Trunk or torso is an anatomical term for the central part of the many animal bodies (including that of the human) from which extend the neck and limbs. The trunk includes the thorax

Thorax

The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...

 and abdomen

Abdomen

In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...

.

Major organs

Most critical organs

Organ (anatomy)

In biology, an organ is a collection of tissues joined in structural unit to serve a common function. Usually there is a main tissue and sporadic tissues . The main tissue is the one that is unique for the specific organ. For example, main tissue in the heart is the myocardium, while sporadic are...

 are housed within the trunk. In the upper chest, the heart

Heart

The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

 and lungs are protected by the rib cage

Human rib cage

-See also:*Terms for bones*Terms for anatomical location*Articulation of head of rib-References:* Clinically Oriented Anatomy, 4th ed. Keith L. Moore and Robert F. Dalley. pp. 62–64...

, and the abdomen contains the majority of organs responsible for digestion

Digestion

Digestion is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance. Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones....

: the liver

Liver

The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...

, which respectively produces bile

Bile

Bile or gall is a bitter-tasting, dark green to yellowish brown fluid, produced by the liver of most vertebrates, that aids the process of digestion of lipids in the small intestine. In many species, bile is stored in the gallbladder and upon eating is discharged into the duodenum...

 necessary for digestion; the large

Large intestine

The large intestine is the third-to-last part of the digestive system — — in vertebrate animals. Its function is to absorb water from the remaining indigestible food matter, and then to pass useless waste material from the body...

 and small intestine

Small intestine

The small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to...

s, which extract nutrients from food; the anus

Anus

The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest,...

, from which fecal wastes

Human feces

Human feces , also known as a stool, is the waste product of the human digestive system including bacteria. It varies significantly in appearance, according to the state of the digestive system, diet and general health....

 are excreted; the rectum

Rectum

The rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...

, which stores feces

Feces

Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...

; the gallbladder

Gallbladder

In vertebrates the gallbladder is a small organ that aids mainly in fat digestion and concentrates bile produced by the liver. In humans the loss of the gallbladder is usually easily tolerated....

, which stores and concentrates bile and produces chyme

Chyme

Chyme is the semifluid mass of partly digested food expelled by the stomach into the duodenum.Also known as chymus, it is the liquid substance found in the stomach before passing through the pyloric valve and entering the duodenum...

; the ureter

Ureter

In human anatomy, the ureters are muscular tubes that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually long and ~3-4 mm in diameter....

s, which passes urine

Urine

Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...

 to the bladder; the bladder

Urinary bladder

The urinary bladder is the organ that collects urine excreted by the kidneys before disposal by urination. A hollow muscular, and distensible organ, the bladder sits on the pelvic floor...

, which stores urine; and the urethra

Urethra

In anatomy, the urethra is a tube that connects the urinary bladder to the genitals for the removal of fluids out of the body. In males, the urethra travels through the penis, and carries semen as well as urine...

, which excretes urine and passes sperm

Sperm

The term sperm is derived from the Greek word sperma and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell...

 through the seminal vesicle

Seminal vesicle

The seminal vesicles or vesicular glands are a pair of simple tubular glands posteroinferior to the urinary bladder of male mammals...

s. Finally, the pelvic region houses both the male and female reproductive organs.

Major muscle groups

The trunk also harbours many of the main groups of muscles in the body, including the:

• pectoral muscles
  Pectoral muscles
  Pectoral muscles can refer to:* Pectoralis major muscle* Pectoralis minor muscle...
  
  
• abdominal muscles
• lateral muscle

Innervation

The organs and muscles etc. are innervated by various nerves, mainly originating from thoracic vertebral segments. For instance, the cutaneous innervation

Cutaneous innervation

Cutaneous innervation refers to the area of the skin which is supplied by a specific cutaneous nerve.Dermatomes are similar; however, a dermatome only specifies the area served by a spinal nerve...

 is provided by:

• Ventral cutaneous branches
  Ventral cutaneous branches
  The ventral cutaneous branches are nerve branches that supply the skin of ventral part of torso. The rest of the torso is innervated by the lateral and dorsal cutaneous branches....
  
  
• Lateral cutaneous branches
• Dorsal cutaneous branches
  Dorsal cutaneous branches
  The dorsal cutaneous branches are nerve branches that supply the skin of dorsal part of torso. The rest of the torso is innervated by the lateral and ventral cutaneous branches....