W9 Muscles/Ligaments

Laterally of the calvicle, there are 2 bony roughened areas. What are they and what are they attached to?

Conoid Tubercle - Conoid Ligament

Trapezoid Line - Trapezoid Ligament

What is attached to subscapular fossa

Subscapularis

The medial aspect of the costal side of the scapula has enlarged bolster bony areas, what attaches here

Serratus Anterior Muscle

What are the 2 fossae on the dorsal side of scapula and which muscles do they attach to?

Supraspinous Fossa - Supraspinatus Muscle

Infraspinous Fossa - Infraspinatus Muscle

There are tubercles sitting superiorly and inferiorly of the glenoid fossa. What are they and what do they attach to?

Supraglenoid Tubercle - Long head of the biceps brachii

Infraglenoid Tubercle - Long head of the triceps brachii

The greater tubercle of the humerus has 3 facets. What are they and what do they attach to?

Superior Facet - Supraspinatus Muscle

Middle Facet - Infraspinatus Muscle

Inferior Facet - Teres Minor Muscle

What is the lesser tubercle attached to?

Subscapularis Muscle

There is a V-shaped tuberosity at the distal end of the humerus. What is it called and what is it attached to?

Deltoid tuberosity - Deltoid Muscle

What is the attachment site for the levator scapulae?

Superior angle

What are the 2 muscles attaching to the medial border (superiorly and inferiorly)?

Superiorly - Rhomboid Minor

Inferiorly - Rhomboid Major

Where does the tendon of long head of biceps brachii go?

Through the intertubercular groove, wraps over the head of humerus and attached to supraglenoid tubercle

What attaches to the intertubercular groove (floor, medial and lateral lip)?

Floor of Intertubercular Groove - Latissimus Dorsi

Lateral Lip - Pectoralis Major

Medial Lip - Teres Major

What are the 3 components of the trapezius muscle - fibre directions + functions?

Superior trapezius - fibre slopes superiorly; elevates scapula

Middle trapezius - fibre slopes horizontally; retracts scapula

Inferior trapezius - fibre slants obliquely in inferior direction; depress scapula @ scapulothoracic joint

What are the middle and lateral attachment sites of the trapezius muscle?

Medial & Superior

• Superior nuchal line (superiorly)

• Nuchal ligament of cervical spine

• T1-T12 Spinous Processes

Lateral

• Lateral 3rd of clavicle

• Spine of scapula

What are the 3 muscles deep to the trapezius muscle?

Levator Scapulae (superiorly)

Rhomboids

Latissimus Dorsi

Where does levator scapulae attach from + function?

Attaches from superior angle of scapula through to C1-C4 transverse processes

Function: elevates scapula

Where does rhomboids attach from + function?

Attachments from thoracic spinous processes to medial vertebral border of the scapula

• Rhomboid Minor - medial attachment sites at C7 and T1 & medial border of scapula superior to where the spine of the scapula intersects the medial border of scapula

• Rhomboid Major - medial attachment sites at T2-T5 segments and attaches to medial aspect of scapula but to a region that’s inferior to scapula spine

Function: Retract scapula

Where does the latissimus dorsi attach from + function?

Medial attachment to throacolumbar fascia (attaches to lumbar spinous processes) & lateral humeral attachment at the floor of the intertubercular groove

Function: if pull along the plane of muscle fibres, 3 actions - extension, adduction, internal rotation @ glenohumeral joint

What is covered by the posterior head of the deltoid?

Teres major & Infraspinatus

What are the anterolateral muscles controlling the shoulder complex?

Pectoralis Muscle - Pectoralis Major and Minor

Serratus Anterior Muscle

Biceps Brachii - Long head and Short head

Coracobrachialis Muscle

What are the 2 heads of the pectoralis major and their attachments + functions?

Laterally, both attaches to the lateral lip of the intertubercular groove

Clavicular head - medially attaches to medial 3rd of the clavicle and descend laterally

Sternocostal head - attachment to sternum and a bit of inferior manubrium and multiple ribs

Function: Flex, adduct, internally rotate the glenohumeral joint

What are the attachments of the pectoralis minor + functions (on both shoulder and thoracic cage)?

Superior attachment @ coracoid process and inferior attachment to 3rd, 4th, 5th ribs
Function on shoulder: Protects the scapulothoracic joint

Function on thoracic cage: accessory muscle of respiration (works with diaphragm during inspiration)

What are the attachments of the serratus anterior muscle + functions?

Posteriorly, attaches to medial aspect of the costal surface of the scapula, moves anterolaterally and fans out in a serrated fashion to attach to first 9 ribs

Function: Protract scapula

What are the 2 heads of the biceps brachii, the attachment sites and function?

Short head of biceps brachii: Proximal attachment to coracoid process. Following distally, muscle fibres will merge with long head of biceps brachii

Long head of biceps brachii: Attaches to superior aspect of glenoid labrum and supraglenoid tubercle

• Has proximal tendon travelling through the intertubercular groove and across the head of the humerus

Function: Both heads of biceps brachii assists glenohumeral flexion

What are the attachments of the coracobrachiallis muscle + functions?

From coracoid process to medial aspect of midshaft of humerus

Function: weak flexor & adductor of glenohumeral joint

Which muscle falls under the lateral muscles?

Deltoid muscle

The deltoid muscle has 3 heads. What are they, where do they attach and what are their individual & combined functions?

Anterior deltoid head - attaches at lateral 3rd of the clavicle

• Function: glenohumeral flexion

Middle deltoid head - attaches at acromion process

• Function: glenohumeral abduction

Posterior deltoid head - attaches at spine of scapula

• Function: glenohumeral extension

What are the 4 important muscles for glenohumeral joint and shoulder complex in general (rotator cuff muscles) + attachment sites + functions?

3 on the dorsal side of scapula: Supraspinatus, Infraspinatus, Teres minor

1 on the costal side of scapula: Subscapularis

Supraspinatus

• medial attachment at suprascapular fossa, lateral attachment at superior facet of greater tubercle of humerus

• function: glenohumeral joint stabiliser and glenohumeral abductor

Infraspinatus

• medial attachment at infrascapular fossa, lateral attachment at middle facet of greater tubercle of humerus

• function: glenohumeral joint stabiliser and external roatation of glenohumeral joint

Teres Minor

• medial attachment from lateral border of scapula, lateral attachment at inferior facet of greater tubercle of humerus

Subscapularis

• medial attachment from subscapular fossa on costal surface, lateral attachment at lesser tubercle of humerus

• function: glenohumeral joint stabiliser, internal rotation and adduction of glenohumeral joint

(Other muscles) What are the attachments of the teres major + functions?

medial attachment at the inferior angle of scapula and lateral attachment at the medial lip of intertubercular groove

Function: extensor, adductor and internal rotator of glenohumeral joint

(Other muscle) What are the attachments of the long head of the triceps muscle + function?

Proximally attached to infraglenoid tubercle, distally attached to olecranon process of ulna

Function: assist rest of shoulder musculature to extend the glenohumeral joint

What are the branches coming off the roots and the muscles they innervate?

Dorsal Scapular Nerve (DSN)

• Innervates the levator scapulae, rhomboid major and rhomboid minor

• has no sensory component

Long Thoracic Nerve (LTN)

• Innervates the serratus anterior muscle, allows protection of scapula

• contributed by C5, C6, C7, C8 and variably T1

What are the branches coming off the upper trunk and the muscles they innervate?

n. to the subclavius muscle

• innervates the subclavius muscle

• only somatic motor

• supplies more than 1 muscle

suprascapular n.

• innervates the supraspinatus and infraspinatus muscle

• travels laterally and posteriorly

• goes through the suprascapular foramen formed by suprascapular notch and transverse scapular ligament to innervate supraspinatus muscle and travel laterally around the supraglenoid notch and goes between the communication of supraspinous and infraspinous fossa

What is the nerve coming off the lateral cord and the muscles they innervate?

Lateral Pectoral n. - pectoralis major muscle

What are the nerves coming off the posterior cord and the muscles they innervate?

Upper Subscapular n. (USSN) - subscapularis muscle

Thoracodorsal n. (TDN) - latissimus dorsi muscle

Lower Subscapular n. (LSSN) - subscapularis muscle & teres major muscle

What are the nerves coming off the medial cord and the muscles they innervate?

Medial Pectoral n. (MPN) - pectoralis major and minor

Medial Brachial Cutaneous (MBC) - medial aspect of brachium

Medial Antebrachial Cutaneous (MAC) - medial aspect of antebrachium

What is the terminal branch coming off the lateral cord and the muscles they innervate?

Musculocutaneous nerve

• pierces through the coracoid brachiallis muscle & supply it w somatic motor innervation

• then it innervates the long and short head of biceps brachii, descend between the biceps brachii and brachialis muscle

• at this point also innervates brachillas muscle

*as it descend distally, it gets to the biceps tendon and gives off sensory branch = lateral antebrachial cutaneous (supplies lateral aspect of antebrachial skin w sensation)

What does the median nerve supply?

(motor and sensory) all action in antebrachium

supply wrist flexes, finger flexes, sensation to lateral 3 and a half digits and part of the palm

What is the 2 terminal branches coming off the posterior cord and the muscles they innervate?

Axillary n.

• supplies teres minor muscle and all 3 heads of deltoid muscle

• passes through axillary fossa, given off by posterior cord, wraps inferiorly underneath the glenohumeral joint and goes through quadrangular space

• has sensory fibres; sensation of skin overlying distal part of middle deltoid hand (silver dollar)

Radial n.

• innervates triceps and forearm extensors of wrist and digits

• pierces into triceps otw to the spiral groove of the humerus

• broad sensory innervation but is the only innervation for webspace between 1st and 2nd metacarpal

What is the terminal branch continuing from the medial cord and the muscles they innervate?

Ulnar nerve

• supplies couple of muscles in forearm and give off sensory branches in the hand

• supplies medial side of palm, medial 1 and a half digits (palmar and dorsal side)

• travels through cubital tunnel (between medial epicondyle of humerus and olecranon process of ulnar)

What are the 4 shoulder joints?

1. Glenohumeral Joint

2. Acromioclavicular Joint

3. Sternoclavicular Joint

4. Scapulothoracic Joint (not a real joint)

What are the motions available at the glenohumeral joint?

Flexion, extension, abduction, adduction, internal/external rotation, horizontal abduction/adduction

What are the 3 thickenings of the glenohumeral joint capsule (ligaments) and what are their importance?

Superior glenohumeral ligament - aid it in preventing inferior dislocation of glenohumeral joint

Middle glenohumeral ligament - prevents anterior translation of humeral head within glenoid fossa

Inferior glenohumeral ligament - generally relaxed, only time it gets taut and stretched is when abducting beyond 90 degrees

What are the additional ligaments that help stabilise the glenohumeral joint?

1. Coraco-acromial Ligament - goes towards providing the coroco-acromial arch that prevents superior dislocation of glenohumeral joint

2. Transverse Humeral Ligament - goes between greater and lesser tubercles of humerus and stabilises the long head of the biceps tendon (prevents dislocation of long head of the biceps tendon out of intertubercular groove; if stable, also prevents superior dislocation of gelnohumeral joint along with coraco-acromial ligament)

What are the ligaments that support the acromioclavicular joints?

1. Coracoclavicular ligament - from coracoid process to underside of clavicle

• Conoid ligament

• Trapezoid ligament

2. Coraco-acromial ligament - supports lateral side of acromioclavicular joint

What are the available movements at the sternoclavicular joint?

Elevation/Depression, Protract/Retract, Spins around the long axis

What are the ligaments stabilising the sternoclavicular joints?

1. Interclavicular ligament - attaches 1 clavicle to the other

2. Costoclavicular ligament - attaches 1st rib to underside of clabicle

What are the motions available around the scapulothoracic joint?

Protraction/Retraction, Elevation/Depression, Rotation