Introduction to the limbs Flashcards
What are the 3 functions of the upper limbs?
- They have almost no locomotor function, however they can be used as a locomotor prop (e.g Crutches to walk)
- Highly mobile joints
- Leavers/allows hand to be brought to any point in space and kept steady
What are the 2 key features of the upper limbs?
They are less stable but highly mobile
What are the 3 functions of the lower limbs?
- Support body weight
- Involved mainly in locomotion
What are the key 3 features of the lower limbs?
The bone of the lower limb are more robust and stable than the bones and joints of the upper arm but less moveable
Where do limbs develop from in a foetus and when?
The upper and lower limb buds
32-35 days
What develops after the limb buds grow?
The digital rays develop which will later become digits (fingers)
42-49 days
When and where do limbs develop?
Around week 4 of development, specialised cells migrate from somites and the lateral plate of the mesoderm and limb buds form where the arms and legs will develop
How does the upper limb develop?
The upper limb develops with the thumb pointing superiorly
What are the 3 different types of muscles?
Skeletal muscle, Cardiac muscle and Smooth muscle
What is the Origin?
The origin is usually the proximal end of the muscle which remains fixed during muscular contraction, making it more stable
What is the Insertion?
The insertion is usually the distal end of the muscle which is moveable, making it less stable
What happens to a muscle when stimulated?
The muscle contracts and shortens, trying to bring its two ends closer (Insertion and Origin)
What muscle moves closer to the other during a muscle being stimulated?
The muscles usually shorten in the Insertion -> Origin direction, so insertion becomes closer to the Origin
What is Isometric muscle contraction?
Increase in muscle tone but muscles don’t change in length or shorten
What is an Isotonic muscle contraction?
Muscle length changes so the muscle wither elongates or shortens but the muscle tone is not changed
Give an example of Isometric muscle contraction?
Carrying an object in front of you
Give an example of Isotonic muscle contraction?
Walking and running
What are the 2 varieties of Isotonic contractions and their differences?
Concentric contraction - Muscle contracts according to the sliding filament mechanism and shortens
Eccentric contraction - The muscle elongates while under tension due to an opposing force greater than the muscle generates - Works as a breaking force in opposition to a concentric contraction to protect from injury (E.g - Bicep Eccentric contraction prevents dropping of weight)
What is a prime mover?
A muscle/muscles that play the primary role in moving a body part
What is an Agonist muscle?
A muscle/ muscles that act directly to produce a desired movement - Aids the prime mover
What are Synergist muscles?
Muscles which prevent unwanted movements associated with the action of prime movers
What are Antagonistic muscles?
Muscles which directly oppose a movement (E.g - flexing elbow, the muscles on back resist to prevent hyperextension
What are Fixating muscles?
Muscles that provide the necessary support to assist in holding the rest of the body in place while movement occurs (Stabilises Origin or Insertion)
What is Fascia and its 2 subdivisions and their properties?
Fascia is a connective tissue (1 continuous sheet with 2 layers)
- Superficial Fascia; Just beneath the skin and contains Adipose tissue (Fat)
- Deep (investing) Fascia;
- Ensheath muscles but are continuous
- Help/facilitate contractions
- Barrier between muscles
- Compartment muscles and neurovascular bundles
- Passages for nerves and vessels
- Point of attachment for muscles (e.g by forming Interosseous membranes - fascia running from bone to bone in arm)
- Becomes thicker in structures (e.g wrist joint) to hold tendons in place (by forming Rentinaculae
What runs between muscles and why?
Septae to separate muscles into compartments for a group of muscles of similar function and vessels/neurovascular bundles
What do Septae form that is an advantage and disadvantage?
Septae form potential spaces to allows the neurovascular bundle to pass and to protect it.
However, potential spaces are also potential tracks for infection spread and blood loss
What is compartment syndrome and why is it important?
Compartment Syndrome is an injury to the muscle within a tough compartment which may cause swelling and increased pressure that compresses the neurovascular bundles
This is a surgical emergency as there is compromised circulation
What divides the arm into an anterior and posterior muscular compartment?
The intermuscular septae
What is the anterior compartment in the arm also referred to as ?
The flexor as the muscles flex the elbow
What is the posterior compartment in the arm also referred to as ?
The extensor as it extends muscles in the elbow
What forms into what membrane which separates the forearm into anterior (flexor) and posterior (extensor) compartments?
The antebrachial fascia forms into the interosseous membrane to separate the forearm into anterior (flexor) and posterior (extensor) compartments
What is in between the flexor retinaculum and what does this contain?
The carpal tunnel which transmits the tendons of the flexors to the fingers and the median nerve
How many compartments does the arm have?
2
How many compartments does the forearm have?
2
How many compartments does the thigh have ?
3
How many compartments does the leg have ?
4
How does fascia vary from arm to leg?
Lower limb fascia is thicker and called fascia lata
What does the fascia lata thicken into laterally in the thigh?
The iliotibial tract
What does the iliotibial tract extend into?
It sends Septae to divide the thigh
What compartments is the thigh divided into?
Anterior, Medial and Posterior compartments
What is the function of the anterior, medial and posterior compartments in the thigh?
Anterior - Extensor
Medial - Adductor
Posterior - Flexor
What does the Fascia lata thicken into in the leg?
The Crural Fascia
What are the 3 anatomical functions of the Crural Fascia?
It fuses with the tibia
forms the Interosseous membrane
Sends Septae do divide the leg
What are the different compartments of the leg and their movements?
Anterior - Extensor
2 Posterior - Superficial and Deep Flexor
Lateral - Has peroneal muscles to move foot at ankle joint
What kind of muscle does the ventral horn go to and via what kind of neuron?
The ventral horn uses a motor neuron to supply skeletal muscles
What kind of muscle does the lateral horn go to and via what kind of neuron?
The lateral horn uses a sympathetic motor neuron to supply organs
What kind of muscle does the dorsal horn receive and via what kind of neuron?
The dorsal horn uses a sensory neuron to receive senses from the skin and organs
What is a Dermatome ?
A dermatome is the strip of skin supplied by 1 spinal nerve
What is a Myotome?
A Myotome is the skeletal muscle or group of skeletal muscles supplied by 1 spinal nerve
How does rotation occur during limb rotation?
1). The thumb and Hallux (big toe) are both on the cranial side of each limb and both palm and sole face anteriorly
2) . The upper limb rotates laterally by 90 degrees
- Thumb moves from medial to lateral (think of limbs in anatomical position)
- Flexor muscle groups move to an anterior position
- Extensors move to a posterior position
3) . The lower limb rotates medially by 90 degrees
- The Hallux moves from lateral to medial
- The flexor group move from an anterior to posterior position
- The extensors move to an anterior position
4). The dermatomes rotate as well
What do the ventral ramus go and form?
Plexuses
What supplies the upper limb with nerves and where from?
Brachial plexus in the Axilla (armpit)
What supplies the lower limb with nerves?
The Lumbo-Sacral Plexus
What is the main Arterial supply of the upper limb?
The Subclavian artery
What is the main Arterial supply of the lower limb?
The external iliac arteries
Why are superficial veins important?
They are in superficial fascia and used for Phlebotomy
What is the Cephalic veins usually used for?
IV line
What is the Median Cubital vein usually used for?
Venous sample
Why are there more connections between superficial and deep veins in the legs than the arms?
As is helps the Venous drainage back to the heart as the legs are going against gravity
What direction does venous flow go in?
From superficial to deep via perforators (connector veins)
What are the 4 ways to help venous blood return to the heart from the legs?
Muscle pump - compresses veins
Arterial pulsation - deep veins lie beside arteries and acts like the muscle pump to pump blood back up
Negative intrathoracic pressure - sucks blood up like vacuum
Valves - prevents backflow
What do lymph vessels follow?
Superficial or deep veins
Where does lymph drain to in the upper and lower limbs?
Upper limbs - Axillary lymph nodes
Lower limbs - Inguinal lymph nodes
What spinal nerves does medial rotation of the elbow use?
C6, C7, C8
What spinal nerves does lateral rotation of the elbow use?
C5
What spinal nerves does abduction of the Glenohumeral joint use?
C5
What spinal nerves does adduction of the Glenohumeral joint use?
C6, C7, C8
What spinal nerves does extension (moving posteriorly) of the Glenohumeral joint use?
C6, C7, C8
What spinal nerves does flexion of the Glenohumeral joint (moving anteriorly) use?
C5
What spinal nerves does flexion of the elbow use?
C5, C6 (Main)
What spinal nerves does extension of the elbow use?
C6, C7 (Main)
What spinal nerves does extension of the wrist use?
C6 (Main), C7
What spinal nerves does flexion of the wrist use?
C6, C7 (Main)
What spinal nerves does pronation of the forearm use?
C7, C8
What spinal nerves does supination of the forearm use ?
C6
What spinal nerves does digital flexion use ?
C7, C8 (Main)
What spinal nerves does digital extension use ?
C7 (Main), C8
What spinal nerves does lateral abduction of the 3rd digit use ?
T1
What spinal nerves does medial abduction of the 3rd digit use ?
T1
What spinal nerves does abduction of digits 2-5 use ?
T1
What spinal nerves does adduction of digits 2-5 use ?
T1
What spinal nerves does lateral external rotation of the hip use ?
L5, L1
What spinal nerves does medial internal rotation of the hip use ?
L1, L2, L3
What spinal nerves does Abduction of the hip use ?
L5, S1
What spinal nerves does Adduction of the hip use ?
L1, L2, L3, L4
What spinal nerves does inversion of the tarsal use ?
L4, L5
What spinal nerves does eversion of the tarsal use ?
L5, S1
What spinal nerves does dorsiflexion of the toes use ?
L5, S1
What spinal nerves does plantar-flexion of the toes use ?
S1, S2
What spinal nerves does extension of the hip use ?
L4, L5
What spinal nerves does flexion of the hip use ?
L2, L3
What spinal nerves does Flexion of the knee use?
L5, S1
What spinal nerves does Extension of the knee use?
L3, L4
What spinal nerves does plantar-flexion of the ankle use ?
S1, S2
What spinal nerves does dorsi-flexion of the ankle use ?
L4, L5
