Upper Limb Question and Answers

Joints Of The Upper Limb

Question 1. Enumerate the components of shoulder complex.
Answer.

The shoulder complex consists of the following five components:

• Glenohumeral joint (shoulder joint proper)
• Acromioclavicular joint
• Sternoclavicular joint
• Subacromial joint (between coracoacromial arch and subacromial bursa)
• Scapulothoracic joint (linkage between scapula and thoracic wall)

The last two components are functional joints.

Read And Learn More: Selective Anatomy Notes And Question And Answers

Factors Providing Stability To Shoulder Joint

• Musculotendinous (rotator) cuff
• Glenoid labrum
• Long head of biceps brachii muscle
• Coracoacromial arch

Synovial Bursae Related To The Shoulder Joint

• Subscapular bursa: Lies deep to subscapularis and communicates with joint cavity through a gap between superior and middle glenohumeral ligaments.
• Subacromial bursa: Lies deep to acromion and upper part of deltoid. It is the largest synovial bursa in the body.
• Between tendons of infraspinatus and teres major.
• Between coracoid process and joint capsule.
• Between teres major and long head of triceps brachii.

Coracoacromial Arch

Coracoacromial Arch is bony-fibrous arch lying above the shoulder joint formed by (a) coracoid process, (b) coracoacromial ligament and (c) acromial process.

The coracoacromial ligament is a flat triangular ligament which extends from the medial border of acromion (narrow end) in front of acromioclavicular articulation to the lateral border of the coracoid process (broad end).

Just below this arch, the supraspinatus muscle passes above the head of humerus on its way to greater tubercle of humerus for insertion. The coracoacromial arch is separated from this muscle by subacromial bursa to allow free movements of shoulder during contraction of supraspinatus.

Coracoacromial Arch Applied Anatomy: The coracoacromial arch acts as a secondary socket of shoulder joint and prevents its superior dislocation.

Types Of Sternoclavicular Joint

The sternoclavicular joint is of following types: synovial, saddle, compound and complex. The details are as under:

• Synovial, because it has synovial cavity filled with synovial fluid
• Saddle, because articulating surfaces are concavo-convex in shape
• Compound, because more than two bones are articulating, i.e. sternal end of clavicle, clavicular notch of manubrium sterni and upper surface of 1st costal cartilage (last two form a continuous concavo-convex surface)

• Complex, because its articular surfaces are covered by fibrocartilage and its cavity is divided into two parts by an intra-articular fibrocartilaginous disc

Abduction At Shoulder Joint

• The abduction at shoulder joint is a complex movement.
• Abduction At Shoulder Joint is performed by conjoint action of both prime movers and synergists.

• Prime movers are
  • Middle fibres of deltoid
  • Supraspinatus
• Synergist muscles are
  • Subscapularis
  • Infraspinatus
  • Teres minor

The sequence of events occurring during abduction at shoulder is as follows:

• Natural range of abduction at shoulder joint is only 60°.
• When the humerus is rotated medially, range of movement of abduction is increased up to 90°.
• When humerus moves in the plane of body of scapula, range of movement is increased up to 120°.
• When humerus is rotated laterally by contraction of infraspinatus and teres minor, range of movement is increased up to 180°.

 Carrying Angle

• Carrying Angle is an angle formed between long axes of arm and forearm when the elbow is fully extended.
• Carrying angle occurs because the medial flange of trochlea lies 6 mm lower than that of lateral flange of trochlea.
• Carrying Angle varies from 10° to 15° in males and 15° to 30° in females.

Carrying Angle Functional significance

• Carrying Angle helps in holding and carrying the objects.
• Carrying Angle prevents rubbing of forearm with pelvis in females.
• Carrying Angle helps to put food in mouth during eating.

Carrying Angle Applied anatomy

An increase in carrying angle causes cubitus valgus deformity of the elbow.

Radioulnar Joints

There are three radioulnar joints, i.e. superior, middle and inferior.

• Superior Radioulnar Joint: It is a pivot type of synovial joint between head of radius and radial notch of ulna. The annular ligament surrounds the head of radius and keeps it in contact with the radial notch of ulna. A fibrous band – the quadrate ligament extending from inferior border of radial notch of ulna to the neck of radius – closes the joint from below.
• Intermediate Radioulnar Joint: It is a fibrous joint of syndesmosis type between the shafts of radius and ulna.
  Here radius and ulna are joined by an interosseous membrane whose fibres are directed downwards and medially.
  It binds the radius and ulna but allows some movement.
• Inferior Radioulnar Joint: It is also a pivot type of synovial joint between head of ulna and ulnar notch of radius.
  A triangular articular disc of fibrocartilage extends from depression near the styloid process of ulna to the articular margins of ulnar notch of radius. It separates this joint from wrist joint.
  The synovial membrane of inferior radioulnar joint projects upwards to form a pouch in front of interosseous membrane – the recessus sacciformis.

Radioulnar Joints Movements

Movements occurring at radioulnar joints are

• Supination
• Pronation

 Interosseous Membrane

• Interosseous Membrane is a fibrous membrane which extends between interosseous borders of radius and ulna.
• The direction of fibres in this membrane is downwards and medially towards ulna.
• Interosseous Membrane  forms intermediate (middle) radioulnar joint of syndesmosis type.
• Superiorly the gap between oblique cord and upper border of membrane, provides passage to posterior interosseous artery to go into the posterior compartment.
• Inferiorly interosseous membrane blends with capsule of inferior radioulnar joint.
• An opening in the inferior part of membrane provides passage to anterior interosseous artery to enter the posterior compartment.
• Membrane is related anteriorly to flexor pollicis longus (FPL), flexor digitorum profundus (FDP) and pronator quadratus (PQ).
• Membrane is related posteriorly to supinator, abductor pollicis longus (APL), extensor pollicis longus (EPL), extensor pollicis brevis (EPB), extensor indicis and posterior interosseous nerve and vessels.

Interosseous Membrane  Functional significance

Interosseous membrane: (a) helps in transmission of force from the radius (received from wrist joint) to the ulna for onward transmission to the humerus and (b) helps in supination and pronation.

Supination And Pronation

Movements

• Supination: It is the movement of forearm in which the palm of hand is turned forwards/upwards.
• Pronation: It is the movement of forearm in which the palm of hand is turned backwards/downwards.

The details of movements of supination and pronation.

Movements of Supination and Pronation

Supination And Pronation Functional Significance

• They help in picking up food and putting it into the mouth.
• They are used in mechanical jobs, e.g. opening and tightening the screws with screw driver.

Range Of Movement At The Wrist Joint

• Flexion = 60°–85°
• Extension = 50°–60°
• Abduction = 15°
• Adduction = 30°–45°

1st Carpometacarpal Joint

1st Carpometacarpal Joint Classification

1st Carpometacarpal Joint  Structural: Synovial joint of saddle variety

1st Carpometacarpal Joint  Functional: Diarthrosis

1st Carpometacarpal Joint  Articular surfaces

Proximally: Distal surface of trapezium

Distally: Proximal surface of the base of 1st metacarpal (MC) bone

1st Carpometacarpal Joint  Ligaments

• Capsular ligament: It is a loose fibrous sac, which encloses the joint cavity. It is thickest dorsally and laterally.
• Lateral ligament: Broad fibrous band extending from the lateral surface of trapezium to the lateral surface of 1st MC.
• Anterior ligament: Extends obliquely from the palmar surface of trapezium to the ulnar side of base of 1st MC.
• Posterior ligament: Extends obliquely from the dorsal surface of trapezium to the ulnar side of 1st MC.

1st Carpometacarpal Joint  Relations

• Anterior: Muscles of thenar eminence
• Posterior: Long and short extensors of thumb
• Medial: First dorsal interosseous muscle
• Lateral: Abductor pollicis longus
• Posteromedial: Radial artery

1st Carpometacarpal Joint  Nerve supply

Median nerve

1st Carpometacarpal Joint  Movements

The movements and muscles producing them with their nerve supply.

Movements of 1st Carpometacarpal Joint

Classification and Movement of MP, PIP and DIP joints

1st Metacarpophalangeal Joint

• Type: Ellipsoid type of synovial joint
• Articular surfaces: Convex articular head of 1st metacarpal and curved articular base of proximal phalanx
• Ligaments: Capsular ligaments, palmar ligaments, and medial and lateral collateral ligaments
  • Capsular ligament: Thick in front and thin behind
  • Palmar ligament: Fibrocartilaginous plate which replaces deep transverse metacarpal ligaments
  • Medial and lateral collateral ligament: Oblique bands extending downwards and forwards from head of metacarpal to the base of proximal phalanx

Movements And Muscle Producing Them

• Flexion: Flexor pollicis brevis
• Extension: Extensors of thumb
• Abduction: Abductor pollicis brevis
• Adduction: Adductor pollicis

Chief Flexors Of MP, PIP And DIP joints

• MP joints: Lumbricals and interossei
• PIP joints: Flexor digitorum superficialis
• DIP joints: Flexor digitorum profundus

Movements Of Thumb Are Tested To Confirm The Integrity Of Radial, Ulnar And Median Nerves

• To test integrity of radial nerve: Test extension of thumb, because this movement of thumb is lost if radial nerve is damaged.
• To test integrity of ulnar nerve: Test adduction of thumb, because this movement of thumb is lost if ulnar nerve is damaged.
• To test integrity of median nerve: Test abduction and opposition of thumb, because both these movements of thumb are lost if median nerve is damaged.