Human Skeletal and Muscular Systems Study Guide

Human Skeletal Anatomy: The Cranium and Facial Bones

The human skull is composed of several distinct bones that provide structure to the head and protect the brain. The frontal bone forms the forehead and the superior portion of the eye orbits. Posterior to the frontal bone are the parietal bones, while the occipital bone forms the base and back of the skull. The temporal bone is located on the sides of the head near the ear region. Facial structure is provided by the nasal bone, which forming the bridge of the nose, and the zygomatic bone, commonly known as the cheekbone. The upper jaw is formed by the maxilla, while the lower jaw is defined by the mandible.

The Axial Skeleton: Vertebral Column and Rib Cage

The vertebral column is composed of several regions. The cervical region begins with the $1^{st}$ cervical vertebra, also known as the atlas, followed by the $2^{nd}$ cervical vertebra, known as the axis. The cervical spine concludes with the $7^{th}$ cervical vertebra. Below this begins the thoracic region, starting at the $1^{st}$ thoracic vertebra and ending at the $12^{th}$ thoracic vertebra. The rib cage is anchored by the sternum and includes several ribs, specifically identifying the $1^{st}$ rib at the top and the $12^{th}$ rib at the base.

The lower back is formed by the lumbar region, extending from the $1^{st}$ lumbar vertebra to the $5^{th}$ lumbar vertebra. The base of the spine consists of the sacrum, a fused bone, and terminates at the coccyx, or tailbone.

The Appendicular Skeleton: Shoulder Girdle and Upper Extremity

The shoulder girdle consists of the clavicle and the scapula. The upper arm is defined by the humerus. The forearm contains two primary bones: the radius and the ulna. The wrist is composed of carpal bones, which connect to the metacarpal bones of the hand.

The phalanges of the fingers are divided into three sections: proximal, middle, and distal phalanges. The thumb follows a unique structure consisting of only the proximal phalanx and the distal phalanx.

The Appendicular Skeleton: Pelvic Girdle and Lower Extremity

The pelvic girdle is anchored by the hipbone, which is composed of three fused elements: the ilium, the pubis, and the ischium. The thigh is supported by the femur, the longest bone in the body, which meets the leg at the patella, or kneecap. The lower leg contains the tibia and the fibula.

The foot and ankle structure begins with the tarsus, which includes the talus and the calcaneus. The lateral cuneiform bone is also situated within the tarsal region. Distal to these are the metatarsal bones, leading to the phalanges of the toes. Similar to the fingers, the toe phalanges are classified as proximal, middle, and distal phalanges.

Human Muscular Anatomy: Anterior View

The anterior musculature includes the Sternocleidomastoid and Trapezius muscles in the neck and upper shoulder region. The chest is dominated by the Pectoralis Major, while the Serratus Anterior is located on the lateral rib cage. The abdominal region consists of the Rectus Abdominus and the External Oblique.

In the upper limbs, the anterior view showcases the Deltoid, Biceps, and Brachioradialis. Forearm muscles include the Palmaris Longus, Flexor Carpi Radialis, and Flexor Digitorum Superficialis. The Lubrical muscles are located in the hand.

Lower limb anterior muscles include the Tensor Faciae Latae, Pectineus, Sartorius, Adductor Longus, and Gracilis. The quadriceps group includes the Rectus Femoris, Vastus Lateralis, and Vastus Medialis. Lower leg muscles include the Tibialis Anterior, Peroneus Longus, Soleus, Gastrocnemius, Extensor Digitorum Brevis, and Extensor Hallucis Brevis.

Human Muscular Anatomy: Posterior View

From the posterior perspective, the upper back is supported by the Trapezius, Rhomboid, Teres Major, and Latissimus Dorsi, with the Thoraco-lumbar Fascia providing structural support in the lower back. The posterior shoulder and arm feature the Deltoid and Triceps. The posterior forearm includes the Extensor Carpi Radialis, Extensor Digitorum, Extensor Carpi Ulnaris, and Extensor Digiti Minim.

The gluteal region is composed of the Gluteus Medius and the Gluteus Maximus. The posterior thigh features the Gracilis, Vastus Lateralis, and the hamstring group consisting of the Semimembranosus, Semitendinosis, and Biceps Femoris. The posterior lower leg is dominated by the Gastrocnemius and the Soleus.