Overview
The
clavicle connects the axial skeleton to the appendicular skeleton. It has a
great deal of muscular attachment, and has a role in protecting the
neurovasculature if the neck and thorax. It is considered a part of the borders
off the thoracis inlet, and has articulations with the scapula and hence the
upper limb. The clavicle is S shaped and
articulates with the acromion process of the scapula laterally and the
clavicular notch of the manubrium medially. It lies in front of the subclavian
vein, and is attached to the first rub by the costoclavicular ligament and the
subclavius muscle.
Gross Anatomy
The
clavicle begins the ossification forces during the 5th-6th
gestational week, and is the last bone to complete ossification (around 20-25
years of age). It is an s shaped bone that articulates with the manubrium of
the sternum via its rounded medial end, and with the acromion process of the
scapula via its flat lateral end.
The shaft
of the clavicle is divided into thirds. The anterior surface of the bone has a
convex surface forwards, that gives rise to the pectoralis major muscle. The sternohyoid
muscle inserts on the posterior surface of the clavicle. The superior surface
of the clavicle is rough and bumpy, and is where the sternocleidomastoid muscle
inserts. The Subclavius and costoclavicular ligament arise from the inferior
surface of the bone, and insert onto the first rib below.
The
deltoid muscle originates from the lateral third of the clavicle. The trapezius
muscle originates from the posterior surface. The conoid and trapezoid
ligaments are coracoclavicular ligaments (the conoid attaches more medially),
which arise from the lateral part of the superior surface of the clavicle and
attach to the coracoid process. The inferior aspect of the clavicle has a
conoid tubercle and a trapezoid line, from which these ligaments arise and
insert onto the coracoid process. The superior surface of the bone lies
directly under the skin. The clavicle has no bone marrow, even though it is
classified as a long bone.
Clinical Anatomy
Quick Anatomy
Key Facts
Developmental precursor- Limb bud (lateral mesodermal mesenchyme)
Aide-Memoire
Summary
The
clavicle (also known as the collar bone) is an s shaped bone, that articulates
with the acromion process of the scapula laterally and the clavicular notch of
the manubrium medially. It lies in front of the subclavian vein, and is
attached to the first rub by the costoclavicular ligament and the subclavius
muscle.