Human Skeletal and Muscular Systems: A Comprehensive Overview

Posted on Nov 24, 2024 in Physical Education

Anatomy of the Human Skeletal and Muscular Systems

Axial Skeleton

The axial skeleton consists of 80 bones, including the skull and craniofacial bones, the hyoid bone, the spine, the ribs, and the sternum.

Appendicular Skeleton

The appendicular skeleton comprises 126 bones, forming the upper and lower limbs.

Key Bones and Joints

  • Paranasal Sinuses: Ethmoid, frontal, sphenoid, and maxillary.
  • Mastoid Spine: Located in the temporal bone of the skull.
  • Sella Turcica: Found in the sphenoid bone.
  • Trochoid Joint: The joint between the first and second cervical vertebrae (atlantoaxial joint).
  • Intervertebral Disc: Composed of a ring of fibrocartilage.

Muscles and Their Functions

  • Knee Flexor Muscle Originating at the Pubis: Gracilis.
  • Adductors of the Glenohumeral Joint: Pectoralis major, latissimus dorsi, teres major, and subscapularis.
  • Pectoralis Major: Originates from the clavicle, sternum, and costal cartilages, and inserts into the humerus. It does not originate from the femoral biceps or scapula.
  • Adductor Muscles of the Hip: Pectineus, gracilis, adductor longus, adductor brevis, and adductor magnus.
  • ACL (Anterior Cruciate Ligament): An extracapsular stabilizing mechanism of the knee.
  • Muscle Not Originating or Inserting into the Pubic Bone: Rectus femoris.
  • Muscle Not an Internal Rotator of the Glenohumeral Joint: Infraspinatus.
  • Molecular Ultrastructure of the Sarcomere: Titin links the Z-disc to the M-line.
  • Cranial Nerve Supplying the Sternocleidomastoid: XI (Accessory nerve).
  • Sensory Neurons: Can be bipolar or multipolar.
  • Motor Neurons: Multipolar.
  • Cell Type Not Part of Neuroglia: Purkinje cells.
  • Not Considered Part of the Peripheral Nervous System: Spinal cord.
  • Location of Gray Matter in the Spinal Cord: Superficial.

Axial Muscles

  • Sternocleidomastoid: Originates from the sternum and clavicle, inserts onto the mastoid process of the temporal bone. Innervated by the 11th cranial nerve (Accessory nerve). Unilateral contraction turns the head to the opposite side; simultaneous contraction flexes the cervical spine and head.
  • Upper Body Muscles (Superficial):
    • Pectoralis Major: Flexes, adducts, and medially rotates the arm.
    • Latissimus Dorsi: Adducts, medially rotates, and extends the arm.
  • Upper Body Muscles (Deep):
    • Anterior Chest Muscles: Subclavius, pectoralis minor, and serratus anterior.
    • Posterior Chest Muscles: Trapezius, levator scapulae, and rhomboids.

Bones and Joints of the Upper Limb

  • Clavicle: Extends from the sternum to the acromion of the scapula.
  • Scapula: Features the subscapular fossa and the coracoid process (attachment for coracobrachialis and short head of biceps brachii).
  • Glenohumeral Joint: Formed by the head of the humerus and the glenoid fossa of the scapula. Stabilized by ligaments and the rotator cuff muscles.
  • Deltoid: Originates from the acromion and spine of the scapula, inserts into the deltoid tuberosity of the humerus. Abducts, flexes, and extends the arm.
  • Rotator Cuff Muscles: Supraspinatus, infraspinatus, teres minor, and subscapularis.
  • Humerus: Proximal end features the head and the deltoid tuberosity. Distal end includes the capitulum, trochlea, olecranon fossa, and epicondyles.
  • Elbow Flexors: Biceps brachii, brachialis, and brachioradialis.
  • Elbow Extensors: Triceps brachii and anconeus.

Muscles of the Forearm and Hand

  • Flexor and Pronator Muscles (Superficial): Flexor carpi radialis, flexor carpi ulnaris, flexor digitorum superficialis, and palmaris longus.
  • Flexor and Pronator Muscles (Deep): Flexor digitorum profundus, flexor pollicis longus, pronator teres, and pronator quadratus.
  • Supinator and Extensor Muscles (Superficial): Extensor carpi radialis, extensor carpi ulnaris, extensor digitorum, and extensor digiti minimi.
  • Supinator and Extensor Muscles (Deep): Supinator, extensor indicis, extensor pollicis longus, extensor pollicis brevis, and abductor pollicis longus.

Bones and Joints of the Lower Limb

  • Pelvic Girdle: Two innominate bones articulated anteriorly at the pubic symphysis and posteriorly with the sacrum at the sacroiliac joints. Each innominate bone is composed of the ilium, ischium, and pubis.
  • Coxofemoral Joint (Hip Joint): Formed by the head of the femur and the acetabulum of the hip bone. Stabilized by the iliofemoral, pubofemoral, and ischiofemoral ligaments.
  • Hip Flexors: Psoas major, iliacus, rectus femoris, tensor fasciae latae, and sartorius.
  • Hip Adductors: Pectineus, adductor longus, adductor brevis, adductor magnus, and gracilis.
  • Hip Extensors, Abductors, and External Rotators: Gluteus maximus (extensor), gluteus medius and minimus (abductors), and several deep rotators (e.g., piriformis, quadratus femoris).
  • Knee Flexors: Semimembranosus, semitendinosus, and biceps femoris.
  • Knee Stabilizers: Menisci (medial and lateral) and cruciate ligaments (anterior and posterior).
  • Ankle Stabilizers: Lateral and medial ligaments.

Muscles of the Leg and Foot

  • Posterior Compartment (Foot Flexors – Superficial): Gastrocnemius, soleus, and plantaris.
  • Posterior Compartment (Foot Flexors – Deep): Tibialis posterior, flexor digitorum longus, and flexor hallucis longus.
  • Lateral Compartment (Foot Flexors): Peroneus longus and peroneus brevis.
  • Anterior Compartment (Foot Extensors): Tibialis anterior, extensor digitorum longus, extensor hallucis longus, and peroneus tertius.