Anatomy of the Lower and Upper Limb

Skeleton and Joints of the Lower Limb: Pelvis and Bony Landmarks

• The pelvis consists of three bones:
  • Ilium
  • Ischium
  • Pubis
• Important bony landmarks for muscle and ligament attachment:
  • Iliac crest:
  • Attachment for several muscles, including the gluteus medius.
  • Anterior superior iliac spine (ASIS):
  • Attachment for the sartorius muscle.
  • Ischial tuberosity:
  • Attachment for hamstring muscles.
  • Pubic symphysis:
  • A cartilaginous joint between the two pubic bones.
  • Acetabulum:
  • The socket for the hip joint.

Bones of the Lower Limb:

• Femur:
  • The longest bone in the body.
  • Key features include:
  • Greater trochanter and lesser trochanter for muscle attachment.
• Tibia and Fibula:
  • Tibia: Weight-bearing bone.
  • Fibula: Involved in muscle attachment and stabilization.
• Patella:
  • A sesamoid bone in the quadriceps tendon that aids in knee movement.
• Tarsals, Metatarsals, Phalanges:
  • Bones of the foot.

Hip Joint (Coxofemoral Joint):

• Type of Joint: Ball-and-socket.
• Bony Articular Surfaces:
  • Acetabulum of the pelvis and head of the femur.
• Actions:
  • Flexion, extension, abduction, adduction, medial rotation, lateral rotation, and circumduction.
• Stabilizing Ligaments:
  • Iliofemoral ligament: Strongest ligament, prevents hyperextension.
  • Pubofemoral ligament: Prevents excessive abduction.
  • Ischiofemoral ligament: Prevents excessive internal rotation.
• Muscles Stabilizing the Joint:
  • Gluteal muscles (gluteus maximus, medius, minimus), iliopsoas, adductors.
• Specialized Structures:
  • Acetabular labrum: A fibrocartilage structure that deepens the acetabulum for better femoral head stability.

Skeleton of the Upper Limb: Bones of the Upper Limb:

• Clavicle (Collarbone):
  • Connects the upper limb to the axial skeleton at the sternoclavicular joint.
• Scapula (Shoulder Blade):
  • Articulates with the clavicle at the acromioclavicular joint and with the humerus at the glenohumeral joint.
  • Key landmarks include:
  • Acromion process: The highest point of the shoulder.
  • Coracoid process: A bony prominence on the anterior surface.
  • Spine of the scapula: Located on the posterior aspect.
  • Glenoid cavity: Shallow socket that articulates with the humeral head.
• Humerus: Upper arm bone
  • Notable landmarks:
  • Greater and lesser tubercles (muscle attachment)
  • Deltoid tuberosity (attachment of deltoid muscle).
• Radius and Ulna: Forearm bones.
  • Radius: Lateral side (thumb side).
  • Ulna: Medial side (pinky side).
• Carpals: Eight small bones forming the wrist.
• Metacarpals and Phalanges: Bones of the hand.

Joints of the Upper Limb:

Glenohumeral Joint (Shoulder Joint):

• Type of Joint: Ball-and-socket joint.
• Bony Articular Surfaces:
  • Glenoid cavity of the scapula and head of the humerus.
• Actions:
  • Flexion, extension, abduction, adduction, medial rotation, lateral rotation, circumduction.
• Ligaments:
  • Glenohumeral ligaments: Stabilize the shoulder by preventing excessive movement.
  • Coracohumeral ligament: Supports the weight of the arm.
  • Transverse humeral ligament: Keeps the long head of the biceps tendon in place.
• Muscles Stabilizing the Joint:
  • Rotator cuff muscles (supraspinatus, infraspinatus, teres minor, subscapularis), deltoid, biceps brachii, triceps brachii.
• Specialized Structures:
  • Glenoid labrum: A fibrocartilage ring that deepens the glenoid cavity, improving joint stability.

Acromioclavicular Joint:

• Type of Joint: Plane synovial joint.
• Bony Articular Surfaces:
  • Acromion process of the scapula and lateral end of the clavicle.
• Actions:
  • Limited gliding and rotational movements.
• Ligaments:
  • Acromioclavicular ligament: Stabilizes the acromioclavicular joint.
  • Coracoclavicular ligament: Prevents excessive separation of the clavicle and scapula.
• Muscles Stabilizing the Joint:
  • Trapezius and deltoid muscles.

Sternoclavicular Joint:

• Type of Joint: Saddle joint.
• Bony Articular Surfaces:
  • Manubrium of the sternum and medial end of the clavicle.
• Actions:
  • Allows limited movement of the clavicle in elevation, depression, protraction, retraction, and slight rotation.
• Ligaments:
  • Anterior and posterior sternoclavicular ligaments.
  • Costoclavicular ligament: Provides stability.
• Muscles Stabilizing the Joint:
  • Sternocleidomastoid, trapezius.

Elbow Joint (Humeroulnar and Humeroradial Joints):

• Type of Joint: Hinge joint (primarily).
• Bony Articular Surfaces:
  • Trochlea of the humerus and the trochlear notch of the ulna.
  • Capitulum of the humerus and head of the radius.
• Actions:
  • Flexion and extension.
• Ligaments:
  • Ulnar collateral ligament (anterior, posterior, and transverse bands): Prevents valgus (outward) stress on the elbow.
  • Radial collateral ligament: Stabilizes the lateral aspect of the elbow.
  • Annular ligament: Holds the head of the radius in place and allows rotation.
• Muscles Stabilizing the Joint:
  • Biceps brachii, triceps brachii, brachialis, brachioradialis.

Proximal Radioulnar Joint:

• Type of Joint: Pivot joint.
• Bony Articular Surfaces:
  • Head of the radius and radial notch of the ulna.
• Actions:
  • Pronation and supination of the forearm.
• Ligaments:
  • Annular ligament: Holds the radius in place at the proximal end.
• Muscles Stabilizing the Joint:
  • Biceps brachii, supinator, pronator teres, pronator quadratus.

Distal Radioulnar Joint:

• Type of Joint: Pivot joint.
• Bony Articular Surfaces:
  • Head of the ulna and ulnar notch of the radius.
• Actions:
  • Pronation and supination.
• Ligaments:
  • Dorsal and palmar radioulnar ligaments: Stabilize the distal radioulnar joint.

Wrist Joint (Radiocarpal Joint):

• Type of Joint: Ellipsoid (condyloid) joint.
• Bony Articular Surfaces:
  • Distal radius and proximal row of carpal bones (scaphoid, lunate, triquetrum).
• Actions:
  • Flexion, extension, abduction, adduction, circumduction.
• Ligaments:
  • Radial collateral ligament and ulnar collateral ligament: Stabilize the wrist joint.
  • Palmar and dorsal radiocarpal ligaments: Provide additional stability.
• Muscles Stabilizing the Joint:
  • Flexor and extensor muscles of the forearm.

Joints of the Hand:

• Interphalangeal (IP) Joints: Hinge joints between the phalanges of each digit.
• Metacarpophalangeal (MCP) Joints: Condyloid joints between the metacarpals and proximal phalanges.
• Carpometacarpal (CMC) Joints: Saddle joint at the base of the thumb (between the trapezium and first metacarpal).

Skin, Fascia, and Vessels of the Upper Limb:

Deep and Investing Fascia:

• Deep fascia: Dense connective tissue enveloping muscles, nerves, and vessels.
• Investing fascia: Surrounds individual muscles and muscle groups.
• Intermuscular Septa: Extensions of deep fascia that divide the upper limb into compartments (e.g., anterior and posterior compartments in the arm).
• Retinacula: Thickened bands of fascia holding tendons in place:
  • Extensor retinaculum: Located on the dorsum of the wrist, keeping extensor tendons in place.
  • Flexor retinaculum: Located on the palm side of the wrist, forming the roof of the carpal tunnel.
• Interosseous Membrane: A fibrous structure between the radius and ulna, providing support and serving as a site for muscle attachment.

Blood Supply and Drainage of the Upper Limb:

• Arterial Supply:
  • Subclavian artery: Primary artery supplying the upper limb.
  • Axillary artery: Continuation supplying the shoulder and arm.
  • Brachial artery: Continuation supplying the forearm.
  • Radial and Ulnar arteries: Branches supplying the forearm and hand.
• Venous Drainage:
  • Superficial veins: Cephalic vein (lateral) and basilic vein (medial) are crucial for venous return and venipuncture.
  • Deep veins: Follow the arteries (e.g., brachial vein, radial vein, ulnar vein).

This summary of the upper limb skeleton, joints, fascial structures, and blood supply provides a foundation for understanding the anatomy and functionality of the upper limb. Let me know if you need more detailed explanations on any specific aspect!