Introduction to the Limbs

Question 1

What is special about the functions of the upper limb of a human compared to the equivalent structure on a quadruped?

Answer 1

– has almost no locomotor function
– has a great degree of freedom of movement
It is an organ for grasping and manipulating

Question 2

What defines the structure and function of the upper limb?

Answer 2

 Highly mobile joints
 Levers
 Enable the hand to be brought to any point in space and keep it steadily

Question 3

What are the functions of the lower limb?

Answer 3

 Supports the body weight
 Involved mainly in locomotion
 The bones of the lower limb are more robust than the bones and joints of the upper limb

Question 4

From where and when do the limbs develop?

Answer 4

 ~Week 4 of development, specialized cells migrate from the somites and the lateral plate mesoderm
 Limb buds form where the arms and legs will develop.

Question 5

What are the three types of muscles in regards to their structure?

Answer 5

Skeletal muscles, Smooth muscles, Cardiac muscles

Question 6

Where can the origin of a muscle normally be found?

Answer 6

usually the proximal end of the muscle, which remains fixed during muscular contraction

Question 7

Where can the insertion of the muscle normally be found?

Answer 7

usually the distal end of the muscle, which is movable

Question 8

What happens when a muscle is stimulated?

Answer 8

a muscle contracts and tries to bring its two ends closer.

Question 9

In what direction do muscles normally contract/shorten?

Answer 9

in the Insertion -> Origin direction

Question 10

What are the two types of muscle contraction?

Answer 10

Isometric contraction

Isotonic contraction

Question 11

What are the two types of isotonic contraction?

Answer 11

A. Concentric contraction

B. Eccentric contraction

Question 12

What is eccentric contraction?

Answer 12

When the muscle elongates while under tension due to an opposing force greater than the muscle generates

Question 13

When does eccentric contraction occur?

Answer 13

Occurs as a braking force in opposition to a concentric contraction to protect from injury
(lowering a dumbbell)

Question 14

What is concentric contraction?

Answer 14

Muscle contracts according to the sliding filament mechanism and shortens
(lifting a dumbbell)

Question 15

What are the 5 types of muscle in regards to their purpose in a movement?

Answer 15

• Prime mover
• Agonist
• Synergist muscles
• Antagonistic muscles
• Fixating muscles

Question 16

What is a prime mover?

Answer 16

Muscle(s) that play the primary role in moving a body part

Question 17

What is an agonist?

Answer 17

Muscle(s) that acts directly to produce a desired movement

Question 18

What are synergist muscles?

Answer 18

Muscle(s) which prevent unwanted movements associated with the action of the prime movers

Question 19

What are antagonistic muscles?

Answer 19

Muscle(s) which directly oppose a movement

Question 20

What are fixating muscles?

Answer 20

Muscle(s) that provide the necessary support to assist in holding the rest of the body in place while the movement occurs

Question 21

What are the two different kinds of fascia in regards to their location?

Answer 21

Superficial fascia and

Deep (investing) fascia

Question 22

What are the features of superficial fascia

Answer 22

• Just beneath the skin

* Contains adipose tissue

Question 23

What are the features of deep (investing) fascia

Answer 23

• Ensheath muscles but continuous
• Facilitate contraction
• Barrier between muscles
• Compartments of muscles
• Passages for nerves and vessels
• Attachment for muscles (eg. by forming Interosseous membranes)
• Hold tendons in place (by forming Retinaculae)

Question 24

What are retinaculae?

Answer 24

A retinaculum (actual plural retinacula) is a band of thickened deep fascia around tendons that holds them in place

Question 25

What do deep fascia form between the muscles?

Answer 25

septae between the muscles to separate them into compartments

Question 26

What do septae form?

Answer 26

potential spaces to allow passage of nerves and blood vessels

Question 27

What is compartment syndrome?

Answer 27

An injury to the muscle within a tough compartment may cause swelling and increased pressure that compresses the neurovascular bundles

Question 28

Where are the deep fascia of the arm (medics arm not layman's)?

Answer 28

The intermuscular septae divide the arm into an anterior (flexor) and a posterior (extensor) muscular compartment

Question 29

What are the two septae of the arm and where are they?

Answer 29

The lateral and medial intermuscular septae, both join the humerus and run roughly along the coronal plane, with the lateral intermuscular seta slightly posterior

Question 30

What are the fascia of the atebrachium?

Answer 30

 The antebrachial fascia forms the interosseous membrane that separates anterior (flexor) and posterior (extensor) compartments  Carpal tunnel

Question 31

What are the deep fascia of the thigh?

Answer 31

 Called fascia lata  The fascia lata thickens laterally as the Iliotibial Tract, and sends septae to divide the thigh into anterior (extensor), medial (adductor) and posterior (flexor) compartments

Question 32

How is the invested fascia of the lower limb different from the invested fascia of the upper limb?

Answer 32

 Deep fascia of the lower limb is thicker

Question 33

What are the deep fascia of the leg(medics not layman's)?

Answer 33

```  Fascia Lata -> Crural fascia  The Crural Fascia - fuses with the tibia - forms the interosseous (IO) membrane - send septae to divide the leg into anterior (extensor), 2 posterior (superficial and deep flexor) and lateral (peroneal) compartments ```

Question 34

What are neurons?

Answer 34

 Excitable nerve cells which transmit information as electric signals or “action potentials”

Question 35

What structures make up a typical neuron?

Answer 35

 A typical neuron has a cell body (soma) and neurite(s). Neurite is either a dendrite or an axon

Question 36

What is an axon?

Answer 36

is single, can be as long as 1 m, covered with myelin or Schwann sheath

Question 37

What are dendrites?

Answer 37

multiple, thin, short extensions

Question 38

What two functions may a neuron have?

Answer 38

motor or sensory

Question 39

What two functions may motor neurons have?

Answer 39

somatic or autonomic

Question 40

Where is the sensory root?

Answer 40

The posterior (dorsal) root/posterior (dorsal) radix to the dorsal root ganglion

Question 41

Where is the motor root?

Answer 41

The anterior (ventral) root/anterior (ventral) radix to the sympathetic ganglion

Question 42

What do the posterior and anterior roots join to form?

Answer 42

The spinal nerve

Question 43

What is a dermatome?

Answer 43

the strip of skin supplied by 1 spinal nerve

Question 44

What is a myotome?

Answer 44

the skeletal muscle or group of skeletal muscles supplied by 1 spinal nerve

Question 45

Describe the initial position of the limbs in development

Answer 45

both the thumb and hallux are on the cranial side of each limb, and both the palm and sole face anteriorly

Question 46

Describe the rotation of the upper limb in development

Answer 46

 The upper limb rotates laterally from its in-utero position • Thumb moves from medial to lateral • Flexor muscle groups move to an anterior position • Extensors move to a posterior position

Question 47

Describe he rotation tf the lower limb in development

Answer 47

 The lower limb rotates medially : • Hallux moves from lateral to medial • Flexor muscle groups move from an anterior to a posterior position • Extensors move to an anterior position

Question 48

What else rotates during the rotation of the limbs in development?

Answer 48

The dermatomes

Question 49

Where do the spinal nerves emerge from?

Answer 49

intervertebral foramina

Question 50

Where do C1 to C7 spinal nerves emerge from?

Answer 50

intervertebral foramina above respective vertebrae

Question 51

Where does the C8 spinal nerve emerge from?

Answer 51

below C7 vertebra

Question 52

Where do T1 and all lower nerves emerge from?

Answer 52

below respective vertebrae intervertebral foramina

Question 53

Where does the neural innervation of the upper limb come from?

Answer 53

The brachial plexus, found in the axilla

Question 54

What nerves form the brachial plexus?

Answer 54

C5 -> T1

Question 55

What nerves emerge from the brachial plexus?

Answer 55

Musculocutaneous, Axillary, Radial, Median, Ulnar

Question 56

Where does the neural innervation of the lower limb come from?

Answer 56

The Lumbo-Sacral plexus, within psoas major on the posterior abdominal wall, and on the lateral wall of the pelvis

Question 57

Where is the psoas major muscle?

Answer 57

It starts on the spine around T12/L1 ish and moves caudo-laterally towards the pelvis idk

Question 58

What nerves are the lumbo-sacral plexus derived from?

Answer 58

the ventral rami of L1 to L5 and S1 to 4

Question 59

Describe the arterial supply of the upper limb

Answer 59

Subclavian -> axillary -> brachial -> radial and ulnar -> Deep and superficial palmar arches

Question 60

Describe the arterial supply of the lower limb

Answer 60

External iliac artery -> Deep and superficial femoral -> popliteal -> tibias posterior and anterior -> plantar arcade

Question 61

Describe the venous drainage of the upper limb

Answer 61

Two main veins: cephalic and basilic The cephalic vein is broadly lateral to the basilic vein, this is much clearer in the brachium. The median cubital vein joins these two and is found in the cubital region (big surprise) In the hands the basilica and cephalic veins from the dorsal and palmar venous networks

Question 62

Describe the venous drainage of the lower limb

Answer 62

The great saphenous vein runs along the medial side of the femoral region and the small saphenous vein runs along the anterior side of the leg

Question 63

Into what vein may one put an IV line?

Answer 63

The cephalic vein

Question 64

From where may one take a venous sample?

Answer 64

The median cubital vein

Question 65

Where may superficial veins be found?

Answer 65

in superficial fascia | Connections of superficial veins with the deep veins are more significant in the lower limb than the upper limb

Question 66

Describe process of venous drainage of the lower limb

Answer 66

 Venous flow is from superficial to deep, via perforators  The muscle pump, arterial pulsation, negative intrathoracic pressure and valves in veins help venous return to the heart, against gravity.

Question 67

Describe lymph drainage of the limbs

Answer 67

 Lymph vessels follow the superficial or deep veins |  Drain to the Axillary (upper limb) and Inguinal (lower limb) lymph nodes

Question 68

Alongside what structures can the deep veins in the limbs be found?

Answer 68

Accompanying the associated arteries of the limbs