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By the end of this section, you will be able to:
  • Identify the muscles of the pectoral girdle and upper limbs
  • Identify the movement and function of the pectoral girdle and upper limbs

Muscles of the shoulder and upper limb can be divided into four groups: muscles that stabilize and position the pectoral girdle, muscles that move the arm, muscles that move the forearm, and muscles that move the wrists, hands, and fingers. The pectoral girdle    , or shoulder girdle, consists of the lateral ends of the clavicle and scapula, along with the proximal end of the humerus, and the muscles covering these three bones to stabilize the shoulder joint. The girdle creates a base from which the head of the humerus, in its ball-and-socket joint with the glenoid fossa of the scapula, can move the arm in multiple directions.

Muscles that position the pectoral girdle

Muscles that position the pectoral girdle are located either on the anterior thorax or on the posterior thorax ( [link] and [link] ). The anterior muscles include the subclavius    , pectoralis minor    , and serratus anterior    . The posterior muscles include the trapezius    , rhomboid major    , and rhomboid minor    . When the rhomboids are contracted, your scapula moves medially, which can pull the shoulder and upper limb posteriorly.

Muscles that position the pectoral girdle

The left panel shows the anterior lateral view of the pectoral girdle muscle, and the right panel shows the posterior view of the pectoral girdle muscle.
The muscles that stabilize the pectoral girdle make it a steady base on which other muscles can move the arm. Note that the pectoralis major and deltoid, which move the humerus, are cut here to show the deeper positioning muscles.
Muscles that Position the Pectoral Girdle
Position in the thorax Movement Target Target motion direction Prime mover Origin Insertion
Anterior thorax Stabilizes clavicle during movement by depressing it Clavicle Depression Subclavius First rib Inferior surface of clavicle
Anterior thorax Rotates shoulder anteriorly (throwing motion); assists with inhalation Scapula; ribs Scapula: depresses; ribs: elevates Pectoralis minor Anterior surfaces of certain ribs (2–4 or 3–5) Coracoid process of scapula
Anterior thorax Moves arm from side of body to front of body; assists with inhalation Scapula; ribs Scapula: protracts; ribs: elevates Serratus anterior Muscle slips from certain ribs (1–8 or 1–9) Anterior surface of vertebral border of scapula
Posterior thorax Elevates shoulders (shrugging); pulls shoulder blades together; tilts head backwards Scapula; cervical spine Scapula: rotests inferiorly, retracts, elevates, and depresses; spine: extends Trapezius Skull; vertebral column Acromion and spine of scapula; clavicle
Posterior thorax Stabilizes scapula during pectoral girdle movement Scapula Retracts; rotates inferiorly Rhomboid major Thoracic vertebrae (T2–T5) Medial border of scapula
Posterior thorax Stabilizes scapula during pectoral girdle movement Scapula Retracts; rotates inferiorly Rhomboid minor Cervical and thoracic vertebrae (C7 and T1) Medial border of scapula

Muscles that move the humerus

Similar to the muscles that position the pectoral girdle, muscles that cross the shoulder joint and move the humerus bone of the arm include both axial and scapular muscles ( [link] and [link] ). The two axial muscles are the pectoralis major and the latissimus dorsi. The pectoralis major    is thick and fan-shaped, covering much of the superior portion of the anterior thorax. The broad, triangular latissimus dorsi    is located on the inferior part of the back, where it inserts into a thick connective tissue shealth called an aponeurosis.

Questions & Answers

why rbc is biconcave?
Sudhakar Reply
to carry oxygen easily
anwaar
What part of the brain controls the body temp
Ridwan
hypothalamus
JAYESH
what are epithelial tissues
Sachibu Reply
epithelial tissue that cover overall parts of the body and it's free from blood and nerves
Bhanu
Epithelial tissues are composed of cells laid out in sheets with strong cell-to-cell attachments.
Duah
Epithelial tissues perform a variety of functions that include; protection, secretion, filtration, diffusion, absorption, etc.
Duah
what control the flow of the blood ?
Donkor Reply
the pumping action of the heart
Holly
what is bony promises on the human body
Kelly Reply
what is the bony promises on human body
Kelly
what are bony prominences on human body
Kelly
support of the body
Bhanu
what are the characteristics of blood
yeboah Reply
they are red in colour
Tawoi
why blood is red in color?
Sudhakar
Me phone no petandi meku doubt vunte nenu phone chesi cheputhanu
Mohan Reply
What is respiratory disease
Rita Reply
emphysema
Sudhakar
What are the importance of homeostasis in human body?
Pablo Reply
homeostasis
Abena
it help to keep our salt and water balance
Husna
Homeostasis regulates and mentain internal equilibrium (ie temperature and pH) of the body.
Edmund
maintain temp and ph so our enzyme works properly
Husna
The inability of the body regulating and maintaining the temp. and pH results in disease affection.
Edmund
formation of the bone
Ali Reply
.
mohamed
عاوز ايه يعني من الفورمايشن
Doctor
notes on cell theory and discovery
Masika Reply
Cell theory are a set of rules for overall knowledge on cells. The most famous set of rules include: All cells arise from other cells. The cell is the functional unit of life. The structure (organelles) and morphology of the cell indicates it's main functions.
Carmelo
Antonie Van L. was the first to actually observe alive microorganisms (such as protist and bacteria) in a microscope in the 1600s.
Carmelo
electro phisiology meand
aparna Reply
rouleaux formation factors
Hridya Reply
can anyone suggest me how to learn forearm and hand topic of anatomy?
Anjali Reply
can anyone suggest me how to learn forearm and hand anatomy topic?
Anjali
can anyone suggest me how to learn forearm and hand topic of anatomy? pls pls tell
Anjali
check out youtube videos for trickss and while learning the boness part keep the bone wid u and learn ..... hope it helps u
Subuhi
ohk
Anjali
formation of the bone
Ali
what is the space between d dura mater and pia mater
Uwakwe Reply
Subdural space
Juveriya
Actually sub dural space is space between dura and arachnoid mater And sub arachnoid space is space between arachnoid and pia mater
Juveriya
the smallest bone in the body
Bahja Reply
stapes is the smallest bone in human Body
dipayan
Yeah
Ridwan
what is cell membrane
Hajara
cell membrane is like a protective cover of a cell and it's cytoplasm
dipayan
thanks
Hajara
list two adpitive mechanism that control homeostasis condition
Hajara
positive and negative feedback Mechanism
dipayan
@Dipayan, a cell membrane encloses and surrounds the cytoplasm of the cell. It's structure varies between species of life (eukaryotes, archaea, bacteria), but it is mostly composed of phospholipid, arachidonic acid, proteins, glycoproteins, glycolipids, and cholesterol.
Carmelo
and the glycoprotein and polysaccharides of the cell membrane forms the glycocalyx which has several functions especially in a bacteria.
Norom

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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