Week 2: Upper Limbs & Back

Question 1

What are the origin and insertion of a muscle?

Answer 1

Origin - attachment point that does not move during contraction of the muscle

Insertion - attachment point that does move during the contraction of the muscle

When a muscle contracts, the insertion moves closer to the origin

Question 2

What organizes limbs into compartment?

Answer 2

Deep fascia and connective tissue wraps muscles into compartments that have their own nerves and blood supplies

Question 3

What are the main components of the upper and lower limb?

Answer 3

Upper:

Axilla, arm, forearm (ant/post compartments), hand

Lower:

Gluteal region, thigh (ant/post/medial compartments), leg (ant/post/lat compartments), foot

Question 4

What are the three main groups of back muscles?

Answer 4

Superficial, intermediate, and deep (intrinsic)

Question 5

What are the superficial muscles of the back, what do they do, and what are they innervated by?

Answer 5

Latissimus dorsi, rhomboids, trapezius and levator scapulae all assist in movement of the upper limb

These are innervated by the brachial plexus, except for the trapezius muscle, which is innervated by CN XI

Question 6

What are the deep muscles of the back, what do they do and what are they innervated by?

Answer 6

The deep/intrinsic muscles are the erector spinae and transversospinalis. They are involved in stabilizing and moving the trunk.

They are innervated by the dorsal rami of the spinal nerves.

Question 7

Label A-E

Answer 7

A - Trapezius

B - Latissimus dorsi

C - Levator scapulae

D - Rhomboid minor

E - Rhomboid major

Question 8

What are the three main muscle movements of the trapezius?

Answer 8

Elevation (shrug up)

Depression (shrug down)

Retraction (pull towards the back)

Question 9

What are the main movements of the latissimus dorsi?

Answer 9

“Swimming” movements of the shoulder/upper humerus of the arm:

extension towards the back

adduction towards the midline

medial rotation of the insertion point

Question 10

What are the main movements of the rhomboid major and minor?

Answer 10

Retraction of the scapulae torwards the back

Elevation of scapula (“shrug” movement)

Question 11

What two muscles would be involved in “flapping” your arms like a bird?

Answer 11

Supraspinatus initiates the first 15 degrees of movement

Deltoid muscle allows for arm abduction beyond 15 degrees

Question 12

What are the main rotator cuff muscles and what do they do?

Answer 12

These are the muscles around the scapula that rotate, abduct and stabilize the shoulder

The infraspinatus(post) allows forlateralrotation(moves shoulder towards the back). Thesupraspinatus (superior) allows for elevation and resists the downward pull of gravity

Teres minor (post) also allows for lateral rotation

Subscapularis is on the anterior side and allows for medial rotation (towards the anterior midline)

Question 13

The ______________ joint is between the shoulder and humerus. What is unique about it?

Answer 13

Glenohumeral. It is a socket-like joint that doesn’t actually have much of a “socket,” so it depends on the muscles and ligaments of the rotator cuffs to hold it in place.

Question 14

What are the main contents of the axilla, and why is it important?

Answer 14

Axillary area is where structures pass from the neck to the upper thorax (i.e. nerves, veins, arteries)

Contents:

Axillary artery/vein

Brachial plexus

Lymphatics and lymph nodes

Question 15

The __________ _____________ starts within the ________ and carries the nerves for the skin and muscles of the upper limb and shoulder. What do these nerves form from?

Answer 15

Brachial plexus

Neck

Nerves form from the anterior rami of the C5 - T1 spinal segments

Question 16

From proximal to distal, what is the organization of nerves deriving from the brachial plexus?

Answer 16

“Road To DC Baby”

Proximal:

Roots (ventral/anterior rami, C5-8, T1)

Trunks (superior (C5,6), middle (C7), inferior (C8, T1)

Divisions (anterior and posterior parts of arm)

Cords (lateral, posterior, medial)

Branches (terminal nerves

Distal

Question 17

What are the four terminal nerves of the brachial plexus and what does each do?

Answer 17

Musculocutaneous - Anterior arm compartment

Median - Forearm: most anterior compartment (except those innervated by ulnar nerve), and Hand: thenar eminence and 2 other muscles + skin of hand

Ulnar - Forearm: 1.5 muscles, and Hand: all intrinsic muscles except those innervated by median nerve, skin of hand

Radial - Posterior compartment of arm and forearm, skin over posterior

Question 18

What three nerves are responsible for the cutaneous innervation of the hand?

Answer 18

Median (lateral palm, fingers)

ulnar (median palm, medial 1.5 fingers)

and radial nerves (posterior lateral part of hand)

Question 19

What is the “M” of the brachial plexus?

Answer 19

Lateral to medial:

Musculocutaneous

Median

Ulnar

(Radial nerve is behind the axillary artery)

Question 20

How can you injure elements of the brachial plexus, and what nerves are involved in injury?

Answer 20

Upper brachial injury is caused by damage to the neck like lateral overstretching, which damages C5 & C6

Lower brachial injury is caused by damage to the axillary region from pulling trauma, which damages C8 and T1

Question 21

What are the major compartments of the arm, what muscles do they contain, what common actions do they commit and how are they innervated?

Answer 21

Compartments are anterior and posterior

Anterior contains the biceps brachii, which is the flexor compartment and is innervated by the musculocutaneous nerve

Posterior contains the triceps brachii, which is the extensor compartment and is innervated by the radial nerve

Question 22

What are the muscles of the anterior arm, what do they do and where do they originate and insert?

Answer 22

The three biceps brachii are the load-bearing flexors and supinators of the forearm.

They originate in the scapula and proximal humerus and insert in the radius, pulling it across the ulna to pronate the hand (ulna is medial)

Question 23

What are the muscles of the posterior arm, what do they do and where do they originate and insert? What innervates it?

Answer 23

The three triceps brachii originate from the scapula (1) and humerus (2) and insert on the posterior ulna

They activate extension of the elbow, which is mediated by the radial nerve

Question 24

What is the cubital fossa and what does it contain?

Answer 24

It is the depression anterior to the elbow joint that contains:

Tendons of biceps muscle

Median nerve

Brachial artery

It also contains the superficial veins used for venipuncture

Question 25

What are the superficial anterior muscles of the forearm, what are they innervated by, and what do they do?

Answer 25

**Flexor carpi ulnaris** - flexes and adducts the wrist (ulnar nerve) **Flexor carpi radialis** - flexes and abducts the wrist (median nerve) **Flexor digitorum superficialis** - flexes digits 2-5 (all but thumb) and proximal interphalangeal joint (PIP joint) (median nerve)

Question 26

What is the deep anterior muscles of the forearm, what are they innervated by, and what does it do?

Answer 26

**Flerxor digitorum profundus** has tendons that go into the deep parts of the phalanges to flex them. It is **innervated by the median and ulnar nerves (1/2)** The muscle **inserts on the distal phalanges** and can activate the **distal (DIP) and proximal (PIP) interphalangeal joints** between the most distal part of a finger and the "middle" part

Question 27

What are the superficial posterior muscles of the forearm, what is their function, and what are they innervated by?

Answer 27

**Extensor carpi radialis longus** and **brevis** - extensors and abductors of the wrist **Extensor carpi ulnaris** - wrist extensor and adductor **Extensor digitorum** - extensors of digits 2-5 **Brachioradialis** - crosses over lateral elbow and is an accessory flexor of the elbow These are all innervated by the **radial nerve.**

Question 28

What are the deep posterior muscles of the forearm, what do they do and what are they innervated by?

Answer 28

The **extensors pollicis longus** and **brevis** (**muscles** that connect to **tendons**) are on the **radial/lateral** sides of the wrist, and form the **anatomical snuffbox.** They are innervated by the **radial nerve.**

Question 29

What is a FOOSH injury? What muscles does it affect?

Answer 29

A **Fall On OutStretched Hand injury** can injure the **extensors pollicis longus** and **brevis**

Question 30

What is a carpal tunnel and what forms it?

Answer 30

It is a compartment of muscles and bones formed by the **arch of carpal bones** and overlayiing **flexor retinaculum**. It is innervated by the **median nerve**. Carpal tunnel is characterized by **feelings of numbness and pain in the thumb and first two fingers** due to **compression of the median nerve**.

Question 31

What are the extrinsic and intrinsic muscles of the hand?

Answer 31

**Extrinsic muscles** move the hand, but the **bellies of the** **muscles themselves lie in the forearm**, with **tendons that extend to the hand**. These are **involved in the power grip.** **Intrinsic muscles** move the hand, and the **bellies of the muscles lie in the hand**. These are **involved in fine, precision grip** and are **innervated by the ulnar and median nerves.** **Thenar** muscles (thumb) = median Most other intrinsics = ulnar