Radius – Bone Land Markings, Muscle Attachment

Last updated: February 7, 2026Reviewed date: February 7, 2026Reading time: 10 min read
Patient Tools

Read, save, and share this guide

Use these quick tools to make this medical article easier to read, print, save, or share with a family member.

Patient Mode

Understand this article easily

Switch between simple English and easy Bangla patient notes. This is for education and does not replace a doctor consultation.

Radius/The radius is the thicker and shorter of the two long bones in the forearm. It is located on the lateral side of the forearm parallel to the ulna (in anatomical position with arms hanging at the sides of the body, palms facing forward) between the thumb...

For severe symptoms, danger signs, pregnancy, child illness, or sudden worsening, seek urgent medical care.

বাংলা রোগী নোট এখনো যোগ করা হয়নি। পোস্ট এডিটরে “RX Bangla Patient Mode” বক্স থেকে সহজ বাংলা সারাংশ যোগ করুন।

এই তথ্য শিক্ষা ও সচেতনতার জন্য। এটি ডাক্তারি পরীক্ষা, রোগ নির্ণয় বা প্রেসক্রিপশনের বিকল্প নয়।

Article Summary

Radius/The radius is the thicker and shorter of the two long bones in the forearm. It is located on the lateral side of the forearm parallel to the ulna (in anatomical position with arms hanging at the sides of the body, palms facing forward) between the thumb and the elbow. The radius and ulna pivot around one another to allow rotation of the wrist. Together, along with...

Key Takeaways

  • This article explains Bone Land Markings of Radius in simple medical language.
  • This article explains Muscle Attachment of  Radius in simple medical language.
Educational health guideWritten for patient understanding and clinical awareness.
Reviewed content workflowUse writer and reviewer profiles for stronger trust.
Emergency safety firstUrgent warning signs are highlighted below.

Seek urgent medical care if you notice

These warning signs are general safety guidance. Local emergency numbers and clinical judgment should always come first.

  • Severe symptoms, breathing difficulty, fainting, confusion, or rapidly worsening illness.
  • New weakness, severe pain, high fever, or symptoms after a serious injury.
  • Any symptom that feels urgent, unusual, or unsafe for the patient.
1

Emergency now

Use emergency care for severe, sudden, rapidly worsening, or life-threatening symptoms.

2

See a doctor

Book a professional medical evaluation if symptoms persist, worsen, recur often, affect daily activities, or occur in a high-risk patient.

3

Learn safely

Use this article to understand possible causes, tests, treatment options, prevention, and questions to ask your clinician.

Before reading

RX Patient Tools

Use these quick guides before reading the article, or return to them when you need help preparing questions for a doctor.

Start here Choose the right pathway for symptoms, reports, medicines, or urgent warning signs. Disease article roadmap Read this topic step by step: meaning, symptoms, warning signs, diagnosis, treatment, prevention, and follow-up. Treatment planner Prepare questions about treatment choices, benefits, risks, side effects, and follow-up. Family & caregiver guide Organize symptoms, reports, medicines, questions, and follow-up safely. Nutrition & diet guide Prepare food, hydration, supplement, and medicine-timing questions safely. Prevention guide Organize risk factors, protective habits, screening, and warning signs. Recovery guide Prepare a safe plan for activity, rehabilitation, warning signs, and follow-up.
Definition

Radius/The radius is the thicker and shorter of the two long bones in the forearm. It is located on the lateral side of the forearm parallel to the ulna (in anatomical position with arms hanging at the sides of the body, palms facing forward) between the thumb and the elbow. The radius and ulna pivot around one another to allow rotation of the wrist. Together, along with the humerus, they create the elbow joint.

The radius or radial bone is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna. The ulna is shorter and smaller than the radius. It is a long bone, prism-shaped and slightly curved longitudinally.

Bone Land Markings of Radius

Proximal radius (head, neck, and tuberosity)

  • The head can be found proximally and is known as the caput radii, which articulates with the capitulum of the humerus as part of the compound joint of the elbow and is concave to look at. The radius also communicates with the head of the ulna by articulating with the ulna’s radial notch via its own circumference.
  • The neck is the area of the bone that narrows in between the head and the radial or bicipital tuberosity. Just below the head and neck of the radius is the radial tuberosity, which is an oval-shaped convexity upon which the biceps brachii inserts.

Radial Shaft

  • The shaft of the radial bone is the long, wide column of bone that is convex on its lateral side but enlarges towards the wrist. It has three borders (anterior, posterior, and interosseous) and three surfaces (anterior, posterior and lateral). There are several anatomical landmarks upon its surfaces, which allows for the origin and insertion of tendons.

Laterally we can find the attachment of two muscles:

  • Supinator muscle (radial head) attaches to the lateral aspect of the radius, covering a large area of it.
  • Pronator teres muscle also adheres to the radial shaft (below the supinator’s attachment) and inserts on the pronator tuberosity, which is a well-demarcated, rough area.

Medially, in between the invagination created by the two laterally attaching muscles, we can see the origins  of another two muscles, as follows:

  • Flexor digitorum superficialis.
  • Flexor pollicis longus (just inferior to the origin of  Flexor digitorum superficialis).

The larger of the two muscular attachments that cover the distal end of the shaft on its medial surface is that of pronator quadratus muscle. Slightly inferior to it on the opposite side sits the insertion of the brachioradialis muscle, which is just above the styloid process – an extrusion of the suprastyloid crest. This is a projection of the lateral aspect of the distal end of the radial bone that margins the carpal articular surface superiorly. Meanwhile, The posterior surface of the radius is the origin of  two more muscles:

  • Abductor pollicis longus which originates just below the posterior margin of the attachment of the supinator muscle.
  • Extensor pollicis longus which can be found distally still.

Distal Radius

  • The last two landmarks of note are not, however, muscle attachments, but bony developments. The dorsal tubercle protrudes on the posterior aspect of the distal head of the radius and is seated between the grooves for the tendons of the extensor carpi radialis longus and brevis as well as the tendon of the extensor pollicis longus. The ulnar notch of the radius is a medial concavity upon the distal head of the bone which directly contacts the distal ulna at the same level.

Borders

  • The volar border (margo volaris; anterior border; palmar😉 –  extends from the lower part of the tuberosity above to the anterior part of the base of the styloid process below, and separates the volar from the lateral surface. Its upper third is prominent, and from its oblique direction has received the name of the oblique line of the radius; it gives origin to the flexor digitorum superficialis muscle (also flexor digitorum sublimis) and flexor pollicis longus muscle; the surface above the line gives insertion to part of the supinator muscle.
  • The dorsal border (margo dorsalis; posterior border) – begins above at the back of the neck, and ends below at the posterior part of the base of the styloid process; it separates the posterior from the lateral surface. is indistinct above and below, but well-marked in the middle third of the bone.
  • The interosseous border (internal border; crista interosseous; interosseous crest;) – begins above, at the back part of the tuberosity, and its upper part is rounded and indistinct; it becomes sharp and prominent as it descends, and at its lower part divides into two ridges which are continued to the anterior and posterior margins of the ulnar notch.

Surfaces

This end of the bone has three non-articular surfaces – volar, dorsal, and lateral.

  • The volar surface – rough and irregular, affords attachment to the volar radiocarpal ligament.
  • The dorsal surface – is convex, affords attachment to the dorsal radiocarpal ligament, and is marked by three grooves. Enumerated from the lateral side:
    • The first groove is broad, but shallow, and subdivided into two by a slight ridge – the lateral of these two, transmits the tendon of the extensor carpi radialis longus muscle; the medial, the tendon of the extensor carpi radialis brevis muscle.
    • The second is deep but narrow, and bounded laterally by a sharply defined ridge; it is directed obliquely from above downward and lateralward and transmits the tendon of the extensor pollicis longus muscle.
    • The third is broad, for the passage of the tendons of the extensor indicis proprius and extensor digitorum communis.
  • The lateral surface is prolonged obliquely downward into a strong, conical projection, the styloid process, which gives attachment by its base to the tendon of the brachioradialis, and by its apex to the radial collateral ligament of wrist joint. The lateral surface of this process is marked by a flat groove, for the tendons of the abductor pollicis longus muscle and extensor pollicis Brevis muscle.

Muscle Attachment of  Radius

Muscles Of Anterior Compartment Of Arm (Flexors Of Arm)

Biceps brachii

  • Function: Major flexion of forearm, supination of the forearm, resists dislocation of the shoulder
  • Origin: Short head originates from the coracoid process. The long head is from the supraglenoid tubercle of the scapula
  • Insertion: Radial tuberosity and forearm fascia (as bicipital aponeurosis)
  • Innervation: Musculocutaneous nerve (C5, C6)

Brachialis

  • Function: Flexion of forearm
  • Origin: Distal anterior humerus
  • Insertion: Coronoid process and ulnar tuberosity
  • Innervation:  musculocutaneous nerve (C5, C6, C7 small contribution)

Coracobrachialis

  • Function: Flexion and adduction of the arm
  • Origin: Coracoid process
  • Insertion: Middle of the humerus, on its medial aspect
  • Innervation: Musculocutaneous nerve (C5, C6, C7)

Muscles Of Posterior Compartment Of Arm (Extensors Of Arm)

Triceps brachii

  • Function: Major extensor of the forearm, resists dislocation of the shoulder
  • Origin: Lateral head: above the radial groove, medial head: below the radial groove, long head: infraglenoid tubercle of the scapula
  • Insertion: Olecranon process of ulna and  forearm fascia
  • Innervation: Radial nerve (C6,C7,C8)

Anconeus

  • Function: Extension of the forearm, stabilization of elbow joint
  • Origin: Lateral epicondyle of humerus
  • Insertion: Olecranon process and posterior ulna
  • Innervation: Radial nerve (C7, C8, T1)

Muscles Of Anterior Compartment Of Forearm (Flexors Of Forearm)

Superficial layer

Pronator teres 

  • Function: Pronation of radio-ulnar joint
  • Origin: Coronoid process and medial epicondyle of humerus
  • Insertion: Lateral surface of the radius
  • Innervation: Median nerve (C6, C7)

Flexor carpi radialis

  • Function: Flexion and adduction at the wrist
  • Origin: Medial epicondyle of humerus
  • Insertion: Base of the second metacarpal
  • Innervation: Median nerve (C6, C7)

Palmaris longus

  • Function: Flexion at the wrist, tensing of the palmar aponeurosis
  • Origin: Medial epicondyle of humerus
  • Insertion: Flexor retinaculum
  • Innervation: Median nerve (C7, C8)

Flexor carpi ulnaris

  • Function: Flexion and adduction at the wrist
  • Origin: Medial epicondyle of humerus and olecranon
  • Insertion: Pisiform, the hook of hamate and fifth metacarpal
  • Innervation: Median nerve (C7, C8)

Intermediate Layer

Flexor digitorum superficialis 

  • Function: Flexion of the proximal interphalangeal joint of the second, third, fourth, and fifth fingers. Also has a weaker flexion action on the metacarpophalangeal joints of the same fingers
  • Origin: Medial epicondyle, coronoid process, and anterior radius
  • Insertion: Second, third, fourth, and fifth middle phalanges
  • Innervation: Median nerve (C7, C8, T1)

Deep Layer

Flexor digitorum profundus

  • Function: Flexion of the distal interphalangeal joint of the second, third, fourth, and fifth finger
  • Origin: Medial and the anterior surface of the proximal ulna and interosseous membrane
  • Insertion: Second, third, fourth, and fifth distal phalanges
  • Innervation: Ulnar nerve (C8, T1) for the medial part, anterior interosseous nerve (C8, T1) for the lateral

Flexor pollicis longus

  • Function: Flexion of the interphalangeal joint of the thumb
  • Origin: Anterior aspect of radius as well as interosseous membrane
  • Insertion: Base of distal phalanx of thumb
  • Innervation: Anterior interosseous nerve (C7, C8)

Pronator quadratus

  • Function: Pronator of the forearm
  • Origin: Anterior aspect of distal ulna
  • Insertion: Anterior aspect of the distal radius
  • Innervation: Anterior interosseous nerve (C7, C8)

Brachioradialis

  • Function: Weak flexor of the forearm
  • Origin: Proximal supracondylar ridge on the humerus
  • Insertion: Lateral surface of the distal end of radius
  • Innervation: Radial nerve (C5, C6, C7)

Muscles Of Posterior Compartment Of Forearm

Superficial

Extensor carpi radialis longus

  • Function: Extension and abduction of the wrist
  • Origin: Proximal supracondylar ridge on the humerus
  • Insertion: Dorsal base of the second metacarpal
  • Innervation: Radial nerve (C6, C7)

Extensor carpi radialis brevis 

  • Function: Extension and abduction of the wrist
  • Origin: Lateral epicondyle of humerus
  • Insertion: Dorsal base of the third metacarpal
  • Innervation: Deep branch of the radial nerve (C7, C8)

Extensor digitorum

  • Function: Extension of the proximal interphalangeal joint of the second, third, fourth, and fifth fingers. Also has a weaker extension action on the metacarpophalangeal joints of the same fingers
  • Origin: Lateral epicondyle of humerus
  • Insertion: Extensor expansions on the dorsal aspect of second, third, fourth, and fifth middle and distal phalanges
  • Innervation: Posterior interosseous nerve (C7, C8)

Extensor digiti minimi

  • Function: Extension of the little finger at the metacarpophalangeal joint and interphalangeal joint
  • Origin: Lateral epicondyle of humerus
  • Insertion: Extensor expansion on the dorsal aspect of the fifth phalanx
  • Innervation: Posterior interosseous nerve (C7, C8)

Extensor carpi ulnaris

  • Function: Extension and adduction of the wrist
  • Origin: Lateral epicondyle of the humerus and posterior ulna
  • Insertion: Fifth metacarpal base
  • Innervation: Posterior interosseous nerve (C7, C8)

Deep Layer

Extensor indices

  • Function: Extension of the index finger
  • Origin: Dorsal surface of the distal ulna and interosseous membrane
  • Insertion: Extensor expansion of the second finger
  • Innervation: Posterior interosseous nerve (C7, C8)

Supinator 

  • Function: Supination of the forearm
  • Origin: Lateral epicondyle and supinator crest of the ulna
  • Insertion: Lateral surface of radius
  • Innervation: Deep branch of the radial nerve (C7, C8)

Abductor policies longus 

  • Function: Abduction of the thumb by acting on the carpometacarpal joint and the metacarpophalangeal joint
  • Origin: Dorsal aspects of the proximal radius, ulna, and interosseous membrane
  • Insertion: Base of the first metacarpal
  • Innervation: Posterior interosseous nerve (C7, C8)

Extensor pollicus longus 

  • Function: Extension of the thumb by acting on the carpometacarpal joint, the metacarpophalangeal joint, and the interphalangeal joint.
  • Origin: Dorsal aspects of the middle ulna and interosseous membrane
  • Insertion: Distal phalanx of 1st finger
  • Innervation: Posterior interosseous nerve (C7, C8)

Extensor pollicus brevis

  • Function: Extension of the thumb by acting on the carpometacarpal joint and the metacarpophalangeal joint
  • Origin: Dorsal aspects of middle radius and interosseous membrane
  • Insertion: Distal phalanx of 1st finger
  • innervation: Posterior interosseous nerve (C7, C8)

References

Doctor visit helper

Prepare before seeing a doctor

A simple rural-patient checklist to help you explain symptoms clearly, ask better questions, and avoid unsafe self-treatment.

Safety note: This is not a prescription or diagnosis. For severe symptoms, pregnancy danger signs, children with serious illness, chest pain, breathing difficulty, stroke-like weakness, or major injury, seek urgent care.

Which doctor may help?

Start with a registered doctor or the nearest qualified health center.

What to tell the doctor

  • Write when the problem started and how it changed.
  • Bring old prescriptions, investigation reports, and current medicines.
  • Write allergies, pregnancy status, diabetes, kidney/liver disease, and major past illnesses.
  • Bring one family member if the patient is weak, elderly, confused, or a child.

Questions to ask

  • What is the most likely cause of my symptoms?
  • Which danger signs mean I should go to hospital quickly?
  • Which tests are necessary now, and which can wait?
  • How should I take medicines safely and what side effects should I watch for?
  • When should I come for follow-up?

Tests to discuss

  • Vital signs: temperature, pulse, blood pressure, oxygen saturation
  • Basic physical examination by a clinician
  • CBC, urine test, blood sugar, or imaging only when clinically needed

Avoid these mistakes

  • Do not use antibiotics, steroid tablets/injections, or strong painkillers without proper medical advice.
  • Do not hide pregnancy, kidney disease, ulcer, allergy, or blood thinner use.
  • Do not delay emergency care when danger signs are present.

Medicine safety and first-aid guide

This section is for patient education only. It does not replace a doctor, pharmacist, or emergency care.

Safe first steps

  • Rest, drink safe water, and observe symptoms carefully.
  • Keep a written note of symptoms, duration, temperature, medicines already taken, and allergy history.
  • Seek medical care quickly if symptoms are severe, worsening, or unusual for the patient.

OTC medicine safety

  • For mild pain or fever, ask a registered pharmacist or doctor before using common over-the-counter pain/fever medicines.
  • Do not combine multiple pain medicines without advice, especially if you have kidney disease, liver disease, stomach ulcer, asthma, pregnancy, or take blood thinners.
  • Do not give adult medicines to children unless a qualified clinician advises it.

Avoid these mistakes

  • Do not start antibiotics without a proper medical decision.
  • Do not use steroid tablets or injections casually for quick relief.
  • Do not delay emergency care because of home remedies.

Get urgent help if

  • Severe symptoms, confusion, fainting, breathing difficulty, chest pain, severe dehydration, or sudden weakness need urgent medical care.
Medicine names, dose, and timing must be decided by a qualified clinician or pharmacist after checking age, pregnancy, allergy, other diseases, and current medicines.

For rural patients and family caregivers

Patient health record and symptom diary

Write your symptoms, medicines already taken, test results, and questions before visiting a doctor. This note stays on your device unless you print or copy it.

Doctor to discuss: Doctor / qualified healthcare provider
Tests to discuss with doctor
  • Basic vital signs: temperature, pulse, blood pressure, oxygen level if needed
  • Relevant blood, urine, imaging, or specialist tests only after clinical assessment
Questions to ask
  • What is the most likely cause of my symptoms?
  • Which warning signs mean I should go to emergency care?
  • Which tests are really needed now?
  • Which medicines are safe for my age, pregnancy status, allergy, kidney/liver/stomach condition, and current medicines?

Emergency warning signs such as chest pain, severe breathing difficulty, sudden weakness, confusion, severe dehydration, major injury, or loss of bladder/bowel control need urgent medical care. Do not wait for online information.

Safe pathway to proper treatment

Care roadmap for: Radius – Bone Land Markings, Muscle Attachment

Use this simple roadmap to understand the next safe steps. It is educational and does not replace examination by a doctor.

Go to emergency care if you notice:
  • Severe or rapidly worsening symptoms
  • Breathing difficulty, chest pain, fainting, confusion, severe weakness, major injury, or severe dehydration
Doctor / service to discuss: Qualified healthcare provider; specialist depends on symptoms and examination.
  1. Step 1

    Check danger signs first

    If danger signs are present, seek emergency care and do not wait for online information.

  2. Step 2

    Record the symptom story

    Write when symptoms started, severity, medicines already taken, allergies, pregnancy status, and test results.

  3. Step 3

    Visit a qualified clinician

    A doctor, nurse, or qualified healthcare provider can examine you and decide which tests or treatment are needed.

  4. Step 4

    Do only useful tests

    Do tests after clinical assessment. Avoid unnecessary tests, random antibiotics, or repeated medicines without diagnosis.

  5. Step 5

    Follow up and return early if worse

    If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

Rural patient practical tips
  • Take a written symptom diary and all previous prescriptions/test reports.
  • Do not hide medicines already taken, even herbal or over-the-counter medicines.
  • Ask which warning signs mean urgent referral to hospital.

This roadmap is for education. A real diagnosis and treatment plan requires history, examination, and clinical judgment.

RX Patient Help

Ask a health question safely

Write your symptom story. A health professional or site editor can review it before any answer is prepared. This box is not for emergency care.

Emergency first: Severe chest pain, breathing trouble, unconsciousness, stroke signs, severe injury, heavy bleeding, or rapidly worsening symptoms need urgent local medical care now.

Frequently Asked Questions

Is this article a replacement for a doctor?

No. It is educational content only. Patients should consult a qualified clinician for diagnosis and treatment.

When should I seek urgent care?

Seek urgent care for severe symptoms, rapidly worsening condition, breathing difficulty, severe pain, neurological changes, or any emergency warning sign.

References

Add references, clinical guidelines, textbooks, journal articles, or trusted medical sources here. You can edit this area from the RX Article Professional Blocks panel.

More from this topic
  1. Isolated Congenital Elbow Dislocation

    DefinitionIsolated congenital? elbow dislocation is a very rare condition present from birth. In most medical papers, the more exact name is congenital? radial head dislocation, because...

    April 2, 2026 • Gastrointestinal, Pelvic & Liver Disease, (A - Z)
  2. Congenital Radial Head Dislocation

    DefinitionCongenital? radial head dislocation means the top part of the radius bone, called the radial head, is out of its normal place at the elbow from...

    April 2, 2026 • Degenerative Bones, Joints, and Spine Care (A - Z)
  3. Congenital Elbow Dislocation

    DefinitionCongenital? elbow dislocation usually means a baby is born with abnormal alignment around the elbow joint, most often a congenital? radial head dislocation. It is rare,...

    April 2, 2026 • Degenerative Bones, Joints, and Spine Care (A - Z)
  4. Congenital Bowing of Long Bones

    DefinitionCongenital? bowing of long bones means a baby is born with one or more arm or leg bones that curve more than usual. It is not...

    March 12, 2026 • Degenerative Bones, Joints, and Spine Care (A - Z)
  5. Humero-Radio-Ulnar Intercalary Transverse Meromelia

    DefinitionHumero-radio-ulnar intercalary transverse meromelia is a rare birth defect of the arm. In this condition the upper arm bone (humerus) and the two forearm bones (radius...

    March 5, 2026 • Degenerative Bones, Joints, and Spine Care (A - Z)
  6. Complete Phocomelia of Upper Limb

    DefinitionComplete phocomelia of the upper limb is a birth problem where almost the whole arm is missing, and the hand is attached very close to the...

    March 5, 2026 • Rx Autoimmune, Genetic and Rare Diseases (A - Z)
  7. Hemimelia

    DefinitionHemimelia is a birth difference where a baby is born with the lower part of an arm or leg missing or not fully formed. Doctors usually...

    March 5, 2026 • Rx Pregnancy, Baby & Mom Care
  8. Radio-Ulnar Terminal Transverse Meromelia

    DefinitionRadio-ulnar terminal transverse meromelia is a birth problem where the baby is born without the forearm bones (radius and ulna) and without the hand on that...

    March 4, 2026 • Rx Musculoskeletal Conditions
  9. Congenital Absence of Both Forearm and Hand

    DefinitionCongenital? absence of both forearm and hand is a rare birth condition. In this condition, the baby is born with the upper arm present, but the...

    March 4, 2026 • Rx Musculoskeletal Conditions
  10. Conductive Hearing Loss-Ptosis-Skeletal Anomalies Syndrome

    DefinitionConductive hearing loss-ptosis-skeletal anomalies syndrome is a very rare genetic condition. In this syndrome, the tiny passages and bones in the outer and middle ear do...

    March 2, 2026 • Rx ENT, Oral and Dental Health (A - Z)