Overview of the Upper Limb and Shoulder Girdle

Study Notes

Overview of the Upper Limb

The upper limb is composed of the shoulder, arm, forearm, and hand.
It's responsible for diverse functions including reaching, grasping, manipulating objects, and many other fine motor skills.
The upper limb's structure is highly specialized for these diverse tasks.
It's essential for fine motor skills and dexterity.

Shoulder Girdle

The shoulder girdle (pectoral girdle) connects the upper limb to the axial skeleton.
It comprises the clavicle and scapula.
Clavicle: A long, s-shaped bone with an acromial end and a sternal end; acts as a strut providing stability to the shoulder.
Scapula: A flat, triangular bone; bears the glenoid cavity that forms the shoulder joint.
The scapula is loosely connected to the thoracic cage through muscles.
The shoulder girdle demonstrates considerable mobility.

Shoulder Joint (Glenohumeral Joint)

The glenohumeral joint is a ball-and-socket joint connecting the humerus to the scapula.
The head of the humerus articulates with the glenoid cavity of the scapula.
Extensive range of motion, including flexion, extension, abduction, adduction, and rotation (internal and external).
The shallow glenoid cavity and loose articular capsule contribute to the joint's flexibility but also increase the risk of dislocation.
Supported by rotator cuff muscles (supraspinatus, infraspinatus, teres minor, subscapularis).
The rotator cuff muscles are crucial for stabilizing the shoulder joint.

Arm

The arm is the segment of the upper limb between the shoulder and elbow.
The humerus is the large bone in the arm.
The humerus has a head, shaft, and distal ends.
Humerus: Provides the framework of the arm; participates in the elbow joint.
Elbow Joint: Hinge joint involving humerus, radius, and ulna.
The elbow enables flexion, extension, and supination (palm up) and pronation (palm down) of the forearm.

Forearm

The forearm is between the elbow and wrist.
Contains two bones: the radius and the ulna.
Radius: Lateral bone of the forearm; crucial for supination and pronation.
Ulna: Medial bone of the forearm; larger of the two; crucial for elbow flexion and extension.
The radius and ulna articulate with the humerus (forming the elbow joint) and with each other (proximal and distal radioulnar joints).

Wrist and Hand

The wrist is the region between the forearm and hand.
The wrist is a complex of eight small carpal bones arranged in two rows.
Carpals: Provide the structural basis of the wrist and assist in its range of motion.
Metacarpals: Five bones forming the palm of the hand.
The phalanges form the fingers and thumb.

Muscles of the Upper Limb

Numerous muscles are crucial for movement and function.
Muscles are categorized according to their location, origin, insertion, and action.
Muscles of the shoulder girdle, rotator cuff, arm, forearm, and hand.
These muscles exert forces on bones to move the limb.
The upper limb features numerous muscles enabling varied and precise movements.

Nerves and Blood Vessels

Nerves and blood vessels of the upper limb are critical for innervation and blood supply.
Major nerves (radial, median, ulnar) and major arteries (brachial, radial, ulnar) run through the limb for critical signaling and nutrition.
These structures accompany the muscles and bones throughout their distribution.
Injury to nerves or blood vessels can result in weakness, numbness, or impaired blood flow.

Description

This quiz covers the anatomy and function of the upper limb, focusing on the shoulder girdle and its components. Detailed information about the clavicle, scapula, and glenohumeral joint is included. Test your understanding of how these structures contribute to mobility and dexterity.