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HUBS1105 - Musculoskeletal Anatomy Lecture 3 - Overview of Muscles, Fascia and Bursa ✴ Describe the core functions of skeletal muscle Skeletal muscle: striated voluntary muscle Functions of skeletal muscle: - transform chemical energy to mechanical energy - movement and stabilisation of position - posture - supports soft tissues - guards entrances and exits - regulate organ volume - generate heat / maintains body temperature - propel fluids and food matter Properties of skeletal muscle: - electrical excitability (muscle action potentials —> can respond to external stimuli) - contractibility - extensibility - elasticity Muscle tissues types: - skeletal striated muscle —> voluntary, can move and stabilise - cardiac striated muscle —> involuntary (walls of heart) - smooth muscle —> involuntary visceral muscle, lines most vessels and hollow organs in body - this course we focus on skeletal striated muscle Skeletal muscle: - has bundles of striated muscle fibres - made up of large cells with numerous nuclei - have 2 types of fibres that have different physiological properties: 1. Slow twitch. Use for endurance, therefore in postural muscles (those used to keep an upright posture). 2. Fast twitch. Used for short, forceful contractions, found in phasic muscles (responsible for moving us). - muscle is dependant on genetics, and partly exercise - muscles usually have white noncontractible bits called tendons - tendons are usually attached directly or indirectly to bone - a motor neurone and all of the muscle cells it stimulates is called a motor unit. The nerve supply to a muscle is what allows it to contract.

Skeletal Muscle continued: - they contain skeletal muscle tissue, connective tissue, blood vessels and nerves - muscle tissue is effected by age, health, use and body biomechanics - many act to hold body upright against gravity (postural muscles) - muscles make 40% total body weight, - with age comes decrease in muscle mass and increase in fat (adipose tissue)

✴ Describe the roles of fascia and bursae within the musculoskeletal system Fascia & Septa - fascia is a collagenous connective tissue - it helps maintain shape and position of muscles - allows muscles to glide on each other with little friction - deep fascia (known as septa) divides and separates each muscle into compartments - Each compartment encloses specific muscles and nerves - fascia wraps limbs and divides muscle into groups - it holds tendons in place - provides attachment for muscles - often thickens to become a retinaculum (band around tendons to hold them in place)

Tendons - white fibrous cord or sheet that attaches muscle to bone (sometimes muscle to muscle) - they vary in shape and size - often contribute to naming of muscle (Semitendinosus – a hamstring muscle) - an aponeurosis is a sheet like tendon (abdominal aponeurosis) - some tendons have small bones lying within them (sesamoid bones - patella) - Function of sesamoid bones: 1. protect tendon from excessive friction 2. act to lengthen effective lever arm

Tendon Sheaths and Bursae - Bursae: closed sacs formed from a membrane that makes synovial fluid - occur in locations subject to friction - often under bony prominences - in some areas (e.g. hand) theres fluid filled tunnels called sheaths - these encase tendons to reduce friction and provide tendon protection and nutrition

Muscle Terminology - its often descriptive and relates to the following features of the muscle: Features

Examples

Orientation

Rectus (meaning straight)

Region of body

Gluteal

Structural Features - shape - length - size - components

Example: deltoid (triangular), rhomboid (rhombus), quadratus longus/brevis maximus/minimus triceps (3heads), biceps (2 heads), quadriceps (4 heads)

Actions

Adductor, flexor

Axial

located on axial skeleton

Appendicular

stabilise/move appendicular skeleton

Aponeurosis

sheet of tissue

Architecture of Skeletal Muscle - shape and structure of skeletal muscle varies and depends greatly on its function - there are several fibre orientations that can be seen in skeletal muscle: 1. Pennate (feather like) 2. Fusiform (spindle shaped) 3. Circular aka sphincters 4. Convergent 5. Quadrangular 6. Multi headed or bellied 7. Flat 8. Strap

✴ Give an example of one of each of the following: a muscle with 2 heads; 3 heads; 4 heads; multiple bellies; a flat muscle; a radially arranged muscle and a convergent muscle. 2 heads: biceps 3 heads: triceps 4 heads: quadriceps femoris multiple bellies: rectus abdominis flat muscle: trapezius radially arranged muscle: ????? convergent muscle: pectoralis major

Names of muscles give us clues about the muscle: Name

Example

SIZE Maximus (largest) Minor (small) Longus (long)

Gluteus Maximus Pectoralis Minor Abductor Polis Longus

SHAPE Rhomboid Deltoid

Rhomboid major and minor Deltoid

LOCATION Pectoralis (chest) Femoris (femur)

Pectoralis major Quadriceps femoris

NO. OF HEADS Triceps (3 heads) Brachi = arm ORIENTATION Rectus (straight) ACTION Extensor (extends a joint) Carpi = wrist and radialis = relates to radius

Triceps brachi

Rectus abdominis Extensor carpi radialis

✴Define the following terms: origin, insertion, action, prime mover (agonist), antagonist, synergist, fixator, isometric, concentric, eccentric and pennation Muscle Definitions Origin —> muscle attachment: bone/area generally fixed, usually proximal Insertion —> muscle attachment: bone/area generally moves, usually distal Action —> movement produced Prime Mover —> agonist: produces main movement Antagonist —> in opposition to antagonist Synergist —> assists agonist, prevents unwanted movement (fixator or stabiliser) Pennation —> a pennate muscle is a muscle with fibres that attach in a slanting position to its tendon. These types of muscles generally allow higher force production but smaller range of motion. Concentric —> muscle length shortens with tension Eccentric —> muscle length increase with tension Isometric —> contraction with constant length (no movement)

Lecture 4 - The Pectoral Girdle

✴ Correctly apply the anatomical terminology relating to the bones of the pectoral girdle and glenohumeral joints The Upper Limb Functions: - upper limb is modified to increase range, direction and accuracy of placing and stabilising the hand - modified to give greater tactile input & manipulative function - the shoulder girdle extends range of movement of limb = reach - clavicle = a strut - glenohumeral joint = great mobility for limb placement - stability vs mobility trade off = glenohumeral is most mobile but least stable - elbow = angular movements to direct hand placement - superior and inferior radioulnar joints = refine hand placement - joints of wrists and fingers = dexterity and sensory info Terms related to the shoulder: Axilla: arm pit Brachium: arm (e.g. biceps brachii) Clavicle: collar bone Scapula: shoulder blade

THE PECTORAL GIRDLE Functions: - extends the ROM of the shoulder. The scapula is a light and flat bone that allows for muscle attachment and a high ROM. The clavicle acts as a strut. The pec girdle gives the upper arm reach.

The Sternum - the sternum is a flat bone - develops via endochondral ossification - articulates with the medial end of the clavicle (sterno-clavicular joint) - sternum is protective …. why?

Relationships of the sternum,sterno-clavicular joint and clavicle - sternum and ribs are protective of vital structures (heart, large vessels and lungs) - clavicle overlies nerves, arteries and veins.

✴ Identify major bony features of the clavicle and scapula Clavicle - blunt, larger ends articulate with sternum - flatter end lies laterally and joins with the acromion of the scapula at the AC (acromioclavicular joint) - smooth superior surface - slightly roughened interior surface for ligament attachments and subclavius (muscle) which inserts onto the clavicle and anchors it down - movement of the clavicle allows for extended reach ability of the shoulder region

The Sternoclavicular Joint - strong capsule, costoclavicular ligament and articular disc - strong but very mobile - saddle joint - two joint components because of the articular disc

Note: Movement of the clavicle allows for extended reach ability of the shoulder region

The Scapula - triangular - mostly a flat bone overlying 2-7th ribs - three fossae —> scooped out areas of bone - two posterior fossae divided by thick spine —> spine broadens laterally to form the acromion - concave costal (ribs) anterior surface that hugs ribs: sub scapular fossa - lateral and slightly forward facing glenoid fossa, rimmed with labrum to deepen socket - coracoid process —> projects anterolaterally (forward and sideways) like a bent finger pointing at the shoulder

Scapula Bony Markings

Surface anatomy of the Shoulder - bony prominences you can palpate for - glenoid fossa faces laterally, anteriorly and slightly superiorly - acromioclavicular joint forms hood over GH joint

Front View

Pectoral Girdle Relationships ✴ Classify the synovial joints found in the pectoral girdle ✴ Identify and name the main ligaments associated with these joints

Joints and Ligaments of Pectoral Girdle Joints: acromioclavicular, scapulothoracic, glenohumeral, sternoclavicular, Ligaments: coracoclavicular, acromio-clavicular, coracoacromial

Pectoral Girdle Stability The stability of the pectoral girdle is reliant on ligaments. Ligaments include: - acromioclavicular ligament - coracoclavicular ligament - two parts: trapezoid is more lateral pointing and conoid goes medially - coracoacromial ligament/arch —> forms a secondary socket —> prevents superior dislocation

Acromioclavicular Joint - lies between acromional end of the clavicle and the acromion of the scapula - a joint capsule surrounds the joint and a small disc lies within - strong ligaments are key to prevent dislocation - commonly injured

Joints of the pectoral girdle - ligaments important for stability - acromioclavicular ligs - coracoclavicular ligs (trap and conoid) - coracoacromial ligs Common injuries —> AC joint dislocation, ligament rupture, clavicle fractures. Can suffer from impingement syndrome. Long head of bicep follows red arrow from the radial tuberosity, over the bicipital groove and into the supraglenoid tubercle

✴ Describe and demonstrate the main movements of the pectoral girdle Scapula movements - protraction, retraction, elevation, depression, medial and lateral rotation (usually when shoulder adducts and abducts)

Fun Question: Is the coracoid process located anteriorly? TRUE

✴ Identify and describe the main origin, insertion and action of the 5 main muscles that move the pectoral girdle

Trapezius - Posterior - Trapezius has three sections, upper middle and lower fibres - Origin: base of scull to T12 spinous process - Insertion: outer clavicle, acromion and spine of scapula - Action: scapula elevation, retraction and depression

Rhomboids - posterior - major and minor - learn these together. - action: retraction and medial rotation of scapula - origin: the spinous process of C7 to T5 - the insertion is medial border of scapula (above and below scapular spine)

Levator scapulae - posterior - raises the shoulder girdle - origin: C1- C4 - insertion: superior angle of scapula - action: elevates and rotates scapula laterally (moves inferior angle medially)

Pectoralis Minor - anterior - origin: ribs 3-5 near costal cartilages - insertion: coracoid process - action: scapula protraction

Serratus Anterior - anterior - origin: lateral 1-8 ribs - insertion: medial border of scapula - action: protraction and lateral rotation of scapula, keeps it against chest wall

The image to the left is called “winged scapula” and results from the weakness of serratus anterior (it keeps scapula to chest wall)

SUMMARY PHOTOS!

Lecture 5 - The Glenohumeral or Shoulder Joint ✴ Identify the major bony features of the humerus and scapula that comprise the glenohumeral joint ✴ Classify the glenohumeral joint – what type of synovial joint? ✴ Name the cartilage that rims the glenoid fossa ✴ Describe and demonstrate main joint movements ✴ Identify and describe the origins, insertions (attachments)and actions of muscles that move the glenohumeral joint. This will also be continued in nextweeks classes…

Shoulder or the Glenohumeral Joint - it is a synovial, ball and socket or spheroidal joint - multi axial - dislocation is common - glenoid fossa is made more congruent (even) by a ring cartilage called the glenoid labrum - head of humerus articulates with glenoid labrum - fibrous capsule is fused with rotator cuff muscle tendons, allowing a large ROM (weakest inferiorly) - coracoacromial arch has a positive and negative role in the shoulder (impingement) - bursae are located sub scapular and sub-acromial, their function is …..

Anterior Humerus

Posterior Humerus

Glenoid Labrum - labrum is the lip - fibrocartilage rim - large difference between size of humeral head and glenoid fossa

Shoulder - Bones & Bumps - must know these

Humerus - The Bone of The Arm (Brachium)

Proximal Humerus

The Glenohumeral Joint - the capsule is reinforced by glenohumeral ligaments that blend into the capsule - the synovial joint holds a synovial membrane, articular cartilage and labrum

Glenohumeral Joint - bursae overlies the capsule and the sheath surrounding the long head of biceps tendon - subscapula bursa - subacromial bursa - they are shown by a space in the x-ray

Glenohumeral Joint - Movements include: - flexion/extension (saggital plane) - abduction/adduction (coronal plane) - medial/lateral rotation (transverse) - circumduction - Stability - with increased mobility comes decreased stability - ligaments and rotator cuff muscles become key in keeping the joint stable

Scapulo-humeral Rhythm -the scapula and humerus move in a 1:2 ratio -when arm is abducted 180 degrees, 60 degrees occurs by rotation of the scapula and 120 degrees occurs due to glenohumeral joint movement

Shoulder Dislocation - capsule of shoulder is weakest inferiorly (meaning dislocation occurs frequently by ball coming out below) - shoulder can be dislocated by extreme force or rotation - usually dislocation in position of extension, abduction and lateral rotation - shoulder instability after dislocation is common

Prime Movers of Glenohumeral Joint - flexion —> deltoid - extension —> deltoid - abduction —> supraspinatus (15 degrees), deltoid - adduction —> pectorals major, lat dorsi, teres major - medial rotation —> subscapularis (also lat dorsi and teres major) - lateral rotation —> infraspinatus, teres minor Deltoid - origin: anterior border and upper surface of the lateral third of the clavicle, acromion, spine of scapula - insertion: deltoid tuberosity of humerus - anterior fibres flex the shoulder - lateral fibres abduct the shoulder - posterior fibres extend, adduct and externally rotate - its a convergent/multipennate muscle with fibres coming from 3 places into one point

Pectoralis Major - origin: anterior border of medial half of clavicle, anterior surface of the sternum, aponeurosis of the external oblique muscle - insertion: crest of greater tubercle - large origin and small insertion - convergent muscle - action: the entire muscle does internal rotation and adduction, the clavicular and sternum parts help with flexion

Latissimus Dorsi - origin: spinous process of vertebrae T7-T12, thoracolumbar fascia, iliac crest, inferior 3 or 4 ribs and inferior angle of scapula - insertion: crest of lesser tubercle of humerus - action: extension, adduction and medial rotation of shoulder (rock climbing, swimming) - note: white bit at bottom of spine and top of iliac crest is the thoracolumbar fascia - large origin and small insertion - convergent muscle

Teres Major - not a rotator cuff muscle - origin: inferior angle of scapula - insertion: crest of lesser tubercle of humerus - action: adduction, medial rotation of humerus

Lecture 6 - The Shoulder (extension of last lecture) ✴ Identify the coracoid process and glenoid cavity of the scapula ✴ Identify on the humerus: the tubercles, head, neck (both), shaft, ! deltoid tuberosity, bicipital groove and radial groove ✴ Identify and describe the origins and insertions (attachments) and actions of the muscles that move the glenohumeral joint and the elbow: - Rotator cuff muscles, deltoid, teres major, pectoralis major and latissimus dorsi - Describe the role that 4 rotator cuff muscles play in joint stabilisation - Anterior compartment of arm (elbow flexors): biceps (short & long heads), brachialis; (shoulder flexor) coracobrachialis, - Posterior compartment of arm (elbow extensors): triceps (3 heads), anconeus !

Rotator Cuff - there are four rotator cuff muscles that provide stability; - subscapularis - supraspinatus - infraspinatus - teres minor

Rotator Cuff Muscles Plus the Teres Major Photo

Supraspinatus and Infraspinatus - supraspinatus aids in abduction of the shoulder - infraspinatus laterally (externally) rotates the shoulder

Rotator Cuff Muscles - they strengthen the capsule of the shoulder joint and help keep head of humerus in the glenoid fossa Subscapularis Origin: subscapular fossa Insertion: lesser tubercle of humerus Action: internally rotates shoulder, stabilises shoulder Supraspinatus Origin: supraspinous fossa Insertion: greater tubercle of humerus Action: abduction of arm, stabilises shoulder

Infraspinatus Origin: infraspinous fossa Insertion: greater tubercle of humerus Action: external rotation of humerus, stabilises shoulder Teres Minor Origin: lateral border of scapula Insertion: greater tubercle of humerus Action: lateral rotation of humerus

Subacromial Arch, Bursa and Rotator Cuff Muscles

Shoulder Design - due to shoulder design, the glenohumeral joint has very little joint stability - stability is improved by: - most stability given by 4 rotator cuff muscles - glenoid labrum - fibrous capsule thickened in places by ligaments The Brachium (arm) - refers to portion between shoulder and elbow Terminology Brachium: arm Cubitus: anterior elbow Carpus: wrist Function of this region Allows reach (@ the shoulder) Produces angular movements (@ elbow) Allows grasp (@ hand)

Humerus - Bone of the Arm

Common Humeral Fractures - fractures of the surgical neck - particularly in old people with osteoporosis - fracture within the humeral shaft - nerve and artery damage may occur

Compartments of the Arm - there are two compartments; anterior and posterior

Elbow Movement - muscles of the anterior arm (mainly biceps brachialis) and posterior arm (mainly triceps and anconeus) produce elbow flexion and extension ANTERIOR Biceps Brachii Origin: SH - coracoid process, LH - supraglenoid tubercle Insertion: radial tuberosity and biceps aponeurosis Action: flexes elbow, supinates forearm (radioulnar joint) Tendon of biceps brachia long head passes through glenohumeral joint

ruputure: long head of bicep frays and with age eventually will rupture Note: biceps to radius, brachiallis to ulna

Brachialis Origin: anterior surface of humerus, mainly distal half Insertion: coronoid process and ulnar tuberosity Action: flexion of elbow joint

Coracobrachialis Origin: coracoid process Insertion: medial humerus Action: adducts humerus and flexes arm at glenohumeral joint

Brachioradialis Origin: lateral supracondylar ridge of humerus Insertion: stypoild process o...