7.3 Muscles and Movements of the Limbs Flashcards
What are all of the classifications/shapes that a muscle can be?
- Convergent
- Circular
- Unipennate
- Bipennate
- Multipennate
- Parallel
- Fusiform
What is the function of and an example of circular muscle?
Function:
- Sphincter muscles that allow the opening and closing of orifices
Example(s):
- Orbicular oris (mouth)
What are the features, function and some examples of the different types of pennate muscle?
Features and function:
- Fibres at an angle to the muscle’s line of action
- High fibre density
- Rotate as they shorten
- Result in a lot of power being generated across the joint
- Unipennate = only one side has the diagonal fibres (looks like a quill)
- Bipennate = two sides have the diagonal fibres
- Multipennate = multiple groups of diagonal fibres
Examples:
- Unipennate, extensor digitorum longus
- Bipennate, rectus femoris
- Multipennate, deltoid muscle
What are the features, function and example(s) of parallel muscles?
Features and function:
- Fibres align themselves parallel to the line of action of the muscle
- Usually long muscles
- Bring about larger but typically weaker movements than pennate muscles
Examples:
- Sartorius
- Sternocleidomastoid
What are the features, function and example(s) of fusiform muscles?
Features and function:
- Spindle-shaped
- Has a ‘muscle belly’ that is wider than the points of origin and insertion
- Provides a large range of motion/larger than other shapes of muscle
Examples:
- Biceps brachii
What are the features, function and examples of convergent muscle?
Features and function: - Triangular/fan- shaped muscles - Wide origins - Narrow insertions -> this results in high risk of tear or damage - Wide variation of fibre angles in muscles allows for multiple actions across joints Examples: - Pectoralis major
What is the origin of a muscle?
An area of a bone to which the muscle is attached via a tendon, but this region won’t move during the muscle’s action
What is the insertion of a muscle?
An area of a bone to which the muscle is attached via a tendon, but this region will move during the muscle’s action
Practice drawing out the diagram of a muscle insertion
Do it! Diagram is from Tom Cosker’s muscle and movement lecture
- Over how many joints are the biceps and gastrocnemius active over?
Both are active over 2 joints
- Where does the biceps insert?
Into the coracoid process (9 things insert into here, don’t mention this unless you can name all of them!)
What is a bursa?
A small fluid filled sac that cushions and reduces friction at a joint, will exist between two tissues that could grate over each other
What is an enthesis?
The name for where a muscle attaches to a bone, referring exactly to the connective tissue between a tendon and a bone (can be cartilaginous or fibrocartilaginous)
How is surface area increased at entheses?
The bone has a rough surface to increase the area articulating with the calcified fibrocartilage of the enthesis
Where is the fibrocartilage in a enthesis/insertion/origin calcified, and where is it now?
- On bursal side of tendon/further from the bone: un-mineralised
- On the bursal side of the bone/closer to the bone: calcified
Revise movements of joints
See set of flash cards on joints
What is the definition of a muscle agonist (with example)?
An agonist is the muscle that provides the primary force driving the joint to perform the movement in question
For example:
- Elbow flexion, agonist = biceps brachii
What is the definition of a muscle antagonist (with example)?
An antagonist is a muscle that opposes the agonist, providing some resistance to the agonist muscle and may reverse the movement in question. May also stabilise action of agonist.
For example:
- Elbow flexion, antagonist = triceps brachii
What is the definition of a muscle synergist (with example)?
A synergist is a muscle that assists the agonist muscle in performing the movement in question
For example:
- Elbow flexion, synergist = brachialis
What rough muscle group carries out flexion of the hip?
Anterior muscle group, e.g. psioas major (innervated by L1-L3 anterior rami), iliacus, pectineus, rectus femoris
What nerve innervates the hip flexor compartment?
Anterior thigh muscle compartment, innervated by the femoral nerve
What rough muscle group carries out extension of the hip?
Posterior thigh muscle compartment, e.g. gluteus maximus and the hamstrings
What nerves innervate the hip extensor compartment?
Posterior thigh muscle compartment, gluteus maximus by the inferior gluteal nerve, the hamstrings by the sciatic nerve
What rough muscle group carries out abduction of the hip?
Muscles on the lateral aspect of the joint, e.g. gluteus medius, gluteus minimus and tensor fasciae latae
What nerve innervates the hip abductors?
Superior gluteal nerve
What rough muscle group carries out the addiction of the hip?
Muscles on the medial aspect of the joint/attached to the pubis bone, e.g. adductor longus, adductor brevis, gracilis and adductor magnus
What nerve innervates the hip adductors?
Obturator nerve
- What muscles carry out medial rotation of the hip?
Adductor longus and tensor fasciae latae
- What muscles carry out lateral rotation of the hip?
Primary: gluteus maximus
Assisted by: piriformis, obturator internus and quadratus femoris
What rough muscle group carries out knee flexion?
Posterior thigh muscle compartment, e.g. hamstrings
What nerve innervates the knee flexors?
Muscles are the hamstrings, innervated by the sciatic nerve
What rough muscle group carries out knee extension?
Anterior thigh muscle compartment, e.g. quadriceps femoris
How many compartments are there in the leg?
4
- Superficial posterior compartment
- Deep posterior compartment
- Lateral compartment
- Anterior compartment
Which muscle groups of the leg carry out ankle plantarflexion?
Both the superior and the deep muscle compartments of the leg
What muscle group of the leg carries out ankle eversion?
Lateral compartment of the leg
What muscle group of the leg carries out ankle inversion and dorsiflexion?
Anterior compartment of the leg
- What is compartment syndrome?
- This is where bleeding into or swelling of the muscle compartments can result in compression of the deep veins, causing further oedema and raised compartmental pressure
- Arteries are not compressed, so blood is coming in but is unable to leave, causing the raised pressure
- Eventually pressure will rise to the point where the artery is also blocked, resulting in ischaemia and death of the tissue
- Surgical emergency, surgical treatment is to make medial incisions into the leg to release the pressure in all 4 compartments
What are fascia?
Fibrous connective tissues that surround muscles or muscle compartments as well as associated vessels, allowing adjacent muscles/muscle compartments to slide over each other
In the lower limb, fascia encourage venous return (return of deoxygenated blood to the heart)
What rough muscle group carries out flexion of the shoulder?
Muscles crossing the shoulder anteriorly, e.g. pectoralis major, coracobrachialis and deltoid
What nerve supplies the deltoid muscle?
Axillary nerve
What rough muscle group carries out extension of the shoulder?
Muscles crossing the shoulder posteriorly, e.g. triceps brachii, deltoid and latissimus dorsi
What nerve innervates the triceps brachii?
Radial nerve
What rough muscle group carries out abduction of the shoulder?
Muscles crossing the shoulder joint laterally/insert into the lateral proximal humerus, e.g. deltoid and supraspinatus
How many degrees of abduction does supraspinatus aid with?
The first 10-15 degrees
What rough muscle group carries out the adduction of the shoulder?
No exact muscle group, adducting muscles are:
- Triceps brachii
- Pectoralis major
- Teres major
- Latissimus dorsi
What is the major medial rotator of the shoulder from the resting position?
Subscapularis
What are some of the major lateral rotators of the shoulder?
Infraspinatus, teres minor
What are the four rotator cuff muscles?
- Supraspinatus
- Infraspinatus
- Teres minor
- Subscapularis
REMEMBER: SITS
Where does subscapularis insert and what nerve innervates the muscle?
- Lesser tuberosity of the humerus (only one of the rotator cuff muscles to insert here)
- Both the upper and lower subscapular nerves
Where does teres minor insert and what nerve innervates the muscle?
- Greater tuberosity of the humerus
- The axillary nerve
Where does supraspinatus insert and what nerve innervates the muscle?
- Greater tuberosity of the humerus
- Suprascapular nerve
Where does infraspinatus insert and what nerve innervates the muscle?
- Greater tuberosity of the humerus
- Suprascapular nerve
What initiation of movement does supraspinatus allow?
The first 30 degrees of abduction
What rough muscle group carries out flexion of the elbow?
Muscles crossing the joint anteriorly, e.g. biceps brachii, brachialis and brachioradialis
What nerve innervates the elbow flexor muscles?
Musculocutaneous nerve
What rough muscle group carries out extension of the elbow?
Muscles crossing the joint posteriorly, e.g. triceps brachii and anconeus
What are the three muscle compartments of the forearm?
Anterior/posterior compartments and the mobile wad
What nerves innervate the anterior compartment of the forearm?
Median and ulnar nerves
- What are the muscles of the anterior compartment of the forearm?
- Flexor digitorum profundus
- Flexor carpi ulnaris
- Flexor digitorum superficialis
- Flexor carpi radialis
- Flexor pollicus longus
- Pronator teres
What nerves innervate the posterior compartment of the forearm?
Radial and posterior interosseous nerves
- What are the muscles of the posterior compartment of the forearm?
- Extensor carpi ulnaris
- Extensor pollicis longus
- Extensor digiti minimi
- Extensor digitorum
- Abductor pollicis longus
- Supinator
- What are the muscles of the mobile wad?
- Brachioradialis
- Extensor carpi radialis longus
- Extensor carpi radialis brevis
What muscle group carries out pronation?
Muscles of the anterior muscle compartment of the forearm, pronator teres and pronator quadratus
What muscle group carries out supination?
Supinator muscle of the posterior compartment of the forearm
- What is tennis elbow?
Where a tendon of one of the extensor muscles of the elbow inserting into the lateral epicondyle of the humerus is damaged, causing pain and restricting movement of the elbow
- What is golfers’ elbow?
Where microtears occur in the tendons of wrist flexor muscles attaching to the medial epicondyle occur, causing pain and limiting movement of the elbow
What movements are more complicated, those of the hand or of the foot?
Those of the hand, as there are a lot more muscles present in the hand which allow more complex movements (the shape of the thumb joint also allows opposition, a unique movement)
What joints and muscles allow pronation and supination?
Pronation muscles: - Pronator teres - Pronator quadratus Supination muscles: - Supinator Joints: - Proximal radioulnar joint -> the radius rotates around the ulna (see joint flashcards for more detail), radius is proximally thin and distally wide, ulna is the opposite
What are reticulina?
Bands of thickened fascia around tendons that hold them in place - not attached to any muscle but play a huge role in stabilising tendons
What is a tendon sheath?
A layer of synovial membrane around a tendon that allows it to stretch and not get stuck to the surrounding fascia. Comes in two layers:
- Synovial sheath (inner)
- Fibrous sheath (outer)
