Lab 17: Muscles of Upper Limb

Pectoral Girdle

Composed of the clavicle and scapula, it supports the arm and allows attachment of the humerus to the axial skeleton.

Protraction

Lateral and anterior movement of the scapula, similar to a punching movement.

Retraction

Medial and posterior movement of the scapula, as in clasping hands behind the back.

Elevation

Superior movement of the scapula, akin to lifting a weight above the head.

Depression

Inferior movement of the scapula, such as pulling down a cat from a tree.

Rotator Cuff

A group of muscles and their tendons that stabilize the shoulder joint, including supraspinatus, infraspinatus, teres minor, and subscapularis.

Pectoralis Minor

An anterior muscle that pulls the scapula in an anterior direction and assists in forced inhalation.

Serratus Anterior

An anterior muscle known for its saw-toothed appearance that protracts the scapula and assists with forced inhalation.

Trapezius

A large, superficial muscle capable of multiple actions including scapular elevation, depression, and rotation.

Deltoid Muscle

A thick muscle that forms the rounded curvature of the shoulder and is the prime mover in arm abduction.

Latissimus Dorsi

A large, superficial muscle that extends and adducts the arm, originating from the lower back.

Teres Major

A muscle that assists with adduction, medial rotation, and extension of the arm.

Diaphragm

The prime mover in inspiration that flattens to increase the volume of the thoracic cavity.

External Intercostals

Muscles between the ribs whose contraction assists in the expansion of the thoracic cavity during inspiration.

Internal Intercostals

Muscles involved in forced expiration, located deep to the external intercostals.

Innermost Intercostals

Deepest layer of intercostal muscles with poorly understood functions.

Action of the Rotator Cuff

Functions to help attach the humerus to the scapula, stabilizing the shoulder joint.

Muscles Acting on the Arm

Muscles that originate at the scapula or axial skeleton and insert at the humerus, resulting in arm movement.

Name the four muscles that make up the Rotator Cuff.

Supraspinatus, Infraspinatus, Teres Minor, and Subscapularis.

What is the primary role of the clavicle?

To act as a strut, holding the scapula and arm laterally away from the body and transmitting forces from the upper limb to the axial skeleton.

List two main functions of the scapula.

Supports the arm, allows attachment of the humerus to the axial skeleton, and serves as an attachment point for various muscles that move the arm and shoulder.

Which muscle is described as the prime mover in arm abduction and forms the rounded curvature of the shoulder?

Deltoid Muscle.

What are the main actions of the Latissimus Dorsi muscle?

Extends, adducts, and medially rotates the arm.

Which intercostal muscles are primarily involved in forced expiration?

Internal Intercostals.