CCH_Anatomy _Muscles of the Upper Extremity and Lower extremity

Muscles of the Upper Extremity

The muscles of the upper extremity include those that attach the scapula to the thorax and generally move the scapula, those that attach the humerus to the scapula and generally move the arm, and those that are located in the arm or forearm that move the forearm, wrist, and hand. The illustration below shows some of the muscles of the upper extremity.

Muscles that move the shoulder and arm include the trapezius and serratus anterior. The pectoralis major, latissimus dorsi, deltoid, and rotator cuff muscles connect to the humerus and move the arm.

The muscles that move the forearm are located along the humerus, which include the triceps brachii, biceps brachii, brachialis, and brachioradialis. The 20 or more muscles that cause most wrist, hand, and finger movements are located along the forearm.

Muscles of the Lower Extremity

The muscles that move the thigh have their origins on some part of the pelvic girdle and their insertions on the femur. The largest muscle mass belongs to the posterior group, the gluteal muscles, which, as a group, adduct the thigh. The iliopsoas, an anterior muscle, flexes the thigh. The muscles in the medial compartment adduct the thigh. The illustration below shows some of the muscles of the lower extremity.

Muscles that move the leg are located in the thigh region. The quadriceps femoris muscle group straightens the leg at the knee. The hamstrings are antagonists to the quadriceps femoris muscle group, which are used to flex the leg at the knee.

The muscles located in the leg that move the ankle and foot are divided into anterior, posterior, and lateral compartments. The tibialis anterior, which dorsiflexes the foot, is antagonistic to the gastrocnemius and soleus muscles, which plantar flex the foot.

Review: Introduction to the Muscular System

Here is what we have learned from Introduction to the Muscular System:

• One of the most predominant characteristics of skeletal muscle tissue is its contractility and nearly all movement in the body is the result of muscle contraction.
• Four functions of muscle contraction are movement, posture, joint stability, and heat production.
• Three types of muscle are skeletal, smooth, and cardiac.
• Each muscle fiber is surrounded by endomysium. The fibers are collected into bundles covered by perimysium. Many bundles, or fasciculi, are wrapped together by the epimysium to form a whole muscle.
• Muscles are attached to bones by tendons.
• Muscle features such as size, shape, direction of fibers, location, number of origin, origin and insertion, and action are often used in naming muscles.
• Four major muscle groups of the body include:
  • Muscles of the head and neck;
  • Muscles of the trunk;
  • Muscles of the upper extremity; and
  • Muscles of the lower extremity.