Skeletal/Muscular System
The skeleton of most snakes consists solely of the
skull, hyoid, vertebral column, and ribs, though henophidian snakes retain
vestiges of the pelvis and rear limbs.
The skull of the snake consists of a solid and
complete braincase, to which many of the other bones are only loosely attached,
particularly the highly mobile jaw bones, which facilitate manipulation and
ingestion of large prey items. The left and right sides of the lower jaw are
joined only by a flexible ligament at the anterior tips, allowing them to
separate widely, while the posterior end of the lower jaw bones articulate with
a quadrate bone, allowing further mobility. The bones of the mandible and
quadrate bones can also pick up ground borne vibrations.
Because the sides of the jaw can move independently of one another, snakes
resting their jaws on a surface have sensitive stereo hearing which can detect
the position of prey. The jaw-quadrate-stapes pathway is capable of detecting
vibrations on the angstrom scale, despite the absence of an outer
ear and the ossicle mechanism of impedance matching used in other vertebrates to
receive vibrations from the air.
The hyoid is a small bone located posterior and ventral to the skull, in the
'neck' region, which serves as an attachment for muscles of the snake's tongue,
as it does in all other tetrapods.
The vertebral column consists of anywhere between 200 to 400 (or more)
vertebrae. Tail vertebrae are comparatively few in number (often less than 20%
of the total) and lack ribs, while body vertebrae each have two ribs
articulating with them. The vertebrae have projections that allow for strong
muscle attachment enabling locomotion without limbs.
Autotomy of the tail, a feature found in some
lizards is absent in most snakes.[38]
Caudal autotomy in snakes is rare and is intervertebral, unlike that in lizards,
which is intravertebral—that is, the break happens along a predefined fracture
plane present on a vertebra.[39][40]
skull, hyoid, vertebral column, and ribs, though henophidian snakes retain
vestiges of the pelvis and rear limbs.
The skull of the snake consists of a solid and
complete braincase, to which many of the other bones are only loosely attached,
particularly the highly mobile jaw bones, which facilitate manipulation and
ingestion of large prey items. The left and right sides of the lower jaw are
joined only by a flexible ligament at the anterior tips, allowing them to
separate widely, while the posterior end of the lower jaw bones articulate with
a quadrate bone, allowing further mobility. The bones of the mandible and
quadrate bones can also pick up ground borne vibrations.
Because the sides of the jaw can move independently of one another, snakes
resting their jaws on a surface have sensitive stereo hearing which can detect
the position of prey. The jaw-quadrate-stapes pathway is capable of detecting
vibrations on the angstrom scale, despite the absence of an outer
ear and the ossicle mechanism of impedance matching used in other vertebrates to
receive vibrations from the air.
The hyoid is a small bone located posterior and ventral to the skull, in the
'neck' region, which serves as an attachment for muscles of the snake's tongue,
as it does in all other tetrapods.
The vertebral column consists of anywhere between 200 to 400 (or more)
vertebrae. Tail vertebrae are comparatively few in number (often less than 20%
of the total) and lack ribs, while body vertebrae each have two ribs
articulating with them. The vertebrae have projections that allow for strong
muscle attachment enabling locomotion without limbs.
Autotomy of the tail, a feature found in some
lizards is absent in most snakes.[38]
Caudal autotomy in snakes is rare and is intervertebral, unlike that in lizards,
which is intravertebral—that is, the break happens along a predefined fracture
plane present on a vertebra.[39][40]