Muscoskeletal System Flashcards
What is the appendicular skeleton?
Upper limb (shoulder, pectoral girdle, arms, forearm, hands) Lower limb (pelvic girdle, legs, lower leg, feet) 126 bones (64 upper limb and 62 lower limb) Mobility
What is the axial skeleton?
Skull (protects brain) Vertebral column (protects the spinal cord) Rib cage (protects heart and lungs) 80 bones (8 cranial, 6 auditory ossicles, 14 facial, 26 vertebral, 26 thoracic)
Protection and support
What are the five types of bone?
Long Flat Short (cuboidal) Irregular Sesamoid
What is an example of the long bone?
Femur
What is an example of a flat bone?
Parietal bone of skull
What is an example of a short bone?
Calcaneus (heel bone)
What is an example of an irregular bone?
Sphenoid of skull
What is an example of a sesamoid bone?
Patella
What is a tuberosity?
Roughened rounded elevation
Ischial tuberosity
What is a tubercle?
Smaller elevation than tuberosity
Greater and lesser tubercle of humerus
What is a spine?
Slender projection
Spine of scapula (posterior)
What is a trochanter?
Large blunt projection
Gated trochanter of the femur
What is a condyle?
Large prominence or rounded surface
Lateral and medial femoral condyles
What is an epicondyle?
Smaller prominence than the condyles above a condyle
Lateral and medial epicondyle of humerus
What is a facet?
Flattened surface for joint, muscle attachments
Superior costal facet on the body of the vertebra for articulation with a rib
What is a crest?
Ridge
Iliac crest
What is a sinus?
Hollow space
What is a meatus?
Tunnel / canal
What is a fossa?
Depression
Infra spinous and supra spinous fossa of scapula
What is a foramen?
Hole, opening
Obturator foramen
What is a fissure?
Cleft or narrow slit
What is a notch?
Large groove
Greater sciatic notch
Where are bone markings and formations found?
Found where fascia, ligaments, tendons or aponeuroses are attached to bone
Are bone markings and formations found at birth?
Not present at birth
Appear after puberty
How do bone markings and formations form?
- Pulling of fibrous structures causes periosteum to be raised and new bone to be deposited beneath- tuberosity, condyles etc.
- Pressure on the bone surface may cause a groove, fossa, notch etc.
What is a joint?
An articulation between two or more bones
What is a fibrous joint?
Fibrous tissue
- syndesmoses (interosseous membrane in forearm- joins radius and ulnar)
- sutures (cranium)
- gomphosis (between root of tooth and alveolar process of jaw)
What is a cartilaginous joint?
Synchondroses- primary cartilage
- hyaline cartilage, growth plates
Sympheses- secondary cartilage
- fibrocartilage, pelvis and pubic symphysis
What is a synovial membrane?
Articular capsule (outer fibrous layer, lined by an articular cartilage at articulating surfaces of bone and a serous synovial membrane at all other surfaces) Synovial fluid
Erosion of the articulating surface = osteoarthritis
Secondary erosion = rheumatoid arthritis
What movements can synovial joints do?
Extension and flexion Adduction and abduction Internal (medial) rotation and external (lateral) rotation Circumduction Gliding
What are the 6 types of synovial joints?
Hinge Saddle Condyloid Pivot Ball and socket Plane
What movements does a hinge do?
Flexion and extension
E.g. Elbow joint
What movements does a saddle do?
Concave and convex joint surfaces
E.g. 1st MPJ
What movements does a plane do?
Gliding, sliding movements
E.g. Acromioclavicular joint
What movements does a pivot do?
Rotation (round bony process fits into a bony ligamentous socket)
E.g. Atlantoaxial joint and proximal radio ulnar joint
What movements does a candyloid do?
Flexion Extension Adduction Abduction Circumduction E.g. MCPJ
What movements does a ball and socket do?
Movements in several axes (rounded head fits into a concavity)
E.g. Shoulder and hip joints
What are joints stabilised by?
Articulation (shape size and surfaces)
Ligaments and capsules
Muscles and muscle tone
What is the Sagittal plane?
Plane that separates left from right
What is the coronal plane?
Separates anterior from posterior
What is the transverse plane?
Separates superior and inferior
What are the two surfaces of the hand?
Dorsal- back of hand
Palmar- palm of hand
What are the two surfaces of the foot?
Dorsal - top of foot
Plantar - sole of foot
What does flexion mean?
Decreasing the angle between joints/ bending
What does extension mean?
Increasing the angle between joints/ straightening
What does abduction mean?
Limb movement away from the midline
What does adduction mean?
Limb movement towards the midline
What does internal (medial) rotation mean?
Towards the midline
What does external (lateral) rotation mean?
Away from the midline
What does circumduction mean?
Combining flexion, extension, abduction and adduction
What does pronation of the hands mean?
Hands face down
Towards the midline
What does supination of the hands mean?
Hands face up
Away from the midline
What does retraction of the shoulder mean?
Posterior movement of scapula
What does protraction of the shoulder mean?
Anterior movement of the scapula
What does flexion of the wrist mean?
Bending the wrist forward
What does extension of the wrist mean?
Bending the wrist back
Describe the following movements of the thumb: extension, flexion, abduction, adduction, opposition, reposition
Act them out
Describe the following movements of the fingers: extension, flexion, adduction, abduction, circumduction
Act them out
What does flexion of the hip mean?
Movement of lower limb forwards
What does extension of the hip mean?
Movement of leg backwards
What does dorsiflexion of the foot mean?
Decreasing angle between dorsal surface of foot and lower leg
What does plantar flexion mean?
Decreasing angle between plantar surface of foot and lower leg
What bones make up the upper limb and pectoral girdle?
Sternum Ribs Clavicle Scapula Humerus Radius Ulnar Carpals- trapezium, trapezoid, capate, hook of hamate, pisiform, triquestrum, lunate, scaphoid Metacarpals, Phalanges
What are the four main muscles in the pectoral region of the body?
Pectoralis major
Pectoralis minor
Subclavius
Serratus anterior
What is the proximal and distal attachment of the pectoralis major?
Proximal- clavicular head (anterior surface of medial half of clavicle) and sternocostal head (anterior surface of sternum, costal cartilages of 1-6; aponeurosis of external oblique muscle)
Distal- lateral lip of intertubercular sulcus of proximal humerus
What nerves innervate the pectoralis major?
Lateral and medial pectoral nerves
What movements can the pectoralis major control?
Adduction of the humerus
Medial rotation of the humerus (draws scapula inferiorly and anteriorly) (BOTH sternocostal head and clavicular head)
Flexion of humerus (clavicular head)
Extension of humerus (sternocostal head)
What are the proximal and distal attachments of the pectoralis minor?
Proximal- 3rd to 5th ribs near bathe costal cartilages
Distal- coracoid process of the scapula
What nerve innervates the pectoralis minor?
Medial pectoral nerve
What movements can the pectoralis minor control?
Stabilises scapula
Draws scapula inferiorly and inferiorly against the thoracic wall
What are the proximal and distal attachments of the subclavius?
Proximal- junction of the first ring and its costal cartilage
Distal- inferior surface of middle surface of the clavicle
What nerve innervates the subclavius?
Nerve to the subclavius
What movements does the subclavius control?
Anchors the clavicle
Depresses the clavicle
What are the proximal and distal attachments of the serratus anterior?
Proximal- external surfaces of the lateral parts of the 1st to 8th rib
Distal- anterior surface of medial border of scapula
What nerve innervates the serratus anterior?
Long thoracic nerve
What movement does the serratus anterior control?
Protracts the scapula (holds it agains the thoracic wall)
Rotates the scapula
What are the main features of the clavicle bone?
S shaped
Convex medially
Concave laterally
Acromioclavicular articulating surface (circular)
Sternoclavicular articulating surface (triangular)
Conoid tubercle (more lateral)
Costal tuberosity (more medial)
Inferior surface is rougher due to the attachments of ligaments
What are the main features of the scapula?
Anterior- subscapular fossa, scapula notch, coracoid process, glenoid cavity
Posterior- spine, supraspinous fossa, infraspinous fossa, acromion
What are the main features of the humerus bone?
Anterior, superior to inferior- head, anatomical and surgical neck, greater tubercle (lateral), lesser tubercle (medial), intertubercular sulcus/ groove, deltoid tuberosity, radial fossa, coronoid fossa, capitulum (lateral-radius) and trochlea (medial-ulnar) articulating surfaces
Posterior, superior to inferior- head, radial groove, olecranon fossa, medial epicondyle (larger) and lateral epicondyle
What are the main features of the radius?
Radial tuberosity
Radial styloid process
Ulnar notch
What are the main features of the ulnar?
Trochlear notch Coronoid process Radial notch Ulnar tuberosity Ulnar styloid process Olecranon process
What is the clinical relevance of the surgical neck of the humerus?
It’s the most commonest site of fractures
What is the clinical relevance of cutting the long thoracic nerve?
Winged scapula
Protraction can no longer occur
Describe some fractures of the clavicle
One of the most frequently fractured bones
Weakest region is junction of its middle and lateral thirds
Common in children (most often incomplete- greenstick fractures one side of bone is broken and other is bent), babies with broad shoulders in delivery,
Caused by indirect force transmitted from an outstretched hand though the bones of the forearm and arm during a fall, or direct fall on shoulder
After a fracture the sternocleidomastoid muscle elevates the medial fragment of bone- readily palpable
After a fracture- Trapezius muscle is unable to hold the lateral fragment of the clavicle up (due to the weight of the upper limb)- so shoulder drops
Pectoralis major may pull the arterial fragment of the clavicle medially (adduction)
Describe some fractures of the scapula
Usually result of severe trauma (RTA/ PTA)
Common with fractured ribs
Require little treatment- as scapula is covered in muscles on both sides
Most fractures include the protruding subcutaneous acromion process
Describe some fractures of the humerus
Surgical neck- (axillary nerve) Common in old people with osteoporosis; most commonly occurs due to minor fall on the hand with the force being transmitted up the forearm bones of the extended limb
Avulsion fracture of greater tubercle of humerus- common in middle aged and elderly people; small part of tubercle is avulsed (torn away); commonly occurs due to fall on acromion; in younger people usually occurs due to a fall on the hand when the armies in abduction; subscapularis muscle (still attached to humerus) plus limb into medial rotation
Transverse fracture of shaft of humerus- commonly occurs due to direct blow to arm; pull of deltoid muscle carries proximal fragment laterally
Spiral fracture of humeral shaft- commonly occurs due to fall on outstretched hand
Intercondylar fracture of the humerus- commonly occurs due to sever fall on flexed elbow; ole random of ulna is driven like a wedge between medial and lateral parts of the condyle of the humerus
Because the humerus is surrounded in muscle and had a well developed periosteum the bone fragments in fractures usually unite well
What nerves are at risk in a fracture of the humerus?
Surgical neck- axillary nerve
Radial groove- radial nerve
Distal end of humerus- median nerve
Medial epicondyle- ulnar nerve
What firmly binds the ulnar and radius?
Shafts of the bone are bound by the interosseous membrane- fracture of the bone is likely to be associated with the dislocation of the nearest joint
Describe some fractures of the radius and ulna?
Commonly occur due to severe injury
Fracture of distal end of radius- common in >50 yo; women with osteoporosis
Colles fracture- complete transverse fracture of distal 2 cm of the radius; most common fracture of forearm; distal fragment displaced dorsally and is often broken into pieces, ulna styloid process is broken off (avulsed); radial styloid process projects farther dismally than ulnar styloid process; commonly occurs when individual slips or trip and tries to break fall with the forearm and hand pronated; rich blood supply means good recovery
Describe some fractures of the carpals
Scaphoid- most frequent; fall on palm when hand is abducted (can be confused with severely sprained wrist)
Hamate- hook fracture; risk of damage to ulnar nerve and ulnar artery = decreased grip strength
How can the pectoral muscles be invaded by a breast tumour (fixed mass)?
Find out
What are the various arrangements of skeletal muscle?
Circular- orbicularis oris Convergent- pectoralis major Parallel- sartorius Unipennate- extensor digitorum longus Bipennate- rectus femur is Fusiform- biceps brachii Multipennate- deltoid
What are some functions of skeletal muscle?
Movement
Posture
Stability
Heat generation
What is the mechanical efficiency of skeletal muscle?
About 20%
So 80% lost as heat
What is the gross anatomy of skeletal muscle?
Epimysium surrounds whole muscle/ bundles of fascicles
Perimysium surrounds individual fascicles/ bundles of muscle fibres
Endomysium surrounds individual muscle fibres/ bundles of myofilaments
What is fasisculation?
Muscle twitching
Occurs when tires
Occurs in motor neurone disease (when motor neurones degenerate)
What are the three classes of levers of skeletal muscle?
First class lever (skull balanced on top of vertebrae), second class lever (gastronemeus and calcaneus bone) and third class lever (biceps brachii)
Which class of lever is the least efficient?
Third class
What is an agonist?
Prime movers- main muscles responsible for a particular movement
What is an antagonist?
Oppose prime movers
What is a synergist?
Assist prime movers
Neutralise extra motion
What is a fixator?
Stabilises the action of prime movers
E.g. Fixes a non moving joint when prime movers act over two joints
What are the compartments of skeletal muscle?
In a transverse section compartments are the anterior and posterior regions
Each compartment has its own fascia
What is the compartment syndrome?
When blood vessels burst
Pressure builds up and is exerted on the nerve
Paraesthesia, numbness, pain
How does muscle contraction occur?
You know this- refer to esa1
How does muscle relaxation occur?
Calcium is pumped back int the sarcoplasmic reticulum via calcium pumps (SERCA)
*some calcium can bind to calmodulin
What is isotonic contraction?
Constant tension
Variable muscle length
Can be: concentric (muscle shortens - lifting a load with the arm) or eccentric (muscle exerts a force while being extended- walking down hill) - result in DOMS (delayed onset muscle soreness a few days after)
What are the muscle fibre types?
Red (slow, oxidative) - darker, aerobic, high myoglobin levels, many mitochondria, rich capillary supply, fatigue resistant, endurance activities, posture
Pink (fast, oxidative) - medium, aerobic, high myoglobin levels, many mitochondria, rich capillary supply, moderate fatigues resistance, walking and sprinting
White (fast, glycolytic) - lighter, anaerobic, low myoglobin levels, few mitochondria, poorer capillary supply, rapidly fatigable, short intense movements
What is spatial summation?
Lots of neurones are activated to recruit a single skeletal muscle
What is temporal summation?
Increased frequency of action potential to muscle fibres causes summation, tetanus (unfused- twitch/ fused- contract)
What is clostridium tetanii?
When a toxin interferes with the feedback control of a motor neurone - tetanus- twitching and contractures
What is a motor unit?
Motor neurone and the muscle fibre it innervates
2-2000 muscle fibres (dependent on necessity)
How does a motor neurone and a muscle fibre communicate in a motor unit?
Via cross talk
Signalling molecules communicate between the nerve and muscle (neurotrophins- neurotrophin3, cytokinesis cardiotrophin1, insulin like growth factors- IGF1)
What us the clinical relevance of atrophy of a nerve or muscle fibre in a motor unit?
Can lead to atrophy of the corresponding nerve or muscle fibre
What is muscle tone?
Baseline tone present in muscles at rest due to: motor neurone activity and muscle elasticity
How is muscle tone controlled?
Via motor control centres in the brain
Via afferent fibre signals originating in the muscle
What is hypotonia?
Decreased muscle tone due to:
Damage to motor cortex/cerebellum (involved with feedback)
Shock/ damage to spinal cord
Lesion of sensory afferents from muscle spindles
Primary degeneration of muscle- myopathies
Lesion of lower motor neurones- poly neuritis
How is the force of contraction controlled?
Proprioception Feedback control of movement Proprioreceptors- muscle spindles Associated with nerve endings Tells the brain how much force the muscle is exerting
What are the sources of energy for contraction?
1 short term stores of ATP in muscle fibre (few seconds)
2 phosphorylation of ATP fro. Creatine phosphate using creatine kinase (15 seconds)
3 anaerobic glycolysis and lactate formation (20-40 seconds) (glycolysis of blood glucose or glucose 6 phosphate from muscle glycogen)
4 aerobic respiration (ox phos)- prolonged aerobic muscular events
What is muscle and peripheral fatigue?
Depletion of muscle glycogen stores
Within one minute if blood flow is interrupted
What is a contracture?
State of continuous contraction
E.g. No ATP - rigor mortis
What are the 6 surfaces of the axilla?
Apex, lateral wall, medial wall, posterior wall, anterior wall, base
What does the apex of the axilla interact with?
First rib, clavicle, superior edge of clavicle
What does the lateral wall of the axilla interact with?
Narrow bony wall formed by intertubercular sulcus in the humerus
What does the medial wall of the axilla interact with?
Formed by thoracic wall (1st to 4th ribs and intercostal muscles) and overlying serratus anterior
What does the base of the axilla interact with?
Skin, subcutaneous tissue and axillary (deep) fascia extending from arm to thoracic wall (at 4th rib level) forming the axilla fossa- armpit
What does the anterior wall of the axilla interact with?
Pectoralis major and minor and pectoral and claviopectoral fascia associated with them
What does the posterior wall of the axilla interact with?
Anterior surface- scapula, subscapularis muscle
Posterior surface- there’s major and latissimus dorsi
How are the arteries of the upper limb arranged?
Brachiocephalic trunk- subclavian- axillary- brachial artery
Axillary-
1st part- between lateral border of 1st rib and medial border of pectoralis minor, enclosed by a sheath, 1 branch- superior thoracic artery
2nd part- posterior to pectoralis minor, 2 branches- thoracoacromial artery (medial to pecmin) and lateral thoracic artery (lateral to pecmin)
3rd part- between inferior border of pectoralis minor to inferior border of teres major, 3 branches- subscapularis artery (LARGEST) , anterior circumflex humeral and posterior circumflex humeral artery (share a common trunk)
What are the branches of the axillary artery?
Superior thoracic artery Thoracoacromial artery Lateral thoracic artery Subscapularis artery Posterior circumflex humeral artery Anterior circumflex humeral artery
How are the veins of the upper limb arranged?
Brachial and basilic vein- axillary vein (or cephalic vein which enters axillary vein superior to the pec minor, close to its transition into the subclavian vein) - subclavian vein
What are the five main groups of axillary lymph nodes and their arrangement?
Pectoral Subscapular Humeral ALL FEED INTO Central WHICH FEED INTO Apical WHICH FEEDS INTO Subclavian lymphatic trunk
What are the five regions of the brachial plexus?
Roots Trunks Division Cords Terminal branches
Describe the brachial plexus
Roots - C5,6,7,8 T1
Trunks- C5 & 6 join to form superior, C7 forms middle, C8 & T1 form inferior
Divisions- anterior and posterior
Cords- lateral, posterior and medial
Terminal branches- musculocutaneous, median, radial, ulnar, axillary
What does each terminal branch of the brachial plexus supply?
Find out
What is axillary clearance (removal of lymph nodes) and the clinical relevance of this?
Removal of the axillary lymph nodes
In breast cancer- important to determine the degree to which the cancer has metastasised, lymph collects in axilla region (pectoral lymph odes drain to apical and central lymph nodes), remove any cancer cells which may have metastasised to axillary lymph nodes
In removal, you must be careful of damaging long thoracic nerve (winged scapula) and thoracodorsal nerve (Weakened medial rotation and adduction of the arm)
What is lymphangitis in the upper limb?
An infection in the upper limb can cause the axillary nodes to enlarge and become tender and inflamed
Usually involves the humeral group of nodes
Lymphangitis is characterised by the development of warm, red, tender streaks in the skin of the limb
What are some clinically significant injuries of the brachial plexus?
Erbs palsy UBP injury
Klumpke palsy LBP injury
What are the anterior muscles of the arm?
Biceps brachialis
Brachialis
Coracobrachialis
What are the posterior muscles of the arms?
Triceps brachii
Deltoid
Anconeus
Describe the structure, location, origin, insertion, innervation and main actions of the biceps brachii
Structure: 2 headed muscle
Location: anterior of humerus, but not attached to humerus
Origin: short head- coracoid process/ long head- supraglenoid cavity of scapula
Insertion: radial tuberosity
Innervation: musculocutaneous nerve
Main action: supination of forearm, flexion of arm at elbow and shoulder (when forearm is supinated)
2 headed muscle
Anterior of humerus
Describe the structure, location, origin, insertion, innervation and main actions of the coracobrachialis
Structure: strap like
Location: lies deep to biceps brachii in the arm
Origin: coracoid process
Insertion: medial side of humeral shaft at the level of the deltoid tubercle
Innervation: musculocutaneous nerve
Main action: flexion of arm at shoulder
Describe the structure, location, origin, insertion, innervation and main actions of the brachialis
Structure:
Location: lies deep to biceps brachii, found more distally than other muscles of the arm, forms base of cubital fossa
Origin: medial and lateral surfaces of humeral shaft
Insertion: tuberosity of ulna- distal to elbow joint
Innervation: musculocutaneous nerve and radial nerve (small portion)
Main action: main flexion at elbow (in all positions)
Describe the structure, location, origin, insertion, innervation and main actions of the triceps brachii
Structure: 3 headed muscle, medial head of triceps lies deeper than the other two, which cover it (so not visible unless the other two heads are dissected away)
Location: posterior compartment
Origin: lateral head- humerus, superior to radial groove/ long head- infraglenoid cavity/ medial head- humerus, inferior to radial groove
Insertion: three heads converge to form one muscle and one tendon which attaches to the olecranon of the ulna
Innervation: radial nerve
Main action: extension of the arm at the elbow
Describe the structure, location, origin, insertion, innervation and main actions of the anconeus
Structure:
Location:
Origin: posterior aspect of lateral epicondyle
Insertion: lateral olecranon
Innervation: radial nerve
Main action: weak elbow extension, abducts ulna during forearm pronation
Describe the structure, location, origin, insertion, innervation and main actions of the deltoid
Structure:
Location:
Origin: outer 1/3 of anterior clavicle, outer border of acromion and lower border of spine of scapula
Insertion: deltoid tuberosity
Innervation: axillary nerve
Main action: abduction of humerus, anterior fibres flex arms, posterior fibres extend arms
What muscles of the back are there?
Trapezius Latissimus dorsi Levator scapulae Rhomboid major and minor Deltoid Teres major Rotator cuff muscles- supraspinatus, infraspinatus, subscapularis, teres minor
Describe the structure, location, origin, insertion, innervation and main actions of the trapezius
Structure:
Location: superficial
Origin: occipital bone, ligamentum nuchae (links cervical vertebrae together, spine of 7th cervical, spines of all thoracic vertebrae
Insertion: upper fibres- lateral third of clavicle/ middle and lower fibres- acromion and spine of scapula
Innervation: spinal part of accessory nerve (motor)
Main action: elevates scapula, retracts scapula, depresses scapula
Describe the structure, location, origin, insertion, innervation and main actions of the latissimus dorsi
Structure:
Location: superficial
Origin: iliac crest, lumbar fascia, spines of lower 6 thoracic vertebrae, lower 3 or 4 ribs, inferior angle of scapula
Insertion: floor of bicipital groove of humerus (intertubercular)
Innervation: thoracodorsal nerve
Main action: extends arm at shoulder joint, powerfully adducts arm at shoulder joint, medially rotates arm at shoulder joint
Describe the structure, location, origin, insertion, innervation and main actions of the levator scapulae
Structure:
Location: deep
Origin: transverse processes of 1st 4 cervical vertebrae
Insertion: medial border of scapula
Innervation: C3 C4 dorsal scapula nerve
Main action: raises medial border of scapula- elevates scapula, rotates scapula
Describe the structure, location, origin, insertion, innervation and main actions of the rhomboid minor
Structure:
Location: deep
Origin: ligamentum nuchae and spines of 7th cervical and 1st thoracic vertebrae
Insertion: medial border of scapula
Innervation: dorsal scapular nerve
Main action: raises medial border of scapula upwards and medially- retracts and rotates scapula
Describe the structure, location, origin, insertion, innervation and main actions of the rhomboid major
Structure: Location: deep Origin: 2nd-5th thoracic spines Insertion: medial border of scapula Innervation: dorsal scapular nerve Main action: raises medial border of scapula upwards and medially, retracts and rotates scapula
Describe the structure, location, origin, insertion, innervation and main actions of the teres major
Structure:
Location: scapulo-humeral
Origin: lower third of lateral border of scapula
Insertion: medial lip of bicipital groove of humerus (intertubercular)
Innervation: lower subscapular nerve
Main action: medially rotates and adducts arms, stabilises shoulder joint
Describe the structure, location, origin, insertion, innervation and main actions of the supraspinatus
Structure:
Location: scapulo-humeral
Origin: supraspinous fossa of scapula
Insertion: greater tuberosity of humerus, capsule of shoulder joint
Innervation: suprascapular nerve
Main action: abducts arms, stabilises shoulder joint
Describe the structure, location, origin, insertion, innervation and main actions of the infraspinatus
Structure:
Location: scapulo-humeral
Origin: infraspinous fossa of scapula
Insertion: greater tuberosity of humerus, capsule of shoulder joint
Innervation: suprascapular nerve
Main action: laterally rotates arm, stabilises shoulder joint
Describe the structure, location, origin, insertion, innervation and main actions of the teres minor
Structure:
Location: scapulo- humeral
Origin: upper 2/3s of lateral border of scapula
Insertion: greater tuberosity of humerus, capsule of shoulder joint
Innervation: axillary nerve
Main action: laterally rotates arm, stabilises shoulder joint
Describe the structure, location, origin, insertion, innervation and main actions of the subscapularis
Structure:
Location: scapulo- humeral
Origin: subscapular fossa of scapula
Insertion: lesser tuberosity of humerus
Innervation:upper and lower subscapular nerves
Main action: medially rotates arm, stabilises shoulder joint
What are the 4 rotator cuff muscles?
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
What are three main features of the shoulder joint?
Relatively unstable: most commonly dislocated joint
Very mobile
Greatest range of movement
What is the glenohumeral joint?
Shoulder joint, synovial joint, ball and socket
What are the articular surfaces of the glenohumeral joint?
Head of humerus and glenoid cavity of scapula
Lined by hyaline cartilage
Glenoid labrum (fibrocartilage rim)- which deepens glenoid cavity and makes it more stable
How does the articulating surface appear in an X ray?
Articular hyaline cartilage is radioluscent and so appears as a clear black space
What is the capsule of the glenohumeral joint?
Capsule is attached to- glenoid labrum, margins of glenoid cavity of scapula, anatomical neck of humerus
Capsule bridges intertubercular (bicipital) groove and dips down medially to the surgical neck- provides laxity of full abduction
Capsule has a small opening anteriorly where the synovial membrane of the shoulder joint communicates with the subscapular bursa
Synovial membrane lines capsule and bone upto the edge of articular surfaces
Tendon of long head of biceps lies within the joint cavity (attached to supra glenoid cavity of scapula)
Tubular sleeve of synovium reflected back around the biceps tendon like a tube
Synovium and joint cavity is continuous with subscapular bursa through a gap in the capsule
What are the intrascapular ligaments?
3 glenohumeral ligaments (superior, middle and inferior)
There are three fibrous bands extending between glenoid labrum and humerus
Form part of the fibrous capsule and reinforce it anteriorly (can only be seen from the inside) of the capsule
What four extra capsular ligaments are there?
Coracoacromial ligament
Coracohumeral ligament
Transverse humeral ligament
Coracoclavicular (trapezoid and conoid)
What is the extra capsular coracoacromial ligament?
Coracoacromial ligament (CAL) Between acromion and coracoid process Coracoacromial arch consists of the ligament, acromion and coracoid process Strong osseoligamentous structure Overties humeral head Prevents upper displacement of humerus
What muscles are involved in flexion of the shoulder joint?
Pectoralis major (clavicular head) Anterior fibres of deltoid Coracobrachialis and biceps brachii
What is the extra capsular coracohumeral ligament?
Ligament which lies between the coracoid process and greater tubercle of the humerus
What is the extra capsular transverse humeral ligament?
Bridges the greater and lesser tubercle
Holds the long head of the biceps brachii in place during shoulder movements
What muscles are involved in extension of the shoulder joint?
Posterior fibres of deltoid
Latissimus dorsi
Teres major
What muscles are involved in abduction of the shoulder joint?
0-20 supraspinatus (initiator of abduction)
20-90 deltoid (central fibres)
Above 90 by rotation of scapula- trapezius, serratus anterior
What muscles are involved in adduction of the shoulder joint?
Pectoralis major
Latissimus dorsi
Teres major
What muscles are involved in medial rotation of the shoulder joint?
Subscapularis
Teres major
Pectoralis major
Latissimus dorsi
What muscles are involved in lateral rotation of the shoulder joint?
Infraspinatus
Teres major
What muscles are associated with the shoulder joint?
Supraspinatus Infraspinatus Teres minor Subscapularis Deltoid Long head of biceps Long head of triceps
What is a bursa?
Small sacs filled with synovial fluid and lined by synovial membrane which facilitate movement of tendons and muscles on one another and bone by reducing friction
What does the subscapular bursa do?
Facilitates movement of the tendon of the subscapularis muscle over the scapula
Communicates with the joint cavity
What does the subacromial bursa do?
Facilitates movement of supraspinatus tendon under the CAA and the deltoid muscle over the shoulder joint capsule and the greater tubercle of the humerus
What is the blood supply of the shoulder joint?
Anterior and posterior circumflex humeral arteries
Suprascapular artery
What is the nerve supply of the shoulder joint?
Suprascapular nerves
Axillary nerves
Lateral pectoral nerves
(From the brachial plexus C5,C6)
What provides the stability of the shoulder joint?
- Tendons of the rotator cuff muscles (posterior, anterior, superior)
- Coracoacromial arch (superior)
- Glenohumeral ligaments (anterior, inferior)
- Coracohumeral ligament (superior)
- Deepening glenoid cavity by labrum (all around)
- Splinting effect of : long heads of biceps (above) and long head of triceps (below)
Which border of the shoulder joint is least supported?
Inferiorly
How do muscle tendons associated with the shoulder joint increase its stability?
Tendons blend with each other as they approach the humeral head to form a cuff
Tendinous cuff also fuses with the capsule (and strengthens it)
Tone in muscles holds the head of the humerus close to the glenoid cavity
Supraspinatus tendon separated from the CAA by subacromial bursa
What do somites consist of?
Sclerotome
Myotome
Dermotome
Surrounding the neural tube
In an adult, what is the remnant of the dermomyotome?
Dermis and muscle
How is a somite associated with the neural tube?
Dermomyotome develops in association with a specific neural level of the embryonic neural tube tissue
Dermomyotome takes its nerve supply with it irrespective of where it ends up in the adult body
What is the adult nervous supply to the dermis and muscle of a dermomyotome?
Spinal segmental nerve
What is the structure of the spinal cord?
Long cylindrical column
Consists of millions of nerve cell bodies (grey) and neurone axons (white)
4 regions: cervical, thoracic, lumbar, sacral
Starts where medulla of brain ends
Ends at conus medullaris (membrane tapers into a ligament - film terminale)
What is the name of the ligament at the end of the spinal cord?
Filum terminale
What is the vertebral foramen?
Hole in which the spinal cord runs through the vertebrae (some of the vertebral column ends above 2/3)
What is the intervertebral foramina?
Holes on either side of each vertebra through which the spinal nerves leave the spinal canal
Describe the structure of the mixed spinal nerve
Dorsal RAMUS of spinal nerve Dorsal root ganglion Afferent dorsal root of spinal nerve Efferent ventral root of spinal nerve Ventral ramus of spinal nerve Sympathetic chain Roots of splanchnic nerve
What is segmentation?
Sensory nerves serve discrete territories of skin (sensations of the segment are fed through this route)
Motor nerves sever myotomial territories (motor instructions of the segment are mediated through this route)
What is the difference between the neural (spinal) and vertebral level?
Neural level is the neural tissue given off by the spinal cord
Vertebral level is the bone tissue at which the spinal cord gives off a pair of nerves - neural level exists)
As the mixed spinal nerve emerges through the intervertebral foramen what two branches does it divide into?
Dorsal RAMUS medial and lateral (small) Ventral RAMUS (large)
What is the nerve supply to the upper limb?
Spinal cord Cervical spinal segment (C5-T2) BRACHIAL plexus (C5-T1) and T2 roots Radial nerve Musculocutaneous nerve Ulnar nerve Median nerve Lateral pectoral, upper subscapular, lower subscapular, dorsal scapular, suprascapular, long thoracic, axillary
What is the nerve supply to the lower limb?
Spinal cord
Lumbar spinal segments (L1-1/2 of L4)- posterior to psoas major muscle (nerves arise medially and laterally to psoas major) Illiohypogastric nerve Illoinguial nerve Lateral cutaneous of thigh Femoral Genitofemoral Obturator Lumbosacral trunk
Sacral spinal segments (1/2 of L4 - S4) - anterior primary rami, within pelvic cavity, near to piriformis, supplies gluteal and perineal region and the lower limb via the sciatic nerve Gluteal nerve Common peroneal nerve Tibial nerve Sciatic nerve Pudendal nerve Perforating cutaneous nerve Posterior cutaneous nerve of the thigh Nerve to obturator internus Nerve to quadratus femoris
Why are limb dermatomes important?
Enable organised examination of integrity and sensory function of skin
Pinpoints regions of skin with disturbed function
Predicts what nerves and spinal segments may be affected by injury
When disturbed its important to anaesthetise segments of nerves and associated skin with accuracy
Define a dermatome
Area of skin supplied by sensory nerve fibres from a single spinal level (neural level)
What does it mean (in reality) that there is a functional overlap between adjacent dermatomes?
There is a functional overlap between adjacent dermatomes
So some regions are served by 2 successive spinal nerve
So a dermatome sandwiched between 2 others will have 3 successory sensory nerves
Why is it advantageous for adjacent dermatomes to have a functional overlap?
Ensures there is no skin without a nerve supply
If you have a lesion, there I backup by two adjacent nerve supplies
Therefore for damage to occur, large amounts of the spinal cord would need to be damaged!
Describe what the axial lines of limbs are
Axial lines of limbs- line of junction between 2 dermatomes supplied by discontinuous spinal levels
Boundaries between flexor and extensor compartments of the limbs
Cephalic and basilic vein in upper limb
Great and small saphenous vein in lower limb
What are the anterior superficial muscles of the forearm?
Pronator teres
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris
What is the anterior intermediate muscle of the forearm?
Flexor digitorum superficialis
What are the anterior deep muscles of the forearm?
Flexor digitorum profundus
Flexor pollicis longus
Pronator quadratus
What forms the roof of the carpal tunnel?
Flexor retinaculum
What forms the base of the carpal tunnel?
Extensor retinaculum
What 10 things run through the carpal tunnel on the anterior surface of the arm?
4 tendons of flexor digitorum superficialis
4 tendons of flexor digitorum profundus
1 tendon of flexor pollicis longus
Median nerve
What muscles does the median nerve supply of the anterior forearm?
Flexor carpi radialis
Pronator teres
Palmaris longus
Flexor digitorum superficialis
Flexor digitorum profundus (anterior interosseous nerve from median)
Flexor pollicis longus (anterior interosseous nerve from median)
Pronator quadratus (anterior interosseous nerve from median)
What muscles does the ulnar nerve supply of the anterior forearm?
Flexor carpi ulnaris
Flexor digitorum profundus
What are the common fractures of the forearm and which structures are damaged?
Mid shaft humeral fracture- Radial nerve injury
Fracture half way up forearm- Median nerve injury
Cubital tunnel / wrist / hand fracture - Ulnar nerve injury
What are the consequences of a mid shaft humeral fracture?
Common in younger and more active people
Injury to radial nerve (humeral radial groove on posterior surface of humerus)
WRIST FUNCTION TEST- paralysis of posterior compartments of forearm- no longer can extend arm- wrist drop
What are the consequences of median nerve injury?
Mostly due to fractures higher up the forearm, not the wrist
TEST- flexion of proximal interphalangeal joints of 1st and 3rd fingers are lost and flexion of distal interphalangeal joints of fingers are reduced- so impossible to make a fist- hand of Benedicts(2nd and 3rd finger remain partially extended
Cutaneous branch of median nerve -loses sensation in forearm
What are the consequences of ulnar nerve injury?
Posterior to medial epicondyle of humerus
Cubital tunnel, wrist, Hand
Numbness and tingling in 5th and 1/2 of 4th digit
TEST- MCPJoints become hyperextended- cannot extend 4th and 5th DIJ which are supplied by the ulnar
Denervation of intrinsic muscles in the hand/ wrist
Adduction is impaired- hand is drawn to the lateral side
Describe the structure, location, origin, insertion, innervation and main actions of the brachioradialis
Structure: border muscle
Location: superficial anterior forearm
Origin: proximal 2/3s of the supra epicondyle ridge of humerus
Insertion: lateral surface of distal end of radius, proximal to styloid process
Innervation: radial nerve
Main action: weak flexion of the arm
Describe the structure, location, origin, insertion, innervation and main actions of the pronator teres
Structure:
Location: superficial anterior forearm
Origin: medial epicondyle of humerus, coronoid process of ulna
Insertion: middle of convexity of lateral surface of radius
Innervation: median nerve
Main action: pronation of forearm at elbow, flexion of forearm at elbow
Describe the structure, location, origin, insertion, innervation and main actions of the flexor carpi radialis
Structure: Location:superficial anterior forearm Origin: medial epicondyle of humerus Insertion: base of 2nd metacarpal Innervation: median nerve Main action: flexion of hand a wrist, abduction of hand at wrist
Describe the structure, location, origin, insertion, innervation and main actions of the palmaris longus
Structure:
Location: superficial anterior forearm
Origin: medial epicondyle of humerus
Insertion: distal half of flexor retinaculum and apex of palmar aponeurosis
Innervation: median nerve
Main action: flexion of hand at wrist, tenses palmar aponeurosis
Describe the structure, location, origin, insertion, innervation and main actions of the flexor carpi ulnaris
Structure:
Location: superficial anterior forearm
Origin: medial epicondyle of humerus, olecranon and posterior border of ulna (via aponeurosis)
Insertion: pisiform, hook of hamate, 5th metacarpal
Innervation: ulnar nerve
Main action: flexion of hand at wrist, adducts hand at wrist
Describe the structure, location, origin, insertion, innervation and main actions of the flexor digitorum superficialis
Structure:
Location: intermediate anterior forearm
Origin: medial epicondyle of humerus, radius (superior half of anterior border)
Insertion: shafts of middle phalanges of medial 4 digits
Innervation: median nerve
Main action: flexes middle phalanges at proximal interphalangeal joint of middle 4 digits, acting more strongly it flexes proximal phalanges at metacarpalphalangeal joints
Describe the structure, location, origin, insertion, innervation and main actions of the flexor digitorum profundus
Structure:
Location: deep anterior forearm
Origin: proximal 3/4 of medial and anterior surfaces of ulna and interosseous membrane
Insertion: base of distal phalanges of 2nd, 3rd, 4th and 5th digits
Innervation: ulnar nerve and anterior interosseous nerve (from median)
Main action: flexes distal phalanges 2,3, 4 and 5 at distal interphalangeal joints
Describe the structure, location, origin, insertion, innervation and main actions of the flexor pollicis longus
Structure:
Location:
Origin: anterior surface of radius and adjacent interosseous membrane
Insertion: base of distal phalanx of thumb
Innervation: anterior interosseous nerve (of median nerve)
Main action: flexes phalanges of thumb
