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    From Musculoskeletal System

    Soleus
    Calf muscle responsible for plantarflexion of the foot.
    Ilium
    Uppermost and largest part of the hip bone.
    Thoracic Vertebrae (T1 - T12)
    Vertebrae in the upper and mid-back (T1-T12).
    Deltoid
    Shoulder muscle responsible for arm abduction.
    Lacrimal Bones
    Bones forming part of the eye socket and housing the tear ducts.
    Ulna
    Forearm bone on the pinky side.
    Radius
    Forearm bone on the thumb side.
    Abductor Digiti Minimi Muscle
    The abductor digiti minimi muscle is a hypothenar muscle that abducts and flexes the little finger, aiding grip and precision in hand movements.
    Fibula
    Smaller bone in the lower leg, located alongside the tibia.
    Acetabulum
    The acetabulum is the pelvic socket that connects with the femoral head to form the hip joint, vital for stability, movement, and weight-bearing.
    Clavicle
    Collarbone connecting the arm to the body.
    Hamstrings
    Biceps Femoris, Semitendinosus, Semimembranosus.
    Thoracic Cage
    Ribs and sternum forming the protective cage for the heart and lungs.
    Acromioclavicular Joint
    The acromioclavicular joint connects the clavicle and scapula at the top of the shoulder, enabling smooth scapular motion and stability during arm movements.
    Zygomatic Bones
    Cheekbones that form part of the orbit.
    Facial Bones
    Bones forming the structure of the face.
    Sternum
    Breastbone located in the center of the chest.
    Scapula
    Shoulder blade providing attachment for muscles of the upper limb.
    Annular Ligament
    The annular ligament is a strong fibrous band encircling the head of the radius, stabilizing the proximal radioulnar joint and allowing smooth rotation of the forearm.
    Nasal Bones
    Bones forming the bridge of the nose.
    Pectoralis Major
    Chest muscle responsible for shoulder movement.
    Phalanges (14 bones)
    14 bones forming the toes.
    Sutures (in the skull)
    Fibrous joints between skull bones.
    Brachioradialis
    Muscle responsible for forearm flexion.
    Ribs (12 Pairs)
    12 pairs of bones that form the sides of the thoracic cage.

    Triceps Brachii

    Reviewed by our medical team

    Muscle responsible for elbow extension.

    1. Overview

    The triceps brachii is a large, three-headed skeletal muscle located on the posterior aspect of the upper arm. As the primary extensor of the elbow joint, it plays a crucial role in straightening the forearm. The triceps is also important for shoulder joint stability and movement. Its powerful action is essential in pushing, throwing, and weight-bearing activities.

    2. Location

    The triceps brachii occupies the posterior compartment of the arm:

    • Proximally: Originates from both the scapula and the humerus.

    • Distally: Inserts on the olecranon process of the ulna.

    • Superficial to: The humerus and deep fascia of the upper arm.

    • Adjacent to: Biceps brachii (anteriorly) and deltoid (superiorly).

    3. Structure

    The triceps brachii has three distinct heads:

    • Long head: Originates from the infraglenoid tubercle of the scapula.

    • Lateral head: Originates from the posterior surface of the humerus, superior to the radial groove.

    • Medial head: Originates from the posterior surface of the humerus, inferior to the radial groove.

    All three heads converge into a common tendon that inserts on the olecranon process of the ulna.

    • Innervation: Radial nerve (C6–C8).

    • Blood supply: Deep brachial artery (profunda brachii) and collateral branches of the brachial artery.

    4. Function

    The triceps brachii has two main actions:

    • Elbow extension: All three heads extend the forearm at the elbow joint.

    • Shoulder extension and adduction: The long head also assists in extension and adduction of the arm at the shoulder joint.

    These actions are essential in movements such as pushing open a door, rising from a chair, or performing a push-up.

    5. Physiological role(s)

    The triceps brachii contributes to several important physiological functions:

    • Upper limb mobility: Allows full range of elbow motion in combination with the biceps brachii.

    • Postural support: Assists in maintaining arm and shoulder posture during load-bearing tasks.

    • Force generation: As a powerful muscle, it generates the force required for explosive movements like throwing or punching.

    • Joint stability: Helps stabilize the shoulder joint, particularly when the arm is adducted or extended behind the body.

    6. Clinical Significance

    The triceps brachii can be affected by various injuries and conditions:

    • Triceps strain or tear:

      • Results from sudden or excessive loading, often seen in athletes performing overhead or pushing motions.

    • Radial nerve palsy:

      • Injury to the radial nerve may weaken or paralyze the triceps, leading to difficulty in elbow extension and “wrist drop.”

    • Tendonitis:

      • Repetitive strain can lead to inflammation of the triceps tendon, especially near the olecranon.

    • Triceps reflex testing:

      • Used clinically to assess the integrity of the C7 and C8 spinal cord segments and radial nerve function.

    • Rehabilitation importance:

      • Commonly targeted in strengthening programs for upper limb recovery, especially after injury or surgery.

    Did you know? Your hand has 5 metacarpal bones.