____ nerve of the arm will cross over the brachial artery, and lie medial to the cubital fossa

Median nerve

Describe the ulnar nerve of the arm

• arises from the medial cord of the brachial plexus

• pierces intermuscular septum ½ way down the arm

• It has no branch in the arm

Describe the median nerve relation in the forearm

• Crosses the ulnar artery and lies between the two.

• Median nerve runs between the flexor digitorum superficialis and FD profundus and enters the carpal tunnel

• Innervates all superficial forearm muscles directly and all deep indirectly with the anterior interosseus n

What is the anterior interosseus n responsible for innervating?

The deep muscles of the forearm including the flexor pollicis longus, flexor digitorum profundus, and pronator quadratus.

The ____ nerve of the forearm will lie between the flexor carpi ulnaris tendon and the flexor digitorum superficialis tendon in the wrist and enter the Ulnar canal (Guyon’s tunnel)

Ulnar nerve

Describe the radial nerve of the forearm

• Enters the forearm deep to the brachioradialis dividing into a superficial and deep branch

• Deep branch passes b/t supinator and becomes the posterior interosseus nerve

Which nerve of the hand enters through the carpal tunnel and divides into recurrent branch of the median nerve and digitial branches?

Median nerve

Describe the ulnar nerve in the hand

• enters hand through the ulnar canal

• innervates the interossei, lumbrical 3 and 4, hypothenar muscles, and deep flexor pollicus brevis

T/F: the radial nerve of the hand has no motor innervation but has sensory innervation

true

Provide the arterial pathway of the upper limb to the hands and the names of the vessels included.

• Upper limb arterial supply is subclavian artery

• Subclavian artery becomes axillary artery (@ first rib)

• Axillary becomes Brachial artery (at teres major)

• Brachial artery will branch (at cubital fossa) to become radial and ulnar arteries

  • radial creates the deep palmar arch

  • Ulnar creates the superficial palmar arch of the hand

    • palmar arches become digital arteries

1. How is the axillary artery divided?

2. What is the range of Part 1 of the axillary artery?

3. What branch arises from Part 1 of the axillary artery?

1. Into 3 parts based on relation of the pectoralis minor

2. From the lateral border of the 1st rib to the superior border of the pectoralis minor.

3. Superior thoracic artery.

Axillary Artery of the shoulder

1. Where is Part 2 of the axillary artery located?

2. What branches arise from Part 2 of the axillary artery?

3. What is the range of Part 3 of the axillary artery?

4. What branches arise from Part 3 of the axillary artery?

1. Posterior to the pectoralis minor muscle.

2. Thoraco-acromial artery and lateral thoracic artery

3. From the lower border of pectoralis minor to the lower border of teres major.

4. Subscapular a., Anterior circumflex humeral artery, and Posterior circumflex humeral artery

Arterial Supply of the Arm

1. What is the main blood supply of the arm?

2. Which area can be palpated? Why is it important?

3. Where does the artery terminate?

4. Does it branch?

1. Brachial artery

2. Medial Bicipital groove (BP here)

3. Cubital Fossa

4. Yes, into radial and ulnar arteries

What is the branches off the brachial artery?

• Deep branch of brachial a. - largest and first branch of brachial artery

  • travels with radial nerve through radial groove

What is the main branch off of the Ulnar Artery?

Common interosseus

• the short branches split into the anterior interosseus and posterior interosseus

Which artery of the forearm will cross the anatomical snuffbox and is a site for arterial blood draw?

Radial artery

The hands are highly vascularized due to which two arteries?

Radial and ulnar arteries and their branches

Describe the Ulnar artery of the hand and it’s branch

Ulnar artery

• enters the hand between the pisiform and hamate

• contributes to superficial and deep arches

Branches to form the superficial palmar arch

• main terminal branch of the ulnar artery

• gives rise to digitial arteries

Describe the Radial artery of the hand and it’s branches

Radial Artery

• Main contributor to deep palmar arch

Forms Deep Palmer Arch and Digital Branches

• DPA is formed primarily with the radial artery and some ulnar artery

• the digital branches supply the digits and arise from the DPA

1. What is the role of the superficial veins of the hand?

2. Where do the veins drain into after leaving the hand and into the forearm?

3. What is the median cubital vein?

1. Drain the superficial tissues and DO NOT accompany the arteries

2. The medial basilic vein and lateral cephalic vein.

3. Formed by the connection of the basilic and cephalic veins and runs across the cubital fossa - site for venipuncture

What occurs at the deltopectoral groove?

The cephalic vein ascends between b/t the deltoid and pec major.

Lymmphatic vessels from the right ¼ of the body drain into the ______ and the remaining ¾ of the body drains into the _____ (left side) or right.

A. Thoracic duct; Lymphatic duct

B. Thoracic duct; Deltopectoral nodes

C. Deltopectoral nodes, Lymphatic duct

D. Lymphatic duct; Thoracic duct

D. Lymphatic duct; Thoracic duct