The clavicle
By : zuhair Mohamed ammarNomenclature
It is also known as collar bone because the two clavicles form half of the pectoral girdle. The two clavicles bones encircle the upper chest much like a collar.
Note
(also known as pectoral girdle, which is consisted of clavicle and scapula and it is connected to the sternum with an axial skeleton like the vertebral column)
Type
It’s a long bone, because it has two ends and shaft, but the shaft has no bone marrow which means that the clavicle doesn't contribute with red blood cell-forming and this makes it a non-typical long bone.
Location
It’s located subcutaneously, directly above the first rib.
It’s located horizontally in position. It’s very easy to palpate the clavicle.
It’s located horizontally in position. It’s very easy to palpate the clavicle.
Shape
Has a S-shape, because it has two curves.see figure 2 .
For determining these curves we will divide the clavicle into two parts:
1- The first part is the lateral third which’s concave anteriorly.
2- The second part is the medial two thirds which’s convex anteriorly.
The clavicle has a flat end and rounding end.
1- The flat end has been articulated with the acromion process of scapula which makes the acromial end and it forms a joint ( Acromioclavicular joint) . see figure 3
2-The rounded end also named the sternum end because it also has been articulated with the sternum at manubrium part of sternum and it also forms a joint (Sternoclavicualr joint). see figure 4
These two joints form the shoulder girdle( or pectoral girdle) .
Important movements of the shoulder girdle are
1-Elevation
2-Depression
3-Protraction
4-Retraction
5-Downward rotation
6-Upward rotation . see figure 5
The clavicle has two surfaces:
1-The superior surface which is the smooth surface (without any process)
2-The inferior surface which is the rough surface and has some processes
See figure 6
For determining these curves we will divide the clavicle into two parts:
1- The first part is the lateral third which’s concave anteriorly.
2- The second part is the medial two thirds which’s convex anteriorly.
The clavicle has a flat end and rounding end.
1- The flat end has been articulated with the acromion process of scapula which makes the acromial end and it forms a joint ( Acromioclavicular joint) . see figure 3
2-The rounded end also named the sternum end because it also has been articulated with the sternum at manubrium part of sternum and it also forms a joint (Sternoclavicualr joint). see figure 4
These two joints form the shoulder girdle( or pectoral girdle) .
Important movements of the shoulder girdle are
1-Elevation
2-Depression
3-Protraction
4-Retraction
5-Downward rotation
6-Upward rotation . see figure 5
The clavicle has two surfaces:
1-The superior surface which is the smooth surface (without any process)
2-The inferior surface which is the rough surface and has some processes
See figure 6
Function
The clavicle bone is connected part between the upper limbs (free limbs ) to the trunk.
This gives the clavicle crane-like property. And for another functions:
1-It allows the limbs to have a free movement away from the trunk.
2-It protects the neurovascular structures near to it.
3-It transmits the force from the upper limbs to axial skeleton (skull ,vertebrae column , thoracic cage ,hyoid bone ).
See figure 7
Note
(the main part of skeleton of body in which all roots like the upper limbs arise from it or they are connected to it )This gives the clavicle crane-like property. And for another functions:
1-It allows the limbs to have a free movement away from the trunk.
2-It protects the neurovascular structures near to it.
3-It transmits the force from the upper limbs to axial skeleton (skull ,vertebrae column , thoracic cage ,hyoid bone ).
See figure 7
Attachments of the clavicle
All attachments on the rough surface of clavicle:
1- Coracoclavicular ligament
It has a V shape and it is a one of the strongest ligaments of the body because it assists the shoulder elevation.
Note about the Coracoclavicular ligament It can be divided into two parts:
1.The more medial conoid ligament
2.The more lateral trapezoid ligament.
1.Conoid ligament
Origin: from coracoid process of the scapula It runs upward, forming an inverted cone as it widely attaches to the inferior surface of the clavicle (around the conoid tubercle).
2.Trapezoid ligament
Origin: trapezoid ridge on the coracoid process of the scapula.It runs laterally and horizontally, attaching to the underside of the clavicle (to the similarly named, trapezoid ridge).
2- Trapezoid ligament see figure 8
3- Subcostal ligament
4-Groove at medial third for the insertion of subclavius muscle
1- Coracoclavicular ligament
Note
(between the conoid tubercle at the lateral third of clavicle and coracoid process of scapula ) which fixes the shoulder with trapezoid ligament. It has a V shape and it is a one of the strongest ligaments of the body because it assists the shoulder elevation.
Note about the Coracoclavicular ligament It can be divided into two parts:
1.The more medial conoid ligament
2.The more lateral trapezoid ligament.
1.Conoid ligament
Origin: from coracoid process of the scapula It runs upward, forming an inverted cone as it widely attaches to the inferior surface of the clavicle (around the conoid tubercle).
2.Trapezoid ligament
Origin: trapezoid ridge on the coracoid process of the scapula.It runs laterally and horizontally, attaching to the underside of the clavicle (to the similarly named, trapezoid ridge).
2- Trapezoid ligament
Note
(between the trapezoid line and corocoid process)3- Subcostal ligament
Note
( between the first rib and clavicle) near the sternoclavicular joint)4-Groove at medial third for the insertion of subclavius muscle
The clinical notes
Due the position of clavicle (subcutaneous) this allows getting damage easily and fracture.
The fracture usually occurs as a result of a fall on the shoulder or outstretched hand.
The fracture occurs on the most weak point of clavicle (middle part between its two thirds ).
After the fracture, the lateral fragment will be depressed by the weight of arm and this fracture will affect the nerves and blood vessels because the space between the clavicle and first rib will become narrowed in some patients .
There are different types of fracture depending upon the position:
A)Type l. See figure 9
In this type, the medial fragment is still stable because the two ligaments are not effected
B)Type ll. see figure 10
In this type, the medial third will be separated from lateral third because each ligament and the weight of arm will pull the lateral fragment away.
The fracture usually occurs as a result of a fall on the shoulder or outstretched hand.
The fracture occurs on the most weak point of clavicle (middle part between its two thirds ).
After the fracture, the lateral fragment will be depressed by the weight of arm and this fracture will affect the nerves and blood vessels because the space between the clavicle and first rib will become narrowed in some patients .
There are different types of fracture depending upon the position:
A)Type l. See figure 9
In this type, the medial fragment is still stable because the two ligaments are not effected
B)Type ll. see figure 10
In this type, the medial third will be separated from lateral third because each ligament and the weight of arm will pull the lateral fragment away.
Notes
•It is very easy to get fractured because of its location
•Distinguishing the direction of clavicle
Distinguish the direction of clavicle is done by the two articulated ends and the two surfaces of it by:
1-Putting the smooth surface superiorly
2-Putting the rough surface inferiorly
3-Focusing on each end to put
a-The round end medially (the which is articulated with sternum)
b-The flat end laterally.
4-Then focusing on the concave and convex borders to put
a-The convex third medially
b-The concave third laterally
•Distinguishing the direction of clavicle
Distinguish the direction of clavicle is done by the two articulated ends and the two surfaces of it by:
1-Putting the smooth surface superiorly
2-Putting the rough surface inferiorly
3-Focusing on each end to put
a-The round end medially (the which is articulated with sternum)
b-The flat end laterally.
4-Then focusing on the concave and convex borders to put
a-The convex third medially
b-The concave third laterally
References
1. Keith L. Moore , Arthur F. Dalley A. M. R. Agur; Moore clinically oriented anatomy 7th edition;ch.6,p.673
2. Dr. Lawrence E. Wineski,PhD;SNELLIS CLINICAL ANATOMY BY REGIONS 10th edition;ch3,p.88
3. Richard Drake ,PhD , A. Wayne Vogl ,PhD ,Adam W. M. Mitchell ,MB BS FRCS FRCR , Richard Tibbitts , Paul Richardson; Gray's Atlas of Anatomy (Gray's Anatomy) 2nd Edition;p.690
4. The Clavicle; Andrew Lim;Kenhub; https://www.kenhub.com/en/library/anatomy/the- clavicle
2. Dr. Lawrence E. Wineski,PhD;SNELLIS CLINICAL ANATOMY BY REGIONS 10th edition;ch3,p.88
3. Richard Drake ,PhD , A. Wayne Vogl ,PhD ,Adam W. M. Mitchell ,MB BS FRCS FRCR , Richard Tibbitts , Paul Richardson; Gray's Atlas of Anatomy (Gray's Anatomy) 2nd Edition;p.690
4. The Clavicle; Andrew Lim;Kenhub; https://www.kenhub.com/en/library/anatomy/the- clavicle
