The pectoral girdle connects the upper limbs to the axial skeleton and consists of the clavicle and scapula in humans. The clavicle is an S-shaped bone that connects the sternum to the scapula. It has a lateral end that articulates with the acromion process of the scapula and a medial end that articulates with the manubrium of the sternum. The clavicle provides support for the shoulder joint and allows for a wide range of arm movement. It is attached to muscles like the deltoid, trapezius, pectoralis major, and sternocleidomastoid.

1. Pectoral Girdle:
 The shoulder girdle or pectoral girdle is the set of bones in the appendicular skeleton which
connects to the arm on each side.
 In humans it consists of the clavicle and scapula; in those species with three bones in the
shoulder, it consists of the clavicle and scapula
 Clavicle:
 The clavicle, or collarbone, is a long bone that serves as a strut between the shoulder blade and
the sternum (breastbone).
 There are two clavicles, one on the left and one on the right.
 The clavicle is the only long bone in the body that lies horizontally.
 Type of Bone:
 Even though it is classified as a long bone, the collarbone has no medullary (bone marrow)
cavity like other long bones
 It is made up of spongy bone with a shell of compact bone.
 Anatomical position:
 The clavicle is an elongated, S-shaped bone that rests horizontally at the sternum across the
upper part of the ribcage, and the acromial end of the scapula.
 Osteologyof bone:

2.  The bone has a cylindrical part called the shaft, and two ends: lateral and medial.
Shaft:
1. Lateral 1/3: flattened in sectionand thinner
 consists of 2 borders : anterior and posterior and 2 surfaces: superior and inferior
 BORDERS:
i. anterior border: concave forwards and gives origin to deltoid muscle
ii. posterior border: convex backwards and gives attachment to trapezius muscle
 SURFACE:
i. superior surface: is subcutaneous
ii. inferior surface: shows conoid tubercle and trapezoid ridge which gives
attachment to conoid ligament (medial part of coracoclavicular ligament) and
trapezoid ligament (lateral part of coracoclavicular ligament) respectively
2. Medial 2/3: circular insectionand thicker
 consists of 4 surfaces
i. anterior surface: convex forwards and gives origin to pectorals major
ii. posterior surface: concave backwards and gives origin to sternohyoid muscle
iii. superior surface: is rough on its medial part
iv. inferior surface: has rough oval impression at the medial end for costoclavicular
ligament and shows subclavian groove which gives attachment to subclavian muscle
Ends:
1. Lateral (Acromial) End: articulates with with the acromian process of the scapula to form
the Acromioclavicular joint
2. Medial (Sternal) End: articulates with the clavicular notch of the manubrium sterni to
form Sternoclavicular joint.
 Side Determination:
 Lateral end is flat and thinner and medial end is round and thicker.
 There is a groove on inferior surface.
 Medial part of shaft is convex anteriorly while lateral part is concave anteriorly.

3.  Functions of clavicle:
 It serves as a rigid support from which the scapula and free limb suspended; an arrangement
that keeps the upper limb away from the thorax so that the arm has maximum range of
movement.
 Articulationof Clavicle:
 The clavicle is an anterior bone whose sternal end articulates with the manubrium of the
sternum at the Sternoclavicular joint. The sternal end is also anchored to the first rib by the
costoclavicular ligament.
 The acromial end of the clavicle articulates with the acromion of the scapula at the
Acromioclavicular joint.
 Muscles attached to clavicle:
 A total of five muscles are attached to the clavicle, found distributed at either the lateral third
or medial two thirds of the bone.
Two muscles are attached to the lateral thirdofthe clavicle:

4. i. The trapezius muscle, which is attached along the posterior surface of the bone.
ii. The deltoidmuscle, where the anterior portionof the muscle is attached to the
periosteum at the anterior surface of the bone.
Three muscles are attached to the medial thirdof the clavicle:
i. The sternocleidomastoidmuscle, where the muscular clavicular head of the muscle is
attached to the superior surface of the bone.
ii. The pectoralis major muscle, which is attached to the anterior surface of the bone.
iii. The subclavius muscle, which is attached to a groove found in the middle of the bone’s
inferior surface. From there, the muscle extends into both lateral and medial areas of the
clavicle.
 Ligaments attached to clavicle:
 Acromioclavicular ligaments (several) and coracoclavicular ligaments (there are
two: trapezoid and conoid). These ligaments stabilize the Acromioclavicular (AC) joint.
 Sternoclavicular ligaments (many) stabilize the Sternoclavicular (SC) joint.
 Bloodsupply:
 Three arteries were found to supply the clavicle:
1. the suprascapular a.;
2. the thoracoacromial a.; and
3. the internal thoracic (mammary)
 The main supply was primarily periosteal.
 No nutrient artery was found.
 Nerve Supply:
 the common trunk of the supraclavicular nerves divides into three groups of descending
branches:
1. the medial supraclavicular nerve,
2. intermediate supraclavicular nerve and
3. Lateral supraclavicular nerve.
 Clinical notes:
 Clavicle Fracture:
Clavicle fractures are fairly common and occur in people of all ages. Most fractures occur in
the middle portion, or shaft, of the bone. Occasionally, the bone will break where it attaches
at the ribcage or shoulder blade.

5. Clavicle fractures vary. The bone can crack just slightly or break into many pieces
(comminuted fracture). The broken pieces of bone may line up straight or may be far out of
place (displaced fracture).
Comminuted
Causes:
Clavicle fractures are most often caused by a direct blow to the shoulder. This can happen
during a fall onto the shoulder or a car collision. A fall onto an outstretched arm can also
cause a clavicle fracture. In a baby, a clavicle fracture can occur during the passage through
the birth canal.