The teres major muscle is a muscle of the

upper limb The upper Limb (anatomy), limbs or upper extremities are the forelimbs of an upright posture, upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digit (anatomy), digits, including all the musc ...

. It attaches to the

scapula The scapula (: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side ...

and the

humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

and is one of the seven scapulohumeral muscles. It is a thick but somewhat flattened muscle. The teres major muscle (from Latin ''teres'', meaning "rounded") is positioned above the

latissimus dorsi muscle The latissimus dorsi () is a large, flat muscle on the back that stretches to the sides, behind the arm, and is partly covered by the trapezius on the back near the midline. The word latissimus dorsi (plural: ''latissimi dorsi'') comes from ...

and assists in the extension and medial rotation of the

. This muscle is commonly confused as a

rotator cuff The rotator cuff (SITS muscles) is a group of muscles and their tendons that act to stabilize the human shoulder and allow for its extensive range of motion. Of the seven scapulohumeral muscles, four make up the rotator cuff. The four muscles a ...

muscle, but it is not, because it does not attach to the capsule of the

shoulder joint The shoulder joint (or glenohumeral joint from Greek ''glene'', eyeball, + -''oid'', 'form of', + Latin ''humerus'', shoulder) is structurally classified as a synovial joint, synovial ball-and-socket joint and functionally as a diarthrosis and m ...

, unlike the teres minor muscle, for example.

Structure

The teres major muscle originates on the dorsal surface of the inferior angle and the lower part of the

lateral border The scapula (: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side ...

of the

. The fibers of teres major insert into the medial lip of the intertubercular sulcus of the

Relations

The

tendon A tendon or sinew is a tough band of fibrous connective tissue, dense fibrous connective tissue that connects skeletal muscle, muscle to bone. It sends the mechanical forces of muscle contraction to the skeletal system, while withstanding tensi ...

, at its insertion, lies behind that of the

latissimus dorsi The latissimus dorsi () is a large, flat muscle on the back that stretches to the sides, behind the arm, and is partly covered by the trapezius on the back near the midline. The word latissimus dorsi (plural: ''latissimi dorsi'') comes from L ...

, from which it is separated by a

bursa Bursa () is a city in northwestern Turkey and the administrative center of Bursa Province. The fourth-most populous city in Turkey and second-most populous in the Marmara Region, Bursa is one of the industrial centers of the country. Most of ...

, the two tendons being, however, united along their lower borders for a short distance. The fibers of these two muscles run parallel to each other, and both muscles insert at the crest of the

lesser tubercle The lesser tubercle of the humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of thre ...

of the humerus (also described as the medial lip of the intertubercular sulcus). Together with teres minor muscle, teres major muscle forms the axillary space, through which several important arteries and veins pass.

Innervation

Teres major is supplied primarily by the lower subscapular nerve and additionally by the thoracodorsal nerve (middle subscapular nerve). These are distal to the upper subscapular nerve. These three nerves branch off the posterior cord of the

brachial plexus The brachial plexus is a network of nerves (nerve plexus) formed by the anterior rami of the lower four Spinal nerve#Cervical nerves, cervical nerves and first Spinal nerve#Thoracic nerves, thoracic nerve (cervical spinal nerve 5, C5, Cervical spi ...

. The nerves that innervate teres major consist of fibers from spinal nerves C5- C8.

Function

The teres major is a medial rotator and adductor of the humerus and assists the

in drawing the previously raised humerus downwards and backwards ( extension, but not hyperextension). It also helps stabilise the humeral head in the

glenoid cavity The glenoid fossa of the scapula or the glenoid cavity is a bone part of the shoulder. The word ''glenoid'' is pronounced or (both are common) and is from , "socket", reflecting the shoulder joint's ball-and-socket form. It is a shallow, pyri ...

Injury

Isolated teres major injuries are rare. They are almost exclusively encountered in professional and high-level recreational

athletes An athlete is most commonly a person who competes in one or more sports involving physical strength, speed, power, or endurance. Sometimes, the word "athlete" is used to refer specifically to sport of athletics competitors, i.e. including trac ...

— baseball pitchers in particular. These injuries can be debilitating, requiring lengthy rehabilitation periods and missed seasons of athletics. No clear indications for surgical treatment exist. Outcomes have been generally good after both nonoperative and operative treatment.

Additional images

File:Teres major muscle animation.gif, Position of teres major muscle (shown in red). Animation. Image:Arm muscles back numbers.png , Muscles on the dorsum of the

, and the Triceps brachii muscle:
#3

#5 teres major muscle
#6 teres minor muscle
#7 supraspinatus muscle
#8 infraspinatus muscle
#13 long head of triceps brachii muscle Image:Gray1211.png , Surface anatomy of the back. (Label for Teres major at upper right.) Image:Gray207.png, Left humerus. Anterior view. File:Teres major muscle.JPG, Teres major muscle Image:Gray203.png, Left scapula. Posterior surface. File:Slide2aaaa.JPG, Teres major muscle

References

External links

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PTCentral
{{Authority control Muscles of the upper limb Shoulder adductors Shoulder extensors Shoulder medial rotators