St._Louis_College_of_Health_Careers_4

Overview of Muscle Anatomy

• Understanding muscles is crucial for studying anatomy, particularly their functions and locations.

Key Muscle Groups and Functions

Upper Body Muscles

• Extensor Digitorum Longus: A muscle responsible for extending the fingers.

• Levator Labii Superioris Alkenazii: A muscle of facial expression.

• Orbicularis Muscles:

  • Orbicularis Oculi: Circular muscle surrounding the eye, responsible for closing the eyelids.

  • Orbicularis Oris: Circular muscle around the mouth, responsible for constricting the lips.

• Zygomatic Muscles: Responsible for smiling (Zygomatic Major and Minor).

• Sternocleidomastoid: Attaches from the mastoid process to the sternum and clavicle; involved in neck rotation.

• Trapezius: Muscle responsible for moving shoulder blades and supporting the arm.

Muscle Groups of Breathing

• External Intercostal Muscles: Elevate ribs during inhalation.

  • Internal Intercostal Muscles: Involved in forced exhalation, with fibers going in the opposite direction of external intercostals.

• Diaphragm: Main muscle of respiration controlled by the phrenic nerve (C3, C4, C5). It is essential for breathing in and out.

Core Muscles

• Rectus Abdominis: Known as the 'six-pack,' involved in trunk flexion and stabilization.

• External Obliques: Run diagonally downwards, involved in trunk rotation and lateral flexion.

• Internal Obliques: Run diagonally upwards, providing similar functions to external obliques.

• Transverse Abdominis: Deepest abdominal muscle, important for core stability.

• Linea Alba: Connective tissue separating the left and right rectus abdominis.

Shoulder Muscles

• Deltoid: Responsible for shoulder abduction and gives contour to the shoulder area.

• Pectoralis Major: Primary muscle of the chest; assists in shoulder movement.

  • Minor Over Major Rule: Minor muscle is superior to major muscle.

• Serratus Anterior: Assists in the protraction and rotation of the scapula.

• Latissimus Dorsi: Known for shoulder extension, internal rotation, and adduction.

Rotator Cuff Muscles

• Supraspinatus and Infraspinatus: Serve to stabilize the shoulder joint and facilitate movement.

  • Teres Major: Not a part of the rotator cuff but works closely with these muscles.

• Subscapularis: Located on the anterior side of the scapula; involved in internal rotation of the shoulder.

Arm Muscles

• Biceps Brachii: Involved in elbow flexion and is made up of two heads.

• Triceps Brachii: Responsible for elbow extension.

• Brachioradialis: Muscle that flexes the elbow and involves radial deviation.

• Pronator Teres and Supinator Muscles: Involved with forearm rotation.

Hip and Thigh Muscles

• Rectus Femoris: A part of the quadriceps, responsible for knee extension and hip flexion.

• Sartorius: A long muscle aiding in flexion, external rotation, and abduction of the hip.

• Iliopsoas: Key muscle complex consisting of the iliacus and psoas major; responsible for hip flexion.

• Adductor Group: Including Adductor Magnus, Brevis, and Longus, these muscles are responsible for hip adduction and are located medially on the thigh.

Gluteus Muscles

• Gluteus Medius: Responsible for hip abduction.

• Gluteus Maximus: Major muscle involved in hip extension and lateral rotation.

Lower Body Muscles

• Gastrocnemius: Major calf muscle involved in plantar flexion.

• Soleus: Works with the gastrocnemius for plantar flexion when seated.