Carrying Angle and First Carpometacarpal Joint Notes

Carrying Angle and First Carpometacarpal Joint Notes

Carrying Angle

Carrying Angle Introduction:

It is an angle formed by the arm with the forearm when the elbow is fully extended and the forearm supinated, which opens laterally.

Carrying Angle Causes:

There are two reasons

1. The medial flange of the trochlea is 6 mm lower than the lateral flange of the trochlea.
2. Obliquity of the superior articular surface.

Carrying Angle Gender difference:

There is not much difference in the carrying angle in males and female . It is less than 10° in males and more than 15° in females.

Read And Learn More: Anatomy Notes And Important Questions and Answers

Carrying Angle Function:

A carrying angle is helpful in holding the object.

Carrying Angle Degree of angle

1. It is 163o in the fully extended elbow and supinated forearm.
2. It is 0° in full flexion and pronation of the forearm.

Question: Name the movements at radioulnar joints and muscles causing them

Answer:

1. Movements at radioulnar joints and muscles Supination

1. Biceps brachii-strong supinator
2. Supinator

2. Movements at radioulnar joints and muscles Pronation

1. Pronator teres
2. Pronator quadratus

Radioulnar Joints

1. Radioulnar joints

2. There are three joints formed by the radius and ulna. They are

1. Superior radioulnar joint,
2. Middle radioulnar joint, and
3. Inferior radioulnar joint.

Superior and inferior radioulnar joints

3. Middle radioulnar joint

1. Classification: Syndesmosis type of fibrous joint.
Inferior radioulnar joint

2. Articulate surfaces: Interosseous borders of radius and ulna.

3. Ligaments:

1. Interosseous membrane: It connects the shafts of the radius and ulna.
2. Oblique cord: It extends from the tuberosity of the radius to the tuberosity of the ulna connecting the two bones.

4. Radioulnar joints Features

Anatomical classification of joint

The radius and the ulna are joined to each other at the superior and inferior radioulnar joints.

The radius and ulna are also connected by the interosseous membrane which constitutes the middle radioulnar joint.

Interosseous Membrane

Interosseous Membrane Features

1. It connects the shafts of the radius and ulna.
2. It is attached to the interosseous borders of these bones.
3. The fibres of the membrane run downwards and medially from the radius to the ulna.

Interosseous Membrane Extent

1. Superiorly, the interosseous membrane begins 2-3 cm below the radial tuberosity.

Between the oblique cord and the interosseous membrane, there is a gap for the passage of the posterior interosseous vessels to the back of the forearm.

2. Inferiorly, a little above its lower margin, there is an aperture for the passage of the anterior interosseous vessels to the back of the forearm.

Interosseous Membrane Relations

Relations of the interosseous membrane

1. Anterior surface is related to the

1. Flexor pollicis longus,
2. Flexor digitorum profundus,
3. Pronator quadratus, and
4. Anterior interosseous vessels and nerve.

2. The posterior surface is related to the

1. Supinator,
2. Abductor pollicis longus,
3. Extensor pollicis brevis,
4. Extensor pollicis longus,
5. Extensor indices,
6. Anterior interosseous artery, and
7. The posterior interosseous nerve.

Interosseous Membrane Functions

1. It binds the radius and ulna to each other.
2. It provides attachments to many muscles.
3. It transmits force.

Question-8: Describe supination and pronation under the following heads

1. Mechanism of action, and
2. Applied anatomy

Answer:

Supination and pronation Introduction:

Supination and pronation movements are mainly evolved for picking up food and keeping it in the mouth.

Comparison between supination and pronation

Supination and Pronation Mechanism of Action

1. The position of the forearm is semiflexed.

2. The type of movement is rotatory.

3. Evolved for picking up food and putting it into the mouth.

4. Range of movements:

1. In flexed elbow: 140°-150°
2. In extended elbow: 360°. It includes rotation of the shoulder.

5. Axis:

1. Plane: Transverse.
2. Representation: It is represented as an axis passing through the center of the head of the radius and apex of the articular disc to the little finger.

6. Homologous movements in the lower limb: Inversion and eversion

7. Joints: Superior and inferior radioulnar joints.

Supination and Pronation Applied Anatomy

1. In children, the head of the radius is not developed as compared to the annular ligament. Hence, subluxation of the superior radioulnar joint is common under the age of 6 years.

2. Pronation and supination movements are used in mechanical jobs, for Example. tightening screws with a screwdriver

Question-9: Classify the radioulnar joints

Answer:

1. Radioulnar joints Anatomical classification

Anatomical classification of joint

Bones Forming Wrist Joint

1. Inferior surface of the lower-end radius,

2. Proximal surface of

1. Scaphoid,
2. Lunate, and
3. Triquetral.

Question-9: Describe the wrist joint (radiocarpal) under the following heads

1. Bones taking part,
2. Classification,
3. Ligaments,
4. Relations,
5. Movements,
6. Blood supply,
7. Nerve supply, and
8. Applied anatomy.

Answer:

Movements at the metacarpophalangeal joint of the middle finger

1. Flexion:

1. Flexor digitorum superficialis, and
2. Flexor digitorum profundus.

2. Extension: Extensor digitorum.

First Carpometacarpal Joint

First Carpometacarpal Joint Classification

1. Structurally: Biaxial, saddle variety of synovial joints.
2. Functionally: Diarthrosis.

First Carpometacarpal Joint Articular surfaces

1. The distal surface of the trapezium, and
2. The proximal surface of the base of the first metacarpal.

First Carpometacarpal Joint Ligament

1. Capsular ligament: Surrounds the joint. It is thickest, dorsally and laterally,
2. Lateral ligament: Broadband, which thickens the capsule,
3. Anterior ligament, and
4. Posterior ligament.

First Carpometacarpal Joint Relations

1. Anterior: Muscles of the thenar eminence.
2. Dorsally: Long and short extensor of thumb.
3. Medially: First dorsal interossei muscle.
4. Laterally: Abductor pollicis longus.

First Carpometacarpal Joint Nerve supply

Median nerve

First Carpometacarpal Joint Movements

Flexion and extension are parallel to the plane of the palm. Abduction and adduction movements are perpendicular to the plane of the palm. Opposition is adduction with medial rotation.

1. Flexion: Flexor pollicis brevis.
2. Extension: Abductor pollicis longus. Extensor pollicis brevis.
3. Abduction: Abductor pollicis brevis. Abductor pollicis longus.
4. Adduction: Adductor pollicis.
5. Opposition: Opponens pollicis.

First Carpometacarpal Joint Applied anatomy

The 1st carpometacarpal joint can undergo degenerative changes with age which is a painful condition of the base of the thumb.

The synovial lining of the tendons of the extensor pollicis brevis and abductor pollicis longus can get inflamed. It is due to repetitive strain.

It can lead to a painful condition called de Quervains tenosynovitis. Movement of the thumb can aggravate pain in this condition.