Muscle of the Upper Limb

Overview of Upper Limb Musculature

• Discussion focused on the skeletal muscle of the upper limb.

• Previous lecture covered axial system muscles.

• Classification of muscles into axial and appendicular groups.

Muscle Classification

• Appendicular System:
    - Comprises muscles associated with the pectoral girdle, arm, forearm, and hand.
    - Lower Extremities:
      - Pelvic girdle attaches lower limbs to the axial system.
      - Extends down to the toes.
    - Muscles of the upper extremity are around 40% of total body muscle mass, while 20-60% is part of the axial system.

Major Muscle Groups of the Upper Limb

• Divided into four large groups:
    1. Muscles of the Pectoral Girdle
    2. Muscles of the Arm
    3. Muscles of the Forearm
    4. Muscles of the Hand

Muscles of the Pectoral Girdle

• Trapezius Muscle:
    - Large muscle located around the neck and extending down to the shoulder.
    - Functions include stabilization of the scapula.

• Levator Scapulae:
    - Muscle responsible for elevating the scapula.

• Rhomboid Muscles:
    - Rhomboid Major: Pulls scapula medially.
    - Rhomboid Minor: Assists in pulling the scapula to the midline.

• Serratus Anterior and Pectoralis Minor:
    - Muscles that pull the scapula anteriorly, leading to forward movement.

Muscles of the Shoulder

• Flexors:
    - Coracobrachialis: Assists in flexing the shoulder.
    - Pectoralis Major: Major muscle of the chest, located beneath the breast.

• Extensors:
    - Teres Major and Latissimus Dorsi: Extend the shoulder.

• Rotators:
    - Teres Minor, Infraspinatus, Subscapularis: Engage in shoulder rotation.

• Supraspinatus: Located above the spine of the scapula, involved in humerus stabilization.

Muscles of the Arm

• Elbow Extendors:
    - Triceps Brachii: Primary muscle responsible for elbow extension.
    - Anconeus: Minor muscle assisting with extension.

• Elbow Flexors:
    - Biceps Brachii: Key muscle for elbow flexion.
    - Brachialis: Works with biceps to allow elbow flexion.
    - Brachioradialis: Assists in flexing the elbow.

• Pronation:
    - Pronator Teres and Pronator Quadratus: Muscles responsible for pronating the forearm.

Muscles of the Hand

• Flexors:
    - Flexor Carpi Radialis: Flexes and abducts the wrist.
    - Flexor Carpi Ulnaris: Flexes and adducts the wrist.
    - Palmaris Longus: Assists in flexing the palm.
    - Flexor Digitorum Superficialis & Flexor Digitorum Profundus: Flex fingers;
      - Superficialis flexes the middle phalanges, while profundus flexes the distal phalanges.

• Extensors:
    - Extensor Carpi Radialis Longus: Extends and abducts the wrist.
    - Extensor Carpi Radialis Brevis: Assists in extending the wrist.
    - Extensor Carpi Ulnaris: Extends and adducts the wrist.
    - Extensor Digitorum: Extends fingers back.

Clinical Application: Carpal Tunnel Syndrome

• Tendons of the flexors travel under a wrist tunnel called the carpal tunnel.

• Conditions that increase weight or repetitive wrist motion (e.g., typing) can thicken this tunnel.

• Thickening can compress the median nerve, causing symptoms known as carpal tunnel syndrome.

• Treatment often involves a surgical procedure to cut the connective tissue in the tunnel to relieve nerve pressure without affecting the tendons.

Summary and Review

• Reiterated importance of understanding not just muscle names but also their origins, insertions, and actions.

• Emphasized practical applications in anatomy and clinical scenarios.

• Reminder of upcoming exam coverage and schedule adjustments.