Appendicular Skeleton

Skeletal System (Appendicular)

Appendicular Skeleton

• Definition: Forms the appendages and attachment points of the body.

• Total Bones: 126 bones.

• Components:

  • Pectoral girdle

  • Upper limbs

  • Pelvic girdle

  • Lower limbs

Pectoral Girdle

• Composition: 2 bones.

  • Clavicle (2)

  • Scapula (2)

• Function: Supports the upper limbs and serves as an attachment point for muscles.

Clavicle

• Connects:

  • Connects to the sternum (manubrium) at the sternal end.

  • Connects to the scapula (acromion) at the acromial end.

Scapula

• Key Features:

  • Medial and lateral borders.

  • Processes:

  • Coracoid process

  • Acromion

  • Fossae:

  • Supraspinous fossa

  • Infraspinous fossa

  • Glenoid cavity.

Upper Limb

• Composition: Forms the framework of the arm, forearm, and hand.

• Function: Provides muscle attachment points.

• Divisions:

  • Arm (shoulder to elbow)

  • Forearm (elbow to wrist)

  • Hand

Humerus (Upper Arm Bone)

• Parts:

  • Shaft (diaphysis)

  • Head

  • Greater tubercle

  • Lesser tubercle

  • Deltoid tuberosity

  • Coronoid fossa

  • Olecranon fossa

  • Medial and lateral epicondyles

  • Capitulum

  • Trochlea

Forearm

• Composition: 2 bones.

  • Ulna:

  • Shaft (diaphysis)

  • Trochlear notch

  • Olecranon

  • Coronoid process

  • Head

  • Styloid process.

  • Radius:

  • Shaft (diaphysis)

  • Head

  • Radial tuberosity

  • Styloid process

  • Interosseous membrane.

Hand

• Structure: Comprising the wrist, palm, and fingers (digits).

• Wrist (Carpus):

  • Bones: 8 bones, divided into 2 groups:

  • Proximal (closer to radius/ulna):

    • Scaphoid

    • Lunate

    • Triquetrum

    • Pisiform

  • Distal (closer to metacarpals):

    • Hamate

    • Capitate

    • Trapezoid

    • Trapezium.

Carpus (Wrist Bones Illustration)

• Bones Visualized:

  • Trapezium (dark yellow)

  • Trapezoid (dark green)

  • Capitate (yellow)

  • Hamate (dark blue)

  • Scaphoid (magenta)

  • Lunate (blue)

  • Triquetrum (green)

  • Pisiform (red)

Metacarpals and Phalanges

• Metacarpals: 5 bones, numbered starting at the pollex (thumb).

• Phalanges: 5 bones, with 3 bones per finger (proximal, middle, distal).

Appendicular Skeleton - Definition: Forms the appendages and attachment points of the body. - Total Bones: 126 bones. - Components: - Pectoral girdle - Upper limbs - Pelvic girdle - Lower limbs

Pectoral Girdle - Composition: 2 bones. - Clavicle (2) - Scapula (2) - Function: Supports the upper limbs and serves as an attachment point for muscles, facilitating movement and stability. #### Clavicle - Connects: - Connects to the sternum (manubrium) at the sternal end. - Connects to the scapula (acromion) at the acromial end. - Significance: Acts as a strut to keep the shoulder in position and allows for a wide range of arm movement. #### Scapula - Key Features: - Medial and lateral borders, which help identify the orientation. - Processes: - Coracoid process: serves as an attachment for muscles such as the pectoralis minor. - Acromion: articulates with the clavicle and provides attachment for muscles like the trapezius. - Fossae: - Supraspinous fossa: provides space for the supraspinatus muscle. - Infraspinous fossa: space for the infraspinatus muscle. - Glenoid cavity: forms a shallow socket for the head of the humerus.

Upper Limb - Composition: Forms the framework of the arm, forearm, and hand. - Function: Provides muscle attachment points, facilitating motion and dexterity. - Divisions: - Arm (shoulder to elbow) - Forearm (elbow to wrist) - Hand #### Humerus (Upper Arm Bone) - Parts: - Shaft (diaphysis): the long cylindrical part, providing structure. - Head: articulates with the glenoid cavity of the scapula. - Greater tubercle: a site for muscle attachment, notably for the rotator cuff. - Lesser tubercle: another site for muscle attachment. - Deltoid tuberosity: midway down the shaft for the deltoid muscle attachment. - Coronoid fossa: receives the coronoid process of the ulna during flexion. - Olecranon fossa: receives the olecranon of the ulna during extension. - Medial and lateral epicondyles: sites for muscle attachment for the forearm muscles. - Capitulum: articulates with the radius; important for elbow movement. - Trochlea: articulates with the ulna, also critical for elbow function. #### Forearm - Composition: 2 bones. - Ulna: - Shaft (diaphysis): provides structure and movement. - Trochlear notch: articulates with the humerus at the elbow. - Olecranon: forms the elbow's bony prominence. - Coronoid process: receives the coronoid fossa of the humerus. - Head: distal end of the ulna; articulates with the wrist bones. - Styloid process: serves as an attachment for ligaments of the wrist. - Radius: - Shaft (diaphysis): allows for rotational movement. - Head: allows for rotation at the elbow. - Radial tuberosity: attachment point for the biceps brachii. - Styloid process: helps stabilize the wrist. - Interosseous membrane: ligament between the ulna and radius, providing additional stability. #### Hand - Structure: Comprising the wrist, palm, and fingers (digits). - Wrist (Carpus): - Bones: 8 bones, divided into 2 groups: - Proximal (closer to radius/ulna): - Scaphoid: most commonly fractured wrist bone. - Lunate: articulates with the radius. - Triquetrum: located on the ulnar side. - Pisiform: a sesamoid bone sitting on top of the triquetrum. - Distal (closer to metacarpals): - Hamate: has a hook for muscle attachment. - Capitate: the largest carpal bone. - Trapezoid: articulates with the index finger's metacarpal. - Trapezium: articulates with the thumb. #### Carpus (Wrist Bones Illustration) - Bones Visualized: - Trapezium (dark yellow) - Trapezoid (dark green) - Capitate (yellow) - Hamate (dark blue) - Scaphoid (magenta) - Lunate (blue) - Triquetrum (green) - Pisiform (red)

Metacarpals and Phalanges - Metacarpals: 5 bones, numbered starting at the pollex (thumb), contributing to the palm's structure. - Phalanges: 5 bones, with 3 bones per finger (proximal, middle, distal), allowing for flexibility and grip function.