Upper limb · Shoulder girdle
Clavicle
The clavicle is the S-shaped strut that runs horizontally across the root of the neck from the sternum to the acromion. It is the only bony link between the upper limb and the axial skeleton.
- Latin (TA)
- Clavicula
- Type
- Long bone, but an atypical one: it lies horizontally, is S-shaped, and ossifies largely in membrane rather than in cartilage
- Side
- Paired — right and left
- Model size
- 14.3 cm longest
Showing a right bone. Rotate it to inspect every surface; switch sides to practise siding.
3D model: Z-Anatomy (CC BY-SA 4.0), derived from BodyParts3D © DBCLS (CC BY-SA 2.1 JP). Adapted by PharmaWallah. Credits & licence
Landmarks
10 of 12 marked on the modelTap a landmark to find it on the bone and read what it is.
The enlarged, rounded medial end of the clavicle.
Where: Medial end of the bone, projecting slightly above the manubrium in the living subject.
Why it matters: Forms the clavicular side of the sternoclavicular joint; tells you which end is medial.
Related: Sternoclavicular joint
Viva: Which end of the clavicle is rounded?
Marked on the model at the point Z-Anatomy places this label.
The articular surface on the sternal end.
Where: Medial face of the sternal end, extending onto its inferior aspect.
Why it matters: Articulates with the clavicular notch of the manubrium and the first costal cartilage, with an articular disc in between.
Related: Sternoclavicular joint (articular disc)
Marked on the model at the point Z-Anatomy places this label.
The S-shaped shaft between the two ends.
Where: Between the sternal and acromial ends.
Why it matters: Its curvatures fix the side; the junction of its two curves is the commonest fracture site.
Marked on the model at the point Z-Anatomy places this label.
The flattened lateral end of the clavicle.
Where: Lateral end of the bone, under the skin at the top of the shoulder.
Why it matters: Identifies the lateral end; carries the facet for the acromion.
Related: Acromioclavicular joint
Marked on the model at the point Z-Anatomy places this label.
A small oval facet on the acromial end.
Where: On the lateral end, facing laterally and slightly downwards.
Why it matters: Articulates with the clavicular facet on the medial border of the acromion.
Related: Acromioclavicular joint
Marked on the model at the point Z-Anatomy places this label.
A rounded tubercle on the under surface of the lateral third.
Where: Inferior surface, near the posterior border, at the junction of the lateral third with the rest of the shaft.
Why it matters: Attachment of the conoid ligament, the medial part of the coracoclavicular ligament.
Related: Coracoclavicular ligament (conoid part)
Viva: What attaches to the conoid tubercle?
Marked on the model at the point Z-Anatomy places this label.
A rough ridge running forwards and laterally from the conoid tubercle.
Where: Inferior surface of the lateral third, lateral to the conoid tubercle.
Why it matters: Attachment of the trapezoid ligament, the lateral part of the coracoclavicular ligament.
Related: Coracoclavicular ligament (trapezoid part)
Marked on the model at the point Z-Anatomy places this label.
A longitudinal groove on the under surface of the middle third.
Where: Inferior surface of the shaft, in its middle part.
Why it matters: Insertion of the subclavius muscle; its edges give attachment to the clavipectoral fascia.
Related: Subclavius (insertion)
Viva: Which muscle inserts into the groove on the inferior surface of the clavicle?
Marked on the model at the point Z-Anatomy places this label.
A rough oval area on the under surface near the sternal end.
Where: Inferior surface of the medial end.
Why it matters: Attachment of the costoclavicular ligament, the main stabiliser of the sternoclavicular joint.
Related: Costoclavicular ligament
Marked on the model at the point Z-Anatomy places this label.
Classification & region
Long bone, but an atypical one: it lies horizontally, is S-shaped, and ossifies largely in membrane rather than in cartilage.
- Sternal (medial) end
- Enlarged, rounded end that articulates with the manubrium of the sternum and the first costal cartilage.
- Body (shaft)
- Medial two-thirds convex forwards and rounded; lateral third concave forwards and flattened.
- Acromial (lateral) end
- Flattened end with a small oval facet for the acromion of the scapula.
Hold it in the anatomical position
- Hold the bone horizontally with the flat end lateral and the rounded, club-like end medial.
- Turn it so that the medial two-thirds bulge forwards (anterior convexity) and the lateral third curves backwards.
- The smooth surface faces upwards; the surface with the groove for subclavius, the conoid tubercle and the rough costoclavicular impression faces downwards.
Right or left? Side determination
- Lateral end: the flattened end is lateral; the rounded, enlarged end is medial (sternal).
- Anterior: the medial two-thirds are convex forwards; the lateral third is concave forwards.
- Inferior: the groove for subclavius, the conoid tubercle and the costoclavicular impression are all on the under surface; the upper surface is smoother.
- With these three fixed, the side to which the lateral end points is the side of the bone.
Check yourself: switch the 3D model to “Left bone” and apply the same steps.
Articulations
- With the manubrium of sternum and first costal cartilage at the Sternoclavicular joint — Sternal articular surface of the sternal end..
- With the acromion of scapula at the Acromioclavicular joint — Acromial facet on the acromial end..
Muscle and ligament attachments
| Structure | Type | Where on the bone |
|---|---|---|
| Sternocleidomastoid (clavicular head) | origin | Superior surface of the medial third. |
| Pectoralis major (clavicular head) | origin | Anterior surface of the medial half. |
| Deltoid (anterior fibres) | origin | Anterior border and surface of the lateral third. |
| Trapezius | insertion | Posterior border of the lateral third. |
| Subclavius | insertion | Groove on the inferior surface of the middle third. |
| Coracoclavicular ligament (conoid and trapezoid parts) | ligament | Conoid tubercle and trapezoid line on the inferior surface of the lateral third. |
| Costoclavicular ligament | ligament | Impression on the inferior surface of the sternal end. |
| Sternoclavicular and interclavicular ligaments | ligament | Around the sternal end. |
| Acromioclavicular ligament | ligament | Around the acromial end. |
Functions
- Acts as a strut that holds the upper limb away from the trunk, so the arm can move freely.
- Transmits forces from the upper limb to the axial skeleton (through the coracoclavicular ligament and the sternoclavicular joint).
- Gives attachment to muscles of the neck, chest, shoulder and back.
- Forms part of the bony boundary of the passage (cervico-axillary canal) by which the brachial plexus and subclavian/axillary vessels reach the arm.
Clinical & practical relevance
- Fracture of the clavicle is common, usually from a fall on the outstretched hand or on the shoulder; it most often breaks at the junction of its middle and lateral thirds, where the two curves meet.
- After fracture the medial fragment tends to be pulled upwards by sternocleidomastoid, while the lateral fragment drops under the weight of the limb and is pulled medially by the adductors.
- The brachial plexus and subclavian vessels lie behind and below the middle third, so a displaced fracture can injure them.
- Acromioclavicular dislocation ("shoulder separation") is graded by whether the coracoclavicular ligament is also torn.
- The clavicle is the first bone in the body to begin ossifying.
Identification tips
- It is the only long bone lying horizontally in the body: if a long bone is S-shaped and lies horizontally, think clavicle.
- Feel your own clavicle: the medial part bulges forwards, the lateral part curves back towards the shoulder.
- The rough features (subclavius groove, conoid tubercle, costoclavicular impression) are all underneath.
Common student mistakes
- Calling the flat end medial. The flat end is the acromial (lateral) end.
- Holding the bone upside down: the groove and tubercles belong on the inferior surface.
- Confusing the conoid tubercle (medial, rounded) with the trapezoid line (lateral, ridge).
Common exam questions
How do you determine the side of a clavicle?Show answer
Flat end lateral, rounded end medial; medial two-thirds convex forwards; groove for subclavius and conoid tubercle on the inferior surface.
What type of bone is the clavicle, and why is it atypical?Show answer
A long bone, atypical because it lies horizontally and ossifies mostly in membrane.
Name the two parts of the coracoclavicular ligament and their attachments on the clavicle.Show answer
Conoid ligament to the conoid tubercle; trapezoid ligament to the trapezoid line.
Where does the clavicle usually fracture?Show answer
At the junction of its middle and lateral thirds.
Which muscle inserts into the clavicle?Show answer
Subclavius, into the groove on its inferior surface (trapezius also inserts on the posterior border of the lateral third).
Which ligament is the main stabiliser of the sternoclavicular joint?Show answer
The costoclavicular ligament.
Which muscles arise from the clavicle?Show answer
Sternocleidomastoid (clavicular head), pectoralis major (clavicular head) and deltoid.
Revision summary
- S-shaped long bone; horizontal; membrane ossification.
- Flat end lateral, rounded end medial.
- Medial two-thirds convex forwards; lateral third concave forwards.
- Under surface: costoclavicular impression, subclavius groove, conoid tubercle, trapezoid line.
- Joints: sternoclavicular (medial), acromioclavicular (lateral).
- Fracture: junction of middle and lateral thirds.
Test yourself on the clavicle
Spotting questions on bones, sides and landmarks — untimed, with explanations.
Joints of the clavicle
References
- Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. 5th ed. Philadelphia: Elsevier; 2023.
- Moore KL, Dalley AF, Agur AMR. Moore's Clinically Oriented Anatomy. 9th ed. Philadelphia: Wolters Kluwer; 2023.
- Federative International Programme for Anatomical Terminology (FIPAT). Terminologia Anatomica. 2nd ed. FIPAT.library.dal.ca; 2019. fipat.library.dal.ca/TA2
- Kervyn G, Zielinski M, Vinent L, et al. Z-Anatomy: the libre 3D atlas of anatomy. Models derived from BodyParts3D, The Database Center for Life Science (CC BY-SA 2.1 JP). CC BY-SA 4.0. www.z-anatomy.com/
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