COLLEGE OF ALLIED HEALTH AND SCIENCES

BY Hermizan HalihanafiahBsc Biomedicine (Hons) UKM

SHOULDER JOINT AND HUMERUS

INTRODUCTION

Upper limbs consist of 60 bones.

1. Arm : Humerus2. Forearm : Ulna and Radius3. Wrist : Carpals4. Palm : Metacarpals5. Hand : Phalanges

HUMERUS BONE

Arm bone. Longest and largest bone of UL. Articulates proximally with the

scapula and distally with both radius and ulna.

Humerus

Proximal end of the humerus features a rounded head that articulates with glenoid cavity of scapula to form glenohumeral joint.

Distal to the head is the anatomical neck, the site of epiphyseal line, which is visible as an oblique groove.

Head

Greater Tubercle

Lesser Tubercle

Intertubecular Sulcus

Anatomical Neck

Surgical Neck

Shaft

Glenohumeral Joint / Shoulder Joint

Humerus

Head

Greater Tubercle

Lesser Tubercle

Intertubecular Sulcus

Anatomical Neck

Surgical Neck

Shaft

The greater tubercle is a lateral projection distal to the anatomical neck.

It is the most laterally palpable bony landmark of the shoulder region.

The lesser tubercle projects anteriorly.

Anterior view of proximal humerus

Humerus

Head

Greater Tubercle

Lesser Tubercle

Intertubecular Sulcus

Anatomical Neck

Surgical Neck

Shaft

Anterior view of proximal humerus

Between both tubercles runs an intertubercular sulcus (bicipital groove).

The surgical neck is a constriction in the humerus just distal to the tubercles, where the head tapers the shaft, name because fractures often occur here.

Cont…

The body (shaft) of the humerus is roughly cylindrical at its proximal end, but gradually becomes triangular until it is flattened and broad at its distal end.

Laterally, at the middle portion of the shaft, there is roughened, V-shape area called the deltoid tuberosity where attachment for deltoid muscle.

Deltoid

Tuberosity

Cont…

Several prominent features are evident at the distal end of the humerus.

The capitulum is a rounded knob on the lateral aspect of the bone that articulates with the head of the radius.

Capitulum

Trochlear

Cont…

Capitulum

Trochlear

The radial fossa is an anterior depression that receive the head of radius when the forearm is flexed.

The trochlea, located medial to the capitulum , is a spool shaped surface that articulates with the ulna.

Radial Fossa

Cont…

Capitulum

Trochlear

The coronoid fossa is anterior depression that receive the coronoid process of the ulna when forearm is flexed. Radial Fossa

Coronoid Fossa

The olecranon fossa is a posterior depression that receives the olecranon of the ulna when the forearm is extended.

Olecranon Fossa

Posterior View

Cont….

The medial epicondyle and lateral epicondyle are rough projections on either side of the distal end to which the tendons of most muscles of the forearm are attached.

The ulnar nerve lies on the posterior surface of the medial epicondyle and may easily be palpated by rolling a finger over the skin above the medial epicondyle.

Medial Epicondyle Lateral Epicondyle

Elbow Joint

Lateral ViewAnterior View

Ulnar Nerve

MOVEMENT OF THE ARM (SHOULDER JOINT)

Flexion

Extension

Abduction

Adduction

MOVEMENT OF THE ARM (SHOULDER JOINT)

Medial rotation

Lateral rotation

Horizontal abduction

Horizontal adduction

Circumduction

Muscles of the Thorax that Move the Humerus

Axial muscles– Pectoralis major– Latissumus dorsi

Scapular muscles– Fiber of deltoid– Rotator cuff– Teres major– Coracobrachalis– Long & short head of biceps– Long head of triceps

Clavicle origin of Pectoralis Major

Origin – medial half of anterior clavicle

Insertion – lateral lip of intertubercular sulcus of humerus

Action – Flexion, adduction and medial rotation arm at shoulder joint.

Nerve supply– Medial and lateral

pectoral nerve

Sternal origin of Pectoralis Major

Origin – anterior surface of sternum, costal cartilage of 2nd -6th ribs.

Insertion – lateral lip of intertubercular sulcus of humerus

Action – extend arm at shoulder joint.

Nerve supply– Medial and lateral pectoral

nerve

Latissimus Dorsi

Origin – Spines of inferior 6 thoracic vertebrae (T6-T12), lumbar vertebrae (L1-L5), crest of sacrum and illiac crest of hip bone and inferior four ribs.

Insertion – Intertubecular sulcus of humerus

Action– Extends, adduction and medial rotation arm at

shoulder joint.

Nerve supply - Thoracodorsal nerve

Latissimus Dorsi

Fiber of Deltoid

Consists 3 fibers Anterior, middle and

posterior fibers. Responsible for

movements of the humerus at GH joint

Nerve supply – axillary nerve.

Anterior Fiber of Deltoid

Origin – anterior border of the lateral one third of the clavicle

Insertion – deltoid tuberosity

Action – flexion and middle rotation arm at GH joint.

Middle fiber of Deltoid

Origin – lateral border and superior surface of the acromion process of the scapula

Insertion – deltoid tuberosity

Action – abduction arm at GH joint

Posterior Fiber of Deltoid

Origin – inferior lip of the crest of the spine of the scapula]

Insertion – deltoid tuberosity

Action – extension and lateral rotation arm at GH joint.

Rotator Cuff Muscles

Consists 4 muscles S – Supraspinatus I – Infraspinatus T – teres minor S – Subscapularis Group of muscles that stabilize GH joint.

Supraspinatus Muscle

Origin – supraspinous fossa of scapula

Insertion – Greater tubercle of humerus (superior aspect)

Action – initially abduction (15 degrees) at shoulder joint, stabilizing shoulder joint

Nerve supply - Suprascapular nerve

Infraspinatus Muscle

Origin – Infraspinous fossa of scapula

Insertion – Greater tubercle of humerus (middle aspect)

Action – Laterally rotation and adduction arm at shoulder joint

Nerve supply - Suprascapular nerve

Teres Minor

Origin – Inferior lateral border of scapula

Insertion – Greater tubercle of humerus (posterior inferior aspect)

Action – Laterally rotation, extends and adduction arm at shoulder joint

Nerve supply – axillary nerve

Subscapularis Muscle

Origin – subscapular fossa of scapula

Insertion – lesser tubercle of humerus

Action – Medial rotation arm at shoulder joint

Nerve supply – upper and lower subscapular nerve

Teres Major

Origin – Inferior angle of scapula

Insertion – medial lip of Intertubecular sulcus of humerus

Action– Extends arm at shoulder

joint– Assist in adduction and

medial rotation of arm at shoulder joint.

Nerve supply– Lower subscapular nerve

Coracobrachialis

Origin - Coracoid process of scapula

Insertion - Middle of medial surface of shaft of humerus.

Action - Flexion and adduction arm at shoulder joint.

Nerve supply - Musculocutaneous nerve

Biceps Brachii

Consists 2 head Long head and short

head of biceps

Short head of Biceps

Origin – Coracoid process of scapula

Insertion – radial tuberosity of radius and bicipital aponeurosis

Action – Flexion forearm at elbow joint, supination at radioulnar joint and assist flexion arm at GH joint .

Nerve supply - Musculocutaneous nerve

Long head of Biceps

Origin – Tubercle above the glenoid cavity of scapula (supraglenoid tubercle)

Insertion – Radial tuberosity of radius and bicipital aponeurosis

Action – flexion forearm at elbow joint, supination forearm at radioulnar joint and assist flexion arm at GH joint.

Nerve supply - Musculocutaneous nerve

Long head of Triceps

Origin – tubercle below to glenoid cavity of scapula (infraglenoid tubercle)

Insertion – Olecranon of ulna

Action - Extends forearm at elbow joint , Extends arm at shoulder joint

Nerve supply - Radial nerve

Shoulder Joint

Definition– Ball and socket joint

– Formed by the head of humerus articulates with glenoid cavity of scapula.

– Also referred as glenohumeral joint or humeroscapular joint.

Glenohumeral Joint / Shoulder Joint

Movements

Allows for flexion, extension, abduction, adduction, medial rotation , lateral rotation and circumduction of arm.

Has more freedom of movement than other joint of body.

Extension / flexion of shoulder

Extension Flexion

Abduction Adduction

Abduction / adduction of Shoulder

Lateral / medial rotation of Shoulder

Lateral / external rotation Medial / internal rotation

Horizontal adduction / abductionof Shoulder

Horizontal Adduction Horizontal Abduction

This freedom of movements results from the looseness of the articular capsule and shallowness of the glenoid cavity in relation to the large size of the head of humerus.

Although the ligaments of the shoulder strengthen it to some extent, most of the strength results from the muscle surround the joint, especially rotator cuff muscles.

Shoulder Joint

Rotator cuff muscles work as a group to hold head of humerus in the glenoid cavity.

Shoulder Joint

Anatomical Components of Shoulder Joint

1. Articular capsule.

Thin, loose sac that completely envelops the joint and extends from glenoid cavity to the anatomical neck of humerus.

Inferior part of the capsule is its weakest area.

2. Coracohumeral Ligament

Strong, broad ligament that strengthen the superior part of the articular capsule.

Provides stability superiorly, preventing superior translation.

Extends from the coracoid process of the scapula to the greater tubercle of humerus.

Anatomical Components of Shoulder Joint

3. Glenohumeral Ligament 3 ligaments (middle, inferior and

superior) over the anterior surface of the joint.

This 3 ligaments joint together known as capsular ligament.

Extend from the glenoid cavity to the lesser tubercle and anatomical neck of the humerus.

Often indistinct or absent and provide only minimum strength

Anatomical Components of Shoulder Joint

4. Transverse Humeral Ligament

Narrow sheet ligament.

Extends from the greater tubercle to the lesser tubercle of the humerus.

Anatomical Components of Shoulder Joint

5. Glenoid labrum Narrow rim of fibrocartilage around the

edge of the glenoid cartilage.

Slightly deepens and enlarges the glenoid cavity.

Anatomical Components of Shoulder Joint

6. Bursae 4 bursae are associated with the shoulder

joint.

They are subscapular bursa, subdeltoid bursa, subacromial bursa and subcoracoid bursa.

It provides a cushion between bones and tendons and/or muscles around a joint; bursae are filled with synovial fluid and are found around almost every major joint of the body.

Anatomical Components of Shoulder Joint

Common Shoulder Injury

Rupture of the long head of biceps Rotator cuff injury / strain Subluxation of shoulder joint Humerus fracture

Introduction of Axilla

The axilla (or armpit, underarm, or oxter) is the area on the human body directly under the joint where the arm connects to the shoulder.

Bones Boundaries

Boundaries of Axilla

1. Superior– Outer border of the 1st ribs– Superior border of scapula– Posterior border of clavicle

2. Medial– Serratus anterior– ribcage

Medial muscles of Axilla

Cont…

3. Anterior– Pectoralis minor– Pectoralis major– Subclavius– The lower border of Pectoralis major forms the rounded

anterior axillary fold

4. Posterior– Subscapularis above– Teres major– Latissimus dorsi– The posterior axillary fold is a compound structure consisting

of the latissimus dorsi and teres major muscles.

Anterior Muscles of Axilla

Posterior Muscles of Axilla

Anterior Axillary Fold

Cont….

5. Lateral– Intertubercular sulcus of humerus– tendon of long head of biceps – coracobrachialis and the short head of the biceps

brachii are in the axilla

6. Floor / base– by the skin (visible surface of armpit)

Lateral of Axilla

Content of the Axilla

The axilla contain the:– Axillary artery and vein and their branches– Brachial plexus and their branches– Axillary lymph nodes – Muscles– Fascia